1 /* 2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "classfile/vmSymbols.hpp" 28 #include "gc/shared/gcLocker.hpp" 29 #include "memory/resourceArea.hpp" 30 #include "memory/universe.inline.hpp" 31 #include "oops/instanceKlass.hpp" 32 #include "oops/klassVtable.hpp" 33 #include "oops/method.hpp" 34 #include "oops/objArrayOop.hpp" 35 #include "oops/oop.inline.hpp" 36 #include "prims/jvmtiRedefineClassesTrace.hpp" 37 #include "runtime/arguments.hpp" 38 #include "runtime/handles.inline.hpp" 39 #include "utilities/copy.hpp" 40 41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 42 43 inline InstanceKlass* klassVtable::ik() const { 44 Klass* k = _klass(); 45 assert(k->oop_is_instance(), "not an InstanceKlass"); 46 return (InstanceKlass*)k; 47 } 48 49 50 // this function computes the vtable size (including the size needed for miranda 51 // methods) and the number of miranda methods in this class. 52 // Note on Miranda methods: Let's say there is a class C that implements 53 // interface I, and none of C's superclasses implements I. 54 // Let's say there is an abstract method m in I that neither C 55 // nor any of its super classes implement (i.e there is no method of any access, 56 // with the same name and signature as m), then m is a Miranda method which is 57 // entered as a public abstract method in C's vtable. From then on it should 58 // treated as any other public method in C for method over-ride purposes. 59 void klassVtable::compute_vtable_size_and_num_mirandas( 60 int* vtable_length_ret, int* num_new_mirandas, 61 GrowableArray<Method*>* all_mirandas, Klass* super, 62 Array<Method*>* methods, AccessFlags class_flags, 63 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 64 TRAPS) { 65 No_Safepoint_Verifier nsv; 66 67 // set up default result values 68 int vtable_length = 0; 69 70 // start off with super's vtable length 71 InstanceKlass* sk = (InstanceKlass*)super; 72 vtable_length = super == NULL ? 0 : sk->vtable_length(); 73 74 // go thru each method in the methods table to see if it needs a new entry 75 int len = methods->length(); 76 for (int i = 0; i < len; i++) { 77 assert(methods->at(i)->is_method(), "must be a Method*"); 78 methodHandle mh(THREAD, methods->at(i)); 79 80 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { 81 vtable_length += vtableEntry::size(); // we need a new entry 82 } 83 } 84 85 GrowableArray<Method*> new_mirandas(20); 86 // compute the number of mirandas methods that must be added to the end 87 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces); 88 *num_new_mirandas = new_mirandas.length(); 89 90 // Interfaces do not need interface methods in their vtables 91 // This includes miranda methods and during later processing, default methods 92 if (!class_flags.is_interface()) { 93 vtable_length += *num_new_mirandas * vtableEntry::size(); 94 } 95 96 if (Universe::is_bootstrapping() && vtable_length == 0) { 97 // array classes don't have their superclass set correctly during 98 // bootstrapping 99 vtable_length = Universe::base_vtable_size(); 100 } 101 102 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 103 if (Universe::is_bootstrapping()) { 104 // Someone is attempting to override java.lang.Object incorrectly on the 105 // bootclasspath. The JVM cannot recover from this error including throwing 106 // an exception 107 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 108 } else { 109 // Someone is attempting to redefine java.lang.Object incorrectly. The 110 // only way this should happen is from 111 // SystemDictionary::resolve_from_stream(), which will detect this later 112 // and throw a security exception. So don't assert here to let 113 // the exception occur. 114 vtable_length = Universe::base_vtable_size(); 115 } 116 } 117 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 118 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 119 120 *vtable_length_ret = vtable_length; 121 } 122 123 int klassVtable::index_of(Method* m, int len) const { 124 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 125 return m->vtable_index(); 126 } 127 128 // Copy super class's vtable to the first part (prefix) of this class's vtable, 129 // and return the number of entries copied. Expects that 'super' is the Java 130 // super class (arrays can have "array" super classes that must be skipped). 131 int klassVtable::initialize_from_super(KlassHandle super) { 132 if (super.is_null()) { 133 return 0; 134 } else { 135 // copy methods from superKlass 136 // can't inherit from array class, so must be InstanceKlass 137 assert(super->oop_is_instance(), "must be instance klass"); 138 InstanceKlass* sk = (InstanceKlass*)super(); 139 klassVtable* superVtable = sk->vtable(); 140 assert(superVtable->length() <= _length, "vtable too short"); 141 #ifdef ASSERT 142 superVtable->verify(tty, true); 143 #endif 144 superVtable->copy_vtable_to(table()); 145 #ifndef PRODUCT 146 if (PrintVtables && Verbose) { 147 ResourceMark rm; 148 tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length); 149 } 150 #endif 151 return superVtable->length(); 152 } 153 } 154 155 // 156 // Revised lookup semantics introduced 1.3 (Kestrel beta) 157 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 158 159 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 160 KlassHandle super (THREAD, klass()->java_super()); 161 int nofNewEntries = 0; 162 163 if (PrintVtables && !klass()->oop_is_array()) { 164 ResourceMark rm(THREAD); 165 tty->print_cr("Initializing: %s", _klass->name()->as_C_string()); 166 } 167 168 #ifdef ASSERT 169 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 170 oop* end_of_vtable = (oop*)&table()[_length]; 171 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 172 #endif 173 174 if (Universe::is_bootstrapping()) { 175 // just clear everything 176 for (int i = 0; i < _length; i++) table()[i].clear(); 177 return; 178 } 179 180 int super_vtable_len = initialize_from_super(super); 181 if (klass()->oop_is_array()) { 182 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 183 } else { 184 assert(_klass->oop_is_instance(), "must be InstanceKlass"); 185 186 Array<Method*>* methods = ik()->methods(); 187 int len = methods->length(); 188 int initialized = super_vtable_len; 189 190 // Check each of this class's methods against super; 191 // if override, replace in copy of super vtable, otherwise append to end 192 for (int i = 0; i < len; i++) { 193 // update_inherited_vtable can stop for gc - ensure using handles 194 HandleMark hm(THREAD); 195 assert(methods->at(i)->is_method(), "must be a Method*"); 196 methodHandle mh(THREAD, methods->at(i)); 197 198 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 199 200 if (needs_new_entry) { 201 put_method_at(mh(), initialized); 202 mh()->set_vtable_index(initialized); // set primary vtable index 203 initialized++; 204 } 205 } 206 207 // update vtable with default_methods 208 Array<Method*>* default_methods = ik()->default_methods(); 209 if (default_methods != NULL) { 210 len = default_methods->length(); 211 if (len > 0) { 212 Array<int>* def_vtable_indices = NULL; 213 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 214 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 215 } else { 216 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 217 } 218 for (int i = 0; i < len; i++) { 219 HandleMark hm(THREAD); 220 assert(default_methods->at(i)->is_method(), "must be a Method*"); 221 methodHandle mh(THREAD, default_methods->at(i)); 222 223 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 224 225 // needs new entry 226 if (needs_new_entry) { 227 put_method_at(mh(), initialized); 228 def_vtable_indices->at_put(i, initialized); //set vtable index 229 initialized++; 230 } 231 } 232 } 233 } 234 235 // add miranda methods; it will also return the updated initialized 236 // Interfaces do not need interface methods in their vtables 237 // This includes miranda methods and during later processing, default methods 238 if (!ik()->is_interface()) { 239 initialized = fill_in_mirandas(initialized); 240 } 241 242 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 243 // package_private -> public/protected), the vtable might actually be smaller than our initial 244 // calculation. 245 assert(initialized <= _length, "vtable initialization failed"); 246 for(;initialized < _length; initialized++) { 247 put_method_at(NULL, initialized); 248 } 249 NOT_PRODUCT(verify(tty, true)); 250 } 251 } 252 253 // Called for cases where a method does not override its superclass' vtable entry 254 // For bytecodes not produced by javac together it is possible that a method does not override 255 // the superclass's method, but might indirectly override a super-super class's vtable entry 256 // If none found, return a null superk, else return the superk of the method this does override 257 // For public and protected methods: if they override a superclass, they will 258 // also be overridden themselves appropriately. 259 // Private methods do not override and are not overridden. 260 // Package Private methods are trickier: 261 // e.g. P1.A, pub m 262 // P2.B extends A, package private m 263 // P1.C extends B, public m 264 // P1.C.m needs to override P1.A.m and can not override P2.B.m 265 // Therefore: all package private methods need their own vtable entries for 266 // them to be the root of an inheritance overriding decision 267 // Package private methods may also override other vtable entries 268 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, 269 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 270 InstanceKlass* superk = initialsuper; 271 while (superk != NULL && superk->super() != NULL) { 272 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 273 klassVtable* ssVtable = supersuperklass->vtable(); 274 if (vtable_index < ssVtable->length()) { 275 Method* super_method = ssVtable->method_at(vtable_index); 276 #ifndef PRODUCT 277 Symbol* name= target_method()->name(); 278 Symbol* signature = target_method()->signature(); 279 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 280 #endif 281 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 282 #ifndef PRODUCT 283 if (PrintVtables && Verbose) { 284 ResourceMark rm(THREAD); 285 char* sig = target_method()->name_and_sig_as_C_string(); 286 tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ", 287 supersuperklass->internal_name(), 288 _klass->internal_name(), sig, vtable_index); 289 super_method->access_flags().print_on(tty); 290 if (super_method->is_default_method()) { 291 tty->print("default "); 292 } 293 tty->print("overriders flags: "); 294 target_method->access_flags().print_on(tty); 295 if (target_method->is_default_method()) { 296 tty->print("default "); 297 } 298 } 299 #endif /*PRODUCT*/ 300 break; // return found superk 301 } 302 } else { 303 // super class has no vtable entry here, stop transitive search 304 superk = (InstanceKlass*)NULL; 305 break; 306 } 307 // if no override found yet, continue to search up 308 superk = InstanceKlass::cast(superk->super()); 309 } 310 311 return superk; 312 } 313 314 // Update child's copy of super vtable for overrides 315 // OR return true if a new vtable entry is required. 316 // Only called for InstanceKlass's, i.e. not for arrays 317 // If that changed, could not use _klass as handle for klass 318 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, 319 int super_vtable_len, int default_index, 320 bool checkconstraints, TRAPS) { 321 ResourceMark rm; 322 bool allocate_new = true; 323 assert(klass->oop_is_instance(), "must be InstanceKlass"); 324 325 Array<int>* def_vtable_indices = NULL; 326 bool is_default = false; 327 // default methods are concrete methods in superinterfaces which are added to the vtable 328 // with their real method_holder 329 // Since vtable and itable indices share the same storage, don't touch 330 // the default method's real vtable/itable index 331 // default_vtable_indices stores the vtable value relative to this inheritor 332 if (default_index >= 0 ) { 333 is_default = true; 334 def_vtable_indices = klass->default_vtable_indices(); 335 assert(def_vtable_indices != NULL, "def vtable alloc?"); 336 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 337 } else { 338 assert(klass == target_method()->method_holder(), "caller resp."); 339 // Initialize the method's vtable index to "nonvirtual". 340 // If we allocate a vtable entry, we will update it to a non-negative number. 341 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 342 } 343 344 // Static and <init> methods are never in 345 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 346 return false; 347 } 348 349 if (target_method->is_final_method(klass->access_flags())) { 350 // a final method never needs a new entry; final methods can be statically 351 // resolved and they have to be present in the vtable only if they override 352 // a super's method, in which case they re-use its entry 353 allocate_new = false; 354 } else if (klass->is_interface()) { 355 allocate_new = false; // see note below in needs_new_vtable_entry 356 // An interface never allocates new vtable slots, only inherits old ones. 357 // This method will either be assigned its own itable index later, 358 // or be assigned an inherited vtable index in the loop below. 359 // default methods inherited by classes store their vtable indices 360 // in the inheritor's default_vtable_indices 361 // default methods inherited by interfaces may already have a 362 // valid itable index, if so, don't change it 363 // overpass methods in an interface will be assigned an itable index later 364 // by an inheriting class 365 if (!is_default || !target_method()->has_itable_index()) { 366 target_method()->set_vtable_index(Method::pending_itable_index); 367 } 368 } 369 370 // we need a new entry if there is no superclass 371 if (klass->super() == NULL) { 372 return allocate_new; 373 } 374 375 // private methods in classes always have a new entry in the vtable 376 // specification interpretation since classic has 377 // private methods not overriding 378 // JDK8 adds private methods in interfaces which require invokespecial 379 if (target_method()->is_private()) { 380 return allocate_new; 381 } 382 383 // search through the vtable and update overridden entries 384 // Since check_signature_loaders acquires SystemDictionary_lock 385 // which can block for gc, once we are in this loop, use handles 386 // For classfiles built with >= jdk7, we now look for transitive overrides 387 388 Symbol* name = target_method()->name(); 389 Symbol* signature = target_method()->signature(); 390 391 KlassHandle target_klass(THREAD, target_method()->method_holder()); 392 if (target_klass == NULL) { 393 target_klass = _klass; 394 } 395 396 Handle target_loader(THREAD, target_klass->class_loader()); 397 398 Symbol* target_classname = target_klass->name(); 399 for(int i = 0; i < super_vtable_len; i++) { 400 Method* super_method = method_at(i); 401 // Check if method name matches 402 if (super_method->name() == name && super_method->signature() == signature) { 403 404 // get super_klass for method_holder for the found method 405 InstanceKlass* super_klass = super_method->method_holder(); 406 407 // private methods are also never overridden 408 if (!super_method->is_private() && 409 (is_default 410 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 411 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 412 && ((super_klass = find_transitive_override(super_klass, 413 target_method, i, target_loader, 414 target_classname, THREAD)) 415 != (InstanceKlass*)NULL))))) 416 { 417 // Package private methods always need a new entry to root their own 418 // overriding. They may also override other methods. 419 if (!target_method()->is_package_private()) { 420 allocate_new = false; 421 } 422 423 if (checkconstraints) { 424 // Override vtable entry if passes loader constraint check 425 // if loader constraint checking requested 426 // No need to visit his super, since he and his super 427 // have already made any needed loader constraints. 428 // Since loader constraints are transitive, it is enough 429 // to link to the first super, and we get all the others. 430 Handle super_loader(THREAD, super_klass->class_loader()); 431 432 if (target_loader() != super_loader()) { 433 ResourceMark rm(THREAD); 434 Symbol* failed_type_symbol = 435 SystemDictionary::check_signature_loaders(signature, target_loader, 436 super_loader, true, 437 CHECK_(false)); 438 if (failed_type_symbol != NULL) { 439 const char* msg = "loader constraint violation: when resolving " 440 "overridden method \"%s\" the class loader (instance" 441 " of %s) of the current class, %s, and its superclass loader " 442 "(instance of %s), have different Class objects for the type " 443 "%s used in the signature"; 444 char* sig = target_method()->name_and_sig_as_C_string(); 445 const char* loader1 = SystemDictionary::loader_name(target_loader()); 446 char* current = target_klass->name()->as_C_string(); 447 const char* loader2 = SystemDictionary::loader_name(super_loader()); 448 char* failed_type_name = failed_type_symbol->as_C_string(); 449 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 450 strlen(current) + strlen(loader2) + strlen(failed_type_name); 451 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 452 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 453 failed_type_name); 454 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 455 } 456 } 457 } 458 459 put_method_at(target_method(), i); 460 if (!is_default) { 461 target_method()->set_vtable_index(i); 462 } else { 463 if (def_vtable_indices != NULL) { 464 def_vtable_indices->at_put(default_index, i); 465 } 466 assert(super_method->is_default_method() || super_method->is_overpass() 467 || super_method->is_abstract(), "default override error"); 468 } 469 470 471 #ifndef PRODUCT 472 if (PrintVtables && Verbose) { 473 ResourceMark rm(THREAD); 474 char* sig = target_method()->name_and_sig_as_C_string(); 475 tty->print("overriding with %s::%s index %d, original flags: ", 476 target_klass->internal_name(), sig, i); 477 super_method->access_flags().print_on(tty); 478 if (super_method->is_default_method()) { 479 tty->print("default "); 480 } 481 if (super_method->is_overpass()) { 482 tty->print("overpass"); 483 } 484 tty->print("overriders flags: "); 485 target_method->access_flags().print_on(tty); 486 if (target_method->is_default_method()) { 487 tty->print("default "); 488 } 489 if (target_method->is_overpass()) { 490 tty->print("overpass"); 491 } 492 tty->cr(); 493 } 494 #endif /*PRODUCT*/ 495 } else { 496 // allocate_new = true; default. We might override one entry, 497 // but not override another. Once we override one, not need new 498 #ifndef PRODUCT 499 if (PrintVtables && Verbose) { 500 ResourceMark rm(THREAD); 501 char* sig = target_method()->name_and_sig_as_C_string(); 502 tty->print("NOT overriding with %s::%s index %d, original flags: ", 503 target_klass->internal_name(), sig,i); 504 super_method->access_flags().print_on(tty); 505 if (super_method->is_default_method()) { 506 tty->print("default "); 507 } 508 if (super_method->is_overpass()) { 509 tty->print("overpass"); 510 } 511 tty->print("overriders flags: "); 512 target_method->access_flags().print_on(tty); 513 if (target_method->is_default_method()) { 514 tty->print("default "); 515 } 516 if (target_method->is_overpass()) { 517 tty->print("overpass"); 518 } 519 tty->cr(); 520 } 521 #endif /*PRODUCT*/ 522 } 523 } 524 } 525 return allocate_new; 526 } 527 528 void klassVtable::put_method_at(Method* m, int index) { 529 #ifndef PRODUCT 530 if (PrintVtables && Verbose) { 531 ResourceMark rm; 532 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 533 tty->print("adding %s at index %d, flags: ", sig, index); 534 if (m != NULL) { 535 m->access_flags().print_on(tty); 536 if (m->is_default_method()) { 537 tty->print("default "); 538 } 539 if (m->is_overpass()) { 540 tty->print("overpass"); 541 } 542 } 543 tty->cr(); 544 } 545 #endif 546 table()[index].set(m); 547 } 548 549 // Find out if a method "m" with superclass "super", loader "classloader" and 550 // name "classname" needs a new vtable entry. Let P be a class package defined 551 // by "classloader" and "classname". 552 // NOTE: The logic used here is very similar to the one used for computing 553 // the vtables indices for a method. We cannot directly use that function because, 554 // we allocate the InstanceKlass at load time, and that requires that the 555 // superclass has been loaded. 556 // However, the vtable entries are filled in at link time, and therefore 557 // the superclass' vtable may not yet have been filled in. 558 bool klassVtable::needs_new_vtable_entry(methodHandle target_method, 559 Klass* super, 560 Handle classloader, 561 Symbol* classname, 562 AccessFlags class_flags, 563 TRAPS) { 564 if (class_flags.is_interface()) { 565 // Interfaces do not use vtables, except for java.lang.Object methods, 566 // so there is no point to assigning 567 // a vtable index to any of their local methods. If we refrain from doing this, 568 // we can use Method::_vtable_index to hold the itable index 569 return false; 570 } 571 572 if (target_method->is_final_method(class_flags) || 573 // a final method never needs a new entry; final methods can be statically 574 // resolved and they have to be present in the vtable only if they override 575 // a super's method, in which case they re-use its entry 576 (target_method()->is_static()) || 577 // static methods don't need to be in vtable 578 (target_method()->name() == vmSymbols::object_initializer_name()) 579 // <init> is never called dynamically-bound 580 ) { 581 return false; 582 } 583 584 // Concrete interface methods do not need new entries, they override 585 // abstract method entries using default inheritance rules 586 if (target_method()->method_holder() != NULL && 587 target_method()->method_holder()->is_interface() && 588 !target_method()->is_abstract() ) { 589 return false; 590 } 591 592 // we need a new entry if there is no superclass 593 if (super == NULL) { 594 return true; 595 } 596 597 // private methods in classes always have a new entry in the vtable 598 // specification interpretation since classic has 599 // private methods not overriding 600 // JDK8 adds private methods in interfaces which require invokespecial 601 if (target_method()->is_private()) { 602 return true; 603 } 604 605 // Package private methods always need a new entry to root their own 606 // overriding. This allows transitive overriding to work. 607 if (target_method()->is_package_private()) { 608 return true; 609 } 610 611 // search through the super class hierarchy to see if we need 612 // a new entry 613 ResourceMark rm; 614 Symbol* name = target_method()->name(); 615 Symbol* signature = target_method()->signature(); 616 Klass* k = super; 617 Method* super_method = NULL; 618 InstanceKlass *holder = NULL; 619 Method* recheck_method = NULL; 620 while (k != NULL) { 621 // lookup through the hierarchy for a method with matching name and sign. 622 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 623 if (super_method == NULL) { 624 break; // we still have to search for a matching miranda method 625 } 626 // get the class holding the matching method 627 // make sure you use that class for is_override 628 InstanceKlass* superk = super_method->method_holder(); 629 // we want only instance method matches 630 // pretend private methods are not in the super vtable 631 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 632 // ignore private, c.m pub does override a.m pub 633 // For classes that were not javac'd together, we also do transitive overriding around 634 // methods that have less accessibility 635 if ((!super_method->is_static()) && 636 (!super_method->is_private())) { 637 if (superk->is_override(super_method, classloader, classname, THREAD)) { 638 return false; 639 // else keep looking for transitive overrides 640 } 641 } 642 643 // Start with lookup result and continue to search up 644 k = superk->super(); // haven't found an override match yet; continue to look 645 } 646 647 // if the target method is public or protected it may have a matching 648 // miranda method in the super, whose entry it should re-use. 649 // Actually, to handle cases that javac would not generate, we need 650 // this check for all access permissions. 651 InstanceKlass *sk = InstanceKlass::cast(super); 652 if (sk->has_miranda_methods()) { 653 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 654 return false; // found a matching miranda; we do not need a new entry 655 } 656 } 657 return true; // found no match; we need a new entry 658 } 659 660 // Support for miranda methods 661 662 // get the vtable index of a miranda method with matching "name" and "signature" 663 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 664 // search from the bottom, might be faster 665 for (int i = (length() - 1); i >= 0; i--) { 666 Method* m = table()[i].method(); 667 if (is_miranda_entry_at(i) && 668 m->name() == name && m->signature() == signature) { 669 return i; 670 } 671 } 672 return Method::invalid_vtable_index; 673 } 674 675 // check if an entry at an index is miranda 676 // requires that method m at entry be declared ("held") by an interface. 677 bool klassVtable::is_miranda_entry_at(int i) { 678 Method* m = method_at(i); 679 Klass* method_holder = m->method_holder(); 680 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 681 682 // miranda methods are public abstract instance interface methods in a class's vtable 683 if (mhk->is_interface()) { 684 assert(m->is_public(), "should be public"); 685 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 686 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 687 return true; 688 } 689 } 690 return false; 691 } 692 693 // Check if a method is a miranda method, given a class's methods table, 694 // its default_method table and its super class. 695 // "Miranda" means an abstract non-private method that would not be 696 // overridden. A "miranda" method should only include non-private interface 697 // instance methods, not private methods, not static methods, 698 // not default methods (concrete interface methods), not overpass methods. 699 // If a given class already has a local (including overpass) method, a 700 // default method, or any of its superclasses has the same which would have 701 // overridden an abstract method, then this is not a miranda method. 702 // 703 // Miranda methods are checked multiple times. 704 // Pass 1: during class load/class file parsing: before vtable size calculation: 705 // include superinterface abstract and default methods (non-private instance). 706 // We include potential default methods to give them space in the vtable. 707 // During the first run, the current instanceKlass has not yet been 708 // created, the superclasses and superinterfaces do have instanceKlasses 709 // but may not have vtables, the default_methods list is empty, no overpasses. 710 // This is seen by default method creation. 711 // 712 // Pass 2: recalculated during vtable initialization: only include abstract methods. 713 // During the second run, default_methods is set up, so concrete methods from 714 // superinterfaces with matching names/signatures to default_methods are already 715 // in the default_methods list and do not need to be appended to the vtable 716 // as mirandas. Abstract methods may already have been handled via 717 // overpasses - either local or superclass overpasses, which may be 718 // in the vtable already. 719 // 720 // Pass 3: They are also checked by link resolution and selection, 721 // for invocation on a method (not interface method) reference that 722 // resolves to a method with an interface as its method_holder. 723 // Used as part of walking from the bottom of the vtable to find 724 // the vtable index for the miranda method. 725 // 726 // Part of the Miranda Rights in the US mean that if you do not have 727 // an attorney one will be appointed to you. 728 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 729 Array<Method*>* default_methods, Klass* super) { 730 if (m->is_static() || m->is_private() || m->is_overpass()) { 731 return false; 732 } 733 Symbol* name = m->name(); 734 Symbol* signature = m->signature(); 735 736 // First look in local methods to see if already covered 737 if (InstanceKlass::find_local_method(class_methods, name, signature, 738 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 739 { 740 return false; 741 } 742 743 // Check local default methods 744 if ((default_methods != NULL) && 745 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 746 { 747 return false; 748 } 749 750 InstanceKlass* cursuper; 751 // Iterate on all superclasses, which should have instanceKlasses 752 // Note that we explicitly look for overpasses at each level. 753 // Overpasses may or may not exist supers for pass 1, 754 // they should have been created for pass 2 and later. 755 756 for (cursuper = InstanceKlass::cast(super); cursuper != NULL; cursuper = (InstanceKlass*)cursuper->super()) 757 { 758 if (cursuper->find_local_method(name, signature, 759 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) { 760 return false; 761 } 762 } 763 764 return true; 765 } 766 767 // Scans current_interface_methods for miranda methods that do not 768 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 769 // in super (superclass). These mirandas are added to all_mirandas if it is 770 // not null; in addition, those that are not duplicates of miranda methods 771 // inherited by super from its interfaces are added to new_mirandas. 772 // Thus, new_mirandas will be the set of mirandas that this class introduces, 773 // all_mirandas will be the set of all mirandas applicable to this class 774 // including all defined in superclasses. 775 void klassVtable::add_new_mirandas_to_lists( 776 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 777 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 778 Array<Method*>* default_methods, Klass* super) { 779 780 // iterate thru the current interface's method to see if it a miranda 781 int num_methods = current_interface_methods->length(); 782 for (int i = 0; i < num_methods; i++) { 783 Method* im = current_interface_methods->at(i); 784 bool is_duplicate = false; 785 int num_of_current_mirandas = new_mirandas->length(); 786 // check for duplicate mirandas in different interfaces we implement 787 for (int j = 0; j < num_of_current_mirandas; j++) { 788 Method* miranda = new_mirandas->at(j); 789 if ((im->name() == miranda->name()) && 790 (im->signature() == miranda->signature())) { 791 is_duplicate = true; 792 break; 793 } 794 } 795 796 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 797 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 798 InstanceKlass *sk = InstanceKlass::cast(super); 799 // check if it is a duplicate of a super's miranda 800 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 801 new_mirandas->append(im); 802 } 803 if (all_mirandas != NULL) { 804 all_mirandas->append(im); 805 } 806 } 807 } 808 } 809 } 810 811 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 812 GrowableArray<Method*>* all_mirandas, 813 Klass* super, Array<Method*>* class_methods, 814 Array<Method*>* default_methods, 815 Array<Klass*>* local_interfaces) { 816 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 817 818 // iterate thru the local interfaces looking for a miranda 819 int num_local_ifs = local_interfaces->length(); 820 for (int i = 0; i < num_local_ifs; i++) { 821 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 822 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 823 ik->methods(), class_methods, 824 default_methods, super); 825 // iterate thru each local's super interfaces 826 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 827 int num_super_ifs = super_ifs->length(); 828 for (int j = 0; j < num_super_ifs; j++) { 829 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 830 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 831 sik->methods(), class_methods, 832 default_methods, super); 833 } 834 } 835 } 836 837 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 838 // and append them into the vtable starting at index initialized, 839 // return the new value of initialized. 840 // Miranda methods use vtable entries, but do not get assigned a vtable_index 841 // The vtable_index is discovered by searching from the end of the vtable 842 int klassVtable::fill_in_mirandas(int initialized) { 843 GrowableArray<Method*> mirandas(20); 844 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 845 ik()->default_methods(), ik()->local_interfaces()); 846 for (int i = 0; i < mirandas.length(); i++) { 847 if (PrintVtables && Verbose) { 848 Method* meth = mirandas.at(i); 849 ResourceMark rm(Thread::current()); 850 if (meth != NULL) { 851 char* sig = meth->name_and_sig_as_C_string(); 852 tty->print("fill in mirandas with %s index %d, flags: ", 853 sig, initialized); 854 meth->access_flags().print_on(tty); 855 if (meth->is_default_method()) { 856 tty->print("default "); 857 } 858 tty->cr(); 859 } 860 } 861 put_method_at(mirandas.at(i), initialized); 862 ++initialized; 863 } 864 return initialized; 865 } 866 867 // Copy this class's vtable to the vtable beginning at start. 868 // Used to copy superclass vtable to prefix of subclass's vtable. 869 void klassVtable::copy_vtable_to(vtableEntry* start) { 870 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 871 } 872 873 #if INCLUDE_JVMTI 874 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 875 // If old_method is default, find this vtable index in default_vtable_indices 876 // and replace that method in the _default_methods list 877 bool updated = false; 878 879 Array<Method*>* default_methods = ik()->default_methods(); 880 if (default_methods != NULL) { 881 int len = default_methods->length(); 882 for (int idx = 0; idx < len; idx++) { 883 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 884 if (default_methods->at(idx) == old_method) { 885 default_methods->at_put(idx, new_method); 886 updated = true; 887 } 888 break; 889 } 890 } 891 } 892 return updated; 893 } 894 895 // search the vtable for uses of either obsolete or EMCP methods 896 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 897 int prn_enabled = 0; 898 for (int index = 0; index < length(); index++) { 899 Method* old_method = unchecked_method_at(index); 900 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 901 continue; // skip uninteresting entries 902 } 903 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 904 905 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 906 907 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 908 assert(old_method != new_method, "sanity check"); 909 910 put_method_at(new_method, index); 911 // For default methods, need to update the _default_methods array 912 // which can only have one method entry for a given signature 913 bool updated_default = false; 914 if (old_method->is_default_method()) { 915 updated_default = adjust_default_method(index, old_method, new_method); 916 } 917 918 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 919 if (!(*trace_name_printed)) { 920 // RC_TRACE_MESG macro has an embedded ResourceMark 921 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s", 922 klass()->external_name(), 923 old_method->method_holder()->external_name())); 924 *trace_name_printed = true; 925 } 926 // RC_TRACE macro has an embedded ResourceMark 927 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s", 928 new_method->name()->as_C_string(), 929 new_method->signature()->as_C_string(), 930 updated_default ? "true" : "false")); 931 } 932 } 933 } 934 935 // a vtable should never contain old or obsolete methods 936 bool klassVtable::check_no_old_or_obsolete_entries() { 937 for (int i = 0; i < length(); i++) { 938 Method* m = unchecked_method_at(i); 939 if (m != NULL && 940 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 941 return false; 942 } 943 } 944 return true; 945 } 946 947 void klassVtable::dump_vtable() { 948 tty->print_cr("vtable dump --"); 949 for (int i = 0; i < length(); i++) { 950 Method* m = unchecked_method_at(i); 951 if (m != NULL) { 952 tty->print(" (%5d) ", i); 953 m->access_flags().print_on(tty); 954 if (m->is_default_method()) { 955 tty->print("default "); 956 } 957 if (m->is_overpass()) { 958 tty->print("overpass"); 959 } 960 tty->print(" -- "); 961 m->print_name(tty); 962 tty->cr(); 963 } 964 } 965 } 966 #endif // INCLUDE_JVMTI 967 968 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 969 void klassVtable::clear_vtable() { 970 for (int i = 0; i < _length; i++) table()[i].clear(); 971 } 972 973 bool klassVtable::is_initialized() { 974 return _length == 0 || table()[0].method() != NULL; 975 } 976 977 //----------------------------------------------------------------------------------------- 978 // Itable code 979 980 // Initialize a itableMethodEntry 981 void itableMethodEntry::initialize(Method* m) { 982 if (m == NULL) return; 983 984 _method = m; 985 } 986 987 klassItable::klassItable(instanceKlassHandle klass) { 988 _klass = klass; 989 990 if (klass->itable_length() > 0) { 991 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 992 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 993 // First offset entry points to the first method_entry 994 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); 995 intptr_t* end = klass->end_of_itable(); 996 997 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); 998 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 999 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1000 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1001 return; 1002 } 1003 } 1004 1005 // The length of the itable was either zero, or it has not yet been initialized. 1006 _table_offset = 0; 1007 _size_offset_table = 0; 1008 _size_method_table = 0; 1009 } 1010 1011 static int initialize_count = 0; 1012 1013 // Initialization 1014 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1015 if (_klass->is_interface()) { 1016 // This needs to go after vtable indices are assigned but 1017 // before implementors need to know the number of itable indices. 1018 assign_itable_indices_for_interface(_klass()); 1019 } 1020 1021 // Cannot be setup doing bootstrapping, interfaces don't have 1022 // itables, and klass with only ones entry have empty itables 1023 if (Universe::is_bootstrapping() || 1024 _klass->is_interface() || 1025 _klass->itable_length() == itableOffsetEntry::size()) return; 1026 1027 // There's alway an extra itable entry so we can null-terminate it. 1028 guarantee(size_offset_table() >= 1, "too small"); 1029 int num_interfaces = size_offset_table() - 1; 1030 if (num_interfaces > 0) { 1031 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count, 1032 _klass->name()->as_C_string()); 1033 1034 1035 // Iterate through all interfaces 1036 int i; 1037 for(i = 0; i < num_interfaces; i++) { 1038 itableOffsetEntry* ioe = offset_entry(i); 1039 HandleMark hm(THREAD); 1040 KlassHandle interf_h (THREAD, ioe->interface_klass()); 1041 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1042 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); 1043 } 1044 1045 } 1046 // Check that the last entry is empty 1047 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1048 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1049 } 1050 1051 1052 inline bool interface_method_needs_itable_index(Method* m) { 1053 if (m->is_static()) return false; // e.g., Stream.empty 1054 if (m->is_initializer()) return false; // <init> or <clinit> 1055 // If an interface redeclares a method from java.lang.Object, 1056 // it should already have a vtable index, don't touch it. 1057 // e.g., CharSequence.toString (from initialize_vtable) 1058 // if (m->has_vtable_index()) return false; // NO! 1059 return true; 1060 } 1061 1062 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1063 // an interface does not have an itable, but its methods need to be numbered 1064 if (TraceItables) tty->print_cr("%3d: Initializing itable indices for interface %s", ++initialize_count, 1065 klass->name()->as_C_string()); 1066 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1067 int nof_methods = methods->length(); 1068 int ime_num = 0; 1069 for (int i = 0; i < nof_methods; i++) { 1070 Method* m = methods->at(i); 1071 if (interface_method_needs_itable_index(m)) { 1072 assert(!m->is_final_method(), "no final interface methods"); 1073 // If m is already assigned a vtable index, do not disturb it. 1074 if (TraceItables && Verbose) { 1075 ResourceMark rm; 1076 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 1077 if (m->has_vtable_index()) { 1078 tty->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1079 } else { 1080 tty->print("itable index %d for method: %s, flags: ", ime_num, sig); 1081 } 1082 if (m != NULL) { 1083 m->access_flags().print_on(tty); 1084 if (m->is_default_method()) { 1085 tty->print("default "); 1086 } 1087 if (m->is_overpass()) { 1088 tty->print("overpass"); 1089 } 1090 } 1091 tty->cr(); 1092 } 1093 if (!m->has_vtable_index()) { 1094 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable"); 1095 m->set_itable_index(ime_num); 1096 // Progress to next itable entry 1097 ime_num++; 1098 } 1099 } 1100 } 1101 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1102 return ime_num; 1103 } 1104 1105 int klassItable::method_count_for_interface(Klass* interf) { 1106 assert(interf->oop_is_instance(), "must be"); 1107 assert(interf->is_interface(), "must be"); 1108 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1109 int nof_methods = methods->length(); 1110 int length = 0; 1111 while (nof_methods > 0) { 1112 Method* m = methods->at(nof_methods-1); 1113 if (m->has_itable_index()) { 1114 length = m->itable_index() + 1; 1115 break; 1116 } 1117 nof_methods -= 1; 1118 } 1119 #ifdef ASSERT 1120 int nof_methods_copy = nof_methods; 1121 while (nof_methods_copy > 0) { 1122 Method* mm = methods->at(--nof_methods_copy); 1123 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1124 } 1125 #endif //ASSERT 1126 // return the rightmost itable index, plus one; or 0 if no methods have 1127 // itable indices 1128 return length; 1129 } 1130 1131 1132 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { 1133 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods(); 1134 int nof_methods = methods->length(); 1135 HandleMark hm; 1136 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1137 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); 1138 1139 int ime_count = method_count_for_interface(interf_h()); 1140 for (int i = 0; i < nof_methods; i++) { 1141 Method* m = methods->at(i); 1142 methodHandle target; 1143 if (m->has_itable_index()) { 1144 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1145 // to correctly enforce loader constraints for interface method inheritance 1146 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1147 } 1148 if (target == NULL || !target->is_public() || target->is_abstract()) { 1149 // Entry does not resolve. Leave it empty for AbstractMethodError. 1150 if (!(target == NULL) && !target->is_public()) { 1151 // Stuff an IllegalAccessError throwing method in there instead. 1152 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()]. 1153 initialize(Universe::throw_illegal_access_error()); 1154 } 1155 } else { 1156 // Entry did resolve, check loader constraints before initializing 1157 // if checkconstraints requested 1158 if (checkconstraints) { 1159 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1160 if (method_holder_loader() != interface_loader()) { 1161 ResourceMark rm(THREAD); 1162 Symbol* failed_type_symbol = 1163 SystemDictionary::check_signature_loaders(m->signature(), 1164 method_holder_loader, 1165 interface_loader, 1166 true, CHECK); 1167 if (failed_type_symbol != NULL) { 1168 const char* msg = "loader constraint violation in interface " 1169 "itable initialization: when resolving method \"%s\" the class" 1170 " loader (instance of %s) of the current class, %s, " 1171 "and the class loader (instance of %s) for interface " 1172 "%s have different Class objects for the type %s " 1173 "used in the signature"; 1174 char* sig = target()->name_and_sig_as_C_string(); 1175 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 1176 char* current = _klass->name()->as_C_string(); 1177 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 1178 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); 1179 char* failed_type_name = failed_type_symbol->as_C_string(); 1180 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 1181 strlen(current) + strlen(loader2) + strlen(iface) + 1182 strlen(failed_type_name); 1183 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1184 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 1185 iface, failed_type_name); 1186 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1187 } 1188 } 1189 } 1190 1191 // ime may have moved during GC so recalculate address 1192 int ime_num = m->itable_index(); 1193 assert(ime_num < ime_count, "oob"); 1194 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target()); 1195 if (TraceItables && Verbose) { 1196 ResourceMark rm(THREAD); 1197 if (target() != NULL) { 1198 char* sig = target()->name_and_sig_as_C_string(); 1199 tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1200 interf_h()->internal_name(), ime_num, sig, 1201 target()->method_holder()->internal_name()); 1202 tty->print("target_method flags: "); 1203 target()->access_flags().print_on(tty); 1204 if (target()->is_default_method()) { 1205 tty->print("default "); 1206 } 1207 tty->cr(); 1208 } 1209 } 1210 } 1211 } 1212 } 1213 1214 // Update entry for specific Method* 1215 void klassItable::initialize_with_method(Method* m) { 1216 itableMethodEntry* ime = method_entry(0); 1217 for(int i = 0; i < _size_method_table; i++) { 1218 if (ime->method() == m) { 1219 ime->initialize(m); 1220 } 1221 ime++; 1222 } 1223 } 1224 1225 #if INCLUDE_JVMTI 1226 // search the itable for uses of either obsolete or EMCP methods 1227 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1228 1229 itableMethodEntry* ime = method_entry(0); 1230 for (int i = 0; i < _size_method_table; i++, ime++) { 1231 Method* old_method = ime->method(); 1232 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1233 continue; // skip uninteresting entries 1234 } 1235 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1236 1237 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1238 1239 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1240 assert(old_method != new_method, "sanity check"); 1241 1242 ime->initialize(new_method); 1243 1244 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 1245 if (!(*trace_name_printed)) { 1246 // RC_TRACE_MESG macro has an embedded ResourceMark 1247 RC_TRACE_MESG(("adjust: name=%s", 1248 old_method->method_holder()->external_name())); 1249 *trace_name_printed = true; 1250 } 1251 // RC_TRACE macro has an embedded ResourceMark 1252 RC_TRACE(0x00200000, ("itable method update: %s(%s)", 1253 new_method->name()->as_C_string(), 1254 new_method->signature()->as_C_string())); 1255 } 1256 } 1257 } 1258 1259 // an itable should never contain old or obsolete methods 1260 bool klassItable::check_no_old_or_obsolete_entries() { 1261 itableMethodEntry* ime = method_entry(0); 1262 for (int i = 0; i < _size_method_table; i++) { 1263 Method* m = ime->method(); 1264 if (m != NULL && 1265 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1266 return false; 1267 } 1268 ime++; 1269 } 1270 return true; 1271 } 1272 1273 void klassItable::dump_itable() { 1274 itableMethodEntry* ime = method_entry(0); 1275 tty->print_cr("itable dump --"); 1276 for (int i = 0; i < _size_method_table; i++) { 1277 Method* m = ime->method(); 1278 if (m != NULL) { 1279 tty->print(" (%5d) ", i); 1280 m->access_flags().print_on(tty); 1281 if (m->is_default_method()) { 1282 tty->print("default "); 1283 } 1284 tty->print(" -- "); 1285 m->print_name(tty); 1286 tty->cr(); 1287 } 1288 ime++; 1289 } 1290 } 1291 #endif // INCLUDE_JVMTI 1292 1293 1294 // Setup 1295 class InterfaceVisiterClosure : public StackObj { 1296 public: 1297 virtual void doit(Klass* intf, int method_count) = 0; 1298 }; 1299 1300 // Visit all interfaces with at least one itable method 1301 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1302 // Handle array argument 1303 for(int i = 0; i < transitive_intf->length(); i++) { 1304 Klass* intf = transitive_intf->at(i); 1305 assert(intf->is_interface(), "sanity check"); 1306 1307 // Find no. of itable methods 1308 int method_count = 0; 1309 // method_count = klassItable::method_count_for_interface(intf); 1310 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1311 if (methods->length() > 0) { 1312 for (int i = methods->length(); --i >= 0; ) { 1313 if (interface_method_needs_itable_index(methods->at(i))) { 1314 method_count++; 1315 } 1316 } 1317 } 1318 1319 // Only count interfaces with at least one method 1320 if (method_count > 0) { 1321 blk->doit(intf, method_count); 1322 } 1323 } 1324 } 1325 1326 class CountInterfacesClosure : public InterfaceVisiterClosure { 1327 private: 1328 int _nof_methods; 1329 int _nof_interfaces; 1330 public: 1331 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1332 1333 int nof_methods() const { return _nof_methods; } 1334 int nof_interfaces() const { return _nof_interfaces; } 1335 1336 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1337 }; 1338 1339 class SetupItableClosure : public InterfaceVisiterClosure { 1340 private: 1341 itableOffsetEntry* _offset_entry; 1342 itableMethodEntry* _method_entry; 1343 address _klass_begin; 1344 public: 1345 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1346 _klass_begin = klass_begin; 1347 _offset_entry = offset_entry; 1348 _method_entry = method_entry; 1349 } 1350 1351 itableMethodEntry* method_entry() const { return _method_entry; } 1352 1353 void doit(Klass* intf, int method_count) { 1354 int offset = ((address)_method_entry) - _klass_begin; 1355 _offset_entry->initialize(intf, offset); 1356 _offset_entry++; 1357 _method_entry += method_count; 1358 } 1359 }; 1360 1361 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1362 // Count no of interfaces and total number of interface methods 1363 CountInterfacesClosure cic; 1364 visit_all_interfaces(transitive_interfaces, &cic); 1365 1366 // There's alway an extra itable entry so we can null-terminate it. 1367 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1368 1369 // Statistics 1370 update_stats(itable_size * HeapWordSize); 1371 1372 return itable_size; 1373 } 1374 1375 1376 // Fill out offset table and interface klasses into the itable space 1377 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { 1378 if (klass->itable_length() == 0) return; 1379 assert(!klass->is_interface(), "Should have zero length itable"); 1380 1381 // Count no of interfaces and total number of interface methods 1382 CountInterfacesClosure cic; 1383 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1384 int nof_methods = cic.nof_methods(); 1385 int nof_interfaces = cic.nof_interfaces(); 1386 1387 // Add one extra entry so we can null-terminate the table 1388 nof_interfaces++; 1389 1390 assert(compute_itable_size(klass->transitive_interfaces()) == 1391 calc_itable_size(nof_interfaces, nof_methods), 1392 "mismatch calculation of itable size"); 1393 1394 // Fill-out offset table 1395 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1396 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1397 intptr_t* end = klass->end_of_itable(); 1398 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1399 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1400 1401 // Visit all interfaces and initialize itable offset table 1402 SetupItableClosure sic((address)klass(), ioe, ime); 1403 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1404 1405 #ifdef ASSERT 1406 ime = sic.method_entry(); 1407 oop* v = (oop*) klass->end_of_itable(); 1408 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1409 #endif 1410 } 1411 1412 1413 // inverse to itable_index 1414 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1415 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1416 assert(intf->verify_itable_index(itable_index), ""); 1417 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1418 1419 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1420 return NULL; // help caller defend against bad indices 1421 1422 int index = itable_index; 1423 Method* m = methods->at(index); 1424 int index2 = -1; 1425 while (!m->has_itable_index() || 1426 (index2 = m->itable_index()) != itable_index) { 1427 assert(index2 < itable_index, "monotonic"); 1428 if (++index == methods->length()) 1429 return NULL; 1430 m = methods->at(index); 1431 } 1432 assert(m->itable_index() == itable_index, "correct inverse"); 1433 1434 return m; 1435 } 1436 1437 void klassVtable::verify(outputStream* st, bool forced) { 1438 // make sure table is initialized 1439 if (!Universe::is_fully_initialized()) return; 1440 #ifndef PRODUCT 1441 // avoid redundant verifies 1442 if (!forced && _verify_count == Universe::verify_count()) return; 1443 _verify_count = Universe::verify_count(); 1444 #endif 1445 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 1446 oop* end_of_vtable = (oop *)&table()[_length]; 1447 if (end_of_vtable > end_of_obj) { 1448 fatal(err_msg("klass %s: klass object too short (vtable extends beyond " 1449 "end)", _klass->internal_name())); 1450 } 1451 1452 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1453 // verify consistency with superKlass vtable 1454 Klass* super = _klass->super(); 1455 if (super != NULL) { 1456 InstanceKlass* sk = InstanceKlass::cast(super); 1457 klassVtable* vt = sk->vtable(); 1458 for (int i = 0; i < vt->length(); i++) { 1459 verify_against(st, vt, i); 1460 } 1461 } 1462 } 1463 1464 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1465 vtableEntry* vte = &vt->table()[index]; 1466 if (vte->method()->name() != table()[index].method()->name() || 1467 vte->method()->signature() != table()[index].method()->signature()) { 1468 fatal("mismatched name/signature of vtable entries"); 1469 } 1470 } 1471 1472 #ifndef PRODUCT 1473 void klassVtable::print() { 1474 ResourceMark rm; 1475 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1476 for (int i = 0; i < length(); i++) { 1477 table()[i].print(); 1478 tty->cr(); 1479 } 1480 } 1481 #endif 1482 1483 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1484 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1485 assert(method() != NULL, "must have set method"); 1486 method()->verify(); 1487 // we sub_type, because it could be a miranda method 1488 if (!vt->klass()->is_subtype_of(method()->method_holder())) { 1489 #ifndef PRODUCT 1490 print(); 1491 #endif 1492 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this)); 1493 } 1494 } 1495 1496 #ifndef PRODUCT 1497 1498 void vtableEntry::print() { 1499 ResourceMark rm; 1500 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1501 if (Verbose) { 1502 tty->print("m %#lx ", (address)method()); 1503 } 1504 } 1505 1506 class VtableStats : AllStatic { 1507 public: 1508 static int no_klasses; // # classes with vtables 1509 static int no_array_klasses; // # array classes 1510 static int no_instance_klasses; // # instanceKlasses 1511 static int sum_of_vtable_len; // total # of vtable entries 1512 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1513 static int fixed; // total fixed overhead in bytes 1514 static int filler; // overhead caused by filler bytes 1515 static int entries; // total bytes consumed by vtable entries 1516 static int array_entries; // total bytes consumed by array vtable entries 1517 1518 static void do_class(Klass* k) { 1519 Klass* kl = k; 1520 klassVtable* vt = kl->vtable(); 1521 if (vt == NULL) return; 1522 no_klasses++; 1523 if (kl->oop_is_instance()) { 1524 no_instance_klasses++; 1525 kl->array_klasses_do(do_class); 1526 } 1527 if (kl->oop_is_array()) { 1528 no_array_klasses++; 1529 sum_of_array_vtable_len += vt->length(); 1530 } 1531 sum_of_vtable_len += vt->length(); 1532 } 1533 1534 static void compute() { 1535 SystemDictionary::classes_do(do_class); 1536 fixed = no_klasses * oopSize; // vtable length 1537 // filler size is a conservative approximation 1538 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1539 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1540 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1541 } 1542 }; 1543 1544 int VtableStats::no_klasses = 0; 1545 int VtableStats::no_array_klasses = 0; 1546 int VtableStats::no_instance_klasses = 0; 1547 int VtableStats::sum_of_vtable_len = 0; 1548 int VtableStats::sum_of_array_vtable_len = 0; 1549 int VtableStats::fixed = 0; 1550 int VtableStats::filler = 0; 1551 int VtableStats::entries = 0; 1552 int VtableStats::array_entries = 0; 1553 1554 void klassVtable::print_statistics() { 1555 ResourceMark rm; 1556 HandleMark hm; 1557 VtableStats::compute(); 1558 tty->print_cr("vtable statistics:"); 1559 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1560 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1561 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1562 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1563 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1564 tty->print_cr("%6d bytes total", total); 1565 } 1566 1567 int klassItable::_total_classes; // Total no. of classes with itables 1568 long klassItable::_total_size; // Total no. of bytes used for itables 1569 1570 void klassItable::print_statistics() { 1571 tty->print_cr("itable statistics:"); 1572 tty->print_cr("%6d classes with itables", _total_classes); 1573 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes); 1574 } 1575 1576 #endif // PRODUCT