1 /* 2 * Copyright (c) 1997, 2018, 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 "jvm.h" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "interpreter/linkResolver.hpp" 31 #include "logging/log.hpp" 32 #include "logging/logStream.hpp" 33 #include "memory/metaspaceShared.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "memory/universe.hpp" 36 #include "oops/instanceKlass.hpp" 37 #include "oops/klassVtable.hpp" 38 #include "oops/method.hpp" 39 #include "oops/objArrayOop.hpp" 40 #include "oops/oop.inline.hpp" 41 #include "runtime/arguments.hpp" 42 #include "runtime/flags/flagSetting.hpp" 43 #include "runtime/handles.inline.hpp" 44 #include "runtime/safepointVerifiers.hpp" 45 #include "utilities/copy.hpp" 46 47 inline InstanceKlass* klassVtable::ik() const { 48 return InstanceKlass::cast(_klass); 49 } 50 51 bool klassVtable::is_preinitialized_vtable() { 52 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite(); 53 } 54 55 56 // this function computes the vtable size (including the size needed for miranda 57 // methods) and the number of miranda methods in this class. 58 // Note on Miranda methods: Let's say there is a class C that implements 59 // interface I, and none of C's superclasses implements I. 60 // Let's say there is an abstract method m in I that neither C 61 // nor any of its super classes implement (i.e there is no method of any access, 62 // with the same name and signature as m), then m is a Miranda method which is 63 // entered as a public abstract method in C's vtable. From then on it should 64 // treated as any other public method in C for method over-ride purposes. 65 void klassVtable::compute_vtable_size_and_num_mirandas( 66 int* vtable_length_ret, int* num_new_mirandas, 67 GrowableArray<Method*>* all_mirandas, const Klass* super, 68 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 69 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 70 TRAPS) { 71 NoSafepointVerifier nsv; 72 73 // set up default result values 74 int vtable_length = 0; 75 76 // start off with super's vtable length 77 vtable_length = super == NULL ? 0 : super->vtable_length(); 78 79 // go thru each method in the methods table to see if it needs a new entry 80 int len = methods->length(); 81 for (int i = 0; i < len; i++) { 82 assert(methods->at(i)->is_method(), "must be a Method*"); 83 methodHandle mh(THREAD, methods->at(i)); 84 85 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) { 86 vtable_length += vtableEntry::size(); // we need a new entry 87 } 88 } 89 90 GrowableArray<Method*> new_mirandas(20); 91 // compute the number of mirandas methods that must be added to the end 92 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces, 93 class_flags.is_interface()); 94 *num_new_mirandas = new_mirandas.length(); 95 96 // Interfaces do not need interface methods in their vtables 97 // This includes miranda methods and during later processing, default methods 98 if (!class_flags.is_interface()) { 99 vtable_length += *num_new_mirandas * vtableEntry::size(); 100 } 101 102 if (Universe::is_bootstrapping() && vtable_length == 0) { 103 // array classes don't have their superclass set correctly during 104 // bootstrapping 105 vtable_length = Universe::base_vtable_size(); 106 } 107 108 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 109 if (Universe::is_bootstrapping()) { 110 // Someone is attempting to override java.lang.Object incorrectly on the 111 // bootclasspath. The JVM cannot recover from this error including throwing 112 // an exception 113 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 114 } else { 115 // Someone is attempting to redefine java.lang.Object incorrectly. The 116 // only way this should happen is from 117 // SystemDictionary::resolve_from_stream(), which will detect this later 118 // and throw a security exception. So don't assert here to let 119 // the exception occur. 120 vtable_length = Universe::base_vtable_size(); 121 } 122 } 123 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 124 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 125 126 *vtable_length_ret = vtable_length; 127 } 128 129 int klassVtable::index_of(Method* m, int len) const { 130 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 131 return m->vtable_index(); 132 } 133 134 // Copy super class's vtable to the first part (prefix) of this class's vtable, 135 // and return the number of entries copied. Expects that 'super' is the Java 136 // super class (arrays can have "array" super classes that must be skipped). 137 int klassVtable::initialize_from_super(Klass* super) { 138 if (super == NULL) { 139 return 0; 140 } else if (is_preinitialized_vtable()) { 141 // A shared class' vtable is preinitialized at dump time. No need to copy 142 // methods from super class for shared class, as that was already done 143 // during archiving time. However, if Jvmti has redefined a class, 144 // copy super class's vtable in case the super class has changed. 145 return super->vtable().length(); 146 } else { 147 // copy methods from superKlass 148 klassVtable superVtable = super->vtable(); 149 assert(superVtable.length() <= _length, "vtable too short"); 150 #ifdef ASSERT 151 superVtable.verify(tty, true); 152 #endif 153 superVtable.copy_vtable_to(table()); 154 if (log_develop_is_enabled(Trace, vtables)) { 155 ResourceMark rm; 156 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 157 super->internal_name(), klass()->internal_name(), 158 _length); 159 } 160 return superVtable.length(); 161 } 162 } 163 164 // 165 // Revised lookup semantics introduced 1.3 (Kestrel beta) 166 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 167 168 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 169 Klass* super = _klass->java_super(); 170 int nofNewEntries = 0; 171 172 bool is_shared = _klass->is_shared(); 173 174 if (!_klass->is_array_klass()) { 175 ResourceMark rm(THREAD); 176 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 177 } 178 179 #ifdef ASSERT 180 oop* end_of_obj = (oop*)_klass + _klass->size(); 181 oop* end_of_vtable = (oop*)&table()[_length]; 182 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 183 #endif 184 185 if (Universe::is_bootstrapping()) { 186 assert(!is_shared, "sanity"); 187 // just clear everything 188 for (int i = 0; i < _length; i++) table()[i].clear(); 189 return; 190 } 191 192 int super_vtable_len = initialize_from_super(super); 193 if (_klass->is_array_klass()) { 194 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 195 } else { 196 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 197 198 Array<Method*>* methods = ik()->methods(); 199 int len = methods->length(); 200 int initialized = super_vtable_len; 201 202 // Check each of this class's methods against super; 203 // if override, replace in copy of super vtable, otherwise append to end 204 for (int i = 0; i < len; i++) { 205 // update_inherited_vtable can stop for gc - ensure using handles 206 HandleMark hm(THREAD); 207 assert(methods->at(i)->is_method(), "must be a Method*"); 208 methodHandle mh(THREAD, methods->at(i)); 209 210 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 211 212 if (needs_new_entry) { 213 put_method_at(mh(), initialized); 214 mh()->set_vtable_index(initialized); // set primary vtable index 215 initialized++; 216 } 217 } 218 219 // update vtable with default_methods 220 Array<Method*>* default_methods = ik()->default_methods(); 221 if (default_methods != NULL) { 222 len = default_methods->length(); 223 if (len > 0) { 224 Array<int>* def_vtable_indices = NULL; 225 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 226 assert(!is_shared, "shared class def_vtable_indices does not exist"); 227 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 228 } else { 229 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 230 } 231 for (int i = 0; i < len; i++) { 232 HandleMark hm(THREAD); 233 assert(default_methods->at(i)->is_method(), "must be a Method*"); 234 methodHandle mh(THREAD, default_methods->at(i)); 235 assert(!mh->is_private(), "private interface method in the default method list"); 236 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 237 238 // needs new entry 239 if (needs_new_entry) { 240 put_method_at(mh(), initialized); 241 if (is_preinitialized_vtable()) { 242 // At runtime initialize_vtable is rerun for a shared class 243 // (loaded by the non-boot loader) as part of link_class_impl(). 244 // The dumptime vtable index should be the same as the runtime index. 245 assert(def_vtable_indices->at(i) == initialized, 246 "dump time vtable index is different from runtime index"); 247 } else { 248 def_vtable_indices->at_put(i, initialized); //set vtable index 249 } 250 initialized++; 251 } 252 } 253 } 254 } 255 256 // add miranda methods; it will also return the updated initialized 257 // Interfaces do not need interface methods in their vtables 258 // This includes miranda methods and during later processing, default methods 259 if (!ik()->is_interface()) { 260 initialized = fill_in_mirandas(initialized); 261 } 262 263 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 264 // package_private -> public/protected), the vtable might actually be smaller than our initial 265 // calculation, for classfile versions for which we do not do transitive override 266 // calculations. 267 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 268 assert(initialized == _length, "vtable initialization failed"); 269 } else { 270 assert(initialized <= _length, "vtable initialization failed"); 271 for(;initialized < _length; initialized++) { 272 table()[initialized].clear(); 273 } 274 } 275 NOT_PRODUCT(verify(tty, true)); 276 } 277 } 278 279 // Called for cases where a method does not override its superclass' vtable entry 280 // For bytecodes not produced by javac together it is possible that a method does not override 281 // the superclass's method, but might indirectly override a super-super class's vtable entry 282 // If none found, return a null superk, else return the superk of the method this does override 283 // For public and protected methods: if they override a superclass, they will 284 // also be overridden themselves appropriately. 285 // Private methods do not override and are not overridden. 286 // Package Private methods are trickier: 287 // e.g. P1.A, pub m 288 // P2.B extends A, package private m 289 // P1.C extends B, public m 290 // P1.C.m needs to override P1.A.m and can not override P2.B.m 291 // Therefore: all package private methods need their own vtable entries for 292 // them to be the root of an inheritance overriding decision 293 // Package private methods may also override other vtable entries 294 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, 295 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 296 InstanceKlass* superk = initialsuper; 297 while (superk != NULL && superk->super() != NULL) { 298 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 299 klassVtable ssVtable = supersuperklass->vtable(); 300 if (vtable_index < ssVtable.length()) { 301 Method* super_method = ssVtable.method_at(vtable_index); 302 #ifndef PRODUCT 303 Symbol* name= target_method()->name(); 304 Symbol* signature = target_method()->signature(); 305 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 306 #endif 307 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 308 if (log_develop_is_enabled(Trace, vtables)) { 309 ResourceMark rm(THREAD); 310 LogTarget(Trace, vtables) lt; 311 LogStream ls(lt); 312 char* sig = target_method()->name_and_sig_as_C_string(); 313 ls.print("transitive overriding superclass %s with %s index %d, original flags: ", 314 supersuperklass->internal_name(), 315 sig, vtable_index); 316 super_method->print_linkage_flags(&ls); 317 ls.print("overriders flags: "); 318 target_method->print_linkage_flags(&ls); 319 ls.cr(); 320 } 321 322 break; // return found superk 323 } 324 } else { 325 // super class has no vtable entry here, stop transitive search 326 superk = (InstanceKlass*)NULL; 327 break; 328 } 329 // if no override found yet, continue to search up 330 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 331 } 332 333 return superk; 334 } 335 336 static void log_vtables(int i, bool overrides, const methodHandle& target_method, 337 Klass* target_klass, Method* super_method, 338 Thread* thread) { 339 #ifndef PRODUCT 340 if (log_develop_is_enabled(Trace, vtables)) { 341 ResourceMark rm(thread); 342 LogTarget(Trace, vtables) lt; 343 LogStream ls(lt); 344 char* sig = target_method()->name_and_sig_as_C_string(); 345 if (overrides) { 346 ls.print("overriding with %s index %d, original flags: ", 347 sig, i); 348 } else { 349 ls.print("NOT overriding with %s index %d, original flags: ", 350 sig, i); 351 } 352 super_method->print_linkage_flags(&ls); 353 ls.print("overriders flags: "); 354 target_method->print_linkage_flags(&ls); 355 ls.cr(); 356 } 357 #endif 358 } 359 360 // Update child's copy of super vtable for overrides 361 // OR return true if a new vtable entry is required. 362 // Only called for InstanceKlass's, i.e. not for arrays 363 // If that changed, could not use _klass as handle for klass 364 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, 365 int super_vtable_len, int default_index, 366 bool checkconstraints, TRAPS) { 367 ResourceMark rm; 368 bool allocate_new = true; 369 assert(klass->is_instance_klass(), "must be InstanceKlass"); 370 371 Array<int>* def_vtable_indices = NULL; 372 bool is_default = false; 373 374 // default methods are non-private concrete methods in superinterfaces which are added 375 // to the vtable with their real method_holder. 376 // Since vtable and itable indices share the same storage, don't touch 377 // the default method's real vtable/itable index. 378 // default_vtable_indices stores the vtable value relative to this inheritor 379 if (default_index >= 0 ) { 380 is_default = true; 381 def_vtable_indices = klass->default_vtable_indices(); 382 assert(!target_method()->is_private(), "private interface method flagged as default"); 383 assert(def_vtable_indices != NULL, "def vtable alloc?"); 384 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 385 } else { 386 assert(klass == target_method()->method_holder(), "caller resp."); 387 // Initialize the method's vtable index to "nonvirtual". 388 // If we allocate a vtable entry, we will update it to a non-negative number. 389 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 390 } 391 392 // Static and <init> methods are never in 393 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 394 return false; 395 } 396 397 if (target_method->is_final_method(klass->access_flags())) { 398 // a final method never needs a new entry; final methods can be statically 399 // resolved and they have to be present in the vtable only if they override 400 // a super's method, in which case they re-use its entry 401 allocate_new = false; 402 } else if (klass->is_interface()) { 403 allocate_new = false; // see note below in needs_new_vtable_entry 404 // An interface never allocates new vtable slots, only inherits old ones. 405 // This method will either be assigned its own itable index later, 406 // or be assigned an inherited vtable index in the loop below. 407 // default methods inherited by classes store their vtable indices 408 // in the inheritor's default_vtable_indices. 409 // default methods inherited by interfaces may already have a 410 // valid itable index, if so, don't change it. 411 // Overpass methods in an interface will be assigned an itable index later 412 // by an inheriting class. 413 // Private interface methods have no itable index and are always invoked nonvirtually, 414 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound() 415 // will return true. 416 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) { 417 target_method()->set_vtable_index(Method::pending_itable_index); 418 } 419 } 420 421 // we need a new entry if there is no superclass 422 Klass* super = klass->super(); 423 if (super == NULL) { 424 return allocate_new; 425 } 426 427 // private methods in classes always have a new entry in the vtable 428 // specification interpretation since classic has 429 // private methods not overriding 430 // JDK8 adds private methods in interfaces which require invokespecial 431 if (target_method()->is_private()) { 432 return allocate_new; 433 } 434 435 // search through the vtable and update overridden entries 436 // Since check_signature_loaders acquires SystemDictionary_lock 437 // which can block for gc, once we are in this loop, use handles 438 // For classfiles built with >= jdk7, we now look for transitive overrides 439 440 Symbol* name = target_method()->name(); 441 Symbol* signature = target_method()->signature(); 442 443 Klass* target_klass = target_method()->method_holder(); 444 if (target_klass == NULL) { 445 target_klass = _klass; 446 } 447 448 Handle target_loader(THREAD, target_klass->class_loader()); 449 450 Symbol* target_classname = target_klass->name(); 451 for(int i = 0; i < super_vtable_len; i++) { 452 Method* super_method; 453 if (is_preinitialized_vtable()) { 454 // If this is a shared class, the vtable is already in the final state (fully 455 // initialized). Need to look at the super's vtable. 456 klassVtable superVtable = super->vtable(); 457 super_method = superVtable.method_at(i); 458 } else { 459 super_method = method_at(i); 460 } 461 // Check if method name matches. Ignore match if klass is an interface and the 462 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4) 463 // This is safe because the method at this slot should never get invoked. 464 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.) 465 if (super_method->name() == name && super_method->signature() == signature && 466 (!_klass->is_interface() || 467 !SystemDictionary::is_nonpublic_Object_method(super_method))) { 468 469 // get super_klass for method_holder for the found method 470 InstanceKlass* super_klass = super_method->method_holder(); 471 472 // Whether the method is being overridden 473 bool overrides = false; 474 475 // private methods are also never overridden 476 if (!super_method->is_private() && 477 (is_default 478 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 479 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 480 && ((super_klass = find_transitive_override(super_klass, 481 target_method, i, target_loader, 482 target_classname, THREAD)) 483 != (InstanceKlass*)NULL))))) 484 { 485 // Package private methods always need a new entry to root their own 486 // overriding. They may also override other methods. 487 if (!target_method()->is_package_private()) { 488 allocate_new = false; 489 } 490 491 // Do not check loader constraints for overpass methods because overpass 492 // methods are created by the jvm to throw exceptions. 493 if (checkconstraints && !target_method()->is_overpass()) { 494 // Override vtable entry if passes loader constraint check 495 // if loader constraint checking requested 496 // No need to visit his super, since he and his super 497 // have already made any needed loader constraints. 498 // Since loader constraints are transitive, it is enough 499 // to link to the first super, and we get all the others. 500 Handle super_loader(THREAD, super_klass->class_loader()); 501 502 if (!oopDesc::equals(target_loader(), super_loader())) { 503 ResourceMark rm(THREAD); 504 Symbol* failed_type_symbol = 505 SystemDictionary::check_signature_loaders(signature, target_loader, 506 super_loader, true, 507 CHECK_(false)); 508 if (failed_type_symbol != NULL) { 509 const char* msg = "loader constraint violation for class %s: when selecting " 510 "overriding method %s the class loader %s of the " 511 "selected method's type %s, and the class loader %s for its super " 512 "type %s have different Class objects for the type %s used in the signature"; 513 const char* curr_class = klass->external_name(); 514 const char* method = target_method()->name_and_sig_as_C_string(); 515 const char* loader1 = java_lang_ClassLoader::describe_external(target_loader()); 516 const char* sel_class = target_klass->external_name(); 517 const char* loader2 = java_lang_ClassLoader::describe_external(super_loader()); 518 const char* super_class = super_klass->external_name(); 519 const char* failed_type_name = failed_type_symbol->as_klass_external_name(); 520 size_t buflen = strlen(msg) + strlen(curr_class) + strlen(method) + 521 strlen(loader1) + strlen(sel_class) + strlen(loader2) + 522 strlen(super_class) + strlen(failed_type_name); 523 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 524 jio_snprintf(buf, buflen, msg, curr_class, method, loader1, sel_class, loader2, 525 super_class, failed_type_name); 526 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 527 } 528 } 529 } 530 531 put_method_at(target_method(), i); 532 overrides = true; 533 if (!is_default) { 534 target_method()->set_vtable_index(i); 535 } else { 536 if (def_vtable_indices != NULL) { 537 if (is_preinitialized_vtable()) { 538 // At runtime initialize_vtable is rerun as part of link_class_impl() 539 // for a shared class loaded by the non-boot loader. 540 // The dumptime vtable index should be the same as the runtime index. 541 assert(def_vtable_indices->at(default_index) == i, 542 "dump time vtable index is different from runtime index"); 543 } else { 544 def_vtable_indices->at_put(default_index, i); 545 } 546 } 547 assert(super_method->is_default_method() || super_method->is_overpass() 548 || super_method->is_abstract(), "default override error"); 549 } 550 } else { 551 overrides = false; 552 } 553 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD); 554 } 555 } 556 return allocate_new; 557 } 558 559 void klassVtable::put_method_at(Method* m, int index) { 560 if (is_preinitialized_vtable()) { 561 // At runtime initialize_vtable is rerun as part of link_class_impl() 562 // for shared class loaded by the non-boot loader to obtain the loader 563 // constraints based on the runtime classloaders' context. The dumptime 564 // method at the vtable index should be the same as the runtime method. 565 assert(table()[index].method() == m, 566 "archived method is different from the runtime method"); 567 } else { 568 if (log_develop_is_enabled(Trace, vtables)) { 569 ResourceMark rm; 570 LogTarget(Trace, vtables) lt; 571 LogStream ls(lt); 572 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 573 ls.print("adding %s at index %d, flags: ", sig, index); 574 if (m != NULL) { 575 m->print_linkage_flags(&ls); 576 } 577 ls.cr(); 578 } 579 table()[index].set(m); 580 } 581 } 582 583 // Find out if a method "m" with superclass "super", loader "classloader" and 584 // name "classname" needs a new vtable entry. Let P be a class package defined 585 // by "classloader" and "classname". 586 // NOTE: The logic used here is very similar to the one used for computing 587 // the vtables indices for a method. We cannot directly use that function because, 588 // we allocate the InstanceKlass at load time, and that requires that the 589 // superclass has been loaded. 590 // However, the vtable entries are filled in at link time, and therefore 591 // the superclass' vtable may not yet have been filled in. 592 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method, 593 const Klass* super, 594 Handle classloader, 595 Symbol* classname, 596 AccessFlags class_flags, 597 u2 major_version, 598 TRAPS) { 599 if (class_flags.is_interface()) { 600 // Interfaces do not use vtables, except for java.lang.Object methods, 601 // so there is no point to assigning 602 // a vtable index to any of their local methods. If we refrain from doing this, 603 // we can use Method::_vtable_index to hold the itable index 604 return false; 605 } 606 607 if (target_method->is_final_method(class_flags) || 608 // a final method never needs a new entry; final methods can be statically 609 // resolved and they have to be present in the vtable only if they override 610 // a super's method, in which case they re-use its entry 611 (target_method()->is_static()) || 612 // static methods don't need to be in vtable 613 (target_method()->name() == vmSymbols::object_initializer_name()) 614 // <init> is never called dynamically-bound 615 ) { 616 return false; 617 } 618 619 // Concrete interface methods do not need new entries, they override 620 // abstract method entries using default inheritance rules 621 if (target_method()->method_holder() != NULL && 622 target_method()->method_holder()->is_interface() && 623 !target_method()->is_abstract()) { 624 assert(target_method()->is_default_method() || target_method()->is_private(), 625 "unexpected interface method type"); 626 return false; 627 } 628 629 // we need a new entry if there is no superclass 630 if (super == NULL) { 631 return true; 632 } 633 634 // private methods in classes always have a new entry in the vtable. 635 // Specification interpretation since classic has private methods not overriding. 636 if (target_method()->is_private()) { 637 return true; 638 } 639 640 // Package private methods always need a new entry to root their own 641 // overriding. This allows transitive overriding to work. 642 if (target_method()->is_package_private()) { 643 return true; 644 } 645 646 // search through the super class hierarchy to see if we need 647 // a new entry 648 ResourceMark rm; 649 Symbol* name = target_method()->name(); 650 Symbol* signature = target_method()->signature(); 651 const Klass* k = super; 652 Method* super_method = NULL; 653 InstanceKlass *holder = NULL; 654 Method* recheck_method = NULL; 655 while (k != NULL) { 656 // lookup through the hierarchy for a method with matching name and sign. 657 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 658 if (super_method == NULL) { 659 break; // we still have to search for a matching miranda method 660 } 661 // get the class holding the matching method 662 // make sure you use that class for is_override 663 InstanceKlass* superk = super_method->method_holder(); 664 // we want only instance method matches 665 // pretend private methods are not in the super vtable 666 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 667 // ignore private, c.m pub does override a.m pub 668 // For classes that were not javac'd together, we also do transitive overriding around 669 // methods that have less accessibility 670 if ((!super_method->is_static()) && 671 (!super_method->is_private())) { 672 if (superk->is_override(super_method, classloader, classname, THREAD)) { 673 return false; 674 // else keep looking for transitive overrides 675 } 676 } 677 678 // Start with lookup result and continue to search up, for versions supporting transitive override 679 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 680 k = superk->super(); // haven't found an override match yet; continue to look 681 } else { 682 break; 683 } 684 } 685 686 // if the target method is public or protected it may have a matching 687 // miranda method in the super, whose entry it should re-use. 688 // Actually, to handle cases that javac would not generate, we need 689 // this check for all access permissions. 690 const InstanceKlass *sk = InstanceKlass::cast(super); 691 if (sk->has_miranda_methods()) { 692 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 693 return false; // found a matching miranda; we do not need a new entry 694 } 695 } 696 return true; // found no match; we need a new entry 697 } 698 699 // Support for miranda methods 700 701 // get the vtable index of a miranda method with matching "name" and "signature" 702 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 703 // search from the bottom, might be faster 704 for (int i = (length() - 1); i >= 0; i--) { 705 Method* m = table()[i].method(); 706 if (is_miranda_entry_at(i) && 707 m->name() == name && m->signature() == signature) { 708 return i; 709 } 710 } 711 return Method::invalid_vtable_index; 712 } 713 714 // check if an entry at an index is miranda 715 // requires that method m at entry be declared ("held") by an interface. 716 bool klassVtable::is_miranda_entry_at(int i) { 717 Method* m = method_at(i); 718 Klass* method_holder = m->method_holder(); 719 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 720 721 // miranda methods are public abstract instance interface methods in a class's vtable 722 if (mhk->is_interface()) { 723 assert(m->is_public(), "should be public"); 724 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 725 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) { 726 return true; 727 } 728 } 729 return false; 730 } 731 732 // Check if a method is a miranda method, given a class's methods array, 733 // its default_method table and its super class. 734 // "Miranda" means an abstract non-private method that would not be 735 // overridden for the local class. 736 // A "miranda" method should only include non-private interface 737 // instance methods, i.e. not private methods, not static methods, 738 // not default methods (concrete interface methods), not overpass methods. 739 // If a given class already has a local (including overpass) method, a 740 // default method, or any of its superclasses has the same which would have 741 // overridden an abstract method, then this is not a miranda method. 742 // 743 // Miranda methods are checked multiple times. 744 // Pass 1: during class load/class file parsing: before vtable size calculation: 745 // include superinterface abstract and default methods (non-private instance). 746 // We include potential default methods to give them space in the vtable. 747 // During the first run, the current instanceKlass has not yet been 748 // created, the superclasses and superinterfaces do have instanceKlasses 749 // but may not have vtables, the default_methods list is empty, no overpasses. 750 // Default method generation uses the all_mirandas array as the starter set for 751 // maximally-specific default method calculation. So, for both classes and 752 // interfaces, it is necessary that the first pass will find all non-private 753 // interface instance methods, whether or not they are concrete. 754 // 755 // Pass 2: recalculated during vtable initialization: only include abstract methods. 756 // The goal of pass 2 is to walk through the superinterfaces to see if any of 757 // the superinterface methods (which were all abstract pre-default methods) 758 // need to be added to the vtable. 759 // With the addition of default methods, we have three new challenges: 760 // overpasses, static interface methods and private interface methods. 761 // Static and private interface methods do not get added to the vtable and 762 // are not seen by the method resolution process, so we skip those. 763 // Overpass methods are already in the vtable, so vtable lookup will 764 // find them and we don't need to add a miranda method to the end of 765 // the vtable. So we look for overpass methods and if they are found we 766 // return false. Note that we inherit our superclasses vtable, so 767 // the superclass' search also needs to use find_overpass so that if 768 // one is found we return false. 769 // False means - we don't need a miranda method added to the vtable. 770 // 771 // During the second run, default_methods is set up, so concrete methods from 772 // superinterfaces with matching names/signatures to default_methods are already 773 // in the default_methods list and do not need to be appended to the vtable 774 // as mirandas. Abstract methods may already have been handled via 775 // overpasses - either local or superclass overpasses, which may be 776 // in the vtable already. 777 // 778 // Pass 3: They are also checked by link resolution and selection, 779 // for invocation on a method (not interface method) reference that 780 // resolves to a method with an interface as its method_holder. 781 // Used as part of walking from the bottom of the vtable to find 782 // the vtable index for the miranda method. 783 // 784 // Part of the Miranda Rights in the US mean that if you do not have 785 // an attorney one will be appointed for you. 786 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 787 Array<Method*>* default_methods, const Klass* super, 788 bool is_interface) { 789 if (m->is_static() || m->is_private() || m->is_overpass()) { 790 return false; 791 } 792 Symbol* name = m->name(); 793 Symbol* signature = m->signature(); 794 795 // First look in local methods to see if already covered 796 if (InstanceKlass::find_local_method(class_methods, name, signature, 797 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 798 { 799 return false; 800 } 801 802 // Check local default methods 803 if ((default_methods != NULL) && 804 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 805 { 806 return false; 807 } 808 809 // Iterate on all superclasses, which should be InstanceKlasses. 810 // Note that we explicitly look for overpasses at each level. 811 // Overpasses may or may not exist for supers for pass 1, 812 // they should have been created for pass 2 and later. 813 814 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 815 { 816 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature, 817 Klass::find_overpass, Klass::skip_static, Klass::skip_private); 818 // Ignore non-public methods in java.lang.Object if klass is an interface. 819 if (found_mth != NULL && (!is_interface || 820 !SystemDictionary::is_nonpublic_Object_method(found_mth))) { 821 return false; 822 } 823 } 824 825 return true; 826 } 827 828 // Scans current_interface_methods for miranda methods that do not 829 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 830 // in super (superclass). These mirandas are added to all_mirandas if it is 831 // not null; in addition, those that are not duplicates of miranda methods 832 // inherited by super from its interfaces are added to new_mirandas. 833 // Thus, new_mirandas will be the set of mirandas that this class introduces, 834 // all_mirandas will be the set of all mirandas applicable to this class 835 // including all defined in superclasses. 836 void klassVtable::add_new_mirandas_to_lists( 837 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 838 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 839 Array<Method*>* default_methods, const Klass* super, bool is_interface) { 840 841 // iterate thru the current interface's method to see if it a miranda 842 int num_methods = current_interface_methods->length(); 843 for (int i = 0; i < num_methods; i++) { 844 Method* im = current_interface_methods->at(i); 845 bool is_duplicate = false; 846 int num_of_current_mirandas = new_mirandas->length(); 847 // check for duplicate mirandas in different interfaces we implement 848 for (int j = 0; j < num_of_current_mirandas; j++) { 849 Method* miranda = new_mirandas->at(j); 850 if ((im->name() == miranda->name()) && 851 (im->signature() == miranda->signature())) { 852 is_duplicate = true; 853 break; 854 } 855 } 856 857 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 858 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all? 859 const InstanceKlass *sk = InstanceKlass::cast(super); 860 // check if it is a duplicate of a super's miranda 861 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 862 new_mirandas->append(im); 863 } 864 if (all_mirandas != NULL) { 865 all_mirandas->append(im); 866 } 867 } 868 } 869 } 870 } 871 872 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 873 GrowableArray<Method*>* all_mirandas, 874 const Klass* super, 875 Array<Method*>* class_methods, 876 Array<Method*>* default_methods, 877 Array<Klass*>* local_interfaces, 878 bool is_interface) { 879 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 880 881 // iterate thru the local interfaces looking for a miranda 882 int num_local_ifs = local_interfaces->length(); 883 for (int i = 0; i < num_local_ifs; i++) { 884 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 885 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 886 ik->methods(), class_methods, 887 default_methods, super, is_interface); 888 // iterate thru each local's super interfaces 889 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 890 int num_super_ifs = super_ifs->length(); 891 for (int j = 0; j < num_super_ifs; j++) { 892 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 893 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 894 sik->methods(), class_methods, 895 default_methods, super, is_interface); 896 } 897 } 898 } 899 900 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 901 // and append them into the vtable starting at index initialized, 902 // return the new value of initialized. 903 // Miranda methods use vtable entries, but do not get assigned a vtable_index 904 // The vtable_index is discovered by searching from the end of the vtable 905 int klassVtable::fill_in_mirandas(int initialized) { 906 GrowableArray<Method*> mirandas(20); 907 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 908 ik()->default_methods(), ik()->local_interfaces(), 909 klass()->is_interface()); 910 for (int i = 0; i < mirandas.length(); i++) { 911 if (log_develop_is_enabled(Trace, vtables)) { 912 Method* meth = mirandas.at(i); 913 ResourceMark rm(Thread::current()); 914 LogTarget(Trace, vtables) lt; 915 LogStream ls(lt); 916 if (meth != NULL) { 917 char* sig = meth->name_and_sig_as_C_string(); 918 ls.print("fill in mirandas with %s index %d, flags: ", 919 sig, initialized); 920 meth->print_linkage_flags(&ls); 921 ls.cr(); 922 } 923 } 924 put_method_at(mirandas.at(i), initialized); 925 ++initialized; 926 } 927 return initialized; 928 } 929 930 // Copy this class's vtable to the vtable beginning at start. 931 // Used to copy superclass vtable to prefix of subclass's vtable. 932 void klassVtable::copy_vtable_to(vtableEntry* start) { 933 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 934 } 935 936 #if INCLUDE_JVMTI 937 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 938 // If old_method is default, find this vtable index in default_vtable_indices 939 // and replace that method in the _default_methods list 940 bool updated = false; 941 942 Array<Method*>* default_methods = ik()->default_methods(); 943 if (default_methods != NULL) { 944 int len = default_methods->length(); 945 for (int idx = 0; idx < len; idx++) { 946 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 947 if (default_methods->at(idx) == old_method) { 948 default_methods->at_put(idx, new_method); 949 updated = true; 950 } 951 break; 952 } 953 } 954 } 955 return updated; 956 } 957 958 // search the vtable for uses of either obsolete or EMCP methods 959 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 960 int prn_enabled = 0; 961 for (int index = 0; index < length(); index++) { 962 Method* old_method = unchecked_method_at(index); 963 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 964 continue; // skip uninteresting entries 965 } 966 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 967 968 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 969 970 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 971 assert(old_method != new_method, "sanity check"); 972 973 put_method_at(new_method, index); 974 // For default methods, need to update the _default_methods array 975 // which can only have one method entry for a given signature 976 bool updated_default = false; 977 if (old_method->is_default_method()) { 978 updated_default = adjust_default_method(index, old_method, new_method); 979 } 980 981 if (log_is_enabled(Info, redefine, class, update)) { 982 ResourceMark rm; 983 if (!(*trace_name_printed)) { 984 log_info(redefine, class, update) 985 ("adjust: klassname=%s for methods from name=%s", 986 _klass->external_name(), old_method->method_holder()->external_name()); 987 *trace_name_printed = true; 988 } 989 log_debug(redefine, class, update, vtables) 990 ("vtable method update: %s(%s), updated default = %s", 991 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false"); 992 } 993 } 994 } 995 996 // a vtable should never contain old or obsolete methods 997 bool klassVtable::check_no_old_or_obsolete_entries() { 998 for (int i = 0; i < length(); i++) { 999 Method* m = unchecked_method_at(i); 1000 if (m != NULL && 1001 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1002 return false; 1003 } 1004 } 1005 return true; 1006 } 1007 1008 void klassVtable::dump_vtable() { 1009 tty->print_cr("vtable dump --"); 1010 for (int i = 0; i < length(); i++) { 1011 Method* m = unchecked_method_at(i); 1012 if (m != NULL) { 1013 tty->print(" (%5d) ", i); 1014 m->access_flags().print_on(tty); 1015 if (m->is_default_method()) { 1016 tty->print("default "); 1017 } 1018 if (m->is_overpass()) { 1019 tty->print("overpass"); 1020 } 1021 tty->print(" -- "); 1022 m->print_name(tty); 1023 tty->cr(); 1024 } 1025 } 1026 } 1027 #endif // INCLUDE_JVMTI 1028 1029 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 1030 void klassVtable::clear_vtable() { 1031 for (int i = 0; i < _length; i++) table()[i].clear(); 1032 } 1033 1034 bool klassVtable::is_initialized() { 1035 return _length == 0 || table()[0].method() != NULL; 1036 } 1037 1038 //----------------------------------------------------------------------------------------- 1039 // Itable code 1040 1041 // Initialize a itableMethodEntry 1042 void itableMethodEntry::initialize(Method* m) { 1043 if (m == NULL) return; 1044 1045 #ifdef ASSERT 1046 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) && 1047 !MetaspaceShared::remapped_readwrite()) { 1048 // At runtime initialize_itable is rerun as part of link_class_impl() 1049 // for a shared class loaded by the non-boot loader. 1050 // The dumptime itable method entry should be the same as the runtime entry. 1051 assert(_method == m, "sanity"); 1052 } 1053 #endif 1054 _method = m; 1055 } 1056 1057 klassItable::klassItable(InstanceKlass* klass) { 1058 _klass = klass; 1059 1060 if (klass->itable_length() > 0) { 1061 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1062 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1063 // First offset entry points to the first method_entry 1064 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1065 intptr_t* end = klass->end_of_itable(); 1066 1067 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1068 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1069 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1070 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1071 return; 1072 } 1073 } 1074 1075 // The length of the itable was either zero, or it has not yet been initialized. 1076 _table_offset = 0; 1077 _size_offset_table = 0; 1078 _size_method_table = 0; 1079 } 1080 1081 static int initialize_count = 0; 1082 1083 // Initialization 1084 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1085 if (_klass->is_interface()) { 1086 // This needs to go after vtable indices are assigned but 1087 // before implementors need to know the number of itable indices. 1088 assign_itable_indices_for_interface(_klass); 1089 } 1090 1091 // Cannot be setup doing bootstrapping, interfaces don't have 1092 // itables, and klass with only ones entry have empty itables 1093 if (Universe::is_bootstrapping() || 1094 _klass->is_interface() || 1095 _klass->itable_length() == itableOffsetEntry::size()) return; 1096 1097 // There's alway an extra itable entry so we can null-terminate it. 1098 guarantee(size_offset_table() >= 1, "too small"); 1099 int num_interfaces = size_offset_table() - 1; 1100 if (num_interfaces > 0) { 1101 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 1102 _klass->name()->as_C_string()); 1103 1104 1105 // Iterate through all interfaces 1106 int i; 1107 for(i = 0; i < num_interfaces; i++) { 1108 itableOffsetEntry* ioe = offset_entry(i); 1109 HandleMark hm(THREAD); 1110 Klass* interf = ioe->interface_klass(); 1111 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1112 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK); 1113 } 1114 1115 } 1116 // Check that the last entry is empty 1117 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1118 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1119 } 1120 1121 1122 inline bool interface_method_needs_itable_index(Method* m) { 1123 if (m->is_static()) return false; // e.g., Stream.empty 1124 if (m->is_initializer()) return false; // <init> or <clinit> 1125 if (m->is_private()) return false; // requires invokeSpecial 1126 // If an interface redeclares a method from java.lang.Object, 1127 // it should already have a vtable index, don't touch it. 1128 // e.g., CharSequence.toString (from initialize_vtable) 1129 // if (m->has_vtable_index()) return false; // NO! 1130 return true; 1131 } 1132 1133 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1134 // an interface does not have an itable, but its methods need to be numbered 1135 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1136 ++initialize_count, klass->name()->as_C_string()); 1137 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1138 int nof_methods = methods->length(); 1139 int ime_num = 0; 1140 for (int i = 0; i < nof_methods; i++) { 1141 Method* m = methods->at(i); 1142 if (interface_method_needs_itable_index(m)) { 1143 assert(!m->is_final_method(), "no final interface methods"); 1144 // If m is already assigned a vtable index, do not disturb it. 1145 if (log_develop_is_enabled(Trace, itables)) { 1146 ResourceMark rm; 1147 LogTarget(Trace, itables) lt; 1148 LogStream ls(lt); 1149 assert(m != NULL, "methods can never be null"); 1150 const char* sig = m->name_and_sig_as_C_string(); 1151 if (m->has_vtable_index()) { 1152 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1153 } else { 1154 ls.print("itable index %d for method: %s, flags: ", ime_num, sig); 1155 } 1156 m->print_linkage_flags(&ls); 1157 ls.cr(); 1158 } 1159 if (!m->has_vtable_index()) { 1160 // A shared method could have an initialized itable_index that 1161 // is < 0. 1162 assert(m->vtable_index() == Method::pending_itable_index || 1163 m->is_shared(), 1164 "set by initialize_vtable"); 1165 m->set_itable_index(ime_num); 1166 // Progress to next itable entry 1167 ime_num++; 1168 } 1169 } 1170 } 1171 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1172 return ime_num; 1173 } 1174 1175 int klassItable::method_count_for_interface(Klass* interf) { 1176 assert(interf->is_instance_klass(), "must be"); 1177 assert(interf->is_interface(), "must be"); 1178 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1179 int nof_methods = methods->length(); 1180 int length = 0; 1181 while (nof_methods > 0) { 1182 Method* m = methods->at(nof_methods-1); 1183 if (m->has_itable_index()) { 1184 length = m->itable_index() + 1; 1185 break; 1186 } 1187 nof_methods -= 1; 1188 } 1189 #ifdef ASSERT 1190 int nof_methods_copy = nof_methods; 1191 while (nof_methods_copy > 0) { 1192 Method* mm = methods->at(--nof_methods_copy); 1193 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1194 } 1195 #endif //ASSERT 1196 // return the rightmost itable index, plus one; or 0 if no methods have 1197 // itable indices 1198 return length; 1199 } 1200 1201 1202 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) { 1203 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1204 int nof_methods = methods->length(); 1205 HandleMark hm; 1206 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader()); 1207 1208 int ime_count = method_count_for_interface(interf); 1209 for (int i = 0; i < nof_methods; i++) { 1210 Method* m = methods->at(i); 1211 methodHandle target; 1212 if (m->has_itable_index()) { 1213 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1214 // to correctly enforce loader constraints for interface method inheritance 1215 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1216 } 1217 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) { 1218 assert(target == NULL || !target->is_overpass() || target->is_public(), 1219 "Non-public overpass method!"); 1220 // Entry does not resolve. Leave it empty for AbstractMethodError or other error. 1221 if (!(target == NULL) && !target->is_public()) { 1222 // Stuff an IllegalAccessError throwing method in there instead. 1223 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1224 initialize(Universe::throw_illegal_access_error()); 1225 } 1226 } else { 1227 // Entry did resolve, check loader constraints before initializing 1228 // if checkconstraints requested 1229 if (checkconstraints) { 1230 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1231 if (!oopDesc::equals(method_holder_loader(), interface_loader())) { 1232 ResourceMark rm(THREAD); 1233 Symbol* failed_type_symbol = 1234 SystemDictionary::check_signature_loaders(m->signature(), 1235 method_holder_loader, 1236 interface_loader, 1237 true, CHECK); 1238 if (failed_type_symbol != NULL) { 1239 const char* msg = "loader constraint violation in interface itable" 1240 " initialization for class %s: when selecting method %s the" 1241 " class loader %s for super interface %s, and the class" 1242 " loader %s of the selected method's type, %s have" 1243 " different Class objects for the type %s used in the signature"; 1244 const char* current = _klass->external_name(); 1245 const char* sig = m->name_and_sig_as_C_string(); 1246 const char* loader1 = java_lang_ClassLoader::describe_external(interface_loader()); 1247 const char* iface = InstanceKlass::cast(interf)->external_name(); 1248 const char* loader2 = java_lang_ClassLoader::describe_external(method_holder_loader()); 1249 const char* mclass = target()->method_holder()->external_name(); 1250 const char* failed_type_name = failed_type_symbol->as_klass_external_name(); 1251 size_t buflen = strlen(msg) + strlen(current) + strlen(sig) + 1252 strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) + 1253 strlen(failed_type_name); 1254 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1255 jio_snprintf(buf, buflen, msg, current, sig, loader1, iface, 1256 loader2, mclass, failed_type_name); 1257 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1258 } 1259 } 1260 } 1261 1262 // ime may have moved during GC so recalculate address 1263 int ime_num = m->itable_index(); 1264 assert(ime_num < ime_count, "oob"); 1265 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target()); 1266 if (log_develop_is_enabled(Trace, itables)) { 1267 ResourceMark rm(THREAD); 1268 if (target() != NULL) { 1269 LogTarget(Trace, itables) lt; 1270 LogStream ls(lt); 1271 char* sig = target()->name_and_sig_as_C_string(); 1272 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1273 interf->internal_name(), ime_num, sig, 1274 target()->method_holder()->internal_name()); 1275 ls.print("target_method flags: "); 1276 target()->print_linkage_flags(&ls); 1277 ls.cr(); 1278 } 1279 } 1280 } 1281 } 1282 } 1283 1284 #if INCLUDE_JVMTI 1285 // search the itable for uses of either obsolete or EMCP methods 1286 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1287 1288 itableMethodEntry* ime = method_entry(0); 1289 for (int i = 0; i < _size_method_table; i++, ime++) { 1290 Method* old_method = ime->method(); 1291 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1292 continue; // skip uninteresting entries 1293 } 1294 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1295 1296 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1297 1298 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1299 assert(old_method != new_method, "sanity check"); 1300 1301 ime->initialize(new_method); 1302 1303 if (log_is_enabled(Info, redefine, class, update)) { 1304 ResourceMark rm; 1305 if (!(*trace_name_printed)) { 1306 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1307 *trace_name_printed = true; 1308 } 1309 log_trace(redefine, class, update, itables) 1310 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string()); 1311 } 1312 } 1313 } 1314 1315 // an itable should never contain old or obsolete methods 1316 bool klassItable::check_no_old_or_obsolete_entries() { 1317 itableMethodEntry* ime = method_entry(0); 1318 for (int i = 0; i < _size_method_table; i++) { 1319 Method* m = ime->method(); 1320 if (m != NULL && 1321 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1322 return false; 1323 } 1324 ime++; 1325 } 1326 return true; 1327 } 1328 1329 void klassItable::dump_itable() { 1330 itableMethodEntry* ime = method_entry(0); 1331 tty->print_cr("itable dump --"); 1332 for (int i = 0; i < _size_method_table; i++) { 1333 Method* m = ime->method(); 1334 if (m != NULL) { 1335 tty->print(" (%5d) ", i); 1336 m->access_flags().print_on(tty); 1337 if (m->is_default_method()) { 1338 tty->print("default "); 1339 } 1340 tty->print(" -- "); 1341 m->print_name(tty); 1342 tty->cr(); 1343 } 1344 ime++; 1345 } 1346 } 1347 #endif // INCLUDE_JVMTI 1348 1349 // Setup 1350 class InterfaceVisiterClosure : public StackObj { 1351 public: 1352 virtual void doit(Klass* intf, int method_count) = 0; 1353 }; 1354 1355 // Visit all interfaces with at least one itable method 1356 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1357 // Handle array argument 1358 for(int i = 0; i < transitive_intf->length(); i++) { 1359 Klass* intf = transitive_intf->at(i); 1360 assert(intf->is_interface(), "sanity check"); 1361 1362 // Find no. of itable methods 1363 int method_count = 0; 1364 // method_count = klassItable::method_count_for_interface(intf); 1365 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1366 if (methods->length() > 0) { 1367 for (int i = methods->length(); --i >= 0; ) { 1368 if (interface_method_needs_itable_index(methods->at(i))) { 1369 method_count++; 1370 } 1371 } 1372 } 1373 1374 // Visit all interfaces which either have any methods or can participate in receiver type check. 1375 // We do not bother to count methods in transitive interfaces, although that would allow us to skip 1376 // this step in the rare case of a zero-method interface extending another zero-method interface. 1377 if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 0) { 1378 blk->doit(intf, method_count); 1379 } 1380 } 1381 } 1382 1383 class CountInterfacesClosure : public InterfaceVisiterClosure { 1384 private: 1385 int _nof_methods; 1386 int _nof_interfaces; 1387 public: 1388 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1389 1390 int nof_methods() const { return _nof_methods; } 1391 int nof_interfaces() const { return _nof_interfaces; } 1392 1393 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1394 }; 1395 1396 class SetupItableClosure : public InterfaceVisiterClosure { 1397 private: 1398 itableOffsetEntry* _offset_entry; 1399 itableMethodEntry* _method_entry; 1400 address _klass_begin; 1401 public: 1402 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1403 _klass_begin = klass_begin; 1404 _offset_entry = offset_entry; 1405 _method_entry = method_entry; 1406 } 1407 1408 itableMethodEntry* method_entry() const { return _method_entry; } 1409 1410 void doit(Klass* intf, int method_count) { 1411 int offset = ((address)_method_entry) - _klass_begin; 1412 _offset_entry->initialize(intf, offset); 1413 _offset_entry++; 1414 _method_entry += method_count; 1415 } 1416 }; 1417 1418 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1419 // Count no of interfaces and total number of interface methods 1420 CountInterfacesClosure cic; 1421 visit_all_interfaces(transitive_interfaces, &cic); 1422 1423 // There's alway an extra itable entry so we can null-terminate it. 1424 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1425 1426 // Statistics 1427 update_stats(itable_size * wordSize); 1428 1429 return itable_size; 1430 } 1431 1432 1433 // Fill out offset table and interface klasses into the itable space 1434 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1435 if (klass->itable_length() == 0) return; 1436 assert(!klass->is_interface(), "Should have zero length itable"); 1437 1438 // Count no of interfaces and total number of interface methods 1439 CountInterfacesClosure cic; 1440 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1441 int nof_methods = cic.nof_methods(); 1442 int nof_interfaces = cic.nof_interfaces(); 1443 1444 // Add one extra entry so we can null-terminate the table 1445 nof_interfaces++; 1446 1447 assert(compute_itable_size(klass->transitive_interfaces()) == 1448 calc_itable_size(nof_interfaces, nof_methods), 1449 "mismatch calculation of itable size"); 1450 1451 // Fill-out offset table 1452 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1453 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1454 intptr_t* end = klass->end_of_itable(); 1455 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1456 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1457 1458 // Visit all interfaces and initialize itable offset table 1459 SetupItableClosure sic((address)klass, ioe, ime); 1460 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1461 1462 #ifdef ASSERT 1463 ime = sic.method_entry(); 1464 oop* v = (oop*) klass->end_of_itable(); 1465 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1466 #endif 1467 } 1468 1469 1470 // inverse to itable_index 1471 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1472 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1473 assert(intf->verify_itable_index(itable_index), ""); 1474 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1475 1476 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1477 return NULL; // help caller defend against bad indices 1478 1479 int index = itable_index; 1480 Method* m = methods->at(index); 1481 int index2 = -1; 1482 while (!m->has_itable_index() || 1483 (index2 = m->itable_index()) != itable_index) { 1484 assert(index2 < itable_index, "monotonic"); 1485 if (++index == methods->length()) 1486 return NULL; 1487 m = methods->at(index); 1488 } 1489 assert(m->itable_index() == itable_index, "correct inverse"); 1490 1491 return m; 1492 } 1493 1494 void klassVtable::verify(outputStream* st, bool forced) { 1495 // make sure table is initialized 1496 if (!Universe::is_fully_initialized()) return; 1497 #ifndef PRODUCT 1498 // avoid redundant verifies 1499 if (!forced && _verify_count == Universe::verify_count()) return; 1500 _verify_count = Universe::verify_count(); 1501 #endif 1502 oop* end_of_obj = (oop*)_klass + _klass->size(); 1503 oop* end_of_vtable = (oop *)&table()[_length]; 1504 if (end_of_vtable > end_of_obj) { 1505 fatal("klass %s: klass object too short (vtable extends beyond end)", 1506 _klass->internal_name()); 1507 } 1508 1509 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1510 // verify consistency with superKlass vtable 1511 Klass* super = _klass->super(); 1512 if (super != NULL) { 1513 InstanceKlass* sk = InstanceKlass::cast(super); 1514 klassVtable vt = sk->vtable(); 1515 for (int i = 0; i < vt.length(); i++) { 1516 verify_against(st, &vt, i); 1517 } 1518 } 1519 } 1520 1521 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1522 vtableEntry* vte = &vt->table()[index]; 1523 if (vte->method()->name() != table()[index].method()->name() || 1524 vte->method()->signature() != table()[index].method()->signature()) { 1525 fatal("mismatched name/signature of vtable entries"); 1526 } 1527 } 1528 1529 #ifndef PRODUCT 1530 void klassVtable::print() { 1531 ResourceMark rm; 1532 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1533 for (int i = 0; i < length(); i++) { 1534 table()[i].print(); 1535 tty->cr(); 1536 } 1537 } 1538 #endif 1539 1540 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1541 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1542 Klass* vtklass = vt->klass(); 1543 if (vtklass->is_instance_klass() && 1544 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1545 assert(method() != NULL, "must have set method"); 1546 } 1547 if (method() != NULL) { 1548 method()->verify(); 1549 // we sub_type, because it could be a miranda method 1550 if (!vtklass->is_subtype_of(method()->method_holder())) { 1551 #ifndef PRODUCT 1552 print(); 1553 #endif 1554 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1555 } 1556 } 1557 } 1558 1559 #ifndef PRODUCT 1560 1561 void vtableEntry::print() { 1562 ResourceMark rm; 1563 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1564 if (Verbose) { 1565 tty->print("m " PTR_FORMAT " ", p2i(method())); 1566 } 1567 } 1568 1569 class VtableStats : AllStatic { 1570 public: 1571 static int no_klasses; // # classes with vtables 1572 static int no_array_klasses; // # array classes 1573 static int no_instance_klasses; // # instanceKlasses 1574 static int sum_of_vtable_len; // total # of vtable entries 1575 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1576 static int fixed; // total fixed overhead in bytes 1577 static int filler; // overhead caused by filler bytes 1578 static int entries; // total bytes consumed by vtable entries 1579 static int array_entries; // total bytes consumed by array vtable entries 1580 1581 static void do_class(Klass* k) { 1582 Klass* kl = k; 1583 klassVtable vt = kl->vtable(); 1584 no_klasses++; 1585 if (kl->is_instance_klass()) { 1586 no_instance_klasses++; 1587 kl->array_klasses_do(do_class); 1588 } 1589 if (kl->is_array_klass()) { 1590 no_array_klasses++; 1591 sum_of_array_vtable_len += vt.length(); 1592 } 1593 sum_of_vtable_len += vt.length(); 1594 } 1595 1596 static void compute() { 1597 ClassLoaderDataGraph::classes_do(do_class); 1598 fixed = no_klasses * oopSize; // vtable length 1599 // filler size is a conservative approximation 1600 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1601 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1602 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1603 } 1604 }; 1605 1606 int VtableStats::no_klasses = 0; 1607 int VtableStats::no_array_klasses = 0; 1608 int VtableStats::no_instance_klasses = 0; 1609 int VtableStats::sum_of_vtable_len = 0; 1610 int VtableStats::sum_of_array_vtable_len = 0; 1611 int VtableStats::fixed = 0; 1612 int VtableStats::filler = 0; 1613 int VtableStats::entries = 0; 1614 int VtableStats::array_entries = 0; 1615 1616 void klassVtable::print_statistics() { 1617 ResourceMark rm; 1618 HandleMark hm; 1619 VtableStats::compute(); 1620 tty->print_cr("vtable statistics:"); 1621 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1622 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1623 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1624 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1625 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1626 tty->print_cr("%6d bytes total", total); 1627 } 1628 1629 int klassItable::_total_classes; // Total no. of classes with itables 1630 long klassItable::_total_size; // Total no. of bytes used for itables 1631 1632 void klassItable::print_statistics() { 1633 tty->print_cr("itable statistics:"); 1634 tty->print_cr("%6d classes with itables", _total_classes); 1635 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes); 1636 } 1637 1638 #endif // PRODUCT