1 /* 2 * Copyright (c) 1997, 2019, 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/classLoaderDataGraph.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "interpreter/linkResolver.hpp" 32 #include "logging/log.hpp" 33 #include "logging/logStream.hpp" 34 #include "memory/metaspaceShared.hpp" 35 #include "memory/resourceArea.hpp" 36 #include "memory/universe.hpp" 37 #include "oops/instanceKlass.hpp" 38 #include "oops/klassVtable.hpp" 39 #include "oops/method.hpp" 40 #include "oops/objArrayOop.hpp" 41 #include "oops/oop.inline.hpp" 42 #include "runtime/arguments.hpp" 43 #include "runtime/flags/flagSetting.hpp" 44 #include "runtime/handles.inline.hpp" 45 #include "runtime/safepointVerifiers.hpp" 46 #include "utilities/copy.hpp" 47 48 inline InstanceKlass* klassVtable::ik() const { 49 return InstanceKlass::cast(_klass); 50 } 51 52 bool klassVtable::is_preinitialized_vtable() { 53 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite(); 54 } 55 56 57 // this function computes the vtable size (including the size needed for miranda 58 // methods) and the number of miranda methods in this class. 59 // Note on Miranda methods: Let's say there is a class C that implements 60 // interface I, and none of C's superclasses implements I. 61 // Let's say there is an abstract method m in I that neither C 62 // nor any of its super classes implement (i.e there is no method of any access, 63 // with the same name and signature as m), then m is a Miranda method which is 64 // entered as a public abstract method in C's vtable. From then on it should 65 // treated as any other public method in C for method over-ride purposes. 66 void klassVtable::compute_vtable_size_and_num_mirandas( 67 int* vtable_length_ret, int* num_new_mirandas, 68 GrowableArray<Method*>* all_mirandas, const Klass* super, 69 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 70 Handle classloader, Symbol* classname, Array<InstanceKlass*>* local_interfaces, 71 TRAPS) { 72 NoSafepointVerifier nsv; 73 74 // set up default result values 75 int vtable_length = 0; 76 77 // start off with super's vtable length 78 vtable_length = super == NULL ? 0 : super->vtable_length(); 79 80 // go thru each method in the methods table to see if it needs a new entry 81 int len = methods->length(); 82 for (int i = 0; i < len; i++) { 83 assert(methods->at(i)->is_method(), "must be a Method*"); 84 methodHandle mh(THREAD, methods->at(i)); 85 86 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) { 87 assert(!methods->at(i)->is_private(), "private methods should not need a vtable entry"); 88 vtable_length += vtableEntry::size(); // we need a new entry 89 } 90 } 91 92 GrowableArray<Method*> new_mirandas(20); 93 // compute the number of mirandas methods that must be added to the end 94 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces, 95 class_flags.is_interface()); 96 *num_new_mirandas = new_mirandas.length(); 97 98 // Interfaces do not need interface methods in their vtables 99 // This includes miranda methods and during later processing, default methods 100 if (!class_flags.is_interface()) { 101 vtable_length += *num_new_mirandas * vtableEntry::size(); 102 } 103 104 if (Universe::is_bootstrapping() && vtable_length == 0) { 105 // array classes don't have their superclass set correctly during 106 // bootstrapping 107 vtable_length = Universe::base_vtable_size(); 108 } 109 110 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 111 if (Universe::is_bootstrapping()) { 112 // Someone is attempting to override java.lang.Object incorrectly on the 113 // bootclasspath. The JVM cannot recover from this error including throwing 114 // an exception 115 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 116 } else { 117 // Someone is attempting to redefine java.lang.Object incorrectly. The 118 // only way this should happen is from 119 // SystemDictionary::resolve_from_stream(), which will detect this later 120 // and throw a security exception. So don't assert here to let 121 // the exception occur. 122 vtable_length = Universe::base_vtable_size(); 123 } 124 } 125 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 126 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 127 128 *vtable_length_ret = vtable_length; 129 } 130 131 int klassVtable::index_of(Method* m, int len) const { 132 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 133 return m->vtable_index(); 134 } 135 136 // Copy super class's vtable to the first part (prefix) of this class's vtable, 137 // and return the number of entries copied. Expects that 'super' is the Java 138 // super class (arrays can have "array" super classes that must be skipped). 139 int klassVtable::initialize_from_super(Klass* super) { 140 if (super == NULL) { 141 return 0; 142 } else if (is_preinitialized_vtable()) { 143 // A shared class' vtable is preinitialized at dump time. No need to copy 144 // methods from super class for shared class, as that was already done 145 // during archiving time. However, if Jvmti has redefined a class, 146 // copy super class's vtable in case the super class has changed. 147 return super->vtable().length(); 148 } else { 149 // copy methods from superKlass 150 klassVtable superVtable = super->vtable(); 151 assert(superVtable.length() <= _length, "vtable too short"); 152 #ifdef ASSERT 153 superVtable.verify(tty, true); 154 #endif 155 superVtable.copy_vtable_to(table()); 156 if (log_develop_is_enabled(Trace, vtables)) { 157 ResourceMark rm; 158 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 159 super->internal_name(), klass()->internal_name(), 160 _length); 161 } 162 return superVtable.length(); 163 } 164 } 165 166 // 167 // Revised lookup semantics introduced 1.3 (Kestrel beta) 168 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 169 170 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 171 InstanceKlass* super = _klass->java_super(); 172 int nofNewEntries = 0; 173 174 bool is_shared = _klass->is_shared(); 175 176 if (!_klass->is_array_klass()) { 177 ResourceMark rm(THREAD); 178 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 179 } 180 181 #ifdef ASSERT 182 oop* end_of_obj = (oop*)_klass + _klass->size(); 183 oop* end_of_vtable = (oop*)&table()[_length]; 184 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 185 #endif 186 187 if (Universe::is_bootstrapping()) { 188 assert(!is_shared, "sanity"); 189 // just clear everything 190 for (int i = 0; i < _length; i++) table()[i].clear(); 191 return; 192 } 193 194 int super_vtable_len = initialize_from_super(super); 195 if (_klass->is_array_klass()) { 196 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 197 } else { 198 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 199 200 Array<Method*>* methods = ik()->methods(); 201 int len = methods->length(); 202 int initialized = super_vtable_len; 203 204 // Check each of this class's methods against super; 205 // if override, replace in copy of super vtable, otherwise append to end 206 for (int i = 0; i < len; i++) { 207 // update_inherited_vtable can stop for gc - ensure using handles 208 HandleMark hm(THREAD); 209 assert(methods->at(i)->is_method(), "must be a Method*"); 210 methodHandle mh(THREAD, methods->at(i)); 211 212 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 213 214 if (needs_new_entry) { 215 put_method_at(mh(), initialized); 216 mh()->set_vtable_index(initialized); // set primary vtable index 217 initialized++; 218 } 219 } 220 221 // update vtable with default_methods 222 Array<Method*>* default_methods = ik()->default_methods(); 223 if (default_methods != NULL) { 224 len = default_methods->length(); 225 if (len > 0) { 226 Array<int>* def_vtable_indices = NULL; 227 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 228 assert(!is_shared, "shared class def_vtable_indices does not exist"); 229 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 230 } else { 231 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 232 } 233 for (int i = 0; i < len; i++) { 234 HandleMark hm(THREAD); 235 assert(default_methods->at(i)->is_method(), "must be a Method*"); 236 methodHandle mh(THREAD, default_methods->at(i)); 237 assert(!mh->is_private(), "private interface method in the default method list"); 238 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 239 240 // needs new entry 241 if (needs_new_entry) { 242 put_method_at(mh(), initialized); 243 if (is_preinitialized_vtable()) { 244 // At runtime initialize_vtable is rerun for a shared class 245 // (loaded by the non-boot loader) as part of link_class_impl(). 246 // The dumptime vtable index should be the same as the runtime index. 247 assert(def_vtable_indices->at(i) == initialized, 248 "dump time vtable index is different from runtime index"); 249 } else { 250 def_vtable_indices->at_put(i, initialized); //set vtable index 251 } 252 initialized++; 253 } 254 } 255 } 256 } 257 258 // add miranda methods; it will also return the updated initialized 259 // Interfaces do not need interface methods in their vtables 260 // This includes miranda methods and during later processing, default methods 261 if (!ik()->is_interface()) { 262 initialized = fill_in_mirandas(initialized, THREAD); 263 } 264 265 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 266 // package_private -> public/protected), the vtable might actually be smaller than our initial 267 // calculation, for classfile versions for which we do not do transitive override 268 // calculations. 269 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 270 assert(initialized == _length, "vtable initialization failed"); 271 } else { 272 assert(initialized <= _length, "vtable initialization failed"); 273 for(;initialized < _length; initialized++) { 274 table()[initialized].clear(); 275 } 276 } 277 NOT_PRODUCT(verify(tty, true)); 278 } 279 } 280 281 // Called for cases where a method does not override its superclass' vtable entry 282 // For bytecodes not produced by javac together it is possible that a method does not override 283 // the superclass's method, but might indirectly override a super-super class's vtable entry 284 // If none found, return a null superk, else return the superk of the method this does override 285 // For public and protected methods: if they override a superclass, they will 286 // also be overridden themselves appropriately. 287 // Private methods do not override, and are not overridden and are not in the vtable. 288 // Package Private methods are trickier: 289 // e.g. P1.A, pub m 290 // P2.B extends A, package private m 291 // P1.C extends B, public m 292 // P1.C.m needs to override P1.A.m and can not override P2.B.m 293 // Therefore: all package private methods need their own vtable entries for 294 // them to be the root of an inheritance overriding decision 295 // Package private methods may also override other vtable entries 296 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, 297 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 298 InstanceKlass* superk = initialsuper; 299 while (superk != NULL && superk->super() != NULL) { 300 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 301 klassVtable ssVtable = supersuperklass->vtable(); 302 if (vtable_index < ssVtable.length()) { 303 Method* super_method = ssVtable.method_at(vtable_index); 304 #ifndef PRODUCT 305 Symbol* name= target_method()->name(); 306 Symbol* signature = target_method()->signature(); 307 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 308 #endif 309 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 310 if (log_develop_is_enabled(Trace, vtables)) { 311 ResourceMark rm(THREAD); 312 LogTarget(Trace, vtables) lt; 313 LogStream ls(lt); 314 char* sig = target_method()->name_and_sig_as_C_string(); 315 ls.print("transitive overriding superclass %s with %s index %d, original flags: ", 316 supersuperklass->internal_name(), 317 sig, vtable_index); 318 super_method->print_linkage_flags(&ls); 319 ls.print("overriders flags: "); 320 target_method->print_linkage_flags(&ls); 321 ls.cr(); 322 } 323 324 break; // return found superk 325 } 326 } else { 327 // super class has no vtable entry here, stop transitive search 328 superk = (InstanceKlass*)NULL; 329 break; 330 } 331 // if no override found yet, continue to search up 332 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 333 } 334 335 return superk; 336 } 337 338 static void log_vtables(int i, bool overrides, const methodHandle& target_method, 339 Klass* target_klass, Method* super_method, 340 Thread* thread) { 341 #ifndef PRODUCT 342 if (log_develop_is_enabled(Trace, vtables)) { 343 ResourceMark rm(thread); 344 LogTarget(Trace, vtables) lt; 345 LogStream ls(lt); 346 char* sig = target_method()->name_and_sig_as_C_string(); 347 if (overrides) { 348 ls.print("overriding with %s index %d, original flags: ", 349 sig, i); 350 } else { 351 ls.print("NOT overriding with %s index %d, original flags: ", 352 sig, i); 353 } 354 super_method->print_linkage_flags(&ls); 355 ls.print("overriders flags: "); 356 target_method->print_linkage_flags(&ls); 357 ls.cr(); 358 } 359 #endif 360 } 361 362 // Update child's copy of super vtable for overrides 363 // OR return true if a new vtable entry is required. 364 // Only called for InstanceKlass's, i.e. not for arrays 365 // If that changed, could not use _klass as handle for klass 366 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, 367 int super_vtable_len, int default_index, 368 bool checkconstraints, TRAPS) { 369 ResourceMark rm(THREAD); 370 bool allocate_new = true; 371 assert(klass->is_instance_klass(), "must be InstanceKlass"); 372 373 Array<int>* def_vtable_indices = NULL; 374 bool is_default = false; 375 376 // default methods are non-private concrete methods in superinterfaces which are added 377 // to the vtable with their real method_holder. 378 // Since vtable and itable indices share the same storage, don't touch 379 // the default method's real vtable/itable index. 380 // default_vtable_indices stores the vtable value relative to this inheritor 381 if (default_index >= 0 ) { 382 is_default = true; 383 def_vtable_indices = klass->default_vtable_indices(); 384 assert(!target_method()->is_private(), "private interface method flagged as default"); 385 assert(def_vtable_indices != NULL, "def vtable alloc?"); 386 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 387 } else { 388 assert(klass == target_method()->method_holder(), "caller resp."); 389 // Initialize the method's vtable index to "nonvirtual". 390 // If we allocate a vtable entry, we will update it to a non-negative number. 391 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 392 } 393 394 // Private, static and <init> methods are never in 395 if (target_method()->is_private() || target_method()->is_static() || 396 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)) { 397 return false; 398 } 399 400 if (target_method->is_final_method(klass->access_flags())) { 401 // a final method never needs a new entry; final methods can be statically 402 // resolved and they have to be present in the vtable only if they override 403 // a super's method, in which case they re-use its entry 404 allocate_new = false; 405 } else if (klass->is_interface()) { 406 allocate_new = false; // see note below in needs_new_vtable_entry 407 // An interface never allocates new vtable slots, only inherits old ones. 408 // This method will either be assigned its own itable index later, 409 // or be assigned an inherited vtable index in the loop below. 410 // default methods inherited by classes store their vtable indices 411 // in the inheritor's default_vtable_indices. 412 // default methods inherited by interfaces may already have a 413 // valid itable index, if so, don't change it. 414 // Overpass methods in an interface will be assigned an itable index later 415 // by an inheriting class. 416 if ((!is_default || !target_method()->has_itable_index())) { 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 // search through the vtable and update overridden entries 428 // Since check_signature_loaders acquires SystemDictionary_lock 429 // which can block for gc, once we are in this loop, use handles 430 // For classfiles built with >= jdk7, we now look for transitive overrides 431 432 Symbol* name = target_method()->name(); 433 Symbol* signature = target_method()->signature(); 434 435 Klass* target_klass = target_method()->method_holder(); 436 if (target_klass == NULL) { 437 target_klass = _klass; 438 } 439 440 Handle target_loader(THREAD, target_klass->class_loader()); 441 442 Symbol* target_classname = target_klass->name(); 443 for(int i = 0; i < super_vtable_len; i++) { 444 Method* super_method; 445 if (is_preinitialized_vtable()) { 446 // If this is a shared class, the vtable is already in the final state (fully 447 // initialized). Need to look at the super's vtable. 448 klassVtable superVtable = super->vtable(); 449 super_method = superVtable.method_at(i); 450 } else { 451 super_method = method_at(i); 452 } 453 // Check if method name matches. Ignore match if klass is an interface and the 454 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4) 455 // This is safe because the method at this slot should never get invoked. 456 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.) 457 if (super_method->name() == name && super_method->signature() == signature && 458 (!_klass->is_interface() || 459 !SystemDictionary::is_nonpublic_Object_method(super_method))) { 460 461 // get super_klass for method_holder for the found method 462 InstanceKlass* super_klass = super_method->method_holder(); 463 464 // Whether the method is being overridden 465 bool overrides = false; 466 467 // private methods are also never overridden 468 if (!super_method->is_private() && 469 (is_default 470 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 471 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 472 && ((super_klass = find_transitive_override(super_klass, 473 target_method, i, target_loader, 474 target_classname, THREAD)) 475 != (InstanceKlass*)NULL))))) 476 { 477 // Package private methods always need a new entry to root their own 478 // overriding. They may also override other methods. 479 if (!target_method()->is_package_private()) { 480 allocate_new = false; 481 } 482 483 // Do not check loader constraints for overpass methods because overpass 484 // methods are created by the jvm to throw exceptions. 485 if (checkconstraints && !target_method()->is_overpass()) { 486 // Override vtable entry if passes loader constraint check 487 // if loader constraint checking requested 488 // No need to visit his super, since he and his super 489 // have already made any needed loader constraints. 490 // Since loader constraints are transitive, it is enough 491 // to link to the first super, and we get all the others. 492 Handle super_loader(THREAD, super_klass->class_loader()); 493 494 if (!oopDesc::equals(target_loader(), super_loader())) { 495 ResourceMark rm(THREAD); 496 Symbol* failed_type_symbol = 497 SystemDictionary::check_signature_loaders(signature, target_loader, 498 super_loader, true, 499 CHECK_(false)); 500 if (failed_type_symbol != NULL) { 501 stringStream ss; 502 ss.print("loader constraint violation for class %s: when selecting " 503 "overriding method '", klass->external_name()); 504 target_method()->print_external_name(&ss), 505 ss.print("' the class loader %s of the " 506 "selected method's type %s, and the class loader %s for its super " 507 "type %s have different Class objects for the type %s used in the signature (%s; %s)", 508 target_klass->class_loader_data()->loader_name_and_id(), 509 target_klass->external_name(), 510 super_klass->class_loader_data()->loader_name_and_id(), 511 super_klass->external_name(), 512 failed_type_symbol->as_klass_external_name(), 513 target_klass->class_in_module_of_loader(false, true), 514 super_klass->class_in_module_of_loader(false, true)); 515 THROW_MSG_(vmSymbols::java_lang_LinkageError(), ss.as_string(), false); 516 } 517 } 518 } 519 520 put_method_at(target_method(), i); 521 overrides = true; 522 if (!is_default) { 523 target_method()->set_vtable_index(i); 524 } else { 525 if (def_vtable_indices != NULL) { 526 if (is_preinitialized_vtable()) { 527 // At runtime initialize_vtable is rerun as part of link_class_impl() 528 // for a shared class loaded by the non-boot loader. 529 // The dumptime vtable index should be the same as the runtime index. 530 assert(def_vtable_indices->at(default_index) == i, 531 "dump time vtable index is different from runtime index"); 532 } else { 533 def_vtable_indices->at_put(default_index, i); 534 } 535 } 536 assert(super_method->is_default_method() || super_method->is_overpass() 537 || super_method->is_abstract(), "default override error"); 538 } 539 } else { 540 overrides = false; 541 } 542 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD); 543 } 544 } 545 return allocate_new; 546 } 547 548 void klassVtable::put_method_at(Method* m, int index) { 549 assert(!m->is_private(), "private methods should not be in vtable"); 550 if (is_preinitialized_vtable()) { 551 // At runtime initialize_vtable is rerun as part of link_class_impl() 552 // for shared class loaded by the non-boot loader to obtain the loader 553 // constraints based on the runtime classloaders' context. The dumptime 554 // method at the vtable index should be the same as the runtime method. 555 assert(table()[index].method() == m, 556 "archived method is different from the runtime method"); 557 } else { 558 if (log_develop_is_enabled(Trace, vtables)) { 559 ResourceMark rm; 560 LogTarget(Trace, vtables) lt; 561 LogStream ls(lt); 562 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 563 ls.print("adding %s at index %d, flags: ", sig, index); 564 if (m != NULL) { 565 m->print_linkage_flags(&ls); 566 } 567 ls.cr(); 568 } 569 table()[index].set(m); 570 } 571 } 572 573 // Find out if a method "m" with superclass "super", loader "classloader" and 574 // name "classname" needs a new vtable entry. Let P be a class package defined 575 // by "classloader" and "classname". 576 // NOTE: The logic used here is very similar to the one used for computing 577 // the vtables indices for a method. We cannot directly use that function because, 578 // we allocate the InstanceKlass at load time, and that requires that the 579 // superclass has been loaded. 580 // However, the vtable entries are filled in at link time, and therefore 581 // the superclass' vtable may not yet have been filled in. 582 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method, 583 const Klass* super, 584 Handle classloader, 585 Symbol* classname, 586 AccessFlags class_flags, 587 u2 major_version, 588 TRAPS) { 589 if (class_flags.is_interface()) { 590 // Interfaces do not use vtables, except for java.lang.Object methods, 591 // so there is no point to assigning 592 // a vtable index to any of their local methods. If we refrain from doing this, 593 // we can use Method::_vtable_index to hold the itable index 594 return false; 595 } 596 597 if (target_method->is_final_method(class_flags) || 598 // a final method never needs a new entry; final methods can be statically 599 // resolved and they have to be present in the vtable only if they override 600 // a super's method, in which case they re-use its entry 601 (target_method()->is_private()) || 602 // private methods don't need to be in vtable 603 (target_method()->is_static()) || 604 // static methods don't need to be in vtable 605 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0) 606 // <init> is never called dynamically-bound 607 ) { 608 return false; 609 } 610 611 // Concrete interface methods do not need new entries, they override 612 // abstract method entries using default inheritance rules 613 if (target_method()->method_holder() != NULL && 614 target_method()->method_holder()->is_interface() && 615 !target_method()->is_abstract()) { 616 assert(target_method()->is_default_method(), 617 "unexpected interface method type"); 618 return false; 619 } 620 621 // we need a new entry if there is no superclass 622 if (super == NULL) { 623 return true; 624 } 625 626 // Package private methods always need a new entry to root their own 627 // overriding. This allows transitive overriding to work. 628 if (target_method()->is_package_private()) { 629 return true; 630 } 631 632 // search through the super class hierarchy to see if we need 633 // a new entry 634 ResourceMark rm; 635 Symbol* name = target_method()->name(); 636 Symbol* signature = target_method()->signature(); 637 const Klass* k = super; 638 Method* super_method = NULL; 639 InstanceKlass *holder = NULL; 640 Method* recheck_method = NULL; 641 bool found_pkg_prvt_method = false; 642 while (k != NULL) { 643 // lookup through the hierarchy for a method with matching name and sign. 644 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 645 if (super_method == NULL) { 646 break; // we still have to search for a matching miranda method 647 } 648 // get the class holding the matching method 649 // make sure you use that class for is_override 650 InstanceKlass* superk = super_method->method_holder(); 651 // we want only instance method matches 652 // ignore private methods found via lookup_method since they do not participate in overriding, 653 // and since we do override around them: e.g. a.m pub/b.m private/c.m pub, 654 // ignore private, c.m pub does override a.m pub 655 // For classes that were not javac'd together, we also do transitive overriding around 656 // methods that have less accessibility 657 if ((!super_method->is_static()) && 658 (!super_method->is_private())) { 659 if (superk->is_override(super_method, classloader, classname, THREAD)) { 660 return false; 661 // else keep looking for transitive overrides 662 } 663 // If we get here then one of the super classes has a package private method 664 // that will not get overridden because it is in a different package. But, 665 // that package private method does 'override' any matching methods in super 666 // interfaces. So, set flag to TRUE for use below where existance of a 667 // miranda method is checked. 668 assert(super_method->is_package_private(), "super_method must be package private"); 669 assert(!superk->is_same_class_package(classloader(), classname), 670 "Must be different packages"); 671 found_pkg_prvt_method = true; 672 } 673 674 // Start with lookup result and continue to search up, for versions supporting transitive override 675 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 676 k = superk->super(); // haven't found an override match yet; continue to look 677 } else { 678 break; 679 } 680 } 681 682 // Only look for a miranda method if the method was not found in a package 683 // private class because, if it was found in a package private class, then 684 // there will be no miranda method, even if the method is also in a super 685 // interface. 686 if (!found_pkg_prvt_method) { 687 // if the target method is public or protected it may have a matching 688 // miranda method in the super, whose entry it should re-use. 689 // Actually, to handle cases that javac would not generate, we need 690 // this check for all access permissions. 691 const InstanceKlass *sk = InstanceKlass::cast(super); 692 if (sk->has_miranda_methods()) { 693 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 694 return false; // found a matching miranda; we do not need a new entry 695 } 696 } 697 } 698 return true; // found no match; we need a new entry 699 } 700 701 // Support for miranda methods 702 703 // get the vtable index of a miranda method with matching "name" and "signature" 704 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 705 // search from the bottom, might be faster 706 for (int i = (length() - 1); i >= 0; i--) { 707 Method* m = table()[i].method(); 708 if (is_miranda_entry_at(i) && 709 m->name() == name && m->signature() == signature) { 710 return i; 711 } 712 } 713 return Method::invalid_vtable_index; 714 } 715 716 // check if an entry at an index is miranda 717 // requires that method m at entry be declared ("held") by an interface. 718 bool klassVtable::is_miranda_entry_at(int i) { 719 Method* m = method_at(i); 720 Klass* method_holder = m->method_holder(); 721 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 722 723 // miranda methods are public abstract instance interface methods in a class's vtable 724 if (mhk->is_interface()) { 725 assert(m->is_public(), "should be public"); 726 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 727 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) { 728 return true; 729 } 730 } 731 return false; 732 } 733 734 // Check if a method is a miranda method, given a class's methods array, 735 // its default_method table and its super class. 736 // "Miranda" means an abstract non-private method that would not be 737 // overridden for the local class. 738 // A "miranda" method should only include non-private interface 739 // instance methods, i.e. not private methods, not static methods, 740 // not default methods (concrete interface methods), not overpass methods. 741 // If a given class already has a local (including overpass) method, a 742 // default method, or any of its superclasses has the same which would have 743 // overridden an abstract method, then this is not a miranda method. 744 // 745 // Miranda methods are checked multiple times. 746 // Pass 1: during class load/class file parsing: before vtable size calculation: 747 // include superinterface abstract and default methods (non-private instance). 748 // We include potential default methods to give them space in the vtable. 749 // During the first run, the current instanceKlass has not yet been 750 // created, the superclasses and superinterfaces do have instanceKlasses 751 // but may not have vtables, the default_methods list is empty, no overpasses. 752 // Default method generation uses the all_mirandas array as the starter set for 753 // maximally-specific default method calculation. So, for both classes and 754 // interfaces, it is necessary that the first pass will find all non-private 755 // interface instance methods, whether or not they are concrete. 756 // 757 // Pass 2: recalculated during vtable initialization: only include abstract methods. 758 // The goal of pass 2 is to walk through the superinterfaces to see if any of 759 // the superinterface methods (which were all abstract pre-default methods) 760 // need to be added to the vtable. 761 // With the addition of default methods, we have three new challenges: 762 // overpasses, static interface methods and private interface methods. 763 // Static and private interface methods do not get added to the vtable and 764 // are not seen by the method resolution process, so we skip those. 765 // Overpass methods are already in the vtable, so vtable lookup will 766 // find them and we don't need to add a miranda method to the end of 767 // the vtable. So we look for overpass methods and if they are found we 768 // return false. Note that we inherit our superclasses vtable, so 769 // the superclass' search also needs to use find_overpass so that if 770 // one is found we return false. 771 // False means - we don't need a miranda method added to the vtable. 772 // 773 // During the second run, default_methods is set up, so concrete methods from 774 // superinterfaces with matching names/signatures to default_methods are already 775 // in the default_methods list and do not need to be appended to the vtable 776 // as mirandas. Abstract methods may already have been handled via 777 // overpasses - either local or superclass overpasses, which may be 778 // in the vtable already. 779 // 780 // Pass 3: They are also checked by link resolution and selection, 781 // for invocation on a method (not interface method) reference that 782 // resolves to a method with an interface as its method_holder. 783 // Used as part of walking from the bottom of the vtable to find 784 // the vtable index for the miranda method. 785 // 786 // Part of the Miranda Rights in the US mean that if you do not have 787 // an attorney one will be appointed for you. 788 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 789 Array<Method*>* default_methods, const Klass* super, 790 bool is_interface) { 791 if (m->is_static() || m->is_private() || m->is_overpass()) { 792 return false; 793 } 794 Symbol* name = m->name(); 795 Symbol* signature = m->signature(); 796 797 // First look in local methods to see if already covered 798 if (InstanceKlass::find_local_method(class_methods, name, signature, 799 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 800 { 801 return false; 802 } 803 804 // Check local default methods 805 if ((default_methods != NULL) && 806 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 807 { 808 return false; 809 } 810 811 // Iterate on all superclasses, which should be InstanceKlasses. 812 // Note that we explicitly look for overpasses at each level. 813 // Overpasses may or may not exist for supers for pass 1, 814 // they should have been created for pass 2 and later. 815 816 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 817 { 818 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature, 819 Klass::find_overpass, Klass::skip_static, Klass::skip_private); 820 // Ignore non-public methods in java.lang.Object if klass is an interface. 821 if (found_mth != NULL && (!is_interface || 822 !SystemDictionary::is_nonpublic_Object_method(found_mth))) { 823 return false; 824 } 825 } 826 827 return true; 828 } 829 830 // Scans current_interface_methods for miranda methods that do not 831 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 832 // in super (superclass). These mirandas are added to all_mirandas if it is 833 // not null; in addition, those that are not duplicates of miranda methods 834 // inherited by super from its interfaces are added to new_mirandas. 835 // Thus, new_mirandas will be the set of mirandas that this class introduces, 836 // all_mirandas will be the set of all mirandas applicable to this class 837 // including all defined in superclasses. 838 void klassVtable::add_new_mirandas_to_lists( 839 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 840 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 841 Array<Method*>* default_methods, const Klass* super, bool is_interface) { 842 843 // iterate thru the current interface's method to see if it a miranda 844 int num_methods = current_interface_methods->length(); 845 for (int i = 0; i < num_methods; i++) { 846 Method* im = current_interface_methods->at(i); 847 bool is_duplicate = false; 848 int num_of_current_mirandas = new_mirandas->length(); 849 // check for duplicate mirandas in different interfaces we implement 850 for (int j = 0; j < num_of_current_mirandas; j++) { 851 Method* miranda = new_mirandas->at(j); 852 if ((im->name() == miranda->name()) && 853 (im->signature() == miranda->signature())) { 854 is_duplicate = true; 855 break; 856 } 857 } 858 859 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 860 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all? 861 const InstanceKlass *sk = InstanceKlass::cast(super); 862 // check if it is a duplicate of a super's miranda 863 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 864 new_mirandas->append(im); 865 } 866 if (all_mirandas != NULL) { 867 all_mirandas->append(im); 868 } 869 } 870 } 871 } 872 } 873 874 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 875 GrowableArray<Method*>* all_mirandas, 876 const Klass* super, 877 Array<Method*>* class_methods, 878 Array<Method*>* default_methods, 879 Array<InstanceKlass*>* local_interfaces, 880 bool is_interface) { 881 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 882 883 // iterate thru the local interfaces looking for a miranda 884 int num_local_ifs = local_interfaces->length(); 885 for (int i = 0; i < num_local_ifs; i++) { 886 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 887 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 888 ik->methods(), class_methods, 889 default_methods, super, is_interface); 890 // iterate thru each local's super interfaces 891 Array<InstanceKlass*>* super_ifs = ik->transitive_interfaces(); 892 int num_super_ifs = super_ifs->length(); 893 for (int j = 0; j < num_super_ifs; j++) { 894 InstanceKlass *sik = super_ifs->at(j); 895 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 896 sik->methods(), class_methods, 897 default_methods, super, is_interface); 898 } 899 } 900 } 901 902 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 903 // and append them into the vtable starting at index initialized, 904 // return the new value of initialized. 905 // Miranda methods use vtable entries, but do not get assigned a vtable_index 906 // The vtable_index is discovered by searching from the end of the vtable 907 int klassVtable::fill_in_mirandas(int initialized, TRAPS) { 908 ResourceMark rm(THREAD); 909 GrowableArray<Method*> mirandas(20); 910 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 911 ik()->default_methods(), ik()->local_interfaces(), 912 klass()->is_interface()); 913 for (int i = 0; i < mirandas.length(); i++) { 914 if (log_develop_is_enabled(Trace, vtables)) { 915 Method* meth = mirandas.at(i); 916 LogTarget(Trace, vtables) lt; 917 LogStream ls(lt); 918 if (meth != NULL) { 919 char* sig = meth->name_and_sig_as_C_string(); 920 ls.print("fill in mirandas with %s index %d, flags: ", 921 sig, initialized); 922 meth->print_linkage_flags(&ls); 923 ls.cr(); 924 } 925 } 926 put_method_at(mirandas.at(i), initialized); 927 ++initialized; 928 } 929 return initialized; 930 } 931 932 // Copy this class's vtable to the vtable beginning at start. 933 // Used to copy superclass vtable to prefix of subclass's vtable. 934 void klassVtable::copy_vtable_to(vtableEntry* start) { 935 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 936 } 937 938 #if INCLUDE_JVMTI 939 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 940 // If old_method is default, find this vtable index in default_vtable_indices 941 // and replace that method in the _default_methods list 942 bool updated = false; 943 944 Array<Method*>* default_methods = ik()->default_methods(); 945 if (default_methods != NULL) { 946 int len = default_methods->length(); 947 for (int idx = 0; idx < len; idx++) { 948 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 949 if (default_methods->at(idx) == old_method) { 950 default_methods->at_put(idx, new_method); 951 updated = true; 952 } 953 break; 954 } 955 } 956 } 957 return updated; 958 } 959 960 // search the vtable for uses of either obsolete or EMCP methods 961 void klassVtable::adjust_method_entries(bool * trace_name_printed) { 962 int prn_enabled = 0; 963 for (int index = 0; index < length(); index++) { 964 Method* old_method = unchecked_method_at(index); 965 if (old_method == NULL || !old_method->is_old()) { 966 continue; // skip uninteresting entries 967 } 968 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 969 970 Method* new_method = old_method->get_new_method(); 971 put_method_at(new_method, index); 972 973 // For default methods, need to update the _default_methods array 974 // which can only have one method entry for a given signature 975 bool updated_default = false; 976 if (old_method->is_default_method()) { 977 updated_default = adjust_default_method(index, old_method, new_method); 978 } 979 980 if (log_is_enabled(Info, redefine, class, update)) { 981 ResourceMark rm; 982 if (!(*trace_name_printed)) { 983 log_info(redefine, class, update) 984 ("adjust: klassname=%s for methods from name=%s", 985 _klass->external_name(), old_method->method_holder()->external_name()); 986 *trace_name_printed = true; 987 } 988 log_debug(redefine, class, update, vtables) 989 ("vtable method update: %s(%s), updated default = %s", 990 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false"); 991 } 992 } 993 } 994 995 // a vtable should never contain old or obsolete methods 996 bool klassVtable::check_no_old_or_obsolete_entries() { 997 for (int i = 0; i < length(); i++) { 998 Method* m = unchecked_method_at(i); 999 if (m != NULL && 1000 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1001 return false; 1002 } 1003 } 1004 return true; 1005 } 1006 1007 void klassVtable::dump_vtable() { 1008 tty->print_cr("vtable dump --"); 1009 for (int i = 0; i < length(); i++) { 1010 Method* m = unchecked_method_at(i); 1011 if (m != NULL) { 1012 tty->print(" (%5d) ", i); 1013 m->access_flags().print_on(tty); 1014 if (m->is_default_method()) { 1015 tty->print("default "); 1016 } 1017 if (m->is_overpass()) { 1018 tty->print("overpass"); 1019 } 1020 tty->print(" -- "); 1021 m->print_name(tty); 1022 tty->cr(); 1023 } 1024 } 1025 } 1026 #endif // INCLUDE_JVMTI 1027 1028 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 1029 void klassVtable::clear_vtable() { 1030 for (int i = 0; i < _length; i++) table()[i].clear(); 1031 } 1032 1033 bool klassVtable::is_initialized() { 1034 return _length == 0 || table()[0].method() != NULL; 1035 } 1036 1037 //----------------------------------------------------------------------------------------- 1038 // Itable code 1039 1040 // Initialize a itableMethodEntry 1041 void itableMethodEntry::initialize(Method* m) { 1042 if (m == NULL) return; 1043 1044 #ifdef ASSERT 1045 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) && 1046 !MetaspaceShared::remapped_readwrite()) { 1047 // At runtime initialize_itable is rerun as part of link_class_impl() 1048 // for a shared class loaded by the non-boot loader. 1049 // The dumptime itable method entry should be the same as the runtime entry. 1050 assert(_method == m, "sanity"); 1051 } 1052 #endif 1053 _method = m; 1054 } 1055 1056 klassItable::klassItable(InstanceKlass* klass) { 1057 _klass = klass; 1058 1059 if (klass->itable_length() > 0) { 1060 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1061 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1062 // First offset entry points to the first method_entry 1063 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1064 intptr_t* end = klass->end_of_itable(); 1065 1066 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1067 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1068 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1069 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1070 return; 1071 } 1072 } 1073 1074 // The length of the itable was either zero, or it has not yet been initialized. 1075 _table_offset = 0; 1076 _size_offset_table = 0; 1077 _size_method_table = 0; 1078 } 1079 1080 static int initialize_count = 0; 1081 1082 // Initialization 1083 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1084 if (_klass->is_interface()) { 1085 // This needs to go after vtable indices are assigned but 1086 // before implementors need to know the number of itable indices. 1087 assign_itable_indices_for_interface(InstanceKlass::cast(_klass), THREAD); 1088 } 1089 1090 // Cannot be setup doing bootstrapping, interfaces don't have 1091 // itables, and klass with only ones entry have empty itables 1092 if (Universe::is_bootstrapping() || 1093 _klass->is_interface() || 1094 _klass->itable_length() == itableOffsetEntry::size()) return; 1095 1096 // There's alway an extra itable entry so we can null-terminate it. 1097 guarantee(size_offset_table() >= 1, "too small"); 1098 int num_interfaces = size_offset_table() - 1; 1099 if (num_interfaces > 0) { 1100 ResourceMark rm(THREAD); 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(), InstanceKlass::cast(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; // uses direct call 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(InstanceKlass* klass, TRAPS) { 1134 // an interface does not have an itable, but its methods need to be numbered 1135 ResourceMark rm(THREAD); 1136 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1137 ++initialize_count, klass->name()->as_C_string()); 1138 Array<Method*>* methods = klass->methods(); 1139 int nof_methods = methods->length(); 1140 int ime_num = 0; 1141 for (int i = 0; i < nof_methods; i++) { 1142 Method* m = methods->at(i); 1143 if (interface_method_needs_itable_index(m)) { 1144 assert(!m->is_final_method(), "no final interface methods"); 1145 // If m is already assigned a vtable index, do not disturb it. 1146 if (log_develop_is_enabled(Trace, itables)) { 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(InstanceKlass* interf) { 1176 assert(interf->is_interface(), "must be"); 1177 Array<Method*>* methods = interf->methods(); 1178 int nof_methods = methods->length(); 1179 int length = 0; 1180 while (nof_methods > 0) { 1181 Method* m = methods->at(nof_methods-1); 1182 if (m->has_itable_index()) { 1183 length = m->itable_index() + 1; 1184 break; 1185 } 1186 nof_methods -= 1; 1187 } 1188 #ifdef ASSERT 1189 int nof_methods_copy = nof_methods; 1190 while (nof_methods_copy > 0) { 1191 Method* mm = methods->at(--nof_methods_copy); 1192 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1193 } 1194 #endif //ASSERT 1195 // return the rightmost itable index, plus one; or 0 if no methods have 1196 // itable indices 1197 return length; 1198 } 1199 1200 1201 void klassItable::initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf, bool checkconstraints, TRAPS) { 1202 assert(interf->is_interface(), "must be"); 1203 Array<Method*>* methods = interf->methods(); 1204 int nof_methods = methods->length(); 1205 HandleMark hm; 1206 Handle interface_loader (THREAD, 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 // Private methods are skipped as a private class method can never be the implementation 1216 // of an interface method. 1217 // Invokespecial does not perform selection based on the receiver, so it does not use 1218 // the cached itable. 1219 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), 1220 Klass::skip_private, CHECK); 1221 } 1222 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) { 1223 assert(target == NULL || !target->is_overpass() || target->is_public(), 1224 "Non-public overpass method!"); 1225 // Entry does not resolve. Leave it empty for AbstractMethodError or other error. 1226 if (!(target == NULL) && !target->is_public()) { 1227 // Stuff an IllegalAccessError throwing method in there instead. 1228 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1229 initialize(Universe::throw_illegal_access_error()); 1230 } 1231 } else { 1232 // Entry did resolve, check loader constraints before initializing 1233 // if checkconstraints requested 1234 if (checkconstraints) { 1235 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1236 if (!oopDesc::equals(method_holder_loader(), interface_loader())) { 1237 ResourceMark rm(THREAD); 1238 Symbol* failed_type_symbol = 1239 SystemDictionary::check_signature_loaders(m->signature(), 1240 method_holder_loader, 1241 interface_loader, 1242 true, CHECK); 1243 if (failed_type_symbol != NULL) { 1244 stringStream ss; 1245 ss.print("loader constraint violation in interface itable" 1246 " initialization for class %s: when selecting method '", 1247 _klass->external_name()); 1248 m->print_external_name(&ss), 1249 ss.print("' the class loader %s for super interface %s, and the class" 1250 " loader %s of the selected method's %s, %s have" 1251 " different Class objects for the type %s used in the signature (%s; %s)", 1252 interf->class_loader_data()->loader_name_and_id(), 1253 interf->external_name(), 1254 target()->method_holder()->class_loader_data()->loader_name_and_id(), 1255 target()->method_holder()->external_kind(), 1256 target()->method_holder()->external_name(), 1257 failed_type_symbol->as_klass_external_name(), 1258 interf->class_in_module_of_loader(false, true), 1259 target()->method_holder()->class_in_module_of_loader(false, true)); 1260 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string()); 1261 } 1262 } 1263 } 1264 1265 // ime may have moved during GC so recalculate address 1266 int ime_num = m->itable_index(); 1267 assert(ime_num < ime_count, "oob"); 1268 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target()); 1269 if (log_develop_is_enabled(Trace, itables)) { 1270 ResourceMark rm(THREAD); 1271 if (target() != NULL) { 1272 LogTarget(Trace, itables) lt; 1273 LogStream ls(lt); 1274 char* sig = target()->name_and_sig_as_C_string(); 1275 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1276 interf->internal_name(), ime_num, sig, 1277 target()->method_holder()->internal_name()); 1278 ls.print("target_method flags: "); 1279 target()->print_linkage_flags(&ls); 1280 ls.cr(); 1281 } 1282 } 1283 } 1284 } 1285 } 1286 1287 #if INCLUDE_JVMTI 1288 // search the itable for uses of either obsolete or EMCP methods 1289 void klassItable::adjust_method_entries(bool * trace_name_printed) { 1290 1291 itableMethodEntry* ime = method_entry(0); 1292 for (int i = 0; i < _size_method_table; i++, ime++) { 1293 Method* old_method = ime->method(); 1294 if (old_method == NULL || !old_method->is_old()) { 1295 continue; // skip uninteresting entries 1296 } 1297 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1298 Method* new_method = old_method->get_new_method(); 1299 ime->initialize(new_method); 1300 1301 if (log_is_enabled(Info, redefine, class, update)) { 1302 ResourceMark rm; 1303 if (!(*trace_name_printed)) { 1304 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1305 *trace_name_printed = true; 1306 } 1307 log_trace(redefine, class, update, itables) 1308 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string()); 1309 } 1310 } 1311 } 1312 1313 // an itable should never contain old or obsolete methods 1314 bool klassItable::check_no_old_or_obsolete_entries() { 1315 itableMethodEntry* ime = method_entry(0); 1316 for (int i = 0; i < _size_method_table; i++) { 1317 Method* m = ime->method(); 1318 if (m != NULL && 1319 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1320 return false; 1321 } 1322 ime++; 1323 } 1324 return true; 1325 } 1326 1327 void klassItable::dump_itable() { 1328 itableMethodEntry* ime = method_entry(0); 1329 tty->print_cr("itable dump --"); 1330 for (int i = 0; i < _size_method_table; i++) { 1331 Method* m = ime->method(); 1332 if (m != NULL) { 1333 tty->print(" (%5d) ", i); 1334 m->access_flags().print_on(tty); 1335 if (m->is_default_method()) { 1336 tty->print("default "); 1337 } 1338 tty->print(" -- "); 1339 m->print_name(tty); 1340 tty->cr(); 1341 } 1342 ime++; 1343 } 1344 } 1345 #endif // INCLUDE_JVMTI 1346 1347 // Setup 1348 class InterfaceVisiterClosure : public StackObj { 1349 public: 1350 virtual void doit(InstanceKlass* intf, int method_count) = 0; 1351 }; 1352 1353 // Visit all interfaces with at least one itable method 1354 void visit_all_interfaces(Array<InstanceKlass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1355 // Handle array argument 1356 for(int i = 0; i < transitive_intf->length(); i++) { 1357 InstanceKlass* intf = transitive_intf->at(i); 1358 assert(intf->is_interface(), "sanity check"); 1359 1360 // Find no. of itable methods 1361 int method_count = 0; 1362 // method_count = klassItable::method_count_for_interface(intf); 1363 Array<Method*>* methods = intf->methods(); 1364 if (methods->length() > 0) { 1365 for (int i = methods->length(); --i >= 0; ) { 1366 if (interface_method_needs_itable_index(methods->at(i))) { 1367 method_count++; 1368 } 1369 } 1370 } 1371 1372 // Visit all interfaces which either have any methods or can participate in receiver type check. 1373 // We do not bother to count methods in transitive interfaces, although that would allow us to skip 1374 // this step in the rare case of a zero-method interface extending another zero-method interface. 1375 if (method_count > 0 || intf->transitive_interfaces()->length() > 0) { 1376 blk->doit(intf, method_count); 1377 } 1378 } 1379 } 1380 1381 class CountInterfacesClosure : public InterfaceVisiterClosure { 1382 private: 1383 int _nof_methods; 1384 int _nof_interfaces; 1385 public: 1386 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1387 1388 int nof_methods() const { return _nof_methods; } 1389 int nof_interfaces() const { return _nof_interfaces; } 1390 1391 void doit(InstanceKlass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1392 }; 1393 1394 class SetupItableClosure : public InterfaceVisiterClosure { 1395 private: 1396 itableOffsetEntry* _offset_entry; 1397 itableMethodEntry* _method_entry; 1398 address _klass_begin; 1399 public: 1400 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1401 _klass_begin = klass_begin; 1402 _offset_entry = offset_entry; 1403 _method_entry = method_entry; 1404 } 1405 1406 itableMethodEntry* method_entry() const { return _method_entry; } 1407 1408 void doit(InstanceKlass* intf, int method_count) { 1409 int offset = ((address)_method_entry) - _klass_begin; 1410 _offset_entry->initialize(intf, offset); 1411 _offset_entry++; 1412 _method_entry += method_count; 1413 } 1414 }; 1415 1416 int klassItable::compute_itable_size(Array<InstanceKlass*>* transitive_interfaces) { 1417 // Count no of interfaces and total number of interface methods 1418 CountInterfacesClosure cic; 1419 visit_all_interfaces(transitive_interfaces, &cic); 1420 1421 // There's alway an extra itable entry so we can null-terminate it. 1422 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1423 1424 // Statistics 1425 update_stats(itable_size * wordSize); 1426 1427 return itable_size; 1428 } 1429 1430 1431 // Fill out offset table and interface klasses into the itable space 1432 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1433 if (klass->itable_length() == 0) return; 1434 assert(!klass->is_interface(), "Should have zero length itable"); 1435 1436 // Count no of interfaces and total number of interface methods 1437 CountInterfacesClosure cic; 1438 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1439 int nof_methods = cic.nof_methods(); 1440 int nof_interfaces = cic.nof_interfaces(); 1441 1442 // Add one extra entry so we can null-terminate the table 1443 nof_interfaces++; 1444 1445 assert(compute_itable_size(klass->transitive_interfaces()) == 1446 calc_itable_size(nof_interfaces, nof_methods), 1447 "mismatch calculation of itable size"); 1448 1449 // Fill-out offset table 1450 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1451 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1452 intptr_t* end = klass->end_of_itable(); 1453 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1454 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1455 1456 // Visit all interfaces and initialize itable offset table 1457 SetupItableClosure sic((address)klass, ioe, ime); 1458 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1459 1460 #ifdef ASSERT 1461 ime = sic.method_entry(); 1462 oop* v = (oop*) klass->end_of_itable(); 1463 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1464 #endif 1465 } 1466 1467 1468 // inverse to itable_index 1469 Method* klassItable::method_for_itable_index(InstanceKlass* intf, int itable_index) { 1470 assert(intf->is_interface(), "sanity check"); 1471 assert(intf->verify_itable_index(itable_index), ""); 1472 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1473 1474 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1475 return NULL; // help caller defend against bad indices 1476 1477 int index = itable_index; 1478 Method* m = methods->at(index); 1479 int index2 = -1; 1480 while (!m->has_itable_index() || 1481 (index2 = m->itable_index()) != itable_index) { 1482 assert(index2 < itable_index, "monotonic"); 1483 if (++index == methods->length()) 1484 return NULL; 1485 m = methods->at(index); 1486 } 1487 assert(m->itable_index() == itable_index, "correct inverse"); 1488 1489 return m; 1490 } 1491 1492 void klassVtable::verify(outputStream* st, bool forced) { 1493 // make sure table is initialized 1494 if (!Universe::is_fully_initialized()) return; 1495 #ifndef PRODUCT 1496 // avoid redundant verifies 1497 if (!forced && _verify_count == Universe::verify_count()) return; 1498 _verify_count = Universe::verify_count(); 1499 #endif 1500 oop* end_of_obj = (oop*)_klass + _klass->size(); 1501 oop* end_of_vtable = (oop *)&table()[_length]; 1502 if (end_of_vtable > end_of_obj) { 1503 ResourceMark rm; 1504 fatal("klass %s: klass object too short (vtable extends beyond end)", 1505 _klass->internal_name()); 1506 } 1507 1508 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1509 // verify consistency with superKlass vtable 1510 Klass* super = _klass->super(); 1511 if (super != NULL) { 1512 InstanceKlass* sk = InstanceKlass::cast(super); 1513 klassVtable vt = sk->vtable(); 1514 for (int i = 0; i < vt.length(); i++) { 1515 verify_against(st, &vt, i); 1516 } 1517 } 1518 } 1519 1520 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1521 vtableEntry* vte = &vt->table()[index]; 1522 if (vte->method()->name() != table()[index].method()->name() || 1523 vte->method()->signature() != table()[index].method()->signature()) { 1524 fatal("mismatched name/signature of vtable entries"); 1525 } 1526 } 1527 1528 #ifndef PRODUCT 1529 void klassVtable::print() { 1530 ResourceMark rm; 1531 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1532 for (int i = 0; i < length(); i++) { 1533 table()[i].print(); 1534 tty->cr(); 1535 } 1536 } 1537 #endif 1538 1539 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1540 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1541 Klass* vtklass = vt->klass(); 1542 if (vtklass->is_instance_klass() && 1543 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1544 assert(method() != NULL, "must have set method"); 1545 } 1546 if (method() != NULL) { 1547 method()->verify(); 1548 // we sub_type, because it could be a miranda method 1549 if (!vtklass->is_subtype_of(method()->method_holder())) { 1550 #ifndef PRODUCT 1551 print(); 1552 #endif 1553 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1554 } 1555 } 1556 } 1557 1558 #ifndef PRODUCT 1559 1560 void vtableEntry::print() { 1561 ResourceMark rm; 1562 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1563 if (Verbose) { 1564 tty->print("m " PTR_FORMAT " ", p2i(method())); 1565 } 1566 } 1567 1568 class VtableStats : AllStatic { 1569 public: 1570 static int no_klasses; // # classes with vtables 1571 static int no_array_klasses; // # array classes 1572 static int no_instance_klasses; // # instanceKlasses 1573 static int sum_of_vtable_len; // total # of vtable entries 1574 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1575 static int fixed; // total fixed overhead in bytes 1576 static int filler; // overhead caused by filler bytes 1577 static int entries; // total bytes consumed by vtable entries 1578 static int array_entries; // total bytes consumed by array vtable entries 1579 1580 static void do_class(Klass* k) { 1581 Klass* kl = k; 1582 klassVtable vt = kl->vtable(); 1583 no_klasses++; 1584 if (kl->is_instance_klass()) { 1585 no_instance_klasses++; 1586 kl->array_klasses_do(do_class); 1587 } 1588 if (kl->is_array_klass()) { 1589 no_array_klasses++; 1590 sum_of_array_vtable_len += vt.length(); 1591 } 1592 sum_of_vtable_len += vt.length(); 1593 } 1594 1595 static void compute() { 1596 LockedClassesDo locked_do_class(&do_class); 1597 ClassLoaderDataGraph::classes_do(&locked_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