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 // the search could find a miranda or a default method 687 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 688 return true; 689 } 690 } 691 return false; 692 } 693 694 // check if a method is a miranda method, given a class's methods table, 695 // its default_method table and its super 696 // Miranda methods are calculated twice: 697 // first: before vtable size calculation: including abstract and superinterface default 698 // We include potential default methods to give them space in the vtable. 699 // During the first run, the default_methods list is empty 700 // This is seen by default method creation 701 // Second: recalculated during vtable initialization: only include abstract methods. 702 // During the second run, default_methods is set up, so concrete methods from 703 // superinterfaces with matching names/signatures to default_methods are already 704 // in the default_methods list and do not need to be appended to the vtable 705 // as mirandas 706 // This is seen by link resolution and selection. 707 // "miranda" means not static, not defined by this class. 708 // private methods in interfaces do not belong in the miranda list. 709 // the caller must make sure that the method belongs to an interface implemented by the class 710 // Miranda methods only include public interface instance methods 711 // Not private methods, not static methods, not default == concrete abstract 712 // Miranda methods also do not include overpass methods in interfaces 713 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 714 Array<Method*>* default_methods, Klass* super) { 715 if (m->is_static() || m->is_private() || m->is_overpass()) { 716 return false; 717 } 718 Symbol* name = m->name(); 719 Symbol* signature = m->signature(); 720 Method* mo; 721 722 if ((mo = InstanceKlass::find_instance_method(class_methods, name, signature)) == NULL) { 723 // did not find it in the method table of the current class 724 if ((default_methods == NULL) || 725 InstanceKlass::find_method(default_methods, name, signature) == NULL) { 726 if (super == NULL) { 727 // super doesn't exist 728 return true; 729 } 730 731 mo = InstanceKlass::cast(super)->lookup_method(name, signature); 732 while (mo != NULL && mo->access_flags().is_static() 733 && mo->method_holder() != NULL 734 && mo->method_holder()->super() != NULL) 735 { 736 mo = mo->method_holder()->super()->uncached_lookup_method(name, signature, Klass::find_overpass); 737 } 738 if (mo == NULL || mo->access_flags().is_private() ) { 739 // super class hierarchy does not implement it or protection is different 740 return true; 741 } 742 } 743 } else { 744 // if the local class has a private method, the miranda will not 745 // override it, so a vtable slot is needed 746 if (mo->access_flags().is_private()) { 747 748 // Second round, weed out any superinterface methods that turned 749 // into default methods, i.e. were concrete not abstract in the end 750 if ((default_methods == NULL) || 751 InstanceKlass::find_method(default_methods, name, signature) == NULL) { 752 return true; 753 } 754 } 755 } 756 757 return false; 758 } 759 760 // Scans current_interface_methods for miranda methods that do not 761 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 762 // in super (superclass). These mirandas are added to all_mirandas if it is 763 // not null; in addition, those that are not duplicates of miranda methods 764 // inherited by super from its interfaces are added to new_mirandas. 765 // Thus, new_mirandas will be the set of mirandas that this class introduces, 766 // all_mirandas will be the set of all mirandas applicable to this class 767 // including all defined in superclasses. 768 void klassVtable::add_new_mirandas_to_lists( 769 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 770 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 771 Array<Method*>* default_methods, Klass* super) { 772 773 // iterate thru the current interface's method to see if it a miranda 774 int num_methods = current_interface_methods->length(); 775 for (int i = 0; i < num_methods; i++) { 776 Method* im = current_interface_methods->at(i); 777 bool is_duplicate = false; 778 int num_of_current_mirandas = new_mirandas->length(); 779 // check for duplicate mirandas in different interfaces we implement 780 for (int j = 0; j < num_of_current_mirandas; j++) { 781 Method* miranda = new_mirandas->at(j); 782 if ((im->name() == miranda->name()) && 783 (im->signature() == miranda->signature())) { 784 is_duplicate = true; 785 break; 786 } 787 } 788 789 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 790 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 791 InstanceKlass *sk = InstanceKlass::cast(super); 792 // check if it is a duplicate of a super's miranda 793 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 794 new_mirandas->append(im); 795 } 796 if (all_mirandas != NULL) { 797 all_mirandas->append(im); 798 } 799 } 800 } 801 } 802 } 803 804 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 805 GrowableArray<Method*>* all_mirandas, 806 Klass* super, Array<Method*>* class_methods, 807 Array<Method*>* default_methods, 808 Array<Klass*>* local_interfaces) { 809 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 810 811 // iterate thru the local interfaces looking for a miranda 812 int num_local_ifs = local_interfaces->length(); 813 for (int i = 0; i < num_local_ifs; i++) { 814 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 815 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 816 ik->methods(), class_methods, 817 default_methods, super); 818 // iterate thru each local's super interfaces 819 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 820 int num_super_ifs = super_ifs->length(); 821 for (int j = 0; j < num_super_ifs; j++) { 822 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 823 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 824 sik->methods(), class_methods, 825 default_methods, super); 826 } 827 } 828 } 829 830 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 831 // and append them into the vtable starting at index initialized, 832 // return the new value of initialized. 833 // Miranda methods use vtable entries, but do not get assigned a vtable_index 834 // The vtable_index is discovered by searching from the end of the vtable 835 int klassVtable::fill_in_mirandas(int initialized) { 836 GrowableArray<Method*> mirandas(20); 837 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 838 ik()->default_methods(), ik()->local_interfaces()); 839 for (int i = 0; i < mirandas.length(); i++) { 840 if (PrintVtables && Verbose) { 841 Method* meth = mirandas.at(i); 842 ResourceMark rm(Thread::current()); 843 if (meth != NULL) { 844 char* sig = meth->name_and_sig_as_C_string(); 845 tty->print("fill in mirandas with %s index %d, flags: ", 846 sig, initialized); 847 meth->access_flags().print_on(tty); 848 if (meth->is_default_method()) { 849 tty->print("default "); 850 } 851 tty->cr(); 852 } 853 } 854 put_method_at(mirandas.at(i), initialized); 855 ++initialized; 856 } 857 return initialized; 858 } 859 860 // Copy this class's vtable to the vtable beginning at start. 861 // Used to copy superclass vtable to prefix of subclass's vtable. 862 void klassVtable::copy_vtable_to(vtableEntry* start) { 863 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 864 } 865 866 #if INCLUDE_JVMTI 867 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 868 // If old_method is default, find this vtable index in default_vtable_indices 869 // and replace that method in the _default_methods list 870 bool updated = false; 871 872 Array<Method*>* default_methods = ik()->default_methods(); 873 if (default_methods != NULL) { 874 int len = default_methods->length(); 875 for (int idx = 0; idx < len; idx++) { 876 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 877 if (default_methods->at(idx) == old_method) { 878 default_methods->at_put(idx, new_method); 879 updated = true; 880 } 881 break; 882 } 883 } 884 } 885 return updated; 886 } 887 888 // search the vtable for uses of either obsolete or EMCP methods 889 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 890 int prn_enabled = 0; 891 for (int index = 0; index < length(); index++) { 892 Method* old_method = unchecked_method_at(index); 893 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 894 continue; // skip uninteresting entries 895 } 896 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 897 898 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 899 900 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 901 assert(old_method != new_method, "sanity check"); 902 903 put_method_at(new_method, index); 904 // For default methods, need to update the _default_methods array 905 // which can only have one method entry for a given signature 906 bool updated_default = false; 907 if (old_method->is_default_method()) { 908 updated_default = adjust_default_method(index, old_method, new_method); 909 } 910 911 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 912 if (!(*trace_name_printed)) { 913 // RC_TRACE_MESG macro has an embedded ResourceMark 914 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s", 915 klass()->external_name(), 916 old_method->method_holder()->external_name())); 917 *trace_name_printed = true; 918 } 919 // RC_TRACE macro has an embedded ResourceMark 920 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s", 921 new_method->name()->as_C_string(), 922 new_method->signature()->as_C_string(), 923 updated_default ? "true" : "false")); 924 } 925 } 926 } 927 928 // a vtable should never contain old or obsolete methods 929 bool klassVtable::check_no_old_or_obsolete_entries() { 930 for (int i = 0; i < length(); i++) { 931 Method* m = unchecked_method_at(i); 932 if (m != NULL && 933 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 934 return false; 935 } 936 } 937 return true; 938 } 939 940 void klassVtable::dump_vtable() { 941 tty->print_cr("vtable dump --"); 942 for (int i = 0; i < length(); i++) { 943 Method* m = unchecked_method_at(i); 944 if (m != NULL) { 945 tty->print(" (%5d) ", i); 946 m->access_flags().print_on(tty); 947 if (m->is_default_method()) { 948 tty->print("default "); 949 } 950 if (m->is_overpass()) { 951 tty->print("overpass"); 952 } 953 tty->print(" -- "); 954 m->print_name(tty); 955 tty->cr(); 956 } 957 } 958 } 959 #endif // INCLUDE_JVMTI 960 961 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 962 void klassVtable::clear_vtable() { 963 for (int i = 0; i < _length; i++) table()[i].clear(); 964 } 965 966 bool klassVtable::is_initialized() { 967 return _length == 0 || table()[0].method() != NULL; 968 } 969 970 //----------------------------------------------------------------------------------------- 971 // Itable code 972 973 // Initialize a itableMethodEntry 974 void itableMethodEntry::initialize(Method* m) { 975 if (m == NULL) return; 976 977 _method = m; 978 } 979 980 klassItable::klassItable(instanceKlassHandle klass) { 981 _klass = klass; 982 983 if (klass->itable_length() > 0) { 984 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 985 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 986 // First offset entry points to the first method_entry 987 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); 988 intptr_t* end = klass->end_of_itable(); 989 990 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); 991 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 992 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 993 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 994 return; 995 } 996 } 997 998 // The length of the itable was either zero, or it has not yet been initialized. 999 _table_offset = 0; 1000 _size_offset_table = 0; 1001 _size_method_table = 0; 1002 } 1003 1004 static int initialize_count = 0; 1005 1006 // Initialization 1007 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1008 if (_klass->is_interface()) { 1009 // This needs to go after vtable indices are assigned but 1010 // before implementors need to know the number of itable indices. 1011 assign_itable_indices_for_interface(_klass()); 1012 } 1013 1014 // Cannot be setup doing bootstrapping, interfaces don't have 1015 // itables, and klass with only ones entry have empty itables 1016 if (Universe::is_bootstrapping() || 1017 _klass->is_interface() || 1018 _klass->itable_length() == itableOffsetEntry::size()) return; 1019 1020 // There's alway an extra itable entry so we can null-terminate it. 1021 guarantee(size_offset_table() >= 1, "too small"); 1022 int num_interfaces = size_offset_table() - 1; 1023 if (num_interfaces > 0) { 1024 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count, 1025 _klass->name()->as_C_string()); 1026 1027 1028 // Iterate through all interfaces 1029 int i; 1030 for(i = 0; i < num_interfaces; i++) { 1031 itableOffsetEntry* ioe = offset_entry(i); 1032 HandleMark hm(THREAD); 1033 KlassHandle interf_h (THREAD, ioe->interface_klass()); 1034 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1035 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); 1036 } 1037 1038 } 1039 // Check that the last entry is empty 1040 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1041 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1042 } 1043 1044 1045 inline bool interface_method_needs_itable_index(Method* m) { 1046 if (m->is_static()) return false; // e.g., Stream.empty 1047 if (m->is_initializer()) return false; // <init> or <clinit> 1048 // If an interface redeclares a method from java.lang.Object, 1049 // it should already have a vtable index, don't touch it. 1050 // e.g., CharSequence.toString (from initialize_vtable) 1051 // if (m->has_vtable_index()) return false; // NO! 1052 return true; 1053 } 1054 1055 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1056 // an interface does not have an itable, but its methods need to be numbered 1057 if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count, 1058 klass->name()->as_C_string()); 1059 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1060 int nof_methods = methods->length(); 1061 int ime_num = 0; 1062 for (int i = 0; i < nof_methods; i++) { 1063 Method* m = methods->at(i); 1064 if (interface_method_needs_itable_index(m)) { 1065 assert(!m->is_final_method(), "no final interface methods"); 1066 // If m is already assigned a vtable index, do not disturb it. 1067 if (TraceItables && Verbose) { 1068 ResourceMark rm; 1069 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 1070 if (m->has_vtable_index()) { 1071 tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig); 1072 } else { 1073 tty->print("itable index %d for method: %s, flags: ", ime_num, sig); 1074 } 1075 if (m != NULL) { 1076 m->access_flags().print_on(tty); 1077 if (m->is_default_method()) { 1078 tty->print("default "); 1079 } 1080 if (m->is_overpass()) { 1081 tty->print("overpass"); 1082 } 1083 } 1084 tty->cr(); 1085 } 1086 if (!m->has_vtable_index()) { 1087 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable"); 1088 m->set_itable_index(ime_num); 1089 // Progress to next itable entry 1090 ime_num++; 1091 } 1092 } 1093 } 1094 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1095 return ime_num; 1096 } 1097 1098 int klassItable::method_count_for_interface(Klass* interf) { 1099 assert(interf->oop_is_instance(), "must be"); 1100 assert(interf->is_interface(), "must be"); 1101 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1102 int nof_methods = methods->length(); 1103 while (nof_methods > 0) { 1104 Method* m = methods->at(nof_methods-1); 1105 if (m->has_itable_index()) { 1106 int length = m->itable_index() + 1; 1107 #ifdef ASSERT 1108 while (nof_methods = 0) { 1109 m = methods->at(--nof_methods); 1110 assert(!m->has_itable_index() || m->itable_index() < length, ""); 1111 } 1112 #endif //ASSERT 1113 return length; // return the rightmost itable index, plus one 1114 } 1115 nof_methods -= 1; 1116 } 1117 // no methods have itable indices 1118 return 0; 1119 } 1120 1121 1122 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { 1123 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods(); 1124 int nof_methods = methods->length(); 1125 HandleMark hm; 1126 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1127 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); 1128 1129 int ime_count = method_count_for_interface(interf_h()); 1130 for (int i = 0; i < nof_methods; i++) { 1131 Method* m = methods->at(i); 1132 methodHandle target; 1133 if (m->has_itable_index()) { 1134 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1135 // to correctly enforce loader constraints for interface method inheritance 1136 LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK); 1137 } 1138 if (target == NULL || !target->is_public() || target->is_abstract()) { 1139 // Entry does not resolve. Leave it empty for AbstractMethodError. 1140 if (!(target == NULL) && !target->is_public()) { 1141 // Stuff an IllegalAccessError throwing method in there instead. 1142 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()]. 1143 initialize(Universe::throw_illegal_access_error()); 1144 } 1145 } else { 1146 // Entry did resolve, check loader constraints before initializing 1147 // if checkconstraints requested 1148 if (checkconstraints) { 1149 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1150 if (method_holder_loader() != interface_loader()) { 1151 ResourceMark rm(THREAD); 1152 Symbol* failed_type_symbol = 1153 SystemDictionary::check_signature_loaders(m->signature(), 1154 method_holder_loader, 1155 interface_loader, 1156 true, CHECK); 1157 if (failed_type_symbol != NULL) { 1158 const char* msg = "loader constraint violation in interface " 1159 "itable initialization: when resolving method \"%s\" the class" 1160 " loader (instance of %s) of the current class, %s, " 1161 "and the class loader (instance of %s) for interface " 1162 "%s have different Class objects for the type %s " 1163 "used in the signature"; 1164 char* sig = target()->name_and_sig_as_C_string(); 1165 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 1166 char* current = _klass->name()->as_C_string(); 1167 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 1168 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); 1169 char* failed_type_name = failed_type_symbol->as_C_string(); 1170 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 1171 strlen(current) + strlen(loader2) + strlen(iface) + 1172 strlen(failed_type_name); 1173 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1174 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 1175 iface, failed_type_name); 1176 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1177 } 1178 } 1179 } 1180 1181 // ime may have moved during GC so recalculate address 1182 int ime_num = m->itable_index(); 1183 assert(ime_num < ime_count, "oob"); 1184 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target()); 1185 if (TraceItables && Verbose) { 1186 ResourceMark rm(THREAD); 1187 if (target() != NULL) { 1188 char* sig = target()->name_and_sig_as_C_string(); 1189 tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1190 interf_h()->internal_name(), ime_num, sig, 1191 target()->method_holder()->internal_name()); 1192 tty->print("target_method flags: "); 1193 target()->access_flags().print_on(tty); 1194 if (target()->is_default_method()) { 1195 tty->print("default "); 1196 } 1197 tty->cr(); 1198 } 1199 } 1200 } 1201 } 1202 } 1203 1204 // Update entry for specific Method* 1205 void klassItable::initialize_with_method(Method* m) { 1206 itableMethodEntry* ime = method_entry(0); 1207 for(int i = 0; i < _size_method_table; i++) { 1208 if (ime->method() == m) { 1209 ime->initialize(m); 1210 } 1211 ime++; 1212 } 1213 } 1214 1215 #if INCLUDE_JVMTI 1216 // search the itable for uses of either obsolete or EMCP methods 1217 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1218 1219 itableMethodEntry* ime = method_entry(0); 1220 for (int i = 0; i < _size_method_table; i++, ime++) { 1221 Method* old_method = ime->method(); 1222 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1223 continue; // skip uninteresting entries 1224 } 1225 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1226 1227 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1228 1229 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1230 assert(old_method != new_method, "sanity check"); 1231 1232 ime->initialize(new_method); 1233 1234 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 1235 if (!(*trace_name_printed)) { 1236 // RC_TRACE_MESG macro has an embedded ResourceMark 1237 RC_TRACE_MESG(("adjust: name=%s", 1238 old_method->method_holder()->external_name())); 1239 *trace_name_printed = true; 1240 } 1241 // RC_TRACE macro has an embedded ResourceMark 1242 RC_TRACE(0x00200000, ("itable method update: %s(%s)", 1243 new_method->name()->as_C_string(), 1244 new_method->signature()->as_C_string())); 1245 } 1246 } 1247 } 1248 1249 // an itable should never contain old or obsolete methods 1250 bool klassItable::check_no_old_or_obsolete_entries() { 1251 itableMethodEntry* ime = method_entry(0); 1252 for (int i = 0; i < _size_method_table; i++) { 1253 Method* m = ime->method(); 1254 if (m != NULL && 1255 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1256 return false; 1257 } 1258 ime++; 1259 } 1260 return true; 1261 } 1262 1263 void klassItable::dump_itable() { 1264 itableMethodEntry* ime = method_entry(0); 1265 tty->print_cr("itable dump --"); 1266 for (int i = 0; i < _size_method_table; i++) { 1267 Method* m = ime->method(); 1268 if (m != NULL) { 1269 tty->print(" (%5d) ", i); 1270 m->access_flags().print_on(tty); 1271 if (m->is_default_method()) { 1272 tty->print("default "); 1273 } 1274 tty->print(" -- "); 1275 m->print_name(tty); 1276 tty->cr(); 1277 } 1278 ime++; 1279 } 1280 } 1281 #endif // INCLUDE_JVMTI 1282 1283 1284 // Setup 1285 class InterfaceVisiterClosure : public StackObj { 1286 public: 1287 virtual void doit(Klass* intf, int method_count) = 0; 1288 }; 1289 1290 // Visit all interfaces with at least one itable method 1291 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1292 // Handle array argument 1293 for(int i = 0; i < transitive_intf->length(); i++) { 1294 Klass* intf = transitive_intf->at(i); 1295 assert(intf->is_interface(), "sanity check"); 1296 1297 // Find no. of itable methods 1298 int method_count = 0; 1299 // method_count = klassItable::method_count_for_interface(intf); 1300 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1301 if (methods->length() > 0) { 1302 for (int i = methods->length(); --i >= 0; ) { 1303 if (interface_method_needs_itable_index(methods->at(i))) { 1304 method_count++; 1305 } 1306 } 1307 } 1308 1309 // Only count interfaces with at least one method 1310 if (method_count > 0) { 1311 blk->doit(intf, method_count); 1312 } 1313 } 1314 } 1315 1316 class CountInterfacesClosure : public InterfaceVisiterClosure { 1317 private: 1318 int _nof_methods; 1319 int _nof_interfaces; 1320 public: 1321 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1322 1323 int nof_methods() const { return _nof_methods; } 1324 int nof_interfaces() const { return _nof_interfaces; } 1325 1326 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1327 }; 1328 1329 class SetupItableClosure : public InterfaceVisiterClosure { 1330 private: 1331 itableOffsetEntry* _offset_entry; 1332 itableMethodEntry* _method_entry; 1333 address _klass_begin; 1334 public: 1335 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1336 _klass_begin = klass_begin; 1337 _offset_entry = offset_entry; 1338 _method_entry = method_entry; 1339 } 1340 1341 itableMethodEntry* method_entry() const { return _method_entry; } 1342 1343 void doit(Klass* intf, int method_count) { 1344 int offset = ((address)_method_entry) - _klass_begin; 1345 _offset_entry->initialize(intf, offset); 1346 _offset_entry++; 1347 _method_entry += method_count; 1348 } 1349 }; 1350 1351 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1352 // Count no of interfaces and total number of interface methods 1353 CountInterfacesClosure cic; 1354 visit_all_interfaces(transitive_interfaces, &cic); 1355 1356 // There's alway an extra itable entry so we can null-terminate it. 1357 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1358 1359 // Statistics 1360 update_stats(itable_size * HeapWordSize); 1361 1362 return itable_size; 1363 } 1364 1365 1366 // Fill out offset table and interface klasses into the itable space 1367 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { 1368 if (klass->itable_length() == 0) return; 1369 assert(!klass->is_interface(), "Should have zero length itable"); 1370 1371 // Count no of interfaces and total number of interface methods 1372 CountInterfacesClosure cic; 1373 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1374 int nof_methods = cic.nof_methods(); 1375 int nof_interfaces = cic.nof_interfaces(); 1376 1377 // Add one extra entry so we can null-terminate the table 1378 nof_interfaces++; 1379 1380 assert(compute_itable_size(klass->transitive_interfaces()) == 1381 calc_itable_size(nof_interfaces, nof_methods), 1382 "mismatch calculation of itable size"); 1383 1384 // Fill-out offset table 1385 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1386 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1387 intptr_t* end = klass->end_of_itable(); 1388 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1389 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1390 1391 // Visit all interfaces and initialize itable offset table 1392 SetupItableClosure sic((address)klass(), ioe, ime); 1393 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1394 1395 #ifdef ASSERT 1396 ime = sic.method_entry(); 1397 oop* v = (oop*) klass->end_of_itable(); 1398 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1399 #endif 1400 } 1401 1402 1403 // inverse to itable_index 1404 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1405 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1406 assert(intf->verify_itable_index(itable_index), ""); 1407 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1408 1409 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1410 return NULL; // help caller defend against bad indices 1411 1412 int index = itable_index; 1413 Method* m = methods->at(index); 1414 int index2 = -1; 1415 while (!m->has_itable_index() || 1416 (index2 = m->itable_index()) != itable_index) { 1417 assert(index2 < itable_index, "monotonic"); 1418 if (++index == methods->length()) 1419 return NULL; 1420 m = methods->at(index); 1421 } 1422 assert(m->itable_index() == itable_index, "correct inverse"); 1423 1424 return m; 1425 } 1426 1427 void klassVtable::verify(outputStream* st, bool forced) { 1428 // make sure table is initialized 1429 if (!Universe::is_fully_initialized()) return; 1430 #ifndef PRODUCT 1431 // avoid redundant verifies 1432 if (!forced && _verify_count == Universe::verify_count()) return; 1433 _verify_count = Universe::verify_count(); 1434 #endif 1435 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 1436 oop* end_of_vtable = (oop *)&table()[_length]; 1437 if (end_of_vtable > end_of_obj) { 1438 fatal(err_msg("klass %s: klass object too short (vtable extends beyond " 1439 "end)", _klass->internal_name())); 1440 } 1441 1442 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1443 // verify consistency with superKlass vtable 1444 Klass* super = _klass->super(); 1445 if (super != NULL) { 1446 InstanceKlass* sk = InstanceKlass::cast(super); 1447 klassVtable* vt = sk->vtable(); 1448 for (int i = 0; i < vt->length(); i++) { 1449 verify_against(st, vt, i); 1450 } 1451 } 1452 } 1453 1454 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1455 vtableEntry* vte = &vt->table()[index]; 1456 if (vte->method()->name() != table()[index].method()->name() || 1457 vte->method()->signature() != table()[index].method()->signature()) { 1458 fatal("mismatched name/signature of vtable entries"); 1459 } 1460 } 1461 1462 #ifndef PRODUCT 1463 void klassVtable::print() { 1464 ResourceMark rm; 1465 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1466 for (int i = 0; i < length(); i++) { 1467 table()[i].print(); 1468 tty->cr(); 1469 } 1470 } 1471 #endif 1472 1473 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1474 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1475 assert(method() != NULL, "must have set method"); 1476 method()->verify(); 1477 // we sub_type, because it could be a miranda method 1478 if (!vt->klass()->is_subtype_of(method()->method_holder())) { 1479 #ifndef PRODUCT 1480 print(); 1481 #endif 1482 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this)); 1483 } 1484 } 1485 1486 #ifndef PRODUCT 1487 1488 void vtableEntry::print() { 1489 ResourceMark rm; 1490 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1491 if (Verbose) { 1492 tty->print("m %#lx ", (address)method()); 1493 } 1494 } 1495 1496 class VtableStats : AllStatic { 1497 public: 1498 static int no_klasses; // # classes with vtables 1499 static int no_array_klasses; // # array classes 1500 static int no_instance_klasses; // # instanceKlasses 1501 static int sum_of_vtable_len; // total # of vtable entries 1502 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1503 static int fixed; // total fixed overhead in bytes 1504 static int filler; // overhead caused by filler bytes 1505 static int entries; // total bytes consumed by vtable entries 1506 static int array_entries; // total bytes consumed by array vtable entries 1507 1508 static void do_class(Klass* k) { 1509 Klass* kl = k; 1510 klassVtable* vt = kl->vtable(); 1511 if (vt == NULL) return; 1512 no_klasses++; 1513 if (kl->oop_is_instance()) { 1514 no_instance_klasses++; 1515 kl->array_klasses_do(do_class); 1516 } 1517 if (kl->oop_is_array()) { 1518 no_array_klasses++; 1519 sum_of_array_vtable_len += vt->length(); 1520 } 1521 sum_of_vtable_len += vt->length(); 1522 } 1523 1524 static void compute() { 1525 SystemDictionary::classes_do(do_class); 1526 fixed = no_klasses * oopSize; // vtable length 1527 // filler size is a conservative approximation 1528 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1529 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1530 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1531 } 1532 }; 1533 1534 int VtableStats::no_klasses = 0; 1535 int VtableStats::no_array_klasses = 0; 1536 int VtableStats::no_instance_klasses = 0; 1537 int VtableStats::sum_of_vtable_len = 0; 1538 int VtableStats::sum_of_array_vtable_len = 0; 1539 int VtableStats::fixed = 0; 1540 int VtableStats::filler = 0; 1541 int VtableStats::entries = 0; 1542 int VtableStats::array_entries = 0; 1543 1544 void klassVtable::print_statistics() { 1545 ResourceMark rm; 1546 HandleMark hm; 1547 VtableStats::compute(); 1548 tty->print_cr("vtable statistics:"); 1549 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1550 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1551 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1552 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1553 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1554 tty->print_cr("%6d bytes total", total); 1555 } 1556 1557 int klassItable::_total_classes; // Total no. of classes with itables 1558 long klassItable::_total_size; // Total no. of bytes used for itables 1559 1560 void klassItable::print_statistics() { 1561 tty->print_cr("itable statistics:"); 1562 tty->print_cr("%6d classes with itables", _total_classes); 1563 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes); 1564 } 1565 1566 #endif // PRODUCT