1 /* 2 * Copyright (c) 1997, 2022, 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 "cds/metaspaceShared.hpp" 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 "jvm.h" 33 #include "logging/log.hpp" 34 #include "logging/logStream.hpp" 35 #include "memory/resourceArea.hpp" 36 #include "memory/universe.hpp" 37 #include "oops/instanceKlass.inline.hpp" 38 #include "oops/klass.inline.hpp" 39 #include "oops/klassVtable.hpp" 40 #include "oops/method.hpp" 41 #include "oops/objArrayOop.hpp" 42 #include "oops/oop.inline.hpp" 43 #include "runtime/flags/flagSetting.hpp" 44 #include "runtime/java.hpp" 45 #include "runtime/handles.inline.hpp" 46 #include "runtime/safepointVerifiers.hpp" 47 #include "utilities/copy.hpp" 48 49 inline InstanceKlass* klassVtable::ik() const { 50 return InstanceKlass::cast(_klass); 51 } 52 53 bool klassVtable::is_preinitialized_vtable() { 54 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite() && _klass->verified_at_dump_time(); 55 } 56 57 58 // this function computes the vtable size (including the size needed for miranda 59 // methods) and the number of miranda methods in this class. 60 // Note on Miranda methods: Let's say there is a class C that implements 61 // interface I, and none of C's superclasses implements I. 62 // Let's say there is an abstract method m in I that neither C 63 // nor any of its super classes implement (i.e there is no method of any access, 64 // with the same name and signature as m), then m is a Miranda method which is 65 // entered as a public abstract method in C's vtable. From then on it should 66 // treated as any other public method in C for method over-ride purposes. 67 void klassVtable::compute_vtable_size_and_num_mirandas( 68 int* vtable_length_ret, int* num_new_mirandas, 69 GrowableArray<Method*>* all_mirandas, const Klass* super, 70 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 71 Handle classloader, Symbol* classname, Array<InstanceKlass*>* local_interfaces) { 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 Method* method = methods->at(i); 84 85 if (needs_new_vtable_entry(method, super, classloader, classname, class_flags, major_version)) { 86 assert(!method->is_private(), "private methods should not need a vtable entry"); 87 vtable_length += vtableEntry::size(); // we need a new entry 88 } 89 } 90 91 GrowableArray<Method*> new_mirandas(20); 92 // compute the number of mirandas methods that must be added to the end 93 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces, 94 class_flags.is_interface()); 95 *num_new_mirandas = new_mirandas.length(); 96 97 // Interfaces do not need interface methods in their vtables 98 // This includes miranda methods and during later processing, default methods 99 if (!class_flags.is_interface()) { 100 vtable_length += *num_new_mirandas * vtableEntry::size(); 101 } 102 103 if (Universe::is_bootstrapping() && vtable_length == 0) { 104 // array classes don't have their superclass set correctly during 105 // bootstrapping 106 vtable_length = Universe::base_vtable_size(); 107 } 108 109 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 110 if (Universe::is_bootstrapping()) { 111 // Someone is attempting to override java.lang.Object incorrectly on the 112 // bootclasspath. The JVM cannot recover from this error including throwing 113 // an exception 114 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 115 } else { 116 // Someone is attempting to redefine java.lang.Object incorrectly. The 117 // only way this should happen is from 118 // SystemDictionary::resolve_from_stream(), which will detect this later 119 // and throw a security exception. So don't assert here to let 120 // the exception occur. 121 vtable_length = Universe::base_vtable_size(); 122 } 123 } 124 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 125 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 126 127 *vtable_length_ret = vtable_length; 128 } 129 130 // Copy super class's vtable to the first part (prefix) of this class's vtable, 131 // and return the number of entries copied. Expects that 'super' is the Java 132 // super class (arrays can have "array" super classes that must be skipped). 133 int klassVtable::initialize_from_super(Klass* super) { 134 if (super == NULL) { 135 return 0; 136 } else if (is_preinitialized_vtable()) { 137 // A shared class' vtable is preinitialized at dump time. No need to copy 138 // methods from super class for shared class, as that was already done 139 // during archiving time. However, if Jvmti has redefined a class, 140 // copy super class's vtable in case the super class has changed. 141 return super->vtable().length(); 142 } else { 143 // copy methods from superKlass 144 klassVtable superVtable = super->vtable(); 145 assert(superVtable.length() <= _length, "vtable too short"); 146 #ifdef ASSERT 147 superVtable.verify(tty, true); 148 #endif 149 superVtable.copy_vtable_to(table()); 150 if (log_develop_is_enabled(Trace, vtables)) { 151 ResourceMark rm; 152 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 153 super->internal_name(), klass()->internal_name(), 154 _length); 155 } 156 return superVtable.length(); 157 } 158 } 159 160 // 161 // Revised lookup semantics introduced 1.3 (Kestrel beta) 162 void klassVtable::initialize_vtable(GrowableArray<InstanceKlass*>* supers) { 163 164 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 165 InstanceKlass* super = _klass->java_super(); 166 167 bool is_shared = _klass->is_shared(); 168 Thread* current = Thread::current(); 169 170 if (!_klass->is_array_klass()) { 171 ResourceMark rm(current); 172 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 173 } 174 175 #ifdef ASSERT 176 oop* end_of_obj = (oop*)_klass + _klass->size(); 177 oop* end_of_vtable = (oop*)&table()[_length]; 178 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 179 #endif 180 181 if (Universe::is_bootstrapping()) { 182 assert(!is_shared, "sanity"); 183 // just clear everything 184 for (int i = 0; i < _length; i++) table()[i].clear(); 185 return; 186 } 187 188 int super_vtable_len = initialize_from_super(super); 189 if (_klass->is_array_klass()) { 190 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 191 } else { 192 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 193 194 Array<Method*>* methods = ik()->methods(); 195 int len = methods->length(); 196 int initialized = super_vtable_len; 197 198 // Check each of this class's methods against super; 199 // if override, replace in copy of super vtable, otherwise append to end 200 for (int i = 0; i < len; i++) { 201 // update_inherited_vtable can stop for gc - ensure using handles 202 methodHandle mh(current, methods->at(i)); 203 204 bool needs_new_entry = update_inherited_vtable(current, mh, super_vtable_len, -1, supers); 205 206 if (needs_new_entry) { 207 put_method_at(mh(), initialized); 208 mh->set_vtable_index(initialized); // set primary vtable index 209 initialized++; 210 } 211 } 212 213 // update vtable with default_methods 214 Array<Method*>* default_methods = ik()->default_methods(); 215 if (default_methods != NULL) { 216 len = default_methods->length(); 217 if (len > 0) { 218 Array<int>* def_vtable_indices = ik()->default_vtable_indices(); 219 assert(def_vtable_indices != NULL, "should be created"); 220 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 221 for (int i = 0; i < len; i++) { 222 bool needs_new_entry; 223 { 224 // Reduce the scope of this handle so that it is fetched again. 225 // The methodHandle keeps it from being deleted by RedefineClasses while 226 // we're using it. 227 methodHandle mh(current, default_methods->at(i)); 228 assert(!mh->is_private(), "private interface method in the default method list"); 229 needs_new_entry = update_inherited_vtable(current, mh, super_vtable_len, i, supers); 230 } 231 232 // needs new entry 233 if (needs_new_entry) { 234 // Refetch this default method in case of redefinition that might 235 // happen during constraint checking in the update_inherited_vtable call above. 236 Method* method = default_methods->at(i); 237 put_method_at(method, initialized); 238 if (is_preinitialized_vtable()) { 239 // At runtime initialize_vtable is rerun for a shared class 240 // (loaded by the non-boot loader) as part of link_class_impl(). 241 // The dumptime vtable index should be the same as the runtime index. 242 assert(def_vtable_indices->at(i) == initialized, 243 "dump time vtable index is different from runtime index"); 244 } else { 245 def_vtable_indices->at_put(i, initialized); //set vtable index 246 } 247 initialized++; 248 } 249 } 250 } 251 } 252 253 // add miranda methods; it will also return the updated initialized 254 // Interfaces do not need interface methods in their vtables 255 // This includes miranda methods and during later processing, default methods 256 if (!ik()->is_interface()) { 257 initialized = fill_in_mirandas(current, initialized); 258 } 259 260 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 261 // package_private -> public/protected), the vtable might actually be smaller than our initial 262 // calculation, for classfile versions for which we do not do transitive override 263 // calculations. 264 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 265 assert(initialized == _length, "vtable initialization failed"); 266 } else { 267 assert(initialized <= _length, "vtable initialization failed"); 268 for(;initialized < _length; initialized++) { 269 table()[initialized].clear(); 270 } 271 } 272 NOT_PRODUCT(verify(tty, true)); 273 } 274 } 275 276 // Returns true iff super_method can be overridden by a method in targetclassname 277 // See JLS 8.4.8.1 278 // Assumes name-signature match 279 // Note that the InstanceKlass of the method in the targetclassname has not always been created yet 280 static bool can_be_overridden(Method* super_method, Handle targetclassloader, Symbol* targetclassname) { 281 // Private methods can not be overridden 282 assert(!super_method->is_private(), "shouldn't call with a private method"); 283 284 // If super method is accessible, then override 285 if ((super_method->is_protected()) || 286 (super_method->is_public())) { 287 return true; 288 } 289 // Package-private methods are not inherited outside of package 290 assert(super_method->is_package_private(), "must be package private"); 291 return(super_method->method_holder()->is_same_class_package(targetclassloader(), targetclassname)); 292 } 293 294 295 // Called for cases where a method does not override its superclass' vtable entry 296 // For bytecodes not produced by javac together it is possible that a method does not override 297 // the superclass's method, but might indirectly override a super-super class's vtable entry 298 // If none found, return a null superk, else return the superk of the method this does override 299 // For public and protected methods: if they override a superclass, they will 300 // also be overridden themselves appropriately. 301 // Private methods do not override, and are not overridden and are not in the vtable. 302 // Package Private methods are trickier: 303 // e.g. P1.A, pub m 304 // P2.B extends A, package private m 305 // P1.C extends B, public m 306 // P1.C.m needs to override P1.A.m and can not override P2.B.m 307 // Therefore: all package private methods need their own vtable entries for 308 // them to be the root of an inheritance overriding decision 309 // Package private methods may also override other vtable entries 310 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, 311 const methodHandle& target_method, 312 int vtable_index, 313 Handle target_loader, 314 Symbol* target_classname) { 315 316 InstanceKlass* superk = initialsuper; 317 while (superk != NULL && superk->super() != NULL) { 318 klassVtable ssVtable = (superk->super())->vtable(); 319 if (vtable_index < ssVtable.length()) { 320 Method* super_method = ssVtable.method_at(vtable_index); 321 #ifndef PRODUCT 322 Symbol* name= target_method()->name(); 323 Symbol* signature = target_method()->signature(); 324 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 325 #endif 326 327 if (can_be_overridden(super_method, target_loader, target_classname)) { 328 if (log_develop_is_enabled(Trace, vtables)) { 329 ResourceMark rm; 330 LogTarget(Trace, vtables) lt; 331 LogStream ls(lt); 332 char* sig = target_method()->name_and_sig_as_C_string(); 333 ls.print("transitive overriding superclass %s with %s index %d, original flags: ", 334 super_method->method_holder()->internal_name(), 335 sig, vtable_index); 336 super_method->print_linkage_flags(&ls); 337 ls.print("overriders flags: "); 338 target_method->print_linkage_flags(&ls); 339 ls.cr(); 340 } 341 342 break; // return found superk 343 } 344 } else { 345 // super class has no vtable entry here, stop transitive search 346 superk = (InstanceKlass*)NULL; 347 break; 348 } 349 // if no override found yet, continue to search up 350 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 351 } 352 353 return superk; 354 } 355 356 static void log_vtables(int i, bool overrides, const methodHandle& target_method, 357 Klass* target_klass, Method* super_method) { 358 #ifndef PRODUCT 359 if (log_develop_is_enabled(Trace, vtables)) { 360 ResourceMark rm; 361 LogTarget(Trace, vtables) lt; 362 LogStream ls(lt); 363 char* sig = target_method()->name_and_sig_as_C_string(); 364 if (overrides) { 365 ls.print("overriding with %s index %d, original flags: ", 366 sig, i); 367 } else { 368 ls.print("NOT overriding with %s index %d, original flags: ", 369 sig, i); 370 } 371 super_method->print_linkage_flags(&ls); 372 ls.print("overriders flags: "); 373 target_method->print_linkage_flags(&ls); 374 ls.cr(); 375 } 376 #endif 377 } 378 379 // Update child's copy of super vtable for overrides 380 // OR return true if a new vtable entry is required. 381 // Only called for InstanceKlass's, i.e. not for arrays 382 // If that changed, could not use _klass as handle for klass 383 bool klassVtable::update_inherited_vtable(Thread* current, 384 const methodHandle& target_method, 385 int super_vtable_len, int default_index, 386 GrowableArray<InstanceKlass*>* supers) { 387 bool allocate_new = true; 388 389 InstanceKlass* klass = ik(); 390 391 Array<int>* def_vtable_indices = NULL; 392 bool is_default = false; 393 394 // default methods are non-private concrete methods in superinterfaces which are added 395 // to the vtable with their real method_holder. 396 // Since vtable and itable indices share the same storage, don't touch 397 // the default method's real vtable/itable index. 398 // default_vtable_indices stores the vtable value relative to this inheritor 399 if (default_index >= 0 ) { 400 is_default = true; 401 def_vtable_indices = klass->default_vtable_indices(); 402 assert(!target_method->is_private(), "private interface method flagged as default"); 403 assert(def_vtable_indices != NULL, "def vtable alloc?"); 404 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 405 } else { 406 assert(klass == target_method->method_holder(), "caller resp."); 407 // Initialize the method's vtable index to "nonvirtual". 408 // If we allocate a vtable entry, we will update it to a non-negative number. 409 target_method->set_vtable_index(Method::nonvirtual_vtable_index); 410 } 411 412 // Private, static and <init> methods are never in 413 if (target_method->is_private() || target_method->is_static() || 414 (target_method->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)) { 415 return false; 416 } 417 418 if (target_method->is_final_method(klass->access_flags())) { 419 // a final method never needs a new entry; final methods can be statically 420 // resolved and they have to be present in the vtable only if they override 421 // a super's method, in which case they re-use its entry 422 allocate_new = false; 423 } else if (klass->is_interface()) { 424 allocate_new = false; // see note below in needs_new_vtable_entry 425 // An interface never allocates new vtable slots, only inherits old ones. 426 // This method will either be assigned its own itable index later, 427 // or be assigned an inherited vtable index in the loop below. 428 // default methods inherited by classes store their vtable indices 429 // in the inheritor's default_vtable_indices. 430 // default methods inherited by interfaces may already have a 431 // valid itable index, if so, don't change it. 432 // Overpass methods in an interface will be assigned an itable index later 433 // by an inheriting class. 434 if ((!is_default || !target_method->has_itable_index())) { 435 target_method->set_vtable_index(Method::pending_itable_index); 436 } 437 } 438 439 // we need a new entry if there is no superclass 440 Klass* super = klass->super(); 441 if (super == NULL) { 442 return allocate_new; 443 } 444 445 // search through the vtable and update overridden entries 446 // Since check_signature_loaders acquires SystemDictionary_lock 447 // which can block for gc, once we are in this loop, use handles 448 // For classfiles built with >= jdk7, we now look for transitive overrides 449 450 Symbol* name = target_method->name(); 451 Symbol* signature = target_method->signature(); 452 453 Klass* target_klass = target_method->method_holder(); 454 assert(target_klass != NULL, "impossible"); 455 if (target_klass == NULL) { 456 target_klass = _klass; 457 } 458 459 HandleMark hm(current); 460 Handle target_loader(current, target_klass->class_loader()); 461 462 Symbol* target_classname = target_klass->name(); 463 for(int i = 0; i < super_vtable_len; i++) { 464 Method* super_method; 465 if (is_preinitialized_vtable()) { 466 // If this is a shared class, the vtable is already in the final state (fully 467 // initialized). Need to look at the super's vtable. 468 klassVtable superVtable = super->vtable(); 469 super_method = superVtable.method_at(i); 470 } else { 471 super_method = method_at(i); 472 } 473 // Check if method name matches. Ignore match if klass is an interface and the 474 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4) 475 // This is safe because the method at this slot should never get invoked. 476 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.) 477 if (super_method->name() == name && super_method->signature() == signature && 478 (!klass->is_interface() || 479 !SystemDictionary::is_nonpublic_Object_method(super_method))) { 480 481 // get super_klass for method_holder for the found method 482 InstanceKlass* super_klass = super_method->method_holder(); 483 484 // Whether the method is being overridden 485 bool overrides = false; 486 487 // private methods are also never overridden 488 if (!super_method->is_private() && 489 (is_default || 490 can_be_overridden(super_method, target_loader, target_classname) || 491 (klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION && 492 (super_klass = find_transitive_override(super_klass, 493 target_method, i, target_loader, 494 target_classname)) != NULL))) { 495 496 // Package private methods always need a new entry to root their own 497 // overriding. They may also override other methods. 498 if (!target_method->is_package_private()) { 499 allocate_new = false; 500 } 501 502 // Set the vtable index before the constraint check safepoint, which potentially 503 // redefines this method if this method is a default method belonging to a 504 // super class or interface. 505 put_method_at(target_method(), i); 506 // Save super for constraint checking. 507 if (supers != NULL) { 508 supers->at_put(i, super_klass); 509 } 510 511 overrides = true; 512 if (!is_default) { 513 target_method->set_vtable_index(i); 514 } else { 515 if (def_vtable_indices != NULL) { 516 if (is_preinitialized_vtable()) { 517 // At runtime initialize_vtable is rerun as part of link_class_impl() 518 // for a shared class loaded by the non-boot loader. 519 // The dumptime vtable index should be the same as the runtime index. 520 assert(def_vtable_indices->at(default_index) == i, 521 "dump time vtable index is different from runtime index"); 522 } else { 523 def_vtable_indices->at_put(default_index, i); 524 } 525 } 526 assert(super_method->is_default_method() || super_method->is_overpass() 527 || super_method->is_abstract(), "default override error"); 528 } 529 } else { 530 overrides = false; 531 } 532 log_vtables(i, overrides, target_method, target_klass, super_method); 533 } 534 } 535 return allocate_new; 536 } 537 538 void klassVtable::put_method_at(Method* m, int index) { 539 assert(!m->is_private(), "private methods should not be in vtable"); 540 JVMTI_ONLY(assert(!m->is_old() || ik()->is_being_redefined(), "old methods should not be in vtable")); 541 if (is_preinitialized_vtable()) { 542 // At runtime initialize_vtable is rerun as part of link_class_impl() 543 // for shared class loaded by the non-boot loader to obtain the loader 544 // constraints based on the runtime classloaders' context. The dumptime 545 // method at the vtable index should be the same as the runtime method. 546 assert(table()[index].method() == m, 547 "archived method is different from the runtime method"); 548 } else { 549 if (log_develop_is_enabled(Trace, vtables)) { 550 ResourceMark rm; 551 LogTarget(Trace, vtables) lt; 552 LogStream ls(lt); 553 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 554 ls.print("adding %s at index %d, flags: ", sig, index); 555 if (m != NULL) { 556 m->print_linkage_flags(&ls); 557 } 558 ls.cr(); 559 } 560 table()[index].set(m); 561 } 562 } 563 564 void klassVtable::check_constraints(GrowableArray<InstanceKlass*>* supers, TRAPS) { 565 assert(supers->length() == length(), "lengths are different"); 566 // For each method in the vtable, check constraints against any super class 567 // if overridden. 568 for (int i = 0; i < length(); i++) { 569 methodHandle target_method(THREAD, unchecked_method_at(i)); 570 InstanceKlass* super_klass = supers->at(i); 571 if (target_method() != NULL && super_klass != NULL) { 572 // Do not check loader constraints for overpass methods because overpass 573 // methods are created by the jvm to throw exceptions. 574 if (!target_method->is_overpass()) { 575 // Override vtable entry if passes loader constraint check 576 // if loader constraint checking requested 577 // No need to visit his super, since he and his super 578 // have already made any needed loader constraints. 579 // Since loader constraints are transitive, it is enough 580 // to link to the first super, and we get all the others. 581 Handle super_loader(THREAD, super_klass->class_loader()); 582 InstanceKlass* target_klass = target_method->method_holder(); 583 Handle target_loader(THREAD, target_klass->class_loader()); 584 585 if (target_loader() != super_loader()) { 586 ResourceMark rm(THREAD); 587 Symbol* failed_type_symbol = 588 SystemDictionary::check_signature_loaders(target_method->signature(), 589 _klass, 590 target_loader, super_loader, 591 true); 592 if (failed_type_symbol != NULL) { 593 stringStream ss; 594 ss.print("loader constraint violation for class %s: when selecting " 595 "overriding method '", _klass->external_name()); 596 target_method->print_external_name(&ss), 597 ss.print("' the class loader %s of the " 598 "selected method's type %s, and the class loader %s for its super " 599 "type %s have different Class objects for the type %s used in the signature (%s; %s)", 600 target_klass->class_loader_data()->loader_name_and_id(), 601 target_klass->external_name(), 602 super_klass->class_loader_data()->loader_name_and_id(), 603 super_klass->external_name(), 604 failed_type_symbol->as_klass_external_name(), 605 target_klass->class_in_module_of_loader(false, true), 606 super_klass->class_in_module_of_loader(false, true)); 607 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string()); 608 } 609 } 610 } 611 } 612 } 613 } 614 615 void klassVtable::initialize_vtable_and_check_constraints(TRAPS) { 616 // Save a superclass from each vtable entry to do constraint checking 617 ResourceMark rm(THREAD); 618 GrowableArray<InstanceKlass*>* supers = new GrowableArray<InstanceKlass*>(_length, _length, NULL); 619 initialize_vtable(supers); 620 check_constraints(supers, CHECK); 621 } 622 623 624 // Find out if a method "m" with superclass "super", loader "classloader" and 625 // name "classname" needs a new vtable entry. Let P be a class package defined 626 // by "classloader" and "classname". 627 // NOTE: The logic used here is very similar to the one used for computing 628 // the vtables indices for a method. We cannot directly use that function because, 629 // we allocate the InstanceKlass at load time, and that requires that the 630 // superclass has been loaded. 631 // However, the vtable entries are filled in at link time, and therefore 632 // the superclass' vtable may not yet have been filled in. 633 bool klassVtable::needs_new_vtable_entry(Method* target_method, 634 const Klass* super, 635 Handle classloader, 636 Symbol* classname, 637 AccessFlags class_flags, 638 u2 major_version) { 639 if (class_flags.is_interface()) { 640 // Interfaces do not use vtables, except for java.lang.Object methods, 641 // so there is no point to assigning 642 // a vtable index to any of their local methods. If we refrain from doing this, 643 // we can use Method::_vtable_index to hold the itable index 644 return false; 645 } 646 647 if (target_method->is_final_method(class_flags) || 648 // a final method never needs a new entry; final methods can be statically 649 // resolved and they have to be present in the vtable only if they override 650 // a super's method, in which case they re-use its entry 651 (target_method->is_private()) || 652 // private methods don't need to be in vtable 653 (target_method->is_static()) || 654 // static methods don't need to be in vtable 655 (target_method->name()->fast_compare(vmSymbols::object_initializer_name()) == 0) 656 // <init> is never called dynamically-bound 657 ) { 658 return false; 659 } 660 661 // Concrete interface methods do not need new entries, they override 662 // abstract method entries using default inheritance rules 663 if (target_method->method_holder() != NULL && 664 target_method->method_holder()->is_interface() && 665 !target_method->is_abstract()) { 666 assert(target_method->is_default_method(), 667 "unexpected interface method type"); 668 return false; 669 } 670 671 // we need a new entry if there is no superclass 672 if (super == NULL) { 673 return true; 674 } 675 676 // Package private methods always need a new entry to root their own 677 // overriding. This allows transitive overriding to work. 678 if (target_method->is_package_private()) { 679 return true; 680 } 681 682 // search through the super class hierarchy to see if we need 683 // a new entry 684 Symbol* name = target_method->name(); 685 Symbol* signature = target_method->signature(); 686 const Klass* k = super; 687 Method* super_method = NULL; 688 InstanceKlass *holder = NULL; 689 Method* recheck_method = NULL; 690 bool found_pkg_prvt_method = false; 691 while (k != NULL) { 692 // lookup through the hierarchy for a method with matching name and sign. 693 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 694 if (super_method == NULL) { 695 break; // we still have to search for a matching miranda method 696 } 697 // get the class holding the matching method 698 InstanceKlass* superk = super_method->method_holder(); 699 // we want only instance method matches 700 // ignore private methods found via lookup_method since they do not participate in overriding, 701 // and since we do override around them: e.g. a.m pub/b.m private/c.m pub, 702 // ignore private, c.m pub does override a.m pub 703 // For classes that were not javac'd together, we also do transitive overriding around 704 // methods that have less accessibility 705 if (!super_method->is_static() && 706 !super_method->is_private()) { 707 if (can_be_overridden(super_method, classloader, classname)) { 708 return false; 709 // else keep looking for transitive overrides 710 } 711 // If we get here then one of the super classes has a package private method 712 // that will not get overridden because it is in a different package. But, 713 // that package private method does "override" any matching methods in super 714 // interfaces, so there will be no miranda vtable entry created. So, set flag 715 // to TRUE for use below, in case there are no methods in super classes that 716 // this target method overrides. 717 assert(super_method->is_package_private(), "super_method must be package private"); 718 assert(!superk->is_same_class_package(classloader(), classname), 719 "Must be different packages"); 720 found_pkg_prvt_method = true; 721 } 722 723 // Start with lookup result and continue to search up, for versions supporting transitive override 724 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 725 k = superk->super(); // haven't found an override match yet; continue to look 726 } else { 727 break; 728 } 729 } 730 731 // If found_pkg_prvt_method is set, then the ONLY matching method in the 732 // superclasses is package private in another package. That matching method will 733 // prevent a miranda vtable entry from being created. Because the target method can not 734 // override the package private method in another package, then it needs to be the root 735 // for its own vtable entry. 736 if (found_pkg_prvt_method) { 737 return true; 738 } 739 740 // if the target method is public or protected it may have a matching 741 // miranda method in the super, whose entry it should re-use. 742 // Actually, to handle cases that javac would not generate, we need 743 // this check for all access permissions. 744 const InstanceKlass *sk = InstanceKlass::cast(super); 745 if (sk->has_miranda_methods()) { 746 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::DefaultsLookupMode::find) != NULL) { 747 return false; // found a matching miranda; we do not need a new entry 748 } 749 } 750 return true; // found no match; we need a new entry 751 } 752 753 // Support for miranda methods 754 755 // get the vtable index of a miranda method with matching "name" and "signature" 756 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 757 // search from the bottom, might be faster 758 for (int i = (length() - 1); i >= 0; i--) { 759 Method* m = table()[i].method(); 760 if (is_miranda_entry_at(i) && 761 m->name() == name && m->signature() == signature) { 762 return i; 763 } 764 } 765 return Method::invalid_vtable_index; 766 } 767 768 // check if an entry at an index is miranda 769 // requires that method m at entry be declared ("held") by an interface. 770 bool klassVtable::is_miranda_entry_at(int i) { 771 Method* m = method_at(i); 772 InstanceKlass* holder = m->method_holder(); 773 774 // miranda methods are public abstract instance interface methods in a class's vtable 775 if (holder->is_interface()) { 776 assert(m->is_public(), "should be public"); 777 assert(ik()->implements_interface(holder) , "this class should implement the interface"); 778 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) { 779 return true; 780 } 781 } 782 return false; 783 } 784 785 // Check if a method is a miranda method, given a class's methods array, 786 // its default_method table and its super class. 787 // "Miranda" means an abstract non-private method that would not be 788 // overridden for the local class. 789 // A "miranda" method should only include non-private interface 790 // instance methods, i.e. not private methods, not static methods, 791 // not default methods (concrete interface methods), not overpass methods. 792 // If a given class already has a local (including overpass) method, a 793 // default method, or any of its superclasses has the same which would have 794 // overridden an abstract method, then this is not a miranda method. 795 // 796 // Miranda methods are checked multiple times. 797 // Pass 1: during class load/class file parsing: before vtable size calculation: 798 // include superinterface abstract and default methods (non-private instance). 799 // We include potential default methods to give them space in the vtable. 800 // During the first run, the current instanceKlass has not yet been 801 // created, the superclasses and superinterfaces do have instanceKlasses 802 // but may not have vtables, the default_methods list is empty, no overpasses. 803 // Default method generation uses the all_mirandas array as the starter set for 804 // maximally-specific default method calculation. So, for both classes and 805 // interfaces, it is necessary that the first pass will find all non-private 806 // interface instance methods, whether or not they are concrete. 807 // 808 // Pass 2: recalculated during vtable initialization: only include abstract methods. 809 // The goal of pass 2 is to walk through the superinterfaces to see if any of 810 // the superinterface methods (which were all abstract pre-default methods) 811 // need to be added to the vtable. 812 // With the addition of default methods, we have three new challenges: 813 // overpasses, static interface methods and private interface methods. 814 // Static and private interface methods do not get added to the vtable and 815 // are not seen by the method resolution process, so we skip those. 816 // Overpass methods are already in the vtable, so vtable lookup will 817 // find them and we don't need to add a miranda method to the end of 818 // the vtable. So we look for overpass methods and if they are found we 819 // return false. Note that we inherit our superclasses vtable, so 820 // the superclass' search also needs to use find_overpass so that if 821 // one is found we return false. 822 // False means - we don't need a miranda method added to the vtable. 823 // 824 // During the second run, default_methods is set up, so concrete methods from 825 // superinterfaces with matching names/signatures to default_methods are already 826 // in the default_methods list and do not need to be appended to the vtable 827 // as mirandas. Abstract methods may already have been handled via 828 // overpasses - either local or superclass overpasses, which may be 829 // in the vtable already. 830 // 831 // Pass 3: They are also checked by link resolution and selection, 832 // for invocation on a method (not interface method) reference that 833 // resolves to a method with an interface as its method_holder. 834 // Used as part of walking from the bottom of the vtable to find 835 // the vtable index for the miranda method. 836 // 837 // Part of the Miranda Rights in the US mean that if you do not have 838 // an attorney one will be appointed for you. 839 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 840 Array<Method*>* default_methods, const Klass* super, 841 bool is_interface) { 842 if (m->is_static() || m->is_private() || m->is_overpass()) { 843 return false; 844 } 845 Symbol* name = m->name(); 846 Symbol* signature = m->signature(); 847 848 // First look in local methods to see if already covered 849 if (InstanceKlass::find_local_method(class_methods, name, signature, 850 Klass::OverpassLookupMode::find, 851 Klass::StaticLookupMode::skip, 852 Klass::PrivateLookupMode::skip) != NULL) 853 { 854 return false; 855 } 856 857 // Check local default methods 858 if ((default_methods != NULL) && 859 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 860 { 861 return false; 862 } 863 864 // Iterate on all superclasses, which should be InstanceKlasses. 865 // Note that we explicitly look for overpasses at each level. 866 // Overpasses may or may not exist for supers for pass 1, 867 // they should have been created for pass 2 and later. 868 869 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 870 { 871 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature, 872 Klass::OverpassLookupMode::find, 873 Klass::StaticLookupMode::skip, 874 Klass::PrivateLookupMode::skip); 875 // Ignore non-public methods in java.lang.Object if klass is an interface. 876 if (found_mth != NULL && (!is_interface || 877 !SystemDictionary::is_nonpublic_Object_method(found_mth))) { 878 return false; 879 } 880 } 881 882 return true; 883 } 884 885 // Scans current_interface_methods for miranda methods that do not 886 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 887 // in super (superclass). These mirandas are added to all_mirandas if it is 888 // not null; in addition, those that are not duplicates of miranda methods 889 // inherited by super from its interfaces are added to new_mirandas. 890 // Thus, new_mirandas will be the set of mirandas that this class introduces, 891 // all_mirandas will be the set of all mirandas applicable to this class 892 // including all defined in superclasses. 893 void klassVtable::add_new_mirandas_to_lists( 894 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 895 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 896 Array<Method*>* default_methods, const Klass* super, bool is_interface) { 897 898 // iterate thru the current interface's method to see if it a miranda 899 int num_methods = current_interface_methods->length(); 900 for (int i = 0; i < num_methods; i++) { 901 Method* im = current_interface_methods->at(i); 902 bool is_duplicate = false; 903 int num_of_current_mirandas = new_mirandas->length(); 904 // check for duplicate mirandas in different interfaces we implement 905 for (int j = 0; j < num_of_current_mirandas; j++) { 906 Method* miranda = new_mirandas->at(j); 907 if ((im->name() == miranda->name()) && 908 (im->signature() == miranda->signature())) { 909 is_duplicate = true; 910 break; 911 } 912 } 913 914 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 915 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all? 916 const InstanceKlass *sk = InstanceKlass::cast(super); 917 // check if it is a duplicate of a super's miranda 918 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::DefaultsLookupMode::find) == NULL) { 919 new_mirandas->append(im); 920 } 921 if (all_mirandas != NULL) { 922 all_mirandas->append(im); 923 } 924 } 925 } 926 } 927 } 928 929 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 930 GrowableArray<Method*>* all_mirandas, 931 const Klass* super, 932 Array<Method*>* class_methods, 933 Array<Method*>* default_methods, 934 Array<InstanceKlass*>* local_interfaces, 935 bool is_interface) { 936 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 937 938 // iterate thru the local interfaces looking for a miranda 939 int num_local_ifs = local_interfaces->length(); 940 for (int i = 0; i < num_local_ifs; i++) { 941 InstanceKlass *ik = local_interfaces->at(i); 942 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 943 ik->methods(), class_methods, 944 default_methods, super, is_interface); 945 // iterate thru each local's super interfaces 946 Array<InstanceKlass*>* super_ifs = ik->transitive_interfaces(); 947 int num_super_ifs = super_ifs->length(); 948 for (int j = 0; j < num_super_ifs; j++) { 949 InstanceKlass *sik = super_ifs->at(j); 950 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 951 sik->methods(), class_methods, 952 default_methods, super, is_interface); 953 } 954 } 955 } 956 957 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 958 // and append them into the vtable starting at index initialized, 959 // return the new value of initialized. 960 // Miranda methods use vtable entries, but do not get assigned a vtable_index 961 // The vtable_index is discovered by searching from the end of the vtable 962 int klassVtable::fill_in_mirandas(Thread* current, int initialized) { 963 ResourceMark rm(current); 964 GrowableArray<Method*> mirandas(20); 965 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 966 ik()->default_methods(), ik()->local_interfaces(), 967 klass()->is_interface()); 968 for (int i = 0; i < mirandas.length(); i++) { 969 if (log_develop_is_enabled(Trace, vtables)) { 970 Method* meth = mirandas.at(i); 971 LogTarget(Trace, vtables) lt; 972 LogStream ls(lt); 973 if (meth != NULL) { 974 char* sig = meth->name_and_sig_as_C_string(); 975 ls.print("fill in mirandas with %s index %d, flags: ", 976 sig, initialized); 977 meth->print_linkage_flags(&ls); 978 ls.cr(); 979 } 980 } 981 put_method_at(mirandas.at(i), initialized); 982 ++initialized; 983 } 984 return initialized; 985 } 986 987 // Copy this class's vtable to the vtable beginning at start. 988 // Used to copy superclass vtable to prefix of subclass's vtable. 989 void klassVtable::copy_vtable_to(vtableEntry* start) { 990 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 991 } 992 993 #if INCLUDE_JVMTI 994 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 995 // If old_method is default, find this vtable index in default_vtable_indices 996 // and replace that method in the _default_methods list 997 bool updated = false; 998 999 Array<Method*>* default_methods = ik()->default_methods(); 1000 if (default_methods != NULL) { 1001 int len = default_methods->length(); 1002 for (int idx = 0; idx < len; idx++) { 1003 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 1004 if (default_methods->at(idx) == old_method) { 1005 default_methods->at_put(idx, new_method); 1006 updated = true; 1007 } 1008 break; 1009 } 1010 } 1011 } 1012 return updated; 1013 } 1014 1015 // search the vtable for uses of either obsolete or EMCP methods 1016 void klassVtable::adjust_method_entries(bool * trace_name_printed) { 1017 int prn_enabled = 0; 1018 ResourceMark rm; 1019 1020 for (int index = 0; index < length(); index++) { 1021 Method* old_method = unchecked_method_at(index); 1022 if (old_method == NULL || !old_method->is_old()) { 1023 continue; // skip uninteresting entries 1024 } 1025 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 1026 1027 Method* new_method = old_method->get_new_method(); 1028 put_method_at(new_method, index); 1029 1030 // For default methods, need to update the _default_methods array 1031 // which can only have one method entry for a given signature 1032 bool updated_default = false; 1033 if (old_method->is_default_method()) { 1034 updated_default = adjust_default_method(index, old_method, new_method); 1035 } 1036 1037 if (!(*trace_name_printed)) { 1038 log_info(redefine, class, update) 1039 ("adjust: klassname=%s for methods from name=%s", 1040 _klass->external_name(), old_method->method_holder()->external_name()); 1041 *trace_name_printed = true; 1042 } 1043 log_trace(redefine, class, update, vtables) 1044 ("vtable method update: class: %s method: %s, updated default = %s", 1045 _klass->external_name(), new_method->external_name(), updated_default ? "true" : "false"); 1046 } 1047 } 1048 1049 // a vtable should never contain old or obsolete methods 1050 bool klassVtable::check_no_old_or_obsolete_entries() { 1051 ResourceMark rm; 1052 1053 for (int i = 0; i < length(); i++) { 1054 Method* m = unchecked_method_at(i); 1055 if (m != NULL && 1056 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1057 log_trace(redefine, class, update, vtables) 1058 ("vtable check found old method entry: class: %s old: %d obsolete: %d, method: %s", 1059 _klass->external_name(), m->is_old(), m->is_obsolete(), m->external_name()); 1060 return false; 1061 } 1062 } 1063 return true; 1064 } 1065 1066 void klassVtable::dump_vtable() { 1067 tty->print_cr("vtable dump --"); 1068 for (int i = 0; i < length(); i++) { 1069 Method* m = unchecked_method_at(i); 1070 if (m != NULL) { 1071 tty->print(" (%5d) ", i); 1072 m->access_flags().print_on(tty); 1073 if (m->is_default_method()) { 1074 tty->print("default "); 1075 } 1076 if (m->is_overpass()) { 1077 tty->print("overpass"); 1078 } 1079 tty->print(" -- "); 1080 m->print_name(tty); 1081 tty->cr(); 1082 } 1083 } 1084 } 1085 #endif // INCLUDE_JVMTI 1086 1087 //----------------------------------------------------------------------------------------- 1088 // Itable code 1089 1090 // Initialize a itableMethodEntry 1091 void itableMethodEntry::initialize(InstanceKlass* klass, Method* m) { 1092 if (m == NULL) return; 1093 1094 #ifdef ASSERT 1095 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) && 1096 !MetaspaceShared::remapped_readwrite() && 1097 m->method_holder()->verified_at_dump_time() && 1098 klass->verified_at_dump_time()) { 1099 // At runtime initialize_itable is rerun as part of link_class_impl() 1100 // for a shared class loaded by the non-boot loader. 1101 // The dumptime itable method entry should be the same as the runtime entry. 1102 // For a shared old class which was not linked during dump time, we can't compare the dumptime 1103 // itable method entry with the runtime entry. 1104 assert(_method == m, "sanity"); 1105 } 1106 #endif 1107 _method = m; 1108 } 1109 1110 klassItable::klassItable(InstanceKlass* klass) { 1111 _klass = klass; 1112 1113 if (klass->itable_length() > 0) { 1114 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1115 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1116 // First offset entry points to the first method_entry 1117 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1118 intptr_t* end = klass->end_of_itable(); 1119 1120 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1121 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1122 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1123 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1124 return; 1125 } 1126 } 1127 1128 // The length of the itable was either zero, or it has not yet been initialized. 1129 _table_offset = 0; 1130 _size_offset_table = 0; 1131 _size_method_table = 0; 1132 } 1133 1134 static int initialize_count = 0; 1135 1136 // Initialization 1137 void klassItable::initialize_itable(GrowableArray<Method*>* supers) { 1138 if (_klass->is_interface()) { 1139 // This needs to go after vtable indices are assigned but 1140 // before implementors need to know the number of itable indices. 1141 assign_itable_indices_for_interface(InstanceKlass::cast(_klass)); 1142 } 1143 1144 // Cannot be setup doing bootstrapping, interfaces don't have 1145 // itables, and klass with only ones entry have empty itables 1146 if (Universe::is_bootstrapping() || 1147 _klass->is_interface() || 1148 _klass->itable_length() == itableOffsetEntry::size()) return; 1149 1150 // There's always an extra itable entry so we can null-terminate it. 1151 guarantee(size_offset_table() >= 1, "too small"); 1152 int num_interfaces = size_offset_table() - 1; 1153 if (num_interfaces > 0) { 1154 if (log_develop_is_enabled(Debug, itables)) { 1155 ResourceMark rm; 1156 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 1157 _klass->name()->as_C_string()); 1158 } 1159 1160 // Iterate through all interfaces 1161 for(int i = 0; i < num_interfaces; i++) { 1162 itableOffsetEntry* ioe = offset_entry(i); 1163 InstanceKlass* interf = ioe->interface_klass(); 1164 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1165 initialize_itable_for_interface(ioe->offset(), interf, supers, 1166 (ioe->offset() - offset_entry(0)->offset())/wordSize); 1167 } 1168 } 1169 // Check that the last entry is empty 1170 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1171 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1172 } 1173 1174 void klassItable::check_constraints(GrowableArray<Method*>* supers, TRAPS) { 1175 1176 assert(_size_method_table == supers->length(), "wrong size"); 1177 itableMethodEntry* ime = method_entry(0); 1178 for (int i = 0; i < _size_method_table; i++) { 1179 Method* target = ime->method(); 1180 Method* interface_method = supers->at(i); // method overridden 1181 1182 if (target != NULL && interface_method != NULL) { 1183 InstanceKlass* method_holder = target->method_holder(); 1184 InstanceKlass* interf = interface_method->method_holder(); 1185 HandleMark hm(THREAD); 1186 Handle method_holder_loader(THREAD, method_holder->class_loader()); 1187 Handle interface_loader(THREAD, interf->class_loader()); 1188 1189 if (method_holder_loader() != interface_loader()) { 1190 ResourceMark rm(THREAD); 1191 Symbol* failed_type_symbol = 1192 SystemDictionary::check_signature_loaders(target->signature(), 1193 _klass, 1194 method_holder_loader, 1195 interface_loader, 1196 true); 1197 if (failed_type_symbol != NULL) { 1198 stringStream ss; 1199 ss.print("loader constraint violation in interface itable" 1200 " initialization for class %s: when selecting method '", 1201 _klass->external_name()); 1202 interface_method->print_external_name(&ss), 1203 ss.print("' the class loader %s for super interface %s, and the class" 1204 " loader %s of the selected method's %s, %s have" 1205 " different Class objects for the type %s used in the signature (%s; %s)", 1206 interf->class_loader_data()->loader_name_and_id(), 1207 interf->external_name(), 1208 method_holder->class_loader_data()->loader_name_and_id(), 1209 method_holder->external_kind(), 1210 method_holder->external_name(), 1211 failed_type_symbol->as_klass_external_name(), 1212 interf->class_in_module_of_loader(false, true), 1213 method_holder->class_in_module_of_loader(false, true)); 1214 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string()); 1215 } 1216 } 1217 } 1218 ime++; 1219 } 1220 } 1221 1222 void klassItable::initialize_itable_and_check_constraints(TRAPS) { 1223 // Save a super interface from each itable entry to do constraint checking 1224 ResourceMark rm(THREAD); 1225 GrowableArray<Method*>* supers = 1226 new GrowableArray<Method*>(_size_method_table, _size_method_table, NULL); 1227 initialize_itable(supers); 1228 check_constraints(supers, CHECK); 1229 } 1230 1231 inline bool interface_method_needs_itable_index(Method* m) { 1232 if (m->is_static()) return false; // e.g., Stream.empty 1233 if (m->is_private()) return false; // uses direct call 1234 if (m->is_object_constructor()) return false; // <init>(...)V 1235 if (m->is_class_initializer()) return false; // <clinit>()V 1236 // If an interface redeclares a method from java.lang.Object, 1237 // it should already have a vtable index, don't touch it. 1238 // e.g., CharSequence.toString (from initialize_vtable) 1239 // if (m->has_vtable_index()) return false; // NO! 1240 return true; 1241 } 1242 1243 int klassItable::assign_itable_indices_for_interface(InstanceKlass* klass) { 1244 // an interface does not have an itable, but its methods need to be numbered 1245 if (log_develop_is_enabled(Trace, itables)) { 1246 ResourceMark rm; 1247 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1248 ++initialize_count, klass->name()->as_C_string()); 1249 } 1250 1251 Array<Method*>* methods = klass->methods(); 1252 int nof_methods = methods->length(); 1253 int ime_num = 0; 1254 for (int i = 0; i < nof_methods; i++) { 1255 Method* m = methods->at(i); 1256 if (interface_method_needs_itable_index(m)) { 1257 assert(!m->is_final_method(), "no final interface methods"); 1258 // If m is already assigned a vtable index, do not disturb it. 1259 if (log_develop_is_enabled(Trace, itables)) { 1260 ResourceMark rm; 1261 LogTarget(Trace, itables) lt; 1262 LogStream ls(lt); 1263 assert(m != NULL, "methods can never be null"); 1264 const char* sig = m->name_and_sig_as_C_string(); 1265 if (m->has_vtable_index()) { 1266 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1267 } else { 1268 ls.print("itable index %d for method: %s, flags: ", ime_num, sig); 1269 } 1270 m->print_linkage_flags(&ls); 1271 ls.cr(); 1272 } 1273 if (!m->has_vtable_index()) { 1274 // A shared method could have an initialized itable_index that 1275 // is < 0. 1276 assert(m->vtable_index() == Method::pending_itable_index || 1277 m->is_shared(), 1278 "set by initialize_vtable"); 1279 m->set_itable_index(ime_num); 1280 // Progress to next itable entry 1281 ime_num++; 1282 } 1283 } 1284 } 1285 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1286 return ime_num; 1287 } 1288 1289 int klassItable::method_count_for_interface(InstanceKlass* interf) { 1290 assert(interf->is_interface(), "must be"); 1291 Array<Method*>* methods = interf->methods(); 1292 int nof_methods = methods->length(); 1293 int length = 0; 1294 while (nof_methods > 0) { 1295 Method* m = methods->at(nof_methods-1); 1296 if (m->has_itable_index()) { 1297 length = m->itable_index() + 1; 1298 break; 1299 } 1300 nof_methods -= 1; 1301 } 1302 #ifdef ASSERT 1303 int nof_methods_copy = nof_methods; 1304 while (nof_methods_copy > 0) { 1305 Method* mm = methods->at(--nof_methods_copy); 1306 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1307 } 1308 #endif //ASSERT 1309 // return the rightmost itable index, plus one; or 0 if no methods have 1310 // itable indices 1311 return length; 1312 } 1313 1314 1315 void klassItable::initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf, 1316 GrowableArray<Method*>* supers, 1317 int start_offset) { 1318 assert(interf->is_interface(), "must be"); 1319 Array<Method*>* methods = interf->methods(); 1320 int nof_methods = methods->length(); 1321 1322 int ime_count = method_count_for_interface(interf); 1323 for (int i = 0; i < nof_methods; i++) { 1324 Method* m = methods->at(i); 1325 Method* target = NULL; 1326 if (m->has_itable_index()) { 1327 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1328 // to correctly enforce loader constraints for interface method inheritance. 1329 // Private methods are skipped as a private class method can never be the implementation 1330 // of an interface method. 1331 // Invokespecial does not perform selection based on the receiver, so it does not use 1332 // the cached itable. 1333 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), 1334 Klass::PrivateLookupMode::skip); 1335 } 1336 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) { 1337 assert(target == NULL || !target->is_overpass() || target->is_public(), 1338 "Non-public overpass method!"); 1339 // Entry does not resolve. Leave it empty for AbstractMethodError or other error. 1340 if (!(target == NULL) && !target->is_public()) { 1341 // Stuff an IllegalAccessError throwing method in there instead. 1342 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1343 initialize(_klass, Universe::throw_illegal_access_error()); 1344 } 1345 } else { 1346 1347 int ime_num = m->itable_index(); 1348 assert(ime_num < ime_count, "oob"); 1349 1350 // Save super interface method to perform constraint checks. 1351 // The method is in the error message, that's why. 1352 if (supers != NULL) { 1353 supers->at_put(start_offset + ime_num, m); 1354 } 1355 1356 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(_klass, target); 1357 if (log_develop_is_enabled(Trace, itables)) { 1358 ResourceMark rm; 1359 if (target != NULL) { 1360 LogTarget(Trace, itables) lt; 1361 LogStream ls(lt); 1362 char* sig = target->name_and_sig_as_C_string(); 1363 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1364 interf->internal_name(), ime_num, sig, 1365 target->method_holder()->internal_name()); 1366 ls.print("target_method flags: "); 1367 target->print_linkage_flags(&ls); 1368 ls.cr(); 1369 } 1370 } 1371 } 1372 } 1373 } 1374 1375 #if INCLUDE_JVMTI 1376 // search the itable for uses of either obsolete or EMCP methods 1377 void klassItable::adjust_method_entries(bool * trace_name_printed) { 1378 ResourceMark rm; 1379 itableMethodEntry* ime = method_entry(0); 1380 1381 for (int i = 0; i < _size_method_table; i++, ime++) { 1382 Method* old_method = ime->method(); 1383 if (old_method == NULL || !old_method->is_old()) { 1384 continue; // skip uninteresting entries 1385 } 1386 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1387 Method* new_method = old_method->get_new_method(); 1388 ime->initialize(_klass, new_method); 1389 1390 if (!(*trace_name_printed)) { 1391 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1392 *trace_name_printed = true; 1393 } 1394 log_trace(redefine, class, update, itables) 1395 ("itable method update: class: %s method: %s", _klass->external_name(), new_method->external_name()); 1396 } 1397 } 1398 1399 // an itable should never contain old or obsolete methods 1400 bool klassItable::check_no_old_or_obsolete_entries() { 1401 ResourceMark rm; 1402 itableMethodEntry* ime = method_entry(0); 1403 1404 for (int i = 0; i < _size_method_table; i++) { 1405 Method* m = ime->method(); 1406 if (m != NULL && 1407 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1408 log_trace(redefine, class, update, itables) 1409 ("itable check found old method entry: class: %s old: %d obsolete: %d, method: %s", 1410 _klass->external_name(), m->is_old(), m->is_obsolete(), m->external_name()); 1411 return false; 1412 } 1413 ime++; 1414 } 1415 return true; 1416 } 1417 1418 void klassItable::dump_itable() { 1419 itableMethodEntry* ime = method_entry(0); 1420 tty->print_cr("itable dump --"); 1421 for (int i = 0; i < _size_method_table; i++) { 1422 Method* m = ime->method(); 1423 if (m != NULL) { 1424 tty->print(" (%5d) ", i); 1425 m->access_flags().print_on(tty); 1426 if (m->is_default_method()) { 1427 tty->print("default "); 1428 } 1429 tty->print(" -- "); 1430 m->print_name(tty); 1431 tty->cr(); 1432 } 1433 ime++; 1434 } 1435 } 1436 #endif // INCLUDE_JVMTI 1437 1438 // Setup 1439 class InterfaceVisiterClosure : public StackObj { 1440 public: 1441 virtual void doit(InstanceKlass* intf, int method_count) = 0; 1442 }; 1443 1444 int count_interface_methods_needing_itable_index(Array<Method*>* methods) { 1445 int method_count = 0; 1446 if (methods->length() > 0) { 1447 for (int i = methods->length(); --i >= 0; ) { 1448 if (interface_method_needs_itable_index(methods->at(i))) { 1449 method_count++; 1450 } 1451 } 1452 } 1453 return method_count; 1454 } 1455 1456 // Visit all interfaces with at least one itable method 1457 void visit_all_interfaces(Array<InstanceKlass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1458 // Handle array argument 1459 for(int i = 0; i < transitive_intf->length(); i++) { 1460 InstanceKlass* intf = transitive_intf->at(i); 1461 assert(intf->is_interface(), "sanity check"); 1462 1463 // Find no. of itable methods 1464 int method_count = 0; 1465 // method_count = klassItable::method_count_for_interface(intf); 1466 Array<Method*>* methods = intf->methods(); 1467 if (methods->length() > 0) { 1468 for (int i = methods->length(); --i >= 0; ) { 1469 if (interface_method_needs_itable_index(methods->at(i))) { 1470 method_count++; 1471 } 1472 } 1473 } 1474 1475 // Visit all interfaces which either have any methods or can participate in receiver type check. 1476 // We do not bother to count methods in transitive interfaces, although that would allow us to skip 1477 // this step in the rare case of a zero-method interface extending another zero-method interface. 1478 if (method_count > 0 || intf->transitive_interfaces()->length() > 0) { 1479 blk->doit(intf, method_count); 1480 } 1481 } 1482 } 1483 1484 class CountInterfacesClosure : public InterfaceVisiterClosure { 1485 private: 1486 int _nof_methods; 1487 int _nof_interfaces; 1488 public: 1489 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1490 1491 int nof_methods() const { return _nof_methods; } 1492 int nof_interfaces() const { return _nof_interfaces; } 1493 1494 void doit(InstanceKlass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1495 }; 1496 1497 class SetupItableClosure : public InterfaceVisiterClosure { 1498 private: 1499 itableOffsetEntry* _offset_entry; 1500 itableMethodEntry* _method_entry; 1501 address _klass_begin; 1502 public: 1503 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1504 _klass_begin = klass_begin; 1505 _offset_entry = offset_entry; 1506 _method_entry = method_entry; 1507 } 1508 1509 itableMethodEntry* method_entry() const { return _method_entry; } 1510 1511 void doit(InstanceKlass* intf, int method_count) { 1512 int offset = ((address)_method_entry) - _klass_begin; 1513 _offset_entry->initialize(intf, offset); 1514 _offset_entry++; 1515 _method_entry += method_count; 1516 } 1517 }; 1518 1519 int klassItable::compute_itable_size(Array<InstanceKlass*>* transitive_interfaces) { 1520 // Count no of interfaces and total number of interface methods 1521 CountInterfacesClosure cic; 1522 visit_all_interfaces(transitive_interfaces, &cic); 1523 1524 // There's always an extra itable entry so we can null-terminate it. 1525 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1526 1527 return itable_size; 1528 } 1529 1530 1531 // Fill out offset table and interface klasses into the itable space 1532 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1533 if (klass->itable_length() == 0) return; 1534 assert(!klass->is_interface(), "Should have zero length itable"); 1535 1536 // Count no of interfaces and total number of interface methods 1537 CountInterfacesClosure cic; 1538 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1539 int nof_methods = cic.nof_methods(); 1540 int nof_interfaces = cic.nof_interfaces(); 1541 1542 // Add one extra entry so we can null-terminate the table 1543 nof_interfaces++; 1544 1545 assert(compute_itable_size(klass->transitive_interfaces()) == 1546 calc_itable_size(nof_interfaces, nof_methods), 1547 "mismatch calculation of itable size"); 1548 1549 // Fill-out offset table 1550 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1551 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1552 intptr_t* end = klass->end_of_itable(); 1553 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1554 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1555 1556 // Visit all interfaces and initialize itable offset table 1557 SetupItableClosure sic((address)klass, ioe, ime); 1558 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1559 1560 #ifdef ASSERT 1561 ime = sic.method_entry(); 1562 oop* v = (oop*) klass->end_of_itable(); 1563 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1564 #endif 1565 } 1566 1567 void klassVtable::verify(outputStream* st, bool forced) { 1568 // make sure table is initialized 1569 if (!Universe::is_fully_initialized()) return; 1570 #ifndef PRODUCT 1571 // avoid redundant verifies 1572 if (!forced && _verify_count == Universe::verify_count()) return; 1573 _verify_count = Universe::verify_count(); 1574 #endif 1575 oop* end_of_obj = (oop*)_klass + _klass->size(); 1576 oop* end_of_vtable = (oop *)&table()[_length]; 1577 if (end_of_vtable > end_of_obj) { 1578 ResourceMark rm; 1579 fatal("klass %s: klass object too short (vtable extends beyond end)", 1580 _klass->internal_name()); 1581 } 1582 1583 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1584 // verify consistency with superKlass vtable 1585 Klass* super = _klass->super(); 1586 if (super != NULL) { 1587 InstanceKlass* sk = InstanceKlass::cast(super); 1588 klassVtable vt = sk->vtable(); 1589 for (int i = 0; i < vt.length(); i++) { 1590 verify_against(st, &vt, i); 1591 } 1592 } 1593 } 1594 1595 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1596 vtableEntry* vte = &vt->table()[index]; 1597 if (vte->method()->name() != table()[index].method()->name() || 1598 vte->method()->signature() != table()[index].method()->signature()) { 1599 fatal("mismatched name/signature of vtable entries"); 1600 } 1601 } 1602 1603 #ifndef PRODUCT 1604 void klassVtable::print() { 1605 ResourceMark rm; 1606 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1607 for (int i = 0; i < length(); i++) { 1608 table()[i].print(); 1609 tty->cr(); 1610 } 1611 } 1612 #endif 1613 1614 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1615 Klass* vtklass = vt->klass(); 1616 if (vtklass->is_instance_klass() && 1617 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1618 assert(method() != NULL, "must have set method"); 1619 } 1620 if (method() != NULL) { 1621 method()->verify(); 1622 // we sub_type, because it could be a miranda method 1623 if (!vtklass->is_subtype_of(method()->method_holder())) { 1624 #ifndef PRODUCT 1625 print(); 1626 #endif 1627 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1628 } 1629 } 1630 } 1631 1632 #ifndef PRODUCT 1633 1634 void vtableEntry::print() { 1635 ResourceMark rm; 1636 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1637 if (Verbose) { 1638 tty->print("m " PTR_FORMAT " ", p2i(method())); 1639 } 1640 } 1641 #endif // PRODUCT