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 "logging/log.hpp" 30 #include "memory/resourceArea.hpp" 31 #include "memory/universe.inline.hpp" 32 #include "oops/instanceKlass.hpp" 33 #include "oops/klassVtable.hpp" 34 #include "oops/method.hpp" 35 #include "oops/objArrayOop.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "prims/jvmtiRedefineClassesTrace.hpp" 38 #include "runtime/arguments.hpp" 39 #include "runtime/handles.inline.hpp" 40 #include "utilities/copy.hpp" 41 42 inline InstanceKlass* klassVtable::ik() const { 43 return InstanceKlass::cast(_klass()); 44 } 45 46 47 // this function computes the vtable size (including the size needed for miranda 48 // methods) and the number of miranda methods in this class. 49 // Note on Miranda methods: Let's say there is a class C that implements 50 // interface I, and none of C's superclasses implements I. 51 // Let's say there is an abstract method m in I that neither C 52 // nor any of its super classes implement (i.e there is no method of any access, 53 // with the same name and signature as m), then m is a Miranda method which is 54 // entered as a public abstract method in C's vtable. From then on it should 55 // treated as any other public method in C for method over-ride purposes. 56 void klassVtable::compute_vtable_size_and_num_mirandas( 57 int* vtable_length_ret, int* num_new_mirandas, 58 GrowableArray<Method*>* all_mirandas, Klass* super, 59 Array<Method*>* methods, AccessFlags class_flags, 60 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 61 TRAPS) { 62 No_Safepoint_Verifier nsv; 63 64 // set up default result values 65 int vtable_length = 0; 66 67 // start off with super's vtable length 68 vtable_length = super == NULL ? 0 : super->vtable_length(); 69 70 // go thru each method in the methods table to see if it needs a new entry 71 int len = methods->length(); 72 for (int i = 0; i < len; i++) { 73 assert(methods->at(i)->is_method(), "must be a Method*"); 74 methodHandle mh(THREAD, methods->at(i)); 75 76 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { 77 vtable_length += vtableEntry::size(); // we need a new entry 78 } 79 } 80 81 GrowableArray<Method*> new_mirandas(20); 82 // compute the number of mirandas methods that must be added to the end 83 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces); 84 *num_new_mirandas = new_mirandas.length(); 85 86 // Interfaces do not need interface methods in their vtables 87 // This includes miranda methods and during later processing, default methods 88 if (!class_flags.is_interface()) { 89 vtable_length += *num_new_mirandas * vtableEntry::size(); 90 } 91 92 if (Universe::is_bootstrapping() && vtable_length == 0) { 93 // array classes don't have their superclass set correctly during 94 // bootstrapping 95 vtable_length = Universe::base_vtable_size(); 96 } 97 98 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 99 if (Universe::is_bootstrapping()) { 100 // Someone is attempting to override java.lang.Object incorrectly on the 101 // bootclasspath. The JVM cannot recover from this error including throwing 102 // an exception 103 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 104 } else { 105 // Someone is attempting to redefine java.lang.Object incorrectly. The 106 // only way this should happen is from 107 // SystemDictionary::resolve_from_stream(), which will detect this later 108 // and throw a security exception. So don't assert here to let 109 // the exception occur. 110 vtable_length = Universe::base_vtable_size(); 111 } 112 } 113 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 114 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 115 116 *vtable_length_ret = vtable_length; 117 } 118 119 int klassVtable::index_of(Method* m, int len) const { 120 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 121 return m->vtable_index(); 122 } 123 124 // Copy super class's vtable to the first part (prefix) of this class's vtable, 125 // and return the number of entries copied. Expects that 'super' is the Java 126 // super class (arrays can have "array" super classes that must be skipped). 127 int klassVtable::initialize_from_super(KlassHandle super) { 128 if (super.is_null()) { 129 return 0; 130 } else { 131 // copy methods from superKlass 132 klassVtable* superVtable = super->vtable(); 133 assert(superVtable->length() <= _length, "vtable too short"); 134 #ifdef ASSERT 135 superVtable->verify(tty, true); 136 #endif 137 superVtable->copy_vtable_to(table()); 138 ResourceMark rm; 139 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 140 super->internal_name(), klass()->internal_name(), 141 _length); 142 return superVtable->length(); 143 } 144 } 145 146 // 147 // Revised lookup semantics introduced 1.3 (Kestrel beta) 148 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 149 150 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 151 KlassHandle super (THREAD, klass()->java_super()); 152 int nofNewEntries = 0; 153 154 if (develop_log_is_enabled(Debug, vtables) && !klass()->is_array_klass()) { 155 ResourceMark rm(THREAD); 156 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 157 } 158 159 #ifdef ASSERT 160 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 161 oop* end_of_vtable = (oop*)&table()[_length]; 162 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 163 #endif 164 165 if (Universe::is_bootstrapping()) { 166 // just clear everything 167 for (int i = 0; i < _length; i++) table()[i].clear(); 168 return; 169 } 170 171 int super_vtable_len = initialize_from_super(super); 172 if (klass()->is_array_klass()) { 173 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 174 } else { 175 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 176 177 Array<Method*>* methods = ik()->methods(); 178 int len = methods->length(); 179 int initialized = super_vtable_len; 180 181 // Check each of this class's methods against super; 182 // if override, replace in copy of super vtable, otherwise append to end 183 for (int i = 0; i < len; i++) { 184 // update_inherited_vtable can stop for gc - ensure using handles 185 HandleMark hm(THREAD); 186 assert(methods->at(i)->is_method(), "must be a Method*"); 187 methodHandle mh(THREAD, methods->at(i)); 188 189 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 190 191 if (needs_new_entry) { 192 put_method_at(mh(), initialized); 193 mh()->set_vtable_index(initialized); // set primary vtable index 194 initialized++; 195 } 196 } 197 198 // update vtable with default_methods 199 Array<Method*>* default_methods = ik()->default_methods(); 200 if (default_methods != NULL) { 201 len = default_methods->length(); 202 if (len > 0) { 203 Array<int>* def_vtable_indices = NULL; 204 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 205 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 206 } else { 207 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 208 } 209 for (int i = 0; i < len; i++) { 210 HandleMark hm(THREAD); 211 assert(default_methods->at(i)->is_method(), "must be a Method*"); 212 methodHandle mh(THREAD, default_methods->at(i)); 213 214 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 215 216 // needs new entry 217 if (needs_new_entry) { 218 put_method_at(mh(), initialized); 219 def_vtable_indices->at_put(i, initialized); //set vtable index 220 initialized++; 221 } 222 } 223 } 224 } 225 226 // add miranda methods; it will also return the updated initialized 227 // Interfaces do not need interface methods in their vtables 228 // This includes miranda methods and during later processing, default methods 229 if (!ik()->is_interface()) { 230 initialized = fill_in_mirandas(initialized); 231 } 232 233 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 234 // package_private -> public/protected), the vtable might actually be smaller than our initial 235 // calculation. 236 assert(initialized <= _length, "vtable initialization failed"); 237 for(;initialized < _length; initialized++) { 238 put_method_at(NULL, initialized); 239 } 240 NOT_PRODUCT(verify(tty, true)); 241 } 242 } 243 244 // Called for cases where a method does not override its superclass' vtable entry 245 // For bytecodes not produced by javac together it is possible that a method does not override 246 // the superclass's method, but might indirectly override a super-super class's vtable entry 247 // If none found, return a null superk, else return the superk of the method this does override 248 // For public and protected methods: if they override a superclass, they will 249 // also be overridden themselves appropriately. 250 // Private methods do not override and are not overridden. 251 // Package Private methods are trickier: 252 // e.g. P1.A, pub m 253 // P2.B extends A, package private m 254 // P1.C extends B, public m 255 // P1.C.m needs to override P1.A.m and can not override P2.B.m 256 // Therefore: all package private methods need their own vtable entries for 257 // them to be the root of an inheritance overriding decision 258 // Package private methods may also override other vtable entries 259 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, 260 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 261 InstanceKlass* superk = initialsuper; 262 while (superk != NULL && superk->super() != NULL) { 263 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 264 klassVtable* ssVtable = supersuperklass->vtable(); 265 if (vtable_index < ssVtable->length()) { 266 Method* super_method = ssVtable->method_at(vtable_index); 267 #ifndef PRODUCT 268 Symbol* name= target_method()->name(); 269 Symbol* signature = target_method()->signature(); 270 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 271 #endif 272 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 273 if (develop_log_is_enabled(Trace, vtables)) { 274 ResourceMark rm(THREAD); 275 outputStream* logst = LogHandle(vtables)::trace_stream(); 276 char* sig = target_method()->name_and_sig_as_C_string(); 277 logst->print("transitive overriding superclass %s with %s::%s index %d, original flags: ", 278 supersuperklass->internal_name(), 279 _klass->internal_name(), sig, vtable_index); 280 super_method->print_linkage_flags(logst); 281 logst->print("overriders flags: "); 282 target_method->print_linkage_flags(logst); 283 logst->cr(); 284 } 285 286 break; // return found superk 287 } 288 } else { 289 // super class has no vtable entry here, stop transitive search 290 superk = (InstanceKlass*)NULL; 291 break; 292 } 293 // if no override found yet, continue to search up 294 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 295 } 296 297 return superk; 298 } 299 300 static void log_vtables(int i, bool allocate_new, methodHandle target_method, 301 KlassHandle target_klass, Method* super_method, 302 Thread* thread) { 303 #ifndef PRODUCT 304 if (develop_log_is_enabled(Trace, vtables)) { 305 ResourceMark rm(thread); 306 outputStream* logst = LogHandle(vtables)::trace_stream(); 307 char* sig = target_method()->name_and_sig_as_C_string(); 308 if (allocate_new) { 309 // allocate_new = true; default. We might override one entry, 310 logst->print("NOT overriding with %s::%s index %d, original flags: ", 311 target_klass->internal_name(), sig, i); 312 } else { 313 logst->print("overriding with %s::%s index %d, original flags: ", 314 target_klass->internal_name(), sig, i); 315 } 316 super_method->print_linkage_flags(logst); 317 logst->print("overriders flags: "); 318 target_method->print_linkage_flags(logst); 319 logst->cr(); 320 } 321 #endif 322 } 323 324 // Update child's copy of super vtable for overrides 325 // OR return true if a new vtable entry is required. 326 // Only called for InstanceKlass's, i.e. not for arrays 327 // If that changed, could not use _klass as handle for klass 328 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, 329 int super_vtable_len, int default_index, 330 bool checkconstraints, TRAPS) { 331 ResourceMark rm; 332 bool allocate_new = true; 333 assert(klass->is_instance_klass(), "must be InstanceKlass"); 334 335 Array<int>* def_vtable_indices = NULL; 336 bool is_default = false; 337 // default methods are concrete methods in superinterfaces which are added to the vtable 338 // with their real method_holder 339 // Since vtable and itable indices share the same storage, don't touch 340 // the default method's real vtable/itable index 341 // default_vtable_indices stores the vtable value relative to this inheritor 342 if (default_index >= 0 ) { 343 is_default = true; 344 def_vtable_indices = klass->default_vtable_indices(); 345 assert(def_vtable_indices != NULL, "def vtable alloc?"); 346 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 347 } else { 348 assert(klass == target_method()->method_holder(), "caller resp."); 349 // Initialize the method's vtable index to "nonvirtual". 350 // If we allocate a vtable entry, we will update it to a non-negative number. 351 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 352 } 353 354 // Static and <init> methods are never in 355 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 356 return false; 357 } 358 359 if (target_method->is_final_method(klass->access_flags())) { 360 // a final method never needs a new entry; final methods can be statically 361 // resolved and they have to be present in the vtable only if they override 362 // a super's method, in which case they re-use its entry 363 allocate_new = false; 364 } else if (klass->is_interface()) { 365 allocate_new = false; // see note below in needs_new_vtable_entry 366 // An interface never allocates new vtable slots, only inherits old ones. 367 // This method will either be assigned its own itable index later, 368 // or be assigned an inherited vtable index in the loop below. 369 // default methods inherited by classes store their vtable indices 370 // in the inheritor's default_vtable_indices 371 // default methods inherited by interfaces may already have a 372 // valid itable index, if so, don't change it 373 // overpass methods in an interface will be assigned an itable index later 374 // by an inheriting class 375 if (!is_default || !target_method()->has_itable_index()) { 376 target_method()->set_vtable_index(Method::pending_itable_index); 377 } 378 } 379 380 // we need a new entry if there is no superclass 381 if (klass->super() == NULL) { 382 return allocate_new; 383 } 384 385 // private methods in classes always have a new entry in the vtable 386 // specification interpretation since classic has 387 // private methods not overriding 388 // JDK8 adds private methods in interfaces which require invokespecial 389 if (target_method()->is_private()) { 390 return allocate_new; 391 } 392 393 // search through the vtable and update overridden entries 394 // Since check_signature_loaders acquires SystemDictionary_lock 395 // which can block for gc, once we are in this loop, use handles 396 // For classfiles built with >= jdk7, we now look for transitive overrides 397 398 Symbol* name = target_method()->name(); 399 Symbol* signature = target_method()->signature(); 400 401 KlassHandle target_klass(THREAD, target_method()->method_holder()); 402 if (target_klass == NULL) { 403 target_klass = _klass; 404 } 405 406 Handle target_loader(THREAD, target_klass->class_loader()); 407 408 Symbol* target_classname = target_klass->name(); 409 for(int i = 0; i < super_vtable_len; i++) { 410 Method* super_method = method_at(i); 411 // Check if method name matches 412 if (super_method->name() == name && super_method->signature() == signature) { 413 414 // get super_klass for method_holder for the found method 415 InstanceKlass* super_klass = super_method->method_holder(); 416 417 // private methods are also never overridden 418 if (!super_method->is_private() && 419 (is_default 420 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 421 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 422 && ((super_klass = find_transitive_override(super_klass, 423 target_method, i, target_loader, 424 target_classname, THREAD)) 425 != (InstanceKlass*)NULL))))) 426 { 427 // Package private methods always need a new entry to root their own 428 // overriding. They may also override other methods. 429 if (!target_method()->is_package_private()) { 430 allocate_new = false; 431 } 432 433 if (checkconstraints) { 434 // Override vtable entry if passes loader constraint check 435 // if loader constraint checking requested 436 // No need to visit his super, since he and his super 437 // have already made any needed loader constraints. 438 // Since loader constraints are transitive, it is enough 439 // to link to the first super, and we get all the others. 440 Handle super_loader(THREAD, super_klass->class_loader()); 441 442 if (target_loader() != super_loader()) { 443 ResourceMark rm(THREAD); 444 Symbol* failed_type_symbol = 445 SystemDictionary::check_signature_loaders(signature, target_loader, 446 super_loader, true, 447 CHECK_(false)); 448 if (failed_type_symbol != NULL) { 449 const char* msg = "loader constraint violation: when resolving " 450 "overridden method \"%s\" the class loader (instance" 451 " of %s) of the current class, %s, and its superclass loader " 452 "(instance of %s), have different Class objects for the type " 453 "%s used in the signature"; 454 char* sig = target_method()->name_and_sig_as_C_string(); 455 const char* loader1 = SystemDictionary::loader_name(target_loader()); 456 char* current = target_klass->name()->as_C_string(); 457 const char* loader2 = SystemDictionary::loader_name(super_loader()); 458 char* failed_type_name = failed_type_symbol->as_C_string(); 459 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 460 strlen(current) + strlen(loader2) + strlen(failed_type_name); 461 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 462 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 463 failed_type_name); 464 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 465 } 466 } 467 } 468 469 put_method_at(target_method(), i); 470 if (!is_default) { 471 target_method()->set_vtable_index(i); 472 } else { 473 if (def_vtable_indices != NULL) { 474 def_vtable_indices->at_put(default_index, i); 475 } 476 assert(super_method->is_default_method() || super_method->is_overpass() 477 || super_method->is_abstract(), "default override error"); 478 } 479 } 480 log_vtables(i, allocate_new, target_method, target_klass, super_method, THREAD); 481 } 482 } 483 return allocate_new; 484 } 485 486 void klassVtable::put_method_at(Method* m, int index) { 487 if (develop_log_is_enabled(Trace, vtables)) { 488 ResourceMark rm; 489 outputStream* logst = LogHandle(vtables)::trace_stream(); 490 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 491 logst->print("adding %s at index %d, flags: ", sig, index); 492 if (m != NULL) { 493 m->print_linkage_flags(logst); 494 } 495 logst->cr(); 496 } 497 table()[index].set(m); 498 } 499 500 // Find out if a method "m" with superclass "super", loader "classloader" and 501 // name "classname" needs a new vtable entry. Let P be a class package defined 502 // by "classloader" and "classname". 503 // NOTE: The logic used here is very similar to the one used for computing 504 // the vtables indices for a method. We cannot directly use that function because, 505 // we allocate the InstanceKlass at load time, and that requires that the 506 // superclass has been loaded. 507 // However, the vtable entries are filled in at link time, and therefore 508 // the superclass' vtable may not yet have been filled in. 509 bool klassVtable::needs_new_vtable_entry(methodHandle target_method, 510 Klass* super, 511 Handle classloader, 512 Symbol* classname, 513 AccessFlags class_flags, 514 TRAPS) { 515 if (class_flags.is_interface()) { 516 // Interfaces do not use vtables, except for java.lang.Object methods, 517 // so there is no point to assigning 518 // a vtable index to any of their local methods. If we refrain from doing this, 519 // we can use Method::_vtable_index to hold the itable index 520 return false; 521 } 522 523 if (target_method->is_final_method(class_flags) || 524 // a final method never needs a new entry; final methods can be statically 525 // resolved and they have to be present in the vtable only if they override 526 // a super's method, in which case they re-use its entry 527 (target_method()->is_static()) || 528 // static methods don't need to be in vtable 529 (target_method()->name() == vmSymbols::object_initializer_name()) 530 // <init> is never called dynamically-bound 531 ) { 532 return false; 533 } 534 535 // Concrete interface methods do not need new entries, they override 536 // abstract method entries using default inheritance rules 537 if (target_method()->method_holder() != NULL && 538 target_method()->method_holder()->is_interface() && 539 !target_method()->is_abstract() ) { 540 return false; 541 } 542 543 // we need a new entry if there is no superclass 544 if (super == NULL) { 545 return true; 546 } 547 548 // private methods in classes always have a new entry in the vtable 549 // specification interpretation since classic has 550 // private methods not overriding 551 // JDK8 adds private methods in interfaces which require invokespecial 552 if (target_method()->is_private()) { 553 return true; 554 } 555 556 // Package private methods always need a new entry to root their own 557 // overriding. This allows transitive overriding to work. 558 if (target_method()->is_package_private()) { 559 return true; 560 } 561 562 // search through the super class hierarchy to see if we need 563 // a new entry 564 ResourceMark rm; 565 Symbol* name = target_method()->name(); 566 Symbol* signature = target_method()->signature(); 567 Klass* k = super; 568 Method* super_method = NULL; 569 InstanceKlass *holder = NULL; 570 Method* recheck_method = NULL; 571 while (k != NULL) { 572 // lookup through the hierarchy for a method with matching name and sign. 573 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 574 if (super_method == NULL) { 575 break; // we still have to search for a matching miranda method 576 } 577 // get the class holding the matching method 578 // make sure you use that class for is_override 579 InstanceKlass* superk = super_method->method_holder(); 580 // we want only instance method matches 581 // pretend private methods are not in the super vtable 582 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 583 // ignore private, c.m pub does override a.m pub 584 // For classes that were not javac'd together, we also do transitive overriding around 585 // methods that have less accessibility 586 if ((!super_method->is_static()) && 587 (!super_method->is_private())) { 588 if (superk->is_override(super_method, classloader, classname, THREAD)) { 589 return false; 590 // else keep looking for transitive overrides 591 } 592 } 593 594 // Start with lookup result and continue to search up 595 k = superk->super(); // haven't found an override match yet; continue to look 596 } 597 598 // if the target method is public or protected it may have a matching 599 // miranda method in the super, whose entry it should re-use. 600 // Actually, to handle cases that javac would not generate, we need 601 // this check for all access permissions. 602 InstanceKlass *sk = InstanceKlass::cast(super); 603 if (sk->has_miranda_methods()) { 604 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 605 return false; // found a matching miranda; we do not need a new entry 606 } 607 } 608 return true; // found no match; we need a new entry 609 } 610 611 // Support for miranda methods 612 613 // get the vtable index of a miranda method with matching "name" and "signature" 614 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 615 // search from the bottom, might be faster 616 for (int i = (length() - 1); i >= 0; i--) { 617 Method* m = table()[i].method(); 618 if (is_miranda_entry_at(i) && 619 m->name() == name && m->signature() == signature) { 620 return i; 621 } 622 } 623 return Method::invalid_vtable_index; 624 } 625 626 // check if an entry at an index is miranda 627 // requires that method m at entry be declared ("held") by an interface. 628 bool klassVtable::is_miranda_entry_at(int i) { 629 Method* m = method_at(i); 630 Klass* method_holder = m->method_holder(); 631 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 632 633 // miranda methods are public abstract instance interface methods in a class's vtable 634 if (mhk->is_interface()) { 635 assert(m->is_public(), "should be public"); 636 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 637 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 638 return true; 639 } 640 } 641 return false; 642 } 643 644 // Check if a method is a miranda method, given a class's methods array, 645 // its default_method table and its super class. 646 // "Miranda" means an abstract non-private method that would not be 647 // overridden for the local class. 648 // A "miranda" method should only include non-private interface 649 // instance methods, i.e. not private methods, not static methods, 650 // not default methods (concrete interface methods), not overpass methods. 651 // If a given class already has a local (including overpass) method, a 652 // default method, or any of its superclasses has the same which would have 653 // overridden an abstract method, then this is not a miranda method. 654 // 655 // Miranda methods are checked multiple times. 656 // Pass 1: during class load/class file parsing: before vtable size calculation: 657 // include superinterface abstract and default methods (non-private instance). 658 // We include potential default methods to give them space in the vtable. 659 // During the first run, the current instanceKlass has not yet been 660 // created, the superclasses and superinterfaces do have instanceKlasses 661 // but may not have vtables, the default_methods list is empty, no overpasses. 662 // This is seen by default method creation. 663 // 664 // Pass 2: recalculated during vtable initialization: only include abstract methods. 665 // The goal of pass 2 is to walk through the superinterfaces to see if any of 666 // the superinterface methods (which were all abstract pre-default methods) 667 // need to be added to the vtable. 668 // With the addition of default methods, we have three new challenges: 669 // overpasses, static interface methods and private interface methods. 670 // Static and private interface methods do not get added to the vtable and 671 // are not seen by the method resolution process, so we skip those. 672 // Overpass methods are already in the vtable, so vtable lookup will 673 // find them and we don't need to add a miranda method to the end of 674 // the vtable. So we look for overpass methods and if they are found we 675 // return false. Note that we inherit our superclasses vtable, so 676 // the superclass' search also needs to use find_overpass so that if 677 // one is found we return false. 678 // False means - we don't need a miranda method added to the vtable. 679 // 680 // During the second run, default_methods is set up, so concrete methods from 681 // superinterfaces with matching names/signatures to default_methods are already 682 // in the default_methods list and do not need to be appended to the vtable 683 // as mirandas. Abstract methods may already have been handled via 684 // overpasses - either local or superclass overpasses, which may be 685 // in the vtable already. 686 // 687 // Pass 3: They are also checked by link resolution and selection, 688 // for invocation on a method (not interface method) reference that 689 // resolves to a method with an interface as its method_holder. 690 // Used as part of walking from the bottom of the vtable to find 691 // the vtable index for the miranda method. 692 // 693 // Part of the Miranda Rights in the US mean that if you do not have 694 // an attorney one will be appointed for you. 695 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 696 Array<Method*>* default_methods, Klass* super) { 697 if (m->is_static() || m->is_private() || m->is_overpass()) { 698 return false; 699 } 700 Symbol* name = m->name(); 701 Symbol* signature = m->signature(); 702 703 // First look in local methods to see if already covered 704 if (InstanceKlass::find_local_method(class_methods, name, signature, 705 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 706 { 707 return false; 708 } 709 710 // Check local default methods 711 if ((default_methods != NULL) && 712 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 713 { 714 return false; 715 } 716 717 // Iterate on all superclasses, which should be InstanceKlasses. 718 // Note that we explicitly look for overpasses at each level. 719 // Overpasses may or may not exist for supers for pass 1, 720 // they should have been created for pass 2 and later. 721 722 for (Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 723 { 724 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature, 725 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) { 726 return false; 727 } 728 } 729 730 return true; 731 } 732 733 // Scans current_interface_methods for miranda methods that do not 734 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 735 // in super (superclass). These mirandas are added to all_mirandas if it is 736 // not null; in addition, those that are not duplicates of miranda methods 737 // inherited by super from its interfaces are added to new_mirandas. 738 // Thus, new_mirandas will be the set of mirandas that this class introduces, 739 // all_mirandas will be the set of all mirandas applicable to this class 740 // including all defined in superclasses. 741 void klassVtable::add_new_mirandas_to_lists( 742 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 743 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 744 Array<Method*>* default_methods, Klass* super) { 745 746 // iterate thru the current interface's method to see if it a miranda 747 int num_methods = current_interface_methods->length(); 748 for (int i = 0; i < num_methods; i++) { 749 Method* im = current_interface_methods->at(i); 750 bool is_duplicate = false; 751 int num_of_current_mirandas = new_mirandas->length(); 752 // check for duplicate mirandas in different interfaces we implement 753 for (int j = 0; j < num_of_current_mirandas; j++) { 754 Method* miranda = new_mirandas->at(j); 755 if ((im->name() == miranda->name()) && 756 (im->signature() == miranda->signature())) { 757 is_duplicate = true; 758 break; 759 } 760 } 761 762 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 763 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 764 InstanceKlass *sk = InstanceKlass::cast(super); 765 // check if it is a duplicate of a super's miranda 766 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 767 new_mirandas->append(im); 768 } 769 if (all_mirandas != NULL) { 770 all_mirandas->append(im); 771 } 772 } 773 } 774 } 775 } 776 777 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 778 GrowableArray<Method*>* all_mirandas, 779 Klass* super, Array<Method*>* class_methods, 780 Array<Method*>* default_methods, 781 Array<Klass*>* local_interfaces) { 782 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 783 784 // iterate thru the local interfaces looking for a miranda 785 int num_local_ifs = local_interfaces->length(); 786 for (int i = 0; i < num_local_ifs; i++) { 787 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 788 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 789 ik->methods(), class_methods, 790 default_methods, super); 791 // iterate thru each local's super interfaces 792 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 793 int num_super_ifs = super_ifs->length(); 794 for (int j = 0; j < num_super_ifs; j++) { 795 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 796 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 797 sik->methods(), class_methods, 798 default_methods, super); 799 } 800 } 801 } 802 803 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 804 // and append them into the vtable starting at index initialized, 805 // return the new value of initialized. 806 // Miranda methods use vtable entries, but do not get assigned a vtable_index 807 // The vtable_index is discovered by searching from the end of the vtable 808 int klassVtable::fill_in_mirandas(int initialized) { 809 GrowableArray<Method*> mirandas(20); 810 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 811 ik()->default_methods(), ik()->local_interfaces()); 812 for (int i = 0; i < mirandas.length(); i++) { 813 if (develop_log_is_enabled(Trace, vtables)) { 814 Method* meth = mirandas.at(i); 815 ResourceMark rm(Thread::current()); 816 outputStream* logst = LogHandle(vtables)::trace_stream(); 817 if (meth != NULL) { 818 char* sig = meth->name_and_sig_as_C_string(); 819 logst->print("fill in mirandas with %s index %d, flags: ", 820 sig, initialized); 821 meth->print_linkage_flags(logst); 822 logst->cr(); 823 } 824 } 825 put_method_at(mirandas.at(i), initialized); 826 ++initialized; 827 } 828 return initialized; 829 } 830 831 // Copy this class's vtable to the vtable beginning at start. 832 // Used to copy superclass vtable to prefix of subclass's vtable. 833 void klassVtable::copy_vtable_to(vtableEntry* start) { 834 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 835 } 836 837 #if INCLUDE_JVMTI 838 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 839 // If old_method is default, find this vtable index in default_vtable_indices 840 // and replace that method in the _default_methods list 841 bool updated = false; 842 843 Array<Method*>* default_methods = ik()->default_methods(); 844 if (default_methods != NULL) { 845 int len = default_methods->length(); 846 for (int idx = 0; idx < len; idx++) { 847 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 848 if (default_methods->at(idx) == old_method) { 849 default_methods->at_put(idx, new_method); 850 updated = true; 851 } 852 break; 853 } 854 } 855 } 856 return updated; 857 } 858 859 // search the vtable for uses of either obsolete or EMCP methods 860 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 861 int prn_enabled = 0; 862 for (int index = 0; index < length(); index++) { 863 Method* old_method = unchecked_method_at(index); 864 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 865 continue; // skip uninteresting entries 866 } 867 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 868 869 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 870 871 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 872 assert(old_method != new_method, "sanity check"); 873 874 put_method_at(new_method, index); 875 // For default methods, need to update the _default_methods array 876 // which can only have one method entry for a given signature 877 bool updated_default = false; 878 if (old_method->is_default_method()) { 879 updated_default = adjust_default_method(index, old_method, new_method); 880 } 881 882 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 883 if (!(*trace_name_printed)) { 884 // RC_TRACE_MESG macro has an embedded ResourceMark 885 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s", 886 klass()->external_name(), 887 old_method->method_holder()->external_name())); 888 *trace_name_printed = true; 889 } 890 // RC_TRACE macro has an embedded ResourceMark 891 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s", 892 new_method->name()->as_C_string(), 893 new_method->signature()->as_C_string(), 894 updated_default ? "true" : "false")); 895 } 896 } 897 } 898 899 // a vtable should never contain old or obsolete methods 900 bool klassVtable::check_no_old_or_obsolete_entries() { 901 for (int i = 0; i < length(); i++) { 902 Method* m = unchecked_method_at(i); 903 if (m != NULL && 904 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 905 return false; 906 } 907 } 908 return true; 909 } 910 911 void klassVtable::dump_vtable() { 912 tty->print_cr("vtable dump --"); 913 for (int i = 0; i < length(); i++) { 914 Method* m = unchecked_method_at(i); 915 if (m != NULL) { 916 tty->print(" (%5d) ", i); 917 m->access_flags().print_on(tty); 918 if (m->is_default_method()) { 919 tty->print("default "); 920 } 921 if (m->is_overpass()) { 922 tty->print("overpass"); 923 } 924 tty->print(" -- "); 925 m->print_name(tty); 926 tty->cr(); 927 } 928 } 929 } 930 #endif // INCLUDE_JVMTI 931 932 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 933 void klassVtable::clear_vtable() { 934 for (int i = 0; i < _length; i++) table()[i].clear(); 935 } 936 937 bool klassVtable::is_initialized() { 938 return _length == 0 || table()[0].method() != NULL; 939 } 940 941 //----------------------------------------------------------------------------------------- 942 // Itable code 943 944 // Initialize a itableMethodEntry 945 void itableMethodEntry::initialize(Method* m) { 946 if (m == NULL) return; 947 948 _method = m; 949 } 950 951 klassItable::klassItable(instanceKlassHandle klass) { 952 _klass = klass; 953 954 if (klass->itable_length() > 0) { 955 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 956 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 957 // First offset entry points to the first method_entry 958 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); 959 intptr_t* end = klass->end_of_itable(); 960 961 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); 962 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 963 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 964 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 965 return; 966 } 967 } 968 969 // The length of the itable was either zero, or it has not yet been initialized. 970 _table_offset = 0; 971 _size_offset_table = 0; 972 _size_method_table = 0; 973 } 974 975 static int initialize_count = 0; 976 977 // Initialization 978 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 979 if (_klass->is_interface()) { 980 // This needs to go after vtable indices are assigned but 981 // before implementors need to know the number of itable indices. 982 assign_itable_indices_for_interface(_klass()); 983 } 984 985 // Cannot be setup doing bootstrapping, interfaces don't have 986 // itables, and klass with only ones entry have empty itables 987 if (Universe::is_bootstrapping() || 988 _klass->is_interface() || 989 _klass->itable_length() == itableOffsetEntry::size()) return; 990 991 // There's alway an extra itable entry so we can null-terminate it. 992 guarantee(size_offset_table() >= 1, "too small"); 993 int num_interfaces = size_offset_table() - 1; 994 if (num_interfaces > 0) { 995 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 996 _klass->name()->as_C_string()); 997 998 999 // Iterate through all interfaces 1000 int i; 1001 for(i = 0; i < num_interfaces; i++) { 1002 itableOffsetEntry* ioe = offset_entry(i); 1003 HandleMark hm(THREAD); 1004 KlassHandle interf_h (THREAD, ioe->interface_klass()); 1005 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1006 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); 1007 } 1008 1009 } 1010 // Check that the last entry is empty 1011 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1012 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1013 } 1014 1015 1016 inline bool interface_method_needs_itable_index(Method* m) { 1017 if (m->is_static()) return false; // e.g., Stream.empty 1018 if (m->is_initializer()) return false; // <init> or <clinit> 1019 // If an interface redeclares a method from java.lang.Object, 1020 // it should already have a vtable index, don't touch it. 1021 // e.g., CharSequence.toString (from initialize_vtable) 1022 // if (m->has_vtable_index()) return false; // NO! 1023 return true; 1024 } 1025 1026 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1027 // an interface does not have an itable, but its methods need to be numbered 1028 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1029 ++initialize_count, klass->name()->as_C_string()); 1030 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1031 int nof_methods = methods->length(); 1032 int ime_num = 0; 1033 for (int i = 0; i < nof_methods; i++) { 1034 Method* m = methods->at(i); 1035 if (interface_method_needs_itable_index(m)) { 1036 assert(!m->is_final_method(), "no final interface methods"); 1037 // If m is already assigned a vtable index, do not disturb it. 1038 if (develop_log_is_enabled(Trace, itables)) { 1039 ResourceMark rm; 1040 outputStream* logst = LogHandle(itables)::trace_stream(); 1041 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 1042 if (m->has_vtable_index()) { 1043 logst->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1044 } else { 1045 logst->print("itable index %d for method: %s, flags: ", ime_num, sig); 1046 } 1047 m->print_linkage_flags(logst); 1048 logst->cr(); 1049 } 1050 if (!m->has_vtable_index()) { 1051 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable"); 1052 m->set_itable_index(ime_num); 1053 // Progress to next itable entry 1054 ime_num++; 1055 } 1056 } 1057 } 1058 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1059 return ime_num; 1060 } 1061 1062 int klassItable::method_count_for_interface(Klass* interf) { 1063 assert(interf->is_instance_klass(), "must be"); 1064 assert(interf->is_interface(), "must be"); 1065 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1066 int nof_methods = methods->length(); 1067 int length = 0; 1068 while (nof_methods > 0) { 1069 Method* m = methods->at(nof_methods-1); 1070 if (m->has_itable_index()) { 1071 length = m->itable_index() + 1; 1072 break; 1073 } 1074 nof_methods -= 1; 1075 } 1076 #ifdef ASSERT 1077 int nof_methods_copy = nof_methods; 1078 while (nof_methods_copy > 0) { 1079 Method* mm = methods->at(--nof_methods_copy); 1080 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1081 } 1082 #endif //ASSERT 1083 // return the rightmost itable index, plus one; or 0 if no methods have 1084 // itable indices 1085 return length; 1086 } 1087 1088 1089 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { 1090 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods(); 1091 int nof_methods = methods->length(); 1092 HandleMark hm; 1093 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1094 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); 1095 1096 int ime_count = method_count_for_interface(interf_h()); 1097 for (int i = 0; i < nof_methods; i++) { 1098 Method* m = methods->at(i); 1099 methodHandle target; 1100 if (m->has_itable_index()) { 1101 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1102 // to correctly enforce loader constraints for interface method inheritance 1103 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1104 } 1105 if (target == NULL || !target->is_public() || target->is_abstract()) { 1106 // Entry does not resolve. Leave it empty for AbstractMethodError. 1107 if (!(target == NULL) && !target->is_public()) { 1108 // Stuff an IllegalAccessError throwing method in there instead. 1109 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()]. 1110 initialize(Universe::throw_illegal_access_error()); 1111 } 1112 } else { 1113 // Entry did resolve, check loader constraints before initializing 1114 // if checkconstraints requested 1115 if (checkconstraints) { 1116 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1117 if (method_holder_loader() != interface_loader()) { 1118 ResourceMark rm(THREAD); 1119 Symbol* failed_type_symbol = 1120 SystemDictionary::check_signature_loaders(m->signature(), 1121 method_holder_loader, 1122 interface_loader, 1123 true, CHECK); 1124 if (failed_type_symbol != NULL) { 1125 const char* msg = "loader constraint violation in interface " 1126 "itable initialization: when resolving method \"%s\" the class" 1127 " loader (instance of %s) of the current class, %s, " 1128 "and the class loader (instance of %s) for interface " 1129 "%s have different Class objects for the type %s " 1130 "used in the signature"; 1131 char* sig = target()->name_and_sig_as_C_string(); 1132 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 1133 char* current = _klass->name()->as_C_string(); 1134 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 1135 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); 1136 char* failed_type_name = failed_type_symbol->as_C_string(); 1137 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 1138 strlen(current) + strlen(loader2) + strlen(iface) + 1139 strlen(failed_type_name); 1140 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1141 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 1142 iface, failed_type_name); 1143 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1144 } 1145 } 1146 } 1147 1148 // ime may have moved during GC so recalculate address 1149 int ime_num = m->itable_index(); 1150 assert(ime_num < ime_count, "oob"); 1151 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target()); 1152 if (develop_log_is_enabled(Trace, itables)) { 1153 ResourceMark rm(THREAD); 1154 if (target() != NULL) { 1155 outputStream* logst = LogHandle(itables)::trace_stream(); 1156 char* sig = target()->name_and_sig_as_C_string(); 1157 logst->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1158 interf_h()->internal_name(), ime_num, sig, 1159 target()->method_holder()->internal_name()); 1160 logst->print("target_method flags: "); 1161 target()->print_linkage_flags(logst); 1162 logst->cr(); 1163 } 1164 } 1165 } 1166 } 1167 } 1168 1169 // Update entry for specific Method* 1170 void klassItable::initialize_with_method(Method* m) { 1171 itableMethodEntry* ime = method_entry(0); 1172 for(int i = 0; i < _size_method_table; i++) { 1173 if (ime->method() == m) { 1174 ime->initialize(m); 1175 } 1176 ime++; 1177 } 1178 } 1179 1180 #if INCLUDE_JVMTI 1181 // search the itable for uses of either obsolete or EMCP methods 1182 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1183 1184 itableMethodEntry* ime = method_entry(0); 1185 for (int i = 0; i < _size_method_table; i++, ime++) { 1186 Method* old_method = ime->method(); 1187 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1188 continue; // skip uninteresting entries 1189 } 1190 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1191 1192 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1193 1194 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1195 assert(old_method != new_method, "sanity check"); 1196 1197 ime->initialize(new_method); 1198 1199 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 1200 if (!(*trace_name_printed)) { 1201 // RC_TRACE_MESG macro has an embedded ResourceMark 1202 RC_TRACE_MESG(("adjust: name=%s", 1203 old_method->method_holder()->external_name())); 1204 *trace_name_printed = true; 1205 } 1206 // RC_TRACE macro has an embedded ResourceMark 1207 RC_TRACE(0x00200000, ("itable method update: %s(%s)", 1208 new_method->name()->as_C_string(), 1209 new_method->signature()->as_C_string())); 1210 } 1211 } 1212 } 1213 1214 // an itable should never contain old or obsolete methods 1215 bool klassItable::check_no_old_or_obsolete_entries() { 1216 itableMethodEntry* ime = method_entry(0); 1217 for (int i = 0; i < _size_method_table; i++) { 1218 Method* m = ime->method(); 1219 if (m != NULL && 1220 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1221 return false; 1222 } 1223 ime++; 1224 } 1225 return true; 1226 } 1227 1228 void klassItable::dump_itable() { 1229 itableMethodEntry* ime = method_entry(0); 1230 tty->print_cr("itable dump --"); 1231 for (int i = 0; i < _size_method_table; i++) { 1232 Method* m = ime->method(); 1233 if (m != NULL) { 1234 tty->print(" (%5d) ", i); 1235 m->access_flags().print_on(tty); 1236 if (m->is_default_method()) { 1237 tty->print("default "); 1238 } 1239 tty->print(" -- "); 1240 m->print_name(tty); 1241 tty->cr(); 1242 } 1243 ime++; 1244 } 1245 } 1246 #endif // INCLUDE_JVMTI 1247 1248 1249 // Setup 1250 class InterfaceVisiterClosure : public StackObj { 1251 public: 1252 virtual void doit(Klass* intf, int method_count) = 0; 1253 }; 1254 1255 // Visit all interfaces with at least one itable method 1256 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1257 // Handle array argument 1258 for(int i = 0; i < transitive_intf->length(); i++) { 1259 Klass* intf = transitive_intf->at(i); 1260 assert(intf->is_interface(), "sanity check"); 1261 1262 // Find no. of itable methods 1263 int method_count = 0; 1264 // method_count = klassItable::method_count_for_interface(intf); 1265 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1266 if (methods->length() > 0) { 1267 for (int i = methods->length(); --i >= 0; ) { 1268 if (interface_method_needs_itable_index(methods->at(i))) { 1269 method_count++; 1270 } 1271 } 1272 } 1273 1274 // Only count interfaces with at least one method 1275 if (method_count > 0) { 1276 blk->doit(intf, method_count); 1277 } 1278 } 1279 } 1280 1281 class CountInterfacesClosure : public InterfaceVisiterClosure { 1282 private: 1283 int _nof_methods; 1284 int _nof_interfaces; 1285 public: 1286 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1287 1288 int nof_methods() const { return _nof_methods; } 1289 int nof_interfaces() const { return _nof_interfaces; } 1290 1291 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1292 }; 1293 1294 class SetupItableClosure : public InterfaceVisiterClosure { 1295 private: 1296 itableOffsetEntry* _offset_entry; 1297 itableMethodEntry* _method_entry; 1298 address _klass_begin; 1299 public: 1300 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1301 _klass_begin = klass_begin; 1302 _offset_entry = offset_entry; 1303 _method_entry = method_entry; 1304 } 1305 1306 itableMethodEntry* method_entry() const { return _method_entry; } 1307 1308 void doit(Klass* intf, int method_count) { 1309 int offset = ((address)_method_entry) - _klass_begin; 1310 _offset_entry->initialize(intf, offset); 1311 _offset_entry++; 1312 _method_entry += method_count; 1313 } 1314 }; 1315 1316 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1317 // Count no of interfaces and total number of interface methods 1318 CountInterfacesClosure cic; 1319 visit_all_interfaces(transitive_interfaces, &cic); 1320 1321 // There's alway an extra itable entry so we can null-terminate it. 1322 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1323 1324 // Statistics 1325 update_stats(itable_size * HeapWordSize); 1326 1327 return itable_size; 1328 } 1329 1330 1331 // Fill out offset table and interface klasses into the itable space 1332 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { 1333 if (klass->itable_length() == 0) return; 1334 assert(!klass->is_interface(), "Should have zero length itable"); 1335 1336 // Count no of interfaces and total number of interface methods 1337 CountInterfacesClosure cic; 1338 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1339 int nof_methods = cic.nof_methods(); 1340 int nof_interfaces = cic.nof_interfaces(); 1341 1342 // Add one extra entry so we can null-terminate the table 1343 nof_interfaces++; 1344 1345 assert(compute_itable_size(klass->transitive_interfaces()) == 1346 calc_itable_size(nof_interfaces, nof_methods), 1347 "mismatch calculation of itable size"); 1348 1349 // Fill-out offset table 1350 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1351 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1352 intptr_t* end = klass->end_of_itable(); 1353 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1354 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1355 1356 // Visit all interfaces and initialize itable offset table 1357 SetupItableClosure sic((address)klass(), ioe, ime); 1358 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1359 1360 #ifdef ASSERT 1361 ime = sic.method_entry(); 1362 oop* v = (oop*) klass->end_of_itable(); 1363 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1364 #endif 1365 } 1366 1367 1368 // inverse to itable_index 1369 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1370 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1371 assert(intf->verify_itable_index(itable_index), ""); 1372 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1373 1374 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1375 return NULL; // help caller defend against bad indices 1376 1377 int index = itable_index; 1378 Method* m = methods->at(index); 1379 int index2 = -1; 1380 while (!m->has_itable_index() || 1381 (index2 = m->itable_index()) != itable_index) { 1382 assert(index2 < itable_index, "monotonic"); 1383 if (++index == methods->length()) 1384 return NULL; 1385 m = methods->at(index); 1386 } 1387 assert(m->itable_index() == itable_index, "correct inverse"); 1388 1389 return m; 1390 } 1391 1392 void klassVtable::verify(outputStream* st, bool forced) { 1393 // make sure table is initialized 1394 if (!Universe::is_fully_initialized()) return; 1395 #ifndef PRODUCT 1396 // avoid redundant verifies 1397 if (!forced && _verify_count == Universe::verify_count()) return; 1398 _verify_count = Universe::verify_count(); 1399 #endif 1400 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 1401 oop* end_of_vtable = (oop *)&table()[_length]; 1402 if (end_of_vtable > end_of_obj) { 1403 fatal("klass %s: klass object too short (vtable extends beyond end)", 1404 _klass->internal_name()); 1405 } 1406 1407 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1408 // verify consistency with superKlass vtable 1409 Klass* super = _klass->super(); 1410 if (super != NULL) { 1411 InstanceKlass* sk = InstanceKlass::cast(super); 1412 klassVtable* vt = sk->vtable(); 1413 for (int i = 0; i < vt->length(); i++) { 1414 verify_against(st, vt, i); 1415 } 1416 } 1417 } 1418 1419 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1420 vtableEntry* vte = &vt->table()[index]; 1421 if (vte->method()->name() != table()[index].method()->name() || 1422 vte->method()->signature() != table()[index].method()->signature()) { 1423 fatal("mismatched name/signature of vtable entries"); 1424 } 1425 } 1426 1427 #ifndef PRODUCT 1428 void klassVtable::print() { 1429 ResourceMark rm; 1430 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1431 for (int i = 0; i < length(); i++) { 1432 table()[i].print(); 1433 tty->cr(); 1434 } 1435 } 1436 #endif 1437 1438 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1439 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1440 assert(method() != NULL, "must have set method"); 1441 method()->verify(); 1442 // we sub_type, because it could be a miranda method 1443 if (!vt->klass()->is_subtype_of(method()->method_holder())) { 1444 #ifndef PRODUCT 1445 print(); 1446 #endif 1447 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1448 } 1449 } 1450 1451 #ifndef PRODUCT 1452 1453 void vtableEntry::print() { 1454 ResourceMark rm; 1455 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1456 if (Verbose) { 1457 tty->print("m " PTR_FORMAT " ", p2i(method())); 1458 } 1459 } 1460 1461 class VtableStats : AllStatic { 1462 public: 1463 static int no_klasses; // # classes with vtables 1464 static int no_array_klasses; // # array classes 1465 static int no_instance_klasses; // # instanceKlasses 1466 static int sum_of_vtable_len; // total # of vtable entries 1467 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1468 static int fixed; // total fixed overhead in bytes 1469 static int filler; // overhead caused by filler bytes 1470 static int entries; // total bytes consumed by vtable entries 1471 static int array_entries; // total bytes consumed by array vtable entries 1472 1473 static void do_class(Klass* k) { 1474 Klass* kl = k; 1475 klassVtable* vt = kl->vtable(); 1476 if (vt == NULL) return; 1477 no_klasses++; 1478 if (kl->is_instance_klass()) { 1479 no_instance_klasses++; 1480 kl->array_klasses_do(do_class); 1481 } 1482 if (kl->is_array_klass()) { 1483 no_array_klasses++; 1484 sum_of_array_vtable_len += vt->length(); 1485 } 1486 sum_of_vtable_len += vt->length(); 1487 } 1488 1489 static void compute() { 1490 SystemDictionary::classes_do(do_class); 1491 fixed = no_klasses * oopSize; // vtable length 1492 // filler size is a conservative approximation 1493 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1494 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1495 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1496 } 1497 }; 1498 1499 int VtableStats::no_klasses = 0; 1500 int VtableStats::no_array_klasses = 0; 1501 int VtableStats::no_instance_klasses = 0; 1502 int VtableStats::sum_of_vtable_len = 0; 1503 int VtableStats::sum_of_array_vtable_len = 0; 1504 int VtableStats::fixed = 0; 1505 int VtableStats::filler = 0; 1506 int VtableStats::entries = 0; 1507 int VtableStats::array_entries = 0; 1508 1509 void klassVtable::print_statistics() { 1510 ResourceMark rm; 1511 HandleMark hm; 1512 VtableStats::compute(); 1513 tty->print_cr("vtable statistics:"); 1514 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1515 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1516 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1517 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1518 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1519 tty->print_cr("%6d bytes total", total); 1520 } 1521 1522 int klassItable::_total_classes; // Total no. of classes with itables 1523 long klassItable::_total_size; // Total no. of bytes used for itables 1524 1525 void klassItable::print_statistics() { 1526 tty->print_cr("itable statistics:"); 1527 tty->print_cr("%6d classes with itables", _total_classes); 1528 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes); 1529 } 1530 1531 #endif // PRODUCT