1 /* 2 * Copyright (c) 1997, 2017, 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/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "gc/shared/gcLocker.hpp" 30 #include "logging/log.hpp" 31 #include "logging/logStream.hpp" 32 #include "memory/metaspaceShared.hpp" 33 #include "memory/resourceArea.hpp" 34 #include "memory/universe.inline.hpp" 35 #include "oops/instanceKlass.hpp" 36 #include "oops/klassVtable.hpp" 37 #include "oops/method.hpp" 38 #include "oops/objArrayOop.hpp" 39 #include "oops/oop.inline.hpp" 40 #include "runtime/arguments.hpp" 41 #include "runtime/handles.inline.hpp" 42 #include "utilities/copy.hpp" 43 44 inline InstanceKlass* klassVtable::ik() const { 45 return InstanceKlass::cast(_klass); 46 } 47 48 bool klassVtable::is_preinitialized_vtable() { 49 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite(); 50 } 51 52 53 // this function computes the vtable size (including the size needed for miranda 54 // methods) and the number of miranda methods in this class. 55 // Note on Miranda methods: Let's say there is a class C that implements 56 // interface I, and none of C's superclasses implements I. 57 // Let's say there is an abstract method m in I that neither C 58 // nor any of its super classes implement (i.e there is no method of any access, 59 // with the same name and signature as m), then m is a Miranda method which is 60 // entered as a public abstract method in C's vtable. From then on it should 61 // treated as any other public method in C for method over-ride purposes. 62 void klassVtable::compute_vtable_size_and_num_mirandas( 63 int* vtable_length_ret, int* num_new_mirandas, 64 GrowableArray<Method*>* all_mirandas, const Klass* super, 65 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 66 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 67 TRAPS) { 68 NoSafepointVerifier nsv; 69 70 // set up default result values 71 int vtable_length = 0; 72 73 // start off with super's vtable length 74 vtable_length = super == NULL ? 0 : super->vtable_length(); 75 76 // go thru each method in the methods table to see if it needs a new entry 77 int len = methods->length(); 78 for (int i = 0; i < len; i++) { 79 assert(methods->at(i)->is_method(), "must be a Method*"); 80 methodHandle mh(THREAD, methods->at(i)); 81 82 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) { 83 vtable_length += vtableEntry::size(); // we need a new entry 84 } 85 } 86 87 GrowableArray<Method*> new_mirandas(20); 88 // compute the number of mirandas methods that must be added to the end 89 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces); 90 *num_new_mirandas = new_mirandas.length(); 91 92 // Interfaces do not need interface methods in their vtables 93 // This includes miranda methods and during later processing, default methods 94 if (!class_flags.is_interface()) { 95 vtable_length += *num_new_mirandas * vtableEntry::size(); 96 } 97 98 if (Universe::is_bootstrapping() && vtable_length == 0) { 99 // array classes don't have their superclass set correctly during 100 // bootstrapping 101 vtable_length = Universe::base_vtable_size(); 102 } 103 104 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 105 if (Universe::is_bootstrapping()) { 106 // Someone is attempting to override java.lang.Object incorrectly on the 107 // bootclasspath. The JVM cannot recover from this error including throwing 108 // an exception 109 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 110 } else { 111 // Someone is attempting to redefine java.lang.Object incorrectly. The 112 // only way this should happen is from 113 // SystemDictionary::resolve_from_stream(), which will detect this later 114 // and throw a security exception. So don't assert here to let 115 // the exception occur. 116 vtable_length = Universe::base_vtable_size(); 117 } 118 } 119 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 120 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 121 122 *vtable_length_ret = vtable_length; 123 } 124 125 int klassVtable::index_of(Method* m, int len) const { 126 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 127 return m->vtable_index(); 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(bool checkconstraints, TRAPS) { 163 164 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 165 Klass* super = _klass->java_super(); 166 int nofNewEntries = 0; 167 168 bool is_shared = _klass->is_shared(); 169 170 if (!_klass->is_array_klass()) { 171 ResourceMark rm(THREAD); 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 HandleMark hm(THREAD); 203 assert(methods->at(i)->is_method(), "must be a Method*"); 204 methodHandle mh(THREAD, methods->at(i)); 205 206 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 207 208 if (needs_new_entry) { 209 put_method_at(mh(), initialized); 210 mh()->set_vtable_index(initialized); // set primary vtable index 211 initialized++; 212 } 213 } 214 215 // update vtable with default_methods 216 Array<Method*>* default_methods = ik()->default_methods(); 217 if (default_methods != NULL) { 218 len = default_methods->length(); 219 if (len > 0) { 220 Array<int>* def_vtable_indices = NULL; 221 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 222 assert(!is_shared, "shared class def_vtable_indices does not exist"); 223 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 224 } else { 225 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 226 } 227 for (int i = 0; i < len; i++) { 228 HandleMark hm(THREAD); 229 assert(default_methods->at(i)->is_method(), "must be a Method*"); 230 methodHandle mh(THREAD, default_methods->at(i)); 231 assert(!mh->is_private(), "private interface method in the default method list"); 232 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 233 234 // needs new entry 235 if (needs_new_entry) { 236 put_method_at(mh(), initialized); 237 if (is_preinitialized_vtable()) { 238 // At runtime initialize_vtable is rerun for a shared class 239 // (loaded by the non-boot loader) as part of link_class_impl(). 240 // The dumptime vtable index should be the same as the runtime index. 241 assert(def_vtable_indices->at(i) == initialized, 242 "dump time vtable index is different from runtime index"); 243 } else { 244 def_vtable_indices->at_put(i, initialized); //set vtable index 245 } 246 initialized++; 247 } 248 } 249 } 250 } 251 252 // add miranda methods; it will also return the updated initialized 253 // Interfaces do not need interface methods in their vtables 254 // This includes miranda methods and during later processing, default methods 255 if (!ik()->is_interface()) { 256 initialized = fill_in_mirandas(initialized); 257 } 258 259 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 260 // package_private -> public/protected), the vtable might actually be smaller than our initial 261 // calculation, for classfile versions for which we do not do transitive override 262 // calculations. 263 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 264 assert(initialized == _length, "vtable initialization failed"); 265 } else { 266 assert(initialized <= _length, "vtable initialization failed"); 267 for(;initialized < _length; initialized++) { 268 table()[initialized].clear(); 269 } 270 } 271 NOT_PRODUCT(verify(tty, true)); 272 } 273 } 274 275 // Called for cases where a method does not override its superclass' vtable entry 276 // For bytecodes not produced by javac together it is possible that a method does not override 277 // the superclass's method, but might indirectly override a super-super class's vtable entry 278 // If none found, return a null superk, else return the superk of the method this does override 279 // For public and protected methods: if they override a superclass, they will 280 // also be overridden themselves appropriately. 281 // Private methods do not override and are not overridden. 282 // Package Private methods are trickier: 283 // e.g. P1.A, pub m 284 // P2.B extends A, package private m 285 // P1.C extends B, public m 286 // P1.C.m needs to override P1.A.m and can not override P2.B.m 287 // Therefore: all package private methods need their own vtable entries for 288 // them to be the root of an inheritance overriding decision 289 // Package private methods may also override other vtable entries 290 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, 291 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 292 InstanceKlass* superk = initialsuper; 293 while (superk != NULL && superk->super() != NULL) { 294 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 295 klassVtable ssVtable = supersuperklass->vtable(); 296 if (vtable_index < ssVtable.length()) { 297 Method* super_method = ssVtable.method_at(vtable_index); 298 #ifndef PRODUCT 299 Symbol* name= target_method()->name(); 300 Symbol* signature = target_method()->signature(); 301 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 302 #endif 303 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 304 if (log_develop_is_enabled(Trace, vtables)) { 305 ResourceMark rm(THREAD); 306 LogTarget(Trace, vtables) lt; 307 LogStream ls(lt); 308 char* sig = target_method()->name_and_sig_as_C_string(); 309 ls.print("transitive overriding superclass %s with %s index %d, original flags: ", 310 supersuperklass->internal_name(), 311 sig, vtable_index); 312 super_method->print_linkage_flags(&ls); 313 ls.print("overriders flags: "); 314 target_method->print_linkage_flags(&ls); 315 ls.cr(); 316 } 317 318 break; // return found superk 319 } 320 } else { 321 // super class has no vtable entry here, stop transitive search 322 superk = (InstanceKlass*)NULL; 323 break; 324 } 325 // if no override found yet, continue to search up 326 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 327 } 328 329 return superk; 330 } 331 332 static void log_vtables(int i, bool overrides, const methodHandle& target_method, 333 Klass* target_klass, Method* super_method, 334 Thread* thread) { 335 #ifndef PRODUCT 336 if (log_develop_is_enabled(Trace, vtables)) { 337 ResourceMark rm(thread); 338 LogTarget(Trace, vtables) lt; 339 LogStream ls(lt); 340 char* sig = target_method()->name_and_sig_as_C_string(); 341 if (overrides) { 342 ls.print("overriding with %s index %d, original flags: ", 343 sig, i); 344 } else { 345 ls.print("NOT overriding with %s index %d, original flags: ", 346 sig, i); 347 } 348 super_method->print_linkage_flags(&ls); 349 ls.print("overriders flags: "); 350 target_method->print_linkage_flags(&ls); 351 ls.cr(); 352 } 353 #endif 354 } 355 356 // Update child's copy of super vtable for overrides 357 // OR return true if a new vtable entry is required. 358 // Only called for InstanceKlass's, i.e. not for arrays 359 // If that changed, could not use _klass as handle for klass 360 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, 361 int super_vtable_len, int default_index, 362 bool checkconstraints, TRAPS) { 363 ResourceMark rm; 364 bool allocate_new = true; 365 assert(klass->is_instance_klass(), "must be InstanceKlass"); 366 367 Array<int>* def_vtable_indices = NULL; 368 bool is_default = false; 369 370 // default methods are non-private concrete methods in superinterfaces which are added 371 // to the vtable with their real method_holder. 372 // Since vtable and itable indices share the same storage, don't touch 373 // the default method's real vtable/itable index. 374 // default_vtable_indices stores the vtable value relative to this inheritor 375 if (default_index >= 0 ) { 376 is_default = true; 377 def_vtable_indices = klass->default_vtable_indices(); 378 assert(!target_method()->is_private(), "private interface method flagged as default"); 379 assert(def_vtable_indices != NULL, "def vtable alloc?"); 380 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 381 } else { 382 assert(klass == target_method()->method_holder(), "caller resp."); 383 // Initialize the method's vtable index to "nonvirtual". 384 // If we allocate a vtable entry, we will update it to a non-negative number. 385 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 386 } 387 388 // Static and <init> methods are never in 389 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 390 return false; 391 } 392 393 if (target_method->is_final_method(klass->access_flags())) { 394 // a final method never needs a new entry; final methods can be statically 395 // resolved and they have to be present in the vtable only if they override 396 // a super's method, in which case they re-use its entry 397 allocate_new = false; 398 } else if (klass->is_interface()) { 399 allocate_new = false; // see note below in needs_new_vtable_entry 400 // An interface never allocates new vtable slots, only inherits old ones. 401 // This method will either be assigned its own itable index later, 402 // or be assigned an inherited vtable index in the loop below. 403 // default methods inherited by classes store their vtable indices 404 // in the inheritor's default_vtable_indices. 405 // default methods inherited by interfaces may already have a 406 // valid itable index, if so, don't change it. 407 // Overpass methods in an interface will be assigned an itable index later 408 // by an inheriting class. 409 // Private interface methods have no itable index and are always invoked nonvirtually, 410 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound() 411 // will return true. 412 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) { 413 target_method()->set_vtable_index(Method::pending_itable_index); 414 } 415 } 416 417 // we need a new entry if there is no superclass 418 Klass* super = klass->super(); 419 if (super == NULL) { 420 return allocate_new; 421 } 422 423 // private methods in classes always have a new entry in the vtable 424 // specification interpretation since classic has 425 // private methods not overriding 426 // JDK8 adds private methods in interfaces which require invokespecial 427 if (target_method()->is_private()) { 428 return allocate_new; 429 } 430 431 // search through the vtable and update overridden entries 432 // Since check_signature_loaders acquires SystemDictionary_lock 433 // which can block for gc, once we are in this loop, use handles 434 // For classfiles built with >= jdk7, we now look for transitive overrides 435 436 Symbol* name = target_method()->name(); 437 Symbol* signature = target_method()->signature(); 438 439 Klass* target_klass = target_method()->method_holder(); 440 if (target_klass == NULL) { 441 target_klass = _klass; 442 } 443 444 Handle target_loader(THREAD, target_klass->class_loader()); 445 446 Symbol* target_classname = target_klass->name(); 447 for(int i = 0; i < super_vtable_len; i++) { 448 Method* super_method; 449 if (is_preinitialized_vtable()) { 450 // If this is a shared class, the vtable is already in the final state (fully 451 // initialized). Need to look at the super's vtable. 452 klassVtable superVtable = super->vtable(); 453 super_method = superVtable.method_at(i); 454 } else { 455 super_method = method_at(i); 456 } 457 // Check if method name matches. Ignore match if klass is an interface and the 458 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4) 459 if (super_method->name() == name && super_method->signature() == signature && 460 (!_klass->is_interface() || 461 !SystemDictionary::is_nonpublic_Object_method(super_method))) { 462 463 // get super_klass for method_holder for the found method 464 InstanceKlass* super_klass = super_method->method_holder(); 465 466 // Whether the method is being overridden 467 bool overrides = false; 468 469 // private methods are also never overridden 470 if (!super_method->is_private() && 471 (is_default 472 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 473 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 474 && ((super_klass = find_transitive_override(super_klass, 475 target_method, i, target_loader, 476 target_classname, THREAD)) 477 != (InstanceKlass*)NULL))))) 478 { 479 // Package private methods always need a new entry to root their own 480 // overriding. They may also override other methods. 481 if (!target_method()->is_package_private()) { 482 allocate_new = false; 483 } 484 485 // Do not check loader constraints for overpass methods because overpass 486 // methods are created by the jvm to throw exceptions. 487 if (checkconstraints && !target_method()->is_overpass()) { 488 // Override vtable entry if passes loader constraint check 489 // if loader constraint checking requested 490 // No need to visit his super, since he and his super 491 // have already made any needed loader constraints. 492 // Since loader constraints are transitive, it is enough 493 // to link to the first super, and we get all the others. 494 Handle super_loader(THREAD, super_klass->class_loader()); 495 496 if (target_loader() != super_loader()) { 497 ResourceMark rm(THREAD); 498 Symbol* failed_type_symbol = 499 SystemDictionary::check_signature_loaders(signature, target_loader, 500 super_loader, true, 501 CHECK_(false)); 502 if (failed_type_symbol != NULL) { 503 const char* msg = "loader constraint violation for class %s: when selecting " 504 "overriding method \"%s\" the class loader (instance of %s) of the " 505 "selected method's type %s, and the class loader (instance of %s) for its super " 506 "type %s have different Class objects for the type %s used in the signature"; 507 char* curr_class = klass->name()->as_C_string(); 508 char* sig = target_method()->name_and_sig_as_C_string(); 509 const char* loader1 = SystemDictionary::loader_name(target_loader()); 510 char* sel_class = target_klass->name()->as_C_string(); 511 const char* loader2 = SystemDictionary::loader_name(super_loader()); 512 char* super_class = super_klass->name()->as_C_string(); 513 char* failed_type_name = failed_type_symbol->as_C_string(); 514 size_t buflen = strlen(msg) + strlen(curr_class) + strlen(sig) + 515 strlen(loader1) + strlen(sel_class) + strlen(loader2) + 516 strlen(super_class) + strlen(failed_type_name); 517 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 518 jio_snprintf(buf, buflen, msg, curr_class, sig, loader1, sel_class, loader2, 519 super_class, failed_type_name); 520 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 521 } 522 } 523 } 524 525 put_method_at(target_method(), i); 526 overrides = true; 527 if (!is_default) { 528 target_method()->set_vtable_index(i); 529 } else { 530 if (def_vtable_indices != NULL) { 531 if (is_preinitialized_vtable()) { 532 // At runtime initialize_vtable is rerun as part of link_class_impl() 533 // for a shared class loaded by the non-boot loader. 534 // The dumptime vtable index should be the same as the runtime index. 535 assert(def_vtable_indices->at(default_index) == i, 536 "dump time vtable index is different from runtime index"); 537 } else { 538 def_vtable_indices->at_put(default_index, i); 539 } 540 } 541 assert(super_method->is_default_method() || super_method->is_overpass() 542 || super_method->is_abstract(), "default override error"); 543 } 544 } else { 545 overrides = false; 546 } 547 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD); 548 } 549 } 550 return allocate_new; 551 } 552 553 void klassVtable::put_method_at(Method* m, int index) { 554 if (is_preinitialized_vtable()) { 555 // At runtime initialize_vtable is rerun as part of link_class_impl() 556 // for shared class loaded by the non-boot loader to obtain the loader 557 // constraints based on the runtime classloaders' context. The dumptime 558 // method at the vtable index should be the same as the runtime method. 559 assert(table()[index].method() == m, 560 "archived method is different from the runtime method"); 561 } else { 562 if (log_develop_is_enabled(Trace, vtables)) { 563 ResourceMark rm; 564 LogTarget(Trace, vtables) lt; 565 LogStream ls(lt); 566 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 567 ls.print("adding %s at index %d, flags: ", sig, index); 568 if (m != NULL) { 569 m->print_linkage_flags(&ls); 570 } 571 ls.cr(); 572 } 573 table()[index].set(m); 574 } 575 } 576 577 // Find out if a method "m" with superclass "super", loader "classloader" and 578 // name "classname" needs a new vtable entry. Let P be a class package defined 579 // by "classloader" and "classname". 580 // NOTE: The logic used here is very similar to the one used for computing 581 // the vtables indices for a method. We cannot directly use that function because, 582 // we allocate the InstanceKlass at load time, and that requires that the 583 // superclass has been loaded. 584 // However, the vtable entries are filled in at link time, and therefore 585 // the superclass' vtable may not yet have been filled in. 586 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method, 587 const Klass* super, 588 Handle classloader, 589 Symbol* classname, 590 AccessFlags class_flags, 591 u2 major_version, 592 TRAPS) { 593 if (class_flags.is_interface()) { 594 // Interfaces do not use vtables, except for java.lang.Object methods, 595 // so there is no point to assigning 596 // a vtable index to any of their local methods. If we refrain from doing this, 597 // we can use Method::_vtable_index to hold the itable index 598 return false; 599 } 600 601 if (target_method->is_final_method(class_flags) || 602 // a final method never needs a new entry; final methods can be statically 603 // resolved and they have to be present in the vtable only if they override 604 // a super's method, in which case they re-use its entry 605 (target_method()->is_static()) || 606 // static methods don't need to be in vtable 607 (target_method()->name() == vmSymbols::object_initializer_name()) 608 // <init> is never called dynamically-bound 609 ) { 610 return false; 611 } 612 613 // Concrete interface methods do not need new entries, they override 614 // abstract method entries using default inheritance rules 615 if (target_method()->method_holder() != NULL && 616 target_method()->method_holder()->is_interface() && 617 !target_method()->is_abstract()) { 618 assert(target_method()->is_default_method() || target_method()->is_private(), 619 "unexpected interface method type"); 620 return false; 621 } 622 623 // we need a new entry if there is no superclass 624 if (super == NULL) { 625 return true; 626 } 627 628 // private methods in classes always have a new entry in the vtable. 629 // Specification interpretation since classic has private methods not overriding. 630 if (target_method()->is_private()) { 631 return true; 632 } 633 634 // Package private methods always need a new entry to root their own 635 // overriding. This allows transitive overriding to work. 636 if (target_method()->is_package_private()) { 637 return true; 638 } 639 640 // search through the super class hierarchy to see if we need 641 // a new entry 642 ResourceMark rm; 643 Symbol* name = target_method()->name(); 644 Symbol* signature = target_method()->signature(); 645 const Klass* k = super; 646 Method* super_method = NULL; 647 InstanceKlass *holder = NULL; 648 Method* recheck_method = NULL; 649 while (k != NULL) { 650 // lookup through the hierarchy for a method with matching name and sign. 651 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 652 if (super_method == NULL) { 653 break; // we still have to search for a matching miranda method 654 } 655 // get the class holding the matching method 656 // make sure you use that class for is_override 657 InstanceKlass* superk = super_method->method_holder(); 658 // we want only instance method matches 659 // pretend private methods are not in the super vtable 660 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 661 // ignore private, c.m pub does override a.m pub 662 // For classes that were not javac'd together, we also do transitive overriding around 663 // methods that have less accessibility 664 if ((!super_method->is_static()) && 665 (!super_method->is_private())) { 666 if (superk->is_override(super_method, classloader, classname, THREAD)) { 667 return false; 668 // else keep looking for transitive overrides 669 } 670 } 671 672 // Start with lookup result and continue to search up, for versions supporting transitive override 673 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 674 k = superk->super(); // haven't found an override match yet; continue to look 675 } else { 676 break; 677 } 678 } 679 680 // if the target method is public or protected it may have a matching 681 // miranda method in the super, whose entry it should re-use. 682 // Actually, to handle cases that javac would not generate, we need 683 // this check for all access permissions. 684 const InstanceKlass *sk = InstanceKlass::cast(super); 685 if (sk->has_miranda_methods()) { 686 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 687 return false; // found a matching miranda; we do not need a new entry 688 } 689 } 690 return true; // found no match; we need a new entry 691 } 692 693 // Support for miranda methods 694 695 // get the vtable index of a miranda method with matching "name" and "signature" 696 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 697 // search from the bottom, might be faster 698 for (int i = (length() - 1); i >= 0; i--) { 699 Method* m = table()[i].method(); 700 if (is_miranda_entry_at(i) && 701 m->name() == name && m->signature() == signature) { 702 return i; 703 } 704 } 705 return Method::invalid_vtable_index; 706 } 707 708 // check if an entry at an index is miranda 709 // requires that method m at entry be declared ("held") by an interface. 710 bool klassVtable::is_miranda_entry_at(int i) { 711 Method* m = method_at(i); 712 Klass* method_holder = m->method_holder(); 713 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 714 715 // miranda methods are public abstract instance interface methods in a class's vtable 716 if (mhk->is_interface()) { 717 assert(m->is_public(), "should be public"); 718 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 719 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 720 return true; 721 } 722 } 723 return false; 724 } 725 726 // Check if a method is a miranda method, given a class's methods array, 727 // its default_method table and its super class. 728 // "Miranda" means an abstract non-private method that would not be 729 // overridden for the local class. 730 // A "miranda" method should only include non-private interface 731 // instance methods, i.e. not private methods, not static methods, 732 // not default methods (concrete interface methods), not overpass methods. 733 // If a given class already has a local (including overpass) method, a 734 // default method, or any of its superclasses has the same which would have 735 // overridden an abstract method, then this is not a miranda method. 736 // 737 // Miranda methods are checked multiple times. 738 // Pass 1: during class load/class file parsing: before vtable size calculation: 739 // include superinterface abstract and default methods (non-private instance). 740 // We include potential default methods to give them space in the vtable. 741 // During the first run, the current instanceKlass has not yet been 742 // created, the superclasses and superinterfaces do have instanceKlasses 743 // but may not have vtables, the default_methods list is empty, no overpasses. 744 // This is seen by default method creation. 745 // 746 // Pass 2: recalculated during vtable initialization: only include abstract methods. 747 // The goal of pass 2 is to walk through the superinterfaces to see if any of 748 // the superinterface methods (which were all abstract pre-default methods) 749 // need to be added to the vtable. 750 // With the addition of default methods, we have three new challenges: 751 // overpasses, static interface methods and private interface methods. 752 // Static and private interface methods do not get added to the vtable and 753 // are not seen by the method resolution process, so we skip those. 754 // Overpass methods are already in the vtable, so vtable lookup will 755 // find them and we don't need to add a miranda method to the end of 756 // the vtable. So we look for overpass methods and if they are found we 757 // return false. Note that we inherit our superclasses vtable, so 758 // the superclass' search also needs to use find_overpass so that if 759 // one is found we return false. 760 // False means - we don't need a miranda method added to the vtable. 761 // 762 // During the second run, default_methods is set up, so concrete methods from 763 // superinterfaces with matching names/signatures to default_methods are already 764 // in the default_methods list and do not need to be appended to the vtable 765 // as mirandas. Abstract methods may already have been handled via 766 // overpasses - either local or superclass overpasses, which may be 767 // in the vtable already. 768 // 769 // Pass 3: They are also checked by link resolution and selection, 770 // for invocation on a method (not interface method) reference that 771 // resolves to a method with an interface as its method_holder. 772 // Used as part of walking from the bottom of the vtable to find 773 // the vtable index for the miranda method. 774 // 775 // Part of the Miranda Rights in the US mean that if you do not have 776 // an attorney one will be appointed for you. 777 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 778 Array<Method*>* default_methods, const Klass* super) { 779 if (m->is_static() || m->is_private() || m->is_overpass()) { 780 return false; 781 } 782 Symbol* name = m->name(); 783 Symbol* signature = m->signature(); 784 785 // First look in local methods to see if already covered 786 if (InstanceKlass::find_local_method(class_methods, name, signature, 787 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 788 { 789 return false; 790 } 791 792 // Check local default methods 793 if ((default_methods != NULL) && 794 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 795 { 796 return false; 797 } 798 799 // Iterate on all superclasses, which should be InstanceKlasses. 800 // Note that we explicitly look for overpasses at each level. 801 // Overpasses may or may not exist for supers for pass 1, 802 // they should have been created for pass 2 and later. 803 804 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 805 { 806 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature, 807 Klass::find_overpass, Klass::skip_static, Klass::skip_private); 808 // Continue looking if found_mth is a non-public method in java.lang.Object 809 // because such methods are skipped over during interface method resolution 810 // and may 'mask' an actual miranda method. 811 if (found_mth != NULL && !SystemDictionary::is_nonpublic_Object_method(found_mth)) { 812 return false; 813 } 814 } 815 816 return true; 817 } 818 819 // Scans current_interface_methods for miranda methods that do not 820 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 821 // in super (superclass). These mirandas are added to all_mirandas if it is 822 // not null; in addition, those that are not duplicates of miranda methods 823 // inherited by super from its interfaces are added to new_mirandas. 824 // Thus, new_mirandas will be the set of mirandas that this class introduces, 825 // all_mirandas will be the set of all mirandas applicable to this class 826 // including all defined in superclasses. 827 void klassVtable::add_new_mirandas_to_lists( 828 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 829 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 830 Array<Method*>* default_methods, const Klass* super) { 831 832 // iterate thru the current interface's method to see if it a miranda 833 int num_methods = current_interface_methods->length(); 834 for (int i = 0; i < num_methods; i++) { 835 Method* im = current_interface_methods->at(i); 836 bool is_duplicate = false; 837 int num_of_current_mirandas = new_mirandas->length(); 838 // check for duplicate mirandas in different interfaces we implement 839 for (int j = 0; j < num_of_current_mirandas; j++) { 840 Method* miranda = new_mirandas->at(j); 841 if ((im->name() == miranda->name()) && 842 (im->signature() == miranda->signature())) { 843 is_duplicate = true; 844 break; 845 } 846 } 847 848 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 849 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 850 const InstanceKlass *sk = InstanceKlass::cast(super); 851 // check if it is a duplicate of a super's miranda 852 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 853 new_mirandas->append(im); 854 } 855 if (all_mirandas != NULL) { 856 all_mirandas->append(im); 857 } 858 } 859 } 860 } 861 } 862 863 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 864 GrowableArray<Method*>* all_mirandas, 865 const Klass* super, 866 Array<Method*>* class_methods, 867 Array<Method*>* default_methods, 868 Array<Klass*>* local_interfaces) { 869 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 870 871 // iterate thru the local interfaces looking for a miranda 872 int num_local_ifs = local_interfaces->length(); 873 for (int i = 0; i < num_local_ifs; i++) { 874 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 875 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 876 ik->methods(), class_methods, 877 default_methods, super); 878 // iterate thru each local's super interfaces 879 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 880 int num_super_ifs = super_ifs->length(); 881 for (int j = 0; j < num_super_ifs; j++) { 882 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 883 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 884 sik->methods(), class_methods, 885 default_methods, super); 886 } 887 } 888 } 889 890 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 891 // and append them into the vtable starting at index initialized, 892 // return the new value of initialized. 893 // Miranda methods use vtable entries, but do not get assigned a vtable_index 894 // The vtable_index is discovered by searching from the end of the vtable 895 int klassVtable::fill_in_mirandas(int initialized) { 896 GrowableArray<Method*> mirandas(20); 897 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 898 ik()->default_methods(), ik()->local_interfaces()); 899 for (int i = 0; i < mirandas.length(); i++) { 900 if (log_develop_is_enabled(Trace, vtables)) { 901 Method* meth = mirandas.at(i); 902 ResourceMark rm(Thread::current()); 903 LogTarget(Trace, vtables) lt; 904 LogStream ls(lt); 905 if (meth != NULL) { 906 char* sig = meth->name_and_sig_as_C_string(); 907 ls.print("fill in mirandas with %s index %d, flags: ", 908 sig, initialized); 909 meth->print_linkage_flags(&ls); 910 ls.cr(); 911 } 912 } 913 put_method_at(mirandas.at(i), initialized); 914 ++initialized; 915 } 916 return initialized; 917 } 918 919 // Copy this class's vtable to the vtable beginning at start. 920 // Used to copy superclass vtable to prefix of subclass's vtable. 921 void klassVtable::copy_vtable_to(vtableEntry* start) { 922 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 923 } 924 925 #if INCLUDE_JVMTI 926 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 927 // If old_method is default, find this vtable index in default_vtable_indices 928 // and replace that method in the _default_methods list 929 bool updated = false; 930 931 Array<Method*>* default_methods = ik()->default_methods(); 932 if (default_methods != NULL) { 933 int len = default_methods->length(); 934 for (int idx = 0; idx < len; idx++) { 935 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 936 if (default_methods->at(idx) == old_method) { 937 default_methods->at_put(idx, new_method); 938 updated = true; 939 } 940 break; 941 } 942 } 943 } 944 return updated; 945 } 946 947 // search the vtable for uses of either obsolete or EMCP methods 948 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 949 int prn_enabled = 0; 950 for (int index = 0; index < length(); index++) { 951 Method* old_method = unchecked_method_at(index); 952 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 953 continue; // skip uninteresting entries 954 } 955 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 956 957 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 958 959 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 960 assert(old_method != new_method, "sanity check"); 961 962 put_method_at(new_method, index); 963 // For default methods, need to update the _default_methods array 964 // which can only have one method entry for a given signature 965 bool updated_default = false; 966 if (old_method->is_default_method()) { 967 updated_default = adjust_default_method(index, old_method, new_method); 968 } 969 970 if (log_is_enabled(Info, redefine, class, update)) { 971 ResourceMark rm; 972 if (!(*trace_name_printed)) { 973 log_info(redefine, class, update) 974 ("adjust: klassname=%s for methods from name=%s", 975 _klass->external_name(), old_method->method_holder()->external_name()); 976 *trace_name_printed = true; 977 } 978 log_debug(redefine, class, update, vtables) 979 ("vtable method update: %s(%s), updated default = %s", 980 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false"); 981 } 982 } 983 } 984 985 // a vtable should never contain old or obsolete methods 986 bool klassVtable::check_no_old_or_obsolete_entries() { 987 for (int i = 0; i < length(); i++) { 988 Method* m = unchecked_method_at(i); 989 if (m != NULL && 990 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 991 return false; 992 } 993 } 994 return true; 995 } 996 997 void klassVtable::dump_vtable() { 998 tty->print_cr("vtable dump --"); 999 for (int i = 0; i < length(); i++) { 1000 Method* m = unchecked_method_at(i); 1001 if (m != NULL) { 1002 tty->print(" (%5d) ", i); 1003 m->access_flags().print_on(tty); 1004 if (m->is_default_method()) { 1005 tty->print("default "); 1006 } 1007 if (m->is_overpass()) { 1008 tty->print("overpass"); 1009 } 1010 tty->print(" -- "); 1011 m->print_name(tty); 1012 tty->cr(); 1013 } 1014 } 1015 } 1016 #endif // INCLUDE_JVMTI 1017 1018 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 1019 void klassVtable::clear_vtable() { 1020 for (int i = 0; i < _length; i++) table()[i].clear(); 1021 } 1022 1023 bool klassVtable::is_initialized() { 1024 return _length == 0 || table()[0].method() != NULL; 1025 } 1026 1027 //----------------------------------------------------------------------------------------- 1028 // Itable code 1029 1030 // Initialize a itableMethodEntry 1031 void itableMethodEntry::initialize(Method* m) { 1032 if (m == NULL) return; 1033 1034 #ifdef ASSERT 1035 if (MetaspaceShared::is_in_shared_space((void*)&_method) && 1036 !MetaspaceShared::remapped_readwrite()) { 1037 // At runtime initialize_itable is rerun as part of link_class_impl() 1038 // for a shared class loaded by the non-boot loader. 1039 // The dumptime itable method entry should be the same as the runtime entry. 1040 assert(_method == m, "sanity"); 1041 } 1042 #endif 1043 _method = m; 1044 } 1045 1046 klassItable::klassItable(InstanceKlass* klass) { 1047 _klass = klass; 1048 1049 if (klass->itable_length() > 0) { 1050 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1051 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1052 // First offset entry points to the first method_entry 1053 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1054 intptr_t* end = klass->end_of_itable(); 1055 1056 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1057 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1058 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1059 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1060 return; 1061 } 1062 } 1063 1064 // The length of the itable was either zero, or it has not yet been initialized. 1065 _table_offset = 0; 1066 _size_offset_table = 0; 1067 _size_method_table = 0; 1068 } 1069 1070 static int initialize_count = 0; 1071 1072 // Initialization 1073 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1074 if (_klass->is_interface()) { 1075 // This needs to go after vtable indices are assigned but 1076 // before implementors need to know the number of itable indices. 1077 assign_itable_indices_for_interface(_klass); 1078 } 1079 1080 // Cannot be setup doing bootstrapping, interfaces don't have 1081 // itables, and klass with only ones entry have empty itables 1082 if (Universe::is_bootstrapping() || 1083 _klass->is_interface() || 1084 _klass->itable_length() == itableOffsetEntry::size()) return; 1085 1086 // There's alway an extra itable entry so we can null-terminate it. 1087 guarantee(size_offset_table() >= 1, "too small"); 1088 int num_interfaces = size_offset_table() - 1; 1089 if (num_interfaces > 0) { 1090 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 1091 _klass->name()->as_C_string()); 1092 1093 1094 // Iterate through all interfaces 1095 int i; 1096 for(i = 0; i < num_interfaces; i++) { 1097 itableOffsetEntry* ioe = offset_entry(i); 1098 HandleMark hm(THREAD); 1099 Klass* interf = ioe->interface_klass(); 1100 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1101 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK); 1102 } 1103 1104 } 1105 // Check that the last entry is empty 1106 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1107 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1108 } 1109 1110 1111 inline bool interface_method_needs_itable_index(Method* m) { 1112 if (m->is_static()) return false; // e.g., Stream.empty 1113 if (m->is_initializer()) return false; // <init> or <clinit> 1114 if (m->is_private()) return false; // requires invokeSpecial 1115 // If an interface redeclares a method from java.lang.Object, 1116 // it should already have a vtable index, don't touch it. 1117 // e.g., CharSequence.toString (from initialize_vtable) 1118 // if (m->has_vtable_index()) return false; // NO! 1119 return true; 1120 } 1121 1122 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1123 // an interface does not have an itable, but its methods need to be numbered 1124 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1125 ++initialize_count, klass->name()->as_C_string()); 1126 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1127 int nof_methods = methods->length(); 1128 int ime_num = 0; 1129 for (int i = 0; i < nof_methods; i++) { 1130 Method* m = methods->at(i); 1131 if (interface_method_needs_itable_index(m)) { 1132 assert(!m->is_final_method(), "no final interface methods"); 1133 // If m is already assigned a vtable index, do not disturb it. 1134 if (log_develop_is_enabled(Trace, itables)) { 1135 ResourceMark rm; 1136 LogTarget(Trace, itables) lt; 1137 LogStream ls(lt); 1138 assert(m != NULL, "methods can never be null"); 1139 const char* sig = m->name_and_sig_as_C_string(); 1140 if (m->has_vtable_index()) { 1141 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1142 } else { 1143 ls.print("itable index %d for method: %s, flags: ", ime_num, sig); 1144 } 1145 m->print_linkage_flags(&ls); 1146 ls.cr(); 1147 } 1148 if (!m->has_vtable_index()) { 1149 // A shared method could have an initialized itable_index that 1150 // is < 0. 1151 assert(m->vtable_index() == Method::pending_itable_index || 1152 m->is_shared(), 1153 "set by initialize_vtable"); 1154 m->set_itable_index(ime_num); 1155 // Progress to next itable entry 1156 ime_num++; 1157 } 1158 } 1159 } 1160 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1161 return ime_num; 1162 } 1163 1164 int klassItable::method_count_for_interface(Klass* interf) { 1165 assert(interf->is_instance_klass(), "must be"); 1166 assert(interf->is_interface(), "must be"); 1167 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1168 int nof_methods = methods->length(); 1169 int length = 0; 1170 while (nof_methods > 0) { 1171 Method* m = methods->at(nof_methods-1); 1172 if (m->has_itable_index()) { 1173 length = m->itable_index() + 1; 1174 break; 1175 } 1176 nof_methods -= 1; 1177 } 1178 #ifdef ASSERT 1179 int nof_methods_copy = nof_methods; 1180 while (nof_methods_copy > 0) { 1181 Method* mm = methods->at(--nof_methods_copy); 1182 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1183 } 1184 #endif //ASSERT 1185 // return the rightmost itable index, plus one; or 0 if no methods have 1186 // itable indices 1187 return length; 1188 } 1189 1190 1191 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) { 1192 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1193 int nof_methods = methods->length(); 1194 HandleMark hm; 1195 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1196 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader()); 1197 1198 int ime_count = method_count_for_interface(interf); 1199 for (int i = 0; i < nof_methods; i++) { 1200 Method* m = methods->at(i); 1201 methodHandle target; 1202 if (m->has_itable_index()) { 1203 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1204 // to correctly enforce loader constraints for interface method inheritance 1205 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1206 } 1207 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) { 1208 assert(target == NULL || !target->is_overpass() || target->is_public(), 1209 "Non-public overpass method!"); 1210 // Entry does not resolve. Leave it empty for AbstractMethodError or other error. 1211 if (!(target == NULL) && !target->is_public()) { 1212 // Stuff an IllegalAccessError throwing method in there instead. 1213 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1214 initialize(Universe::throw_illegal_access_error()); 1215 } 1216 } else { 1217 // Entry did resolve, check loader constraints before initializing 1218 // if checkconstraints requested 1219 if (checkconstraints) { 1220 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1221 if (method_holder_loader() != interface_loader()) { 1222 ResourceMark rm(THREAD); 1223 Symbol* failed_type_symbol = 1224 SystemDictionary::check_signature_loaders(m->signature(), 1225 method_holder_loader, 1226 interface_loader, 1227 true, CHECK); 1228 if (failed_type_symbol != NULL) { 1229 const char* msg = "loader constraint violation in interface itable" 1230 " initialization for class %s: when selecting method \"%s\" the" 1231 " class loader (instance of %s) for super interface %s, and the class" 1232 " loader (instance of %s) of the selected method's type, %s have" 1233 " different Class objects for the type %s used in the signature"; 1234 char* current = _klass->name()->as_C_string(); 1235 char* sig = m->name_and_sig_as_C_string(); 1236 const char* loader1 = SystemDictionary::loader_name(interface_loader()); 1237 char* iface = InstanceKlass::cast(interf)->name()->as_C_string(); 1238 const char* loader2 = SystemDictionary::loader_name(method_holder_loader()); 1239 char* mclass = target()->method_holder()->name()->as_C_string(); 1240 char* failed_type_name = failed_type_symbol->as_C_string(); 1241 size_t buflen = strlen(msg) + strlen(current) + strlen(sig) + 1242 strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) + 1243 strlen(failed_type_name); 1244 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1245 jio_snprintf(buf, buflen, msg, current, sig, loader1, iface, 1246 loader2, mclass, failed_type_name); 1247 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1248 } 1249 } 1250 } 1251 1252 // ime may have moved during GC so recalculate address 1253 int ime_num = m->itable_index(); 1254 assert(ime_num < ime_count, "oob"); 1255 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target()); 1256 if (log_develop_is_enabled(Trace, itables)) { 1257 ResourceMark rm(THREAD); 1258 if (target() != NULL) { 1259 LogTarget(Trace, itables) lt; 1260 LogStream ls(lt); 1261 char* sig = target()->name_and_sig_as_C_string(); 1262 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1263 interf->internal_name(), ime_num, sig, 1264 target()->method_holder()->internal_name()); 1265 ls.print("target_method flags: "); 1266 target()->print_linkage_flags(&ls); 1267 ls.cr(); 1268 } 1269 } 1270 } 1271 } 1272 } 1273 1274 #if INCLUDE_JVMTI 1275 // search the itable for uses of either obsolete or EMCP methods 1276 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1277 1278 itableMethodEntry* ime = method_entry(0); 1279 for (int i = 0; i < _size_method_table; i++, ime++) { 1280 Method* old_method = ime->method(); 1281 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1282 continue; // skip uninteresting entries 1283 } 1284 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1285 1286 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1287 1288 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1289 assert(old_method != new_method, "sanity check"); 1290 1291 ime->initialize(new_method); 1292 1293 if (log_is_enabled(Info, redefine, class, update)) { 1294 ResourceMark rm; 1295 if (!(*trace_name_printed)) { 1296 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1297 *trace_name_printed = true; 1298 } 1299 log_trace(redefine, class, update, itables) 1300 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string()); 1301 } 1302 } 1303 } 1304 1305 // an itable should never contain old or obsolete methods 1306 bool klassItable::check_no_old_or_obsolete_entries() { 1307 itableMethodEntry* ime = method_entry(0); 1308 for (int i = 0; i < _size_method_table; i++) { 1309 Method* m = ime->method(); 1310 if (m != NULL && 1311 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1312 return false; 1313 } 1314 ime++; 1315 } 1316 return true; 1317 } 1318 1319 void klassItable::dump_itable() { 1320 itableMethodEntry* ime = method_entry(0); 1321 tty->print_cr("itable dump --"); 1322 for (int i = 0; i < _size_method_table; i++) { 1323 Method* m = ime->method(); 1324 if (m != NULL) { 1325 tty->print(" (%5d) ", i); 1326 m->access_flags().print_on(tty); 1327 if (m->is_default_method()) { 1328 tty->print("default "); 1329 } 1330 tty->print(" -- "); 1331 m->print_name(tty); 1332 tty->cr(); 1333 } 1334 ime++; 1335 } 1336 } 1337 #endif // INCLUDE_JVMTI 1338 1339 // Setup 1340 class InterfaceVisiterClosure : public StackObj { 1341 public: 1342 virtual void doit(Klass* intf, int method_count) = 0; 1343 }; 1344 1345 // Visit all interfaces with at least one itable method 1346 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1347 // Handle array argument 1348 for(int i = 0; i < transitive_intf->length(); i++) { 1349 Klass* intf = transitive_intf->at(i); 1350 assert(intf->is_interface(), "sanity check"); 1351 1352 // Find no. of itable methods 1353 int method_count = 0; 1354 // method_count = klassItable::method_count_for_interface(intf); 1355 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1356 if (methods->length() > 0) { 1357 for (int i = methods->length(); --i >= 0; ) { 1358 if (interface_method_needs_itable_index(methods->at(i))) { 1359 method_count++; 1360 } 1361 } 1362 } 1363 1364 // Only count interfaces with at least one method 1365 if (method_count > 0) { 1366 blk->doit(intf, method_count); 1367 } 1368 } 1369 } 1370 1371 class CountInterfacesClosure : public InterfaceVisiterClosure { 1372 private: 1373 int _nof_methods; 1374 int _nof_interfaces; 1375 public: 1376 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1377 1378 int nof_methods() const { return _nof_methods; } 1379 int nof_interfaces() const { return _nof_interfaces; } 1380 1381 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1382 }; 1383 1384 class SetupItableClosure : public InterfaceVisiterClosure { 1385 private: 1386 itableOffsetEntry* _offset_entry; 1387 itableMethodEntry* _method_entry; 1388 address _klass_begin; 1389 public: 1390 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1391 _klass_begin = klass_begin; 1392 _offset_entry = offset_entry; 1393 _method_entry = method_entry; 1394 } 1395 1396 itableMethodEntry* method_entry() const { return _method_entry; } 1397 1398 void doit(Klass* intf, int method_count) { 1399 int offset = ((address)_method_entry) - _klass_begin; 1400 _offset_entry->initialize(intf, offset); 1401 _offset_entry++; 1402 _method_entry += method_count; 1403 } 1404 }; 1405 1406 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1407 // Count no of interfaces and total number of interface methods 1408 CountInterfacesClosure cic; 1409 visit_all_interfaces(transitive_interfaces, &cic); 1410 1411 // There's alway an extra itable entry so we can null-terminate it. 1412 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1413 1414 // Statistics 1415 update_stats(itable_size * wordSize); 1416 1417 return itable_size; 1418 } 1419 1420 1421 // Fill out offset table and interface klasses into the itable space 1422 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1423 if (klass->itable_length() == 0) return; 1424 assert(!klass->is_interface(), "Should have zero length itable"); 1425 1426 // Count no of interfaces and total number of interface methods 1427 CountInterfacesClosure cic; 1428 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1429 int nof_methods = cic.nof_methods(); 1430 int nof_interfaces = cic.nof_interfaces(); 1431 1432 // Add one extra entry so we can null-terminate the table 1433 nof_interfaces++; 1434 1435 assert(compute_itable_size(klass->transitive_interfaces()) == 1436 calc_itable_size(nof_interfaces, nof_methods), 1437 "mismatch calculation of itable size"); 1438 1439 // Fill-out offset table 1440 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1441 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1442 intptr_t* end = klass->end_of_itable(); 1443 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1444 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1445 1446 // Visit all interfaces and initialize itable offset table 1447 SetupItableClosure sic((address)klass, ioe, ime); 1448 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1449 1450 #ifdef ASSERT 1451 ime = sic.method_entry(); 1452 oop* v = (oop*) klass->end_of_itable(); 1453 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1454 #endif 1455 } 1456 1457 1458 // inverse to itable_index 1459 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1460 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1461 assert(intf->verify_itable_index(itable_index), ""); 1462 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1463 1464 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1465 return NULL; // help caller defend against bad indices 1466 1467 int index = itable_index; 1468 Method* m = methods->at(index); 1469 int index2 = -1; 1470 while (!m->has_itable_index() || 1471 (index2 = m->itable_index()) != itable_index) { 1472 assert(index2 < itable_index, "monotonic"); 1473 if (++index == methods->length()) 1474 return NULL; 1475 m = methods->at(index); 1476 } 1477 assert(m->itable_index() == itable_index, "correct inverse"); 1478 1479 return m; 1480 } 1481 1482 void klassVtable::verify(outputStream* st, bool forced) { 1483 // make sure table is initialized 1484 if (!Universe::is_fully_initialized()) return; 1485 #ifndef PRODUCT 1486 // avoid redundant verifies 1487 if (!forced && _verify_count == Universe::verify_count()) return; 1488 _verify_count = Universe::verify_count(); 1489 #endif 1490 oop* end_of_obj = (oop*)_klass + _klass->size(); 1491 oop* end_of_vtable = (oop *)&table()[_length]; 1492 if (end_of_vtable > end_of_obj) { 1493 fatal("klass %s: klass object too short (vtable extends beyond end)", 1494 _klass->internal_name()); 1495 } 1496 1497 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1498 // verify consistency with superKlass vtable 1499 Klass* super = _klass->super(); 1500 if (super != NULL) { 1501 InstanceKlass* sk = InstanceKlass::cast(super); 1502 klassVtable vt = sk->vtable(); 1503 for (int i = 0; i < vt.length(); i++) { 1504 verify_against(st, &vt, i); 1505 } 1506 } 1507 } 1508 1509 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1510 vtableEntry* vte = &vt->table()[index]; 1511 if (vte->method()->name() != table()[index].method()->name() || 1512 vte->method()->signature() != table()[index].method()->signature()) { 1513 fatal("mismatched name/signature of vtable entries"); 1514 } 1515 } 1516 1517 #ifndef PRODUCT 1518 void klassVtable::print() { 1519 ResourceMark rm; 1520 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1521 for (int i = 0; i < length(); i++) { 1522 table()[i].print(); 1523 tty->cr(); 1524 } 1525 } 1526 #endif 1527 1528 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1529 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1530 Klass* vtklass = vt->klass(); 1531 if (vtklass->is_instance_klass() && 1532 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1533 assert(method() != NULL, "must have set method"); 1534 } 1535 if (method() != NULL) { 1536 method()->verify(); 1537 // we sub_type, because it could be a miranda method 1538 if (!vtklass->is_subtype_of(method()->method_holder())) { 1539 #ifndef PRODUCT 1540 print(); 1541 #endif 1542 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1543 } 1544 } 1545 } 1546 1547 #ifndef PRODUCT 1548 1549 void vtableEntry::print() { 1550 ResourceMark rm; 1551 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1552 if (Verbose) { 1553 tty->print("m " PTR_FORMAT " ", p2i(method())); 1554 } 1555 } 1556 1557 class VtableStats : AllStatic { 1558 public: 1559 static int no_klasses; // # classes with vtables 1560 static int no_array_klasses; // # array classes 1561 static int no_instance_klasses; // # instanceKlasses 1562 static int sum_of_vtable_len; // total # of vtable entries 1563 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1564 static int fixed; // total fixed overhead in bytes 1565 static int filler; // overhead caused by filler bytes 1566 static int entries; // total bytes consumed by vtable entries 1567 static int array_entries; // total bytes consumed by array vtable entries 1568 1569 static void do_class(Klass* k) { 1570 Klass* kl = k; 1571 klassVtable vt = kl->vtable(); 1572 no_klasses++; 1573 if (kl->is_instance_klass()) { 1574 no_instance_klasses++; 1575 kl->array_klasses_do(do_class); 1576 } 1577 if (kl->is_array_klass()) { 1578 no_array_klasses++; 1579 sum_of_array_vtable_len += vt.length(); 1580 } 1581 sum_of_vtable_len += vt.length(); 1582 } 1583 1584 static void compute() { 1585 ClassLoaderDataGraph::classes_do(do_class); 1586 fixed = no_klasses * oopSize; // vtable length 1587 // filler size is a conservative approximation 1588 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1589 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1590 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1591 } 1592 }; 1593 1594 int VtableStats::no_klasses = 0; 1595 int VtableStats::no_array_klasses = 0; 1596 int VtableStats::no_instance_klasses = 0; 1597 int VtableStats::sum_of_vtable_len = 0; 1598 int VtableStats::sum_of_array_vtable_len = 0; 1599 int VtableStats::fixed = 0; 1600 int VtableStats::filler = 0; 1601 int VtableStats::entries = 0; 1602 int VtableStats::array_entries = 0; 1603 1604 void klassVtable::print_statistics() { 1605 ResourceMark rm; 1606 HandleMark hm; 1607 VtableStats::compute(); 1608 tty->print_cr("vtable statistics:"); 1609 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1610 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1611 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1612 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1613 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1614 tty->print_cr("%6d bytes total", total); 1615 } 1616 1617 int klassItable::_total_classes; // Total no. of classes with itables 1618 long klassItable::_total_size; // Total no. of bytes used for itables 1619 1620 void klassItable::print_statistics() { 1621 tty->print_cr("itable statistics:"); 1622 tty->print_cr("%6d classes with itables", _total_classes); 1623 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes); 1624 } 1625 1626 #endif // PRODUCT