1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "interpreter/linkResolver.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.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 "runtime/safepointVerifiers.hpp" 43 #include "utilities/copy.hpp" 44 45 inline InstanceKlass* klassVtable::ik() const { 46 return InstanceKlass::cast(_klass); 47 } 48 49 bool klassVtable::is_preinitialized_vtable() { 50 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite(); 51 } 52 53 54 // this function computes the vtable size (including the size needed for miranda 55 // methods) and the number of miranda methods in this class. 56 // Note on Miranda methods: Let's say there is a class C that implements 57 // interface I, and none of C's superclasses implements I. 58 // Let's say there is an abstract method m in I that neither C 59 // nor any of its super classes implement (i.e there is no method of any access, 60 // with the same name and signature as m), then m is a Miranda method which is 61 // entered as a public abstract method in C's vtable. From then on it should 62 // treated as any other public method in C for method over-ride purposes. 63 void klassVtable::compute_vtable_size_and_num_mirandas( 64 int* vtable_length_ret, int* num_new_mirandas, 65 GrowableArray<Method*>* all_mirandas, const Klass* super, 66 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 67 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 68 TRAPS) { 69 NoSafepointVerifier nsv; 70 71 // set up default result values 72 int vtable_length = 0; 73 74 // start off with super's vtable length 75 vtable_length = super == NULL ? 0 : super->vtable_length(); 76 77 // go thru each method in the methods table to see if it needs a new entry 78 int len = methods->length(); 79 for (int i = 0; i < len; i++) { 80 assert(methods->at(i)->is_method(), "must be a Method*"); 81 methodHandle mh(THREAD, methods->at(i)); 82 83 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) { 84 vtable_length += vtableEntry::size(); // we need a new entry 85 } 86 } 87 88 GrowableArray<Method*> new_mirandas(20); 89 // compute the number of mirandas methods that must be added to the end 90 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces, 91 class_flags.is_interface()); 92 *num_new_mirandas = new_mirandas.length(); 93 94 // Interfaces do not need interface methods in their vtables 95 // This includes miranda methods and during later processing, default methods 96 if (!class_flags.is_interface()) { 97 vtable_length += *num_new_mirandas * vtableEntry::size(); 98 } 99 100 if (Universe::is_bootstrapping() && vtable_length == 0) { 101 // array classes don't have their superclass set correctly during 102 // bootstrapping 103 vtable_length = Universe::base_vtable_size(); 104 } 105 106 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 107 if (Universe::is_bootstrapping()) { 108 // Someone is attempting to override java.lang.Object incorrectly on the 109 // bootclasspath. The JVM cannot recover from this error including throwing 110 // an exception 111 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 112 } else { 113 // Someone is attempting to redefine java.lang.Object incorrectly. The 114 // only way this should happen is from 115 // SystemDictionary::resolve_from_stream(), which will detect this later 116 // and throw a security exception. So don't assert here to let 117 // the exception occur. 118 vtable_length = Universe::base_vtable_size(); 119 } 120 } 121 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 122 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 123 124 *vtable_length_ret = vtable_length; 125 } 126 127 int klassVtable::index_of(Method* m, int len) const { 128 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 129 return m->vtable_index(); 130 } 131 132 // Copy super class's vtable to the first part (prefix) of this class's vtable, 133 // and return the number of entries copied. Expects that 'super' is the Java 134 // super class (arrays can have "array" super classes that must be skipped). 135 int klassVtable::initialize_from_super(Klass* super) { 136 if (super == NULL) { 137 return 0; 138 } else if (is_preinitialized_vtable()) { 139 // A shared class' vtable is preinitialized at dump time. No need to copy 140 // methods from super class for shared class, as that was already done 141 // during archiving time. However, if Jvmti has redefined a class, 142 // copy super class's vtable in case the super class has changed. 143 return super->vtable().length(); 144 } else { 145 // copy methods from superKlass 146 klassVtable superVtable = super->vtable(); 147 assert(superVtable.length() <= _length, "vtable too short"); 148 #ifdef ASSERT 149 superVtable.verify(tty, true); 150 #endif 151 superVtable.copy_vtable_to(table()); 152 if (log_develop_is_enabled(Trace, vtables)) { 153 ResourceMark rm; 154 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 155 super->internal_name(), klass()->internal_name(), 156 _length); 157 } 158 return superVtable.length(); 159 } 160 } 161 162 // 163 // Revised lookup semantics introduced 1.3 (Kestrel beta) 164 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 165 166 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 167 Klass* super = _klass->java_super(); 168 int nofNewEntries = 0; 169 170 bool is_shared = _klass->is_shared(); 171 172 if (!_klass->is_array_klass()) { 173 ResourceMark rm(THREAD); 174 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 175 } 176 177 #ifdef ASSERT 178 oop* end_of_obj = (oop*)_klass + _klass->size(); 179 oop* end_of_vtable = (oop*)&table()[_length]; 180 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 181 #endif 182 183 if (Universe::is_bootstrapping()) { 184 assert(!is_shared, "sanity"); 185 // just clear everything 186 for (int i = 0; i < _length; i++) table()[i].clear(); 187 return; 188 } 189 190 int super_vtable_len = initialize_from_super(super); 191 if (_klass->is_array_klass()) { 192 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 193 } else { 194 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 195 196 Array<Method*>* methods = ik()->methods(); 197 int len = methods->length(); 198 int initialized = super_vtable_len; 199 200 // Check each of this class's methods against super; 201 // if override, replace in copy of super vtable, otherwise append to end 202 for (int i = 0; i < len; i++) { 203 // update_inherited_vtable can stop for gc - ensure using handles 204 HandleMark hm(THREAD); 205 assert(methods->at(i)->is_method(), "must be a Method*"); 206 methodHandle mh(THREAD, methods->at(i)); 207 208 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 209 210 if (needs_new_entry) { 211 put_method_at(mh(), initialized); 212 mh()->set_vtable_index(initialized); // set primary vtable index 213 initialized++; 214 } 215 } 216 217 // update vtable with default_methods 218 Array<Method*>* default_methods = ik()->default_methods(); 219 if (default_methods != NULL) { 220 len = default_methods->length(); 221 if (len > 0) { 222 Array<int>* def_vtable_indices = NULL; 223 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 224 assert(!is_shared, "shared class def_vtable_indices does not exist"); 225 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 226 } else { 227 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 228 } 229 for (int i = 0; i < len; i++) { 230 HandleMark hm(THREAD); 231 assert(default_methods->at(i)->is_method(), "must be a Method*"); 232 methodHandle mh(THREAD, default_methods->at(i)); 233 assert(!mh->is_private(), "private interface method in the default method list"); 234 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 235 236 // needs new entry 237 if (needs_new_entry) { 238 put_method_at(mh(), initialized); 239 if (is_preinitialized_vtable()) { 240 // At runtime initialize_vtable is rerun for a shared class 241 // (loaded by the non-boot loader) as part of link_class_impl(). 242 // The dumptime vtable index should be the same as the runtime index. 243 assert(def_vtable_indices->at(i) == initialized, 244 "dump time vtable index is different from runtime index"); 245 } else { 246 def_vtable_indices->at_put(i, initialized); //set vtable index 247 } 248 initialized++; 249 } 250 } 251 } 252 } 253 254 // add miranda methods; it will also return the updated initialized 255 // Interfaces do not need interface methods in their vtables 256 // This includes miranda methods and during later processing, default methods 257 if (!ik()->is_interface()) { 258 initialized = fill_in_mirandas(initialized); 259 } 260 261 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 262 // package_private -> public/protected), the vtable might actually be smaller than our initial 263 // calculation, for classfile versions for which we do not do transitive override 264 // calculations. 265 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 266 assert(initialized == _length, "vtable initialization failed"); 267 } else { 268 assert(initialized <= _length, "vtable initialization failed"); 269 for(;initialized < _length; initialized++) { 270 table()[initialized].clear(); 271 } 272 } 273 NOT_PRODUCT(verify(tty, true)); 274 } 275 } 276 277 // Called for cases where a method does not override its superclass' vtable entry 278 // For bytecodes not produced by javac together it is possible that a method does not override 279 // the superclass's method, but might indirectly override a super-super class's vtable entry 280 // If none found, return a null superk, else return the superk of the method this does override 281 // For public and protected methods: if they override a superclass, they will 282 // also be overridden themselves appropriately. 283 // Private methods do not override and are not overridden. 284 // Package Private methods are trickier: 285 // e.g. P1.A, pub m 286 // P2.B extends A, package private m 287 // P1.C extends B, public m 288 // P1.C.m needs to override P1.A.m and can not override P2.B.m 289 // Therefore: all package private methods need their own vtable entries for 290 // them to be the root of an inheritance overriding decision 291 // Package private methods may also override other vtable entries 292 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, 293 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 294 InstanceKlass* superk = initialsuper; 295 while (superk != NULL && superk->super() != NULL) { 296 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 297 klassVtable ssVtable = supersuperklass->vtable(); 298 if (vtable_index < ssVtable.length()) { 299 Method* super_method = ssVtable.method_at(vtable_index); 300 #ifndef PRODUCT 301 Symbol* name= target_method()->name(); 302 Symbol* signature = target_method()->signature(); 303 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 304 #endif 305 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 306 if (log_develop_is_enabled(Trace, vtables)) { 307 ResourceMark rm(THREAD); 308 LogTarget(Trace, vtables) lt; 309 LogStream ls(lt); 310 char* sig = target_method()->name_and_sig_as_C_string(); 311 ls.print("transitive overriding superclass %s with %s index %d, original flags: ", 312 supersuperklass->internal_name(), 313 sig, vtable_index); 314 super_method->print_linkage_flags(&ls); 315 ls.print("overriders flags: "); 316 target_method->print_linkage_flags(&ls); 317 ls.cr(); 318 } 319 320 break; // return found superk 321 } 322 } else { 323 // super class has no vtable entry here, stop transitive search 324 superk = (InstanceKlass*)NULL; 325 break; 326 } 327 // if no override found yet, continue to search up 328 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 329 } 330 331 return superk; 332 } 333 334 static void log_vtables(int i, bool overrides, const methodHandle& target_method, 335 Klass* target_klass, Method* super_method, 336 Thread* thread) { 337 #ifndef PRODUCT 338 if (log_develop_is_enabled(Trace, vtables)) { 339 ResourceMark rm(thread); 340 LogTarget(Trace, vtables) lt; 341 LogStream ls(lt); 342 char* sig = target_method()->name_and_sig_as_C_string(); 343 if (overrides) { 344 ls.print("overriding with %s index %d, original flags: ", 345 sig, i); 346 } else { 347 ls.print("NOT overriding with %s index %d, original flags: ", 348 sig, i); 349 } 350 super_method->print_linkage_flags(&ls); 351 ls.print("overriders flags: "); 352 target_method->print_linkage_flags(&ls); 353 ls.cr(); 354 } 355 #endif 356 } 357 358 // Update child's copy of super vtable for overrides 359 // OR return true if a new vtable entry is required. 360 // Only called for InstanceKlass's, i.e. not for arrays 361 // If that changed, could not use _klass as handle for klass 362 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, 363 int super_vtable_len, int default_index, 364 bool checkconstraints, TRAPS) { 365 ResourceMark rm; 366 bool allocate_new = true; 367 assert(klass->is_instance_klass(), "must be InstanceKlass"); 368 369 Array<int>* def_vtable_indices = NULL; 370 bool is_default = false; 371 372 // default methods are non-private concrete methods in superinterfaces which are added 373 // to the vtable with their real method_holder. 374 // Since vtable and itable indices share the same storage, don't touch 375 // the default method's real vtable/itable index. 376 // default_vtable_indices stores the vtable value relative to this inheritor 377 if (default_index >= 0 ) { 378 is_default = true; 379 def_vtable_indices = klass->default_vtable_indices(); 380 assert(!target_method()->is_private(), "private interface method flagged as default"); 381 assert(def_vtable_indices != NULL, "def vtable alloc?"); 382 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 383 } else { 384 assert(klass == target_method()->method_holder(), "caller resp."); 385 // Initialize the method's vtable index to "nonvirtual". 386 // If we allocate a vtable entry, we will update it to a non-negative number. 387 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 388 } 389 390 // Static and <init> methods are never in 391 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 392 return false; 393 } 394 395 if (target_method->is_final_method(klass->access_flags())) { 396 // a final method never needs a new entry; final methods can be statically 397 // resolved and they have to be present in the vtable only if they override 398 // a super's method, in which case they re-use its entry 399 allocate_new = false; 400 } else if (klass->is_interface()) { 401 allocate_new = false; // see note below in needs_new_vtable_entry 402 // An interface never allocates new vtable slots, only inherits old ones. 403 // This method will either be assigned its own itable index later, 404 // or be assigned an inherited vtable index in the loop below. 405 // default methods inherited by classes store their vtable indices 406 // in the inheritor's default_vtable_indices. 407 // default methods inherited by interfaces may already have a 408 // valid itable index, if so, don't change it. 409 // Overpass methods in an interface will be assigned an itable index later 410 // by an inheriting class. 411 // Private interface methods have no itable index and are always invoked nonvirtually, 412 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound() 413 // will return true. 414 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) { 415 target_method()->set_vtable_index(Method::pending_itable_index); 416 } 417 } 418 419 // we need a new entry if there is no superclass 420 Klass* super = klass->super(); 421 if (super == NULL) { 422 return allocate_new; 423 } 424 425 // private methods in classes always have a new entry in the vtable 426 // specification interpretation since classic has 427 // private methods not overriding 428 // JDK8 adds private methods in interfaces which require invokespecial 429 if (target_method()->is_private()) { 430 return allocate_new; 431 } 432 433 // search through the vtable and update overridden entries 434 // Since check_signature_loaders acquires SystemDictionary_lock 435 // which can block for gc, once we are in this loop, use handles 436 // For classfiles built with >= jdk7, we now look for transitive overrides 437 438 Symbol* name = target_method()->name(); 439 Symbol* signature = target_method()->signature(); 440 441 Klass* target_klass = target_method()->method_holder(); 442 if (target_klass == NULL) { 443 target_klass = _klass; 444 } 445 446 Handle target_loader(THREAD, target_klass->class_loader()); 447 448 Symbol* target_classname = target_klass->name(); 449 for(int i = 0; i < super_vtable_len; i++) { 450 Method* super_method; 451 if (is_preinitialized_vtable()) { 452 // If this is a shared class, the vtable is already in the final state (fully 453 // initialized). Need to look at the super's vtable. 454 klassVtable superVtable = super->vtable(); 455 super_method = superVtable.method_at(i); 456 } else { 457 super_method = method_at(i); 458 } 459 // Check if method name matches. Ignore match if klass is an interface and the 460 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4) 461 // This is safe because the method at this slot should never get invoked. 462 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.) 463 if (super_method->name() == name && super_method->signature() == signature && 464 (!_klass->is_interface() || 465 !SystemDictionary::is_nonpublic_Object_method(super_method))) { 466 467 // get super_klass for method_holder for the found method 468 InstanceKlass* super_klass = super_method->method_holder(); 469 470 // Whether the method is being overridden 471 bool overrides = false; 472 473 // private methods are also never overridden 474 if (!super_method->is_private() && 475 (is_default 476 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 477 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 478 && ((super_klass = find_transitive_override(super_klass, 479 target_method, i, target_loader, 480 target_classname, THREAD)) 481 != (InstanceKlass*)NULL))))) 482 { 483 // Package private methods always need a new entry to root their own 484 // overriding. They may also override other methods. 485 if (!target_method()->is_package_private()) { 486 allocate_new = false; 487 } 488 489 // Do not check loader constraints for overpass methods because overpass 490 // methods are created by the jvm to throw exceptions. 491 if (checkconstraints && !target_method()->is_overpass()) { 492 // Override vtable entry if passes loader constraint check 493 // if loader constraint checking requested 494 // No need to visit his super, since he and his super 495 // have already made any needed loader constraints. 496 // Since loader constraints are transitive, it is enough 497 // to link to the first super, and we get all the others. 498 Handle super_loader(THREAD, super_klass->class_loader()); 499 500 if (!oopDesc::equals(target_loader(), super_loader())) { 501 ResourceMark rm(THREAD); 502 Symbol* failed_type_symbol = 503 SystemDictionary::check_signature_loaders(signature, target_loader, 504 super_loader, true, 505 CHECK_(false)); 506 if (failed_type_symbol != NULL) { 507 const char* msg = "loader constraint violation for class %s: when selecting " 508 "overriding method \"%s\" the class loader (instance of %s) of the " 509 "selected method's type %s, and the class loader (instance of %s) for its super " 510 "type %s have different Class objects for the type %s used in the signature"; 511 char* curr_class = klass->name()->as_C_string(); 512 char* sig = target_method()->name_and_sig_as_C_string(); 513 const char* loader1 = SystemDictionary::loader_name(target_loader()); 514 char* sel_class = target_klass->name()->as_C_string(); 515 const char* loader2 = SystemDictionary::loader_name(super_loader()); 516 char* super_class = super_klass->name()->as_C_string(); 517 char* failed_type_name = failed_type_symbol->as_C_string(); 518 size_t buflen = strlen(msg) + strlen(curr_class) + strlen(sig) + 519 strlen(loader1) + strlen(sel_class) + strlen(loader2) + 520 strlen(super_class) + strlen(failed_type_name); 521 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 522 jio_snprintf(buf, buflen, msg, curr_class, sig, loader1, sel_class, loader2, 523 super_class, failed_type_name); 524 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 525 } 526 } 527 } 528 529 put_method_at(target_method(), i); 530 overrides = true; 531 if (!is_default) { 532 target_method()->set_vtable_index(i); 533 } else { 534 if (def_vtable_indices != NULL) { 535 if (is_preinitialized_vtable()) { 536 // At runtime initialize_vtable is rerun as part of link_class_impl() 537 // for a shared class loaded by the non-boot loader. 538 // The dumptime vtable index should be the same as the runtime index. 539 assert(def_vtable_indices->at(default_index) == i, 540 "dump time vtable index is different from runtime index"); 541 } else { 542 def_vtable_indices->at_put(default_index, i); 543 } 544 } 545 assert(super_method->is_default_method() || super_method->is_overpass() 546 || super_method->is_abstract(), "default override error"); 547 } 548 } else { 549 overrides = false; 550 } 551 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD); 552 } 553 } 554 return allocate_new; 555 } 556 557 void klassVtable::put_method_at(Method* m, int index) { 558 if (is_preinitialized_vtable()) { 559 // At runtime initialize_vtable is rerun as part of link_class_impl() 560 // for shared class loaded by the non-boot loader to obtain the loader 561 // constraints based on the runtime classloaders' context. The dumptime 562 // method at the vtable index should be the same as the runtime method. 563 assert(table()[index].method() == m, 564 "archived method is different from the runtime method"); 565 } else { 566 if (log_develop_is_enabled(Trace, vtables)) { 567 ResourceMark rm; 568 LogTarget(Trace, vtables) lt; 569 LogStream ls(lt); 570 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 571 ls.print("adding %s at index %d, flags: ", sig, index); 572 if (m != NULL) { 573 m->print_linkage_flags(&ls); 574 } 575 ls.cr(); 576 } 577 table()[index].set(m); 578 } 579 } 580 581 // Find out if a method "m" with superclass "super", loader "classloader" and 582 // name "classname" needs a new vtable entry. Let P be a class package defined 583 // by "classloader" and "classname". 584 // NOTE: The logic used here is very similar to the one used for computing 585 // the vtables indices for a method. We cannot directly use that function because, 586 // we allocate the InstanceKlass at load time, and that requires that the 587 // superclass has been loaded. 588 // However, the vtable entries are filled in at link time, and therefore 589 // the superclass' vtable may not yet have been filled in. 590 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method, 591 const Klass* super, 592 Handle classloader, 593 Symbol* classname, 594 AccessFlags class_flags, 595 u2 major_version, 596 TRAPS) { 597 if (class_flags.is_interface()) { 598 // Interfaces do not use vtables, except for java.lang.Object methods, 599 // so there is no point to assigning 600 // a vtable index to any of their local methods. If we refrain from doing this, 601 // we can use Method::_vtable_index to hold the itable index 602 return false; 603 } 604 605 if (target_method->is_final_method(class_flags) || 606 // a final method never needs a new entry; final methods can be statically 607 // resolved and they have to be present in the vtable only if they override 608 // a super's method, in which case they re-use its entry 609 (target_method()->is_static()) || 610 // static methods don't need to be in vtable 611 (target_method()->name() == vmSymbols::object_initializer_name()) 612 // <init> is never called dynamically-bound 613 ) { 614 return false; 615 } 616 617 // Concrete interface methods do not need new entries, they override 618 // abstract method entries using default inheritance rules 619 if (target_method()->method_holder() != NULL && 620 target_method()->method_holder()->is_interface() && 621 !target_method()->is_abstract()) { 622 assert(target_method()->is_default_method() || target_method()->is_private(), 623 "unexpected interface method type"); 624 return false; 625 } 626 627 // we need a new entry if there is no superclass 628 if (super == NULL) { 629 return true; 630 } 631 632 // private methods in classes always have a new entry in the vtable. 633 // Specification interpretation since classic has private methods not overriding. 634 if (target_method()->is_private()) { 635 return true; 636 } 637 638 // Package private methods always need a new entry to root their own 639 // overriding. This allows transitive overriding to work. 640 if (target_method()->is_package_private()) { 641 return true; 642 } 643 644 // search through the super class hierarchy to see if we need 645 // a new entry 646 ResourceMark rm; 647 Symbol* name = target_method()->name(); 648 Symbol* signature = target_method()->signature(); 649 const Klass* k = super; 650 Method* super_method = NULL; 651 InstanceKlass *holder = NULL; 652 Method* recheck_method = NULL; 653 while (k != NULL) { 654 // lookup through the hierarchy for a method with matching name and sign. 655 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 656 if (super_method == NULL) { 657 break; // we still have to search for a matching miranda method 658 } 659 // get the class holding the matching method 660 // make sure you use that class for is_override 661 InstanceKlass* superk = super_method->method_holder(); 662 // we want only instance method matches 663 // pretend private methods are not in the super vtable 664 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 665 // ignore private, c.m pub does override a.m pub 666 // For classes that were not javac'd together, we also do transitive overriding around 667 // methods that have less accessibility 668 if ((!super_method->is_static()) && 669 (!super_method->is_private())) { 670 if (superk->is_override(super_method, classloader, classname, THREAD)) { 671 return false; 672 // else keep looking for transitive overrides 673 } 674 } 675 676 // Start with lookup result and continue to search up, for versions supporting transitive override 677 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 678 k = superk->super(); // haven't found an override match yet; continue to look 679 } else { 680 break; 681 } 682 } 683 684 // if the target method is public or protected it may have a matching 685 // miranda method in the super, whose entry it should re-use. 686 // Actually, to handle cases that javac would not generate, we need 687 // this check for all access permissions. 688 const InstanceKlass *sk = InstanceKlass::cast(super); 689 if (sk->has_miranda_methods()) { 690 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 691 return false; // found a matching miranda; we do not need a new entry 692 } 693 } 694 return true; // found no match; we need a new entry 695 } 696 697 // Support for miranda methods 698 699 // get the vtable index of a miranda method with matching "name" and "signature" 700 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 701 // search from the bottom, might be faster 702 for (int i = (length() - 1); i >= 0; i--) { 703 Method* m = table()[i].method(); 704 if (is_miranda_entry_at(i) && 705 m->name() == name && m->signature() == signature) { 706 return i; 707 } 708 } 709 return Method::invalid_vtable_index; 710 } 711 712 // check if an entry at an index is miranda 713 // requires that method m at entry be declared ("held") by an interface. 714 bool klassVtable::is_miranda_entry_at(int i) { 715 Method* m = method_at(i); 716 Klass* method_holder = m->method_holder(); 717 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 718 719 // miranda methods are public abstract instance interface methods in a class's vtable 720 if (mhk->is_interface()) { 721 assert(m->is_public(), "should be public"); 722 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 723 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) { 724 return true; 725 } 726 } 727 return false; 728 } 729 730 // Check if a method is a miranda method, given a class's methods array, 731 // its default_method table and its super class. 732 // "Miranda" means an abstract non-private method that would not be 733 // overridden for the local class. 734 // A "miranda" method should only include non-private interface 735 // instance methods, i.e. not private methods, not static methods, 736 // not default methods (concrete interface methods), not overpass methods. 737 // If a given class already has a local (including overpass) method, a 738 // default method, or any of its superclasses has the same which would have 739 // overridden an abstract method, then this is not a miranda method. 740 // 741 // Miranda methods are checked multiple times. 742 // Pass 1: during class load/class file parsing: before vtable size calculation: 743 // include superinterface abstract and default methods (non-private instance). 744 // We include potential default methods to give them space in the vtable. 745 // During the first run, the current instanceKlass has not yet been 746 // created, the superclasses and superinterfaces do have instanceKlasses 747 // but may not have vtables, the default_methods list is empty, no overpasses. 748 // Default method generation uses the all_mirandas array as the starter set for 749 // maximally-specific default method calculation. So, for both classes and 750 // interfaces, it is necessary that the first pass will find all non-private 751 // interface instance methods, whether or not they are concrete. 752 // 753 // Pass 2: recalculated during vtable initialization: only include abstract methods. 754 // The goal of pass 2 is to walk through the superinterfaces to see if any of 755 // the superinterface methods (which were all abstract pre-default methods) 756 // need to be added to the vtable. 757 // With the addition of default methods, we have three new challenges: 758 // overpasses, static interface methods and private interface methods. 759 // Static and private interface methods do not get added to the vtable and 760 // are not seen by the method resolution process, so we skip those. 761 // Overpass methods are already in the vtable, so vtable lookup will 762 // find them and we don't need to add a miranda method to the end of 763 // the vtable. So we look for overpass methods and if they are found we 764 // return false. Note that we inherit our superclasses vtable, so 765 // the superclass' search also needs to use find_overpass so that if 766 // one is found we return false. 767 // False means - we don't need a miranda method added to the vtable. 768 // 769 // During the second run, default_methods is set up, so concrete methods from 770 // superinterfaces with matching names/signatures to default_methods are already 771 // in the default_methods list and do not need to be appended to the vtable 772 // as mirandas. Abstract methods may already have been handled via 773 // overpasses - either local or superclass overpasses, which may be 774 // in the vtable already. 775 // 776 // Pass 3: They are also checked by link resolution and selection, 777 // for invocation on a method (not interface method) reference that 778 // resolves to a method with an interface as its method_holder. 779 // Used as part of walking from the bottom of the vtable to find 780 // the vtable index for the miranda method. 781 // 782 // Part of the Miranda Rights in the US mean that if you do not have 783 // an attorney one will be appointed for you. 784 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 785 Array<Method*>* default_methods, const Klass* super, 786 bool is_interface) { 787 if (m->is_static() || m->is_private() || m->is_overpass()) { 788 return false; 789 } 790 Symbol* name = m->name(); 791 Symbol* signature = m->signature(); 792 793 // First look in local methods to see if already covered 794 if (InstanceKlass::find_local_method(class_methods, name, signature, 795 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 796 { 797 return false; 798 } 799 800 // Check local default methods 801 if ((default_methods != NULL) && 802 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 803 { 804 return false; 805 } 806 807 // Iterate on all superclasses, which should be InstanceKlasses. 808 // Note that we explicitly look for overpasses at each level. 809 // Overpasses may or may not exist for supers for pass 1, 810 // they should have been created for pass 2 and later. 811 812 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 813 { 814 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature, 815 Klass::find_overpass, Klass::skip_static, Klass::skip_private); 816 // Ignore non-public methods in java.lang.Object if klass is an interface. 817 if (found_mth != NULL && (!is_interface || 818 !SystemDictionary::is_nonpublic_Object_method(found_mth))) { 819 return false; 820 } 821 } 822 823 return true; 824 } 825 826 // Scans current_interface_methods for miranda methods that do not 827 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 828 // in super (superclass). These mirandas are added to all_mirandas if it is 829 // not null; in addition, those that are not duplicates of miranda methods 830 // inherited by super from its interfaces are added to new_mirandas. 831 // Thus, new_mirandas will be the set of mirandas that this class introduces, 832 // all_mirandas will be the set of all mirandas applicable to this class 833 // including all defined in superclasses. 834 void klassVtable::add_new_mirandas_to_lists( 835 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 836 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 837 Array<Method*>* default_methods, const Klass* super, bool is_interface) { 838 839 // iterate thru the current interface's method to see if it a miranda 840 int num_methods = current_interface_methods->length(); 841 for (int i = 0; i < num_methods; i++) { 842 Method* im = current_interface_methods->at(i); 843 bool is_duplicate = false; 844 int num_of_current_mirandas = new_mirandas->length(); 845 // check for duplicate mirandas in different interfaces we implement 846 for (int j = 0; j < num_of_current_mirandas; j++) { 847 Method* miranda = new_mirandas->at(j); 848 if ((im->name() == miranda->name()) && 849 (im->signature() == miranda->signature())) { 850 is_duplicate = true; 851 break; 852 } 853 } 854 855 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 856 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all? 857 const InstanceKlass *sk = InstanceKlass::cast(super); 858 // check if it is a duplicate of a super's miranda 859 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 860 new_mirandas->append(im); 861 } 862 if (all_mirandas != NULL) { 863 all_mirandas->append(im); 864 } 865 } 866 } 867 } 868 } 869 870 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 871 GrowableArray<Method*>* all_mirandas, 872 const Klass* super, 873 Array<Method*>* class_methods, 874 Array<Method*>* default_methods, 875 Array<Klass*>* local_interfaces, 876 bool is_interface) { 877 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 878 879 // iterate thru the local interfaces looking for a miranda 880 int num_local_ifs = local_interfaces->length(); 881 for (int i = 0; i < num_local_ifs; i++) { 882 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 883 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 884 ik->methods(), class_methods, 885 default_methods, super, is_interface); 886 // iterate thru each local's super interfaces 887 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 888 int num_super_ifs = super_ifs->length(); 889 for (int j = 0; j < num_super_ifs; j++) { 890 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 891 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 892 sik->methods(), class_methods, 893 default_methods, super, is_interface); 894 } 895 } 896 } 897 898 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 899 // and append them into the vtable starting at index initialized, 900 // return the new value of initialized. 901 // Miranda methods use vtable entries, but do not get assigned a vtable_index 902 // The vtable_index is discovered by searching from the end of the vtable 903 int klassVtable::fill_in_mirandas(int initialized) { 904 GrowableArray<Method*> mirandas(20); 905 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 906 ik()->default_methods(), ik()->local_interfaces(), 907 klass()->is_interface()); 908 for (int i = 0; i < mirandas.length(); i++) { 909 if (log_develop_is_enabled(Trace, vtables)) { 910 Method* meth = mirandas.at(i); 911 ResourceMark rm(Thread::current()); 912 LogTarget(Trace, vtables) lt; 913 LogStream ls(lt); 914 if (meth != NULL) { 915 char* sig = meth->name_and_sig_as_C_string(); 916 ls.print("fill in mirandas with %s index %d, flags: ", 917 sig, initialized); 918 meth->print_linkage_flags(&ls); 919 ls.cr(); 920 } 921 } 922 put_method_at(mirandas.at(i), initialized); 923 ++initialized; 924 } 925 return initialized; 926 } 927 928 // Copy this class's vtable to the vtable beginning at start. 929 // Used to copy superclass vtable to prefix of subclass's vtable. 930 void klassVtable::copy_vtable_to(vtableEntry* start) { 931 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 932 } 933 934 #if INCLUDE_JVMTI 935 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 936 // If old_method is default, find this vtable index in default_vtable_indices 937 // and replace that method in the _default_methods list 938 bool updated = false; 939 940 Array<Method*>* default_methods = ik()->default_methods(); 941 if (default_methods != NULL) { 942 int len = default_methods->length(); 943 for (int idx = 0; idx < len; idx++) { 944 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 945 if (default_methods->at(idx) == old_method) { 946 default_methods->at_put(idx, new_method); 947 updated = true; 948 } 949 break; 950 } 951 } 952 } 953 return updated; 954 } 955 956 // search the vtable for uses of either obsolete or EMCP methods 957 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 958 int prn_enabled = 0; 959 for (int index = 0; index < length(); index++) { 960 Method* old_method = unchecked_method_at(index); 961 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 962 continue; // skip uninteresting entries 963 } 964 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 965 966 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 967 968 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 969 assert(old_method != new_method, "sanity check"); 970 971 put_method_at(new_method, index); 972 // For default methods, need to update the _default_methods array 973 // which can only have one method entry for a given signature 974 bool updated_default = false; 975 if (old_method->is_default_method()) { 976 updated_default = adjust_default_method(index, old_method, new_method); 977 } 978 979 if (log_is_enabled(Info, redefine, class, update)) { 980 ResourceMark rm; 981 if (!(*trace_name_printed)) { 982 log_info(redefine, class, update) 983 ("adjust: klassname=%s for methods from name=%s", 984 _klass->external_name(), old_method->method_holder()->external_name()); 985 *trace_name_printed = true; 986 } 987 log_debug(redefine, class, update, vtables) 988 ("vtable method update: %s(%s), updated default = %s", 989 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false"); 990 } 991 } 992 } 993 994 // a vtable should never contain old or obsolete methods 995 bool klassVtable::check_no_old_or_obsolete_entries() { 996 for (int i = 0; i < length(); i++) { 997 Method* m = unchecked_method_at(i); 998 if (m != NULL && 999 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1000 return false; 1001 } 1002 } 1003 return true; 1004 } 1005 1006 void klassVtable::dump_vtable() { 1007 tty->print_cr("vtable dump --"); 1008 for (int i = 0; i < length(); i++) { 1009 Method* m = unchecked_method_at(i); 1010 if (m != NULL) { 1011 tty->print(" (%5d) ", i); 1012 m->access_flags().print_on(tty); 1013 if (m->is_default_method()) { 1014 tty->print("default "); 1015 } 1016 if (m->is_overpass()) { 1017 tty->print("overpass"); 1018 } 1019 tty->print(" -- "); 1020 m->print_name(tty); 1021 tty->cr(); 1022 } 1023 } 1024 } 1025 #endif // INCLUDE_JVMTI 1026 1027 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 1028 void klassVtable::clear_vtable() { 1029 for (int i = 0; i < _length; i++) table()[i].clear(); 1030 } 1031 1032 bool klassVtable::is_initialized() { 1033 return _length == 0 || table()[0].method() != NULL; 1034 } 1035 1036 //----------------------------------------------------------------------------------------- 1037 // Itable code 1038 1039 // Initialize a itableMethodEntry 1040 void itableMethodEntry::initialize(Method* m) { 1041 if (m == NULL) return; 1042 1043 #ifdef ASSERT 1044 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) && 1045 !MetaspaceShared::remapped_readwrite()) { 1046 // At runtime initialize_itable is rerun as part of link_class_impl() 1047 // for a shared class loaded by the non-boot loader. 1048 // The dumptime itable method entry should be the same as the runtime entry. 1049 assert(_method == m, "sanity"); 1050 } 1051 #endif 1052 _method = m; 1053 } 1054 1055 klassItable::klassItable(InstanceKlass* klass) { 1056 _klass = klass; 1057 1058 if (klass->itable_length() > 0) { 1059 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1060 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1061 // First offset entry points to the first method_entry 1062 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1063 intptr_t* end = klass->end_of_itable(); 1064 1065 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1066 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1067 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1068 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1069 return; 1070 } 1071 } 1072 1073 // The length of the itable was either zero, or it has not yet been initialized. 1074 _table_offset = 0; 1075 _size_offset_table = 0; 1076 _size_method_table = 0; 1077 } 1078 1079 static int initialize_count = 0; 1080 1081 // Initialization 1082 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1083 if (_klass->is_interface()) { 1084 // This needs to go after vtable indices are assigned but 1085 // before implementors need to know the number of itable indices. 1086 assign_itable_indices_for_interface(_klass); 1087 } 1088 1089 // Cannot be setup doing bootstrapping, interfaces don't have 1090 // itables, and klass with only ones entry have empty itables 1091 if (Universe::is_bootstrapping() || 1092 _klass->is_interface() || 1093 _klass->itable_length() == itableOffsetEntry::size()) return; 1094 1095 // There's alway an extra itable entry so we can null-terminate it. 1096 guarantee(size_offset_table() >= 1, "too small"); 1097 int num_interfaces = size_offset_table() - 1; 1098 if (num_interfaces > 0) { 1099 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 1100 _klass->name()->as_C_string()); 1101 1102 1103 // Iterate through all interfaces 1104 int i; 1105 for(i = 0; i < num_interfaces; i++) { 1106 itableOffsetEntry* ioe = offset_entry(i); 1107 HandleMark hm(THREAD); 1108 Klass* interf = ioe->interface_klass(); 1109 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1110 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK); 1111 } 1112 1113 } 1114 // Check that the last entry is empty 1115 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1116 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1117 } 1118 1119 1120 inline bool interface_method_needs_itable_index(Method* m) { 1121 if (m->is_static()) return false; // e.g., Stream.empty 1122 if (m->is_initializer()) return false; // <init> or <clinit> 1123 if (m->is_private()) return false; // requires invokeSpecial 1124 // If an interface redeclares a method from java.lang.Object, 1125 // it should already have a vtable index, don't touch it. 1126 // e.g., CharSequence.toString (from initialize_vtable) 1127 // if (m->has_vtable_index()) return false; // NO! 1128 return true; 1129 } 1130 1131 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1132 // an interface does not have an itable, but its methods need to be numbered 1133 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1134 ++initialize_count, klass->name()->as_C_string()); 1135 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1136 int nof_methods = methods->length(); 1137 int ime_num = 0; 1138 for (int i = 0; i < nof_methods; i++) { 1139 Method* m = methods->at(i); 1140 if (interface_method_needs_itable_index(m)) { 1141 assert(!m->is_final_method(), "no final interface methods"); 1142 // If m is already assigned a vtable index, do not disturb it. 1143 if (log_develop_is_enabled(Trace, itables)) { 1144 ResourceMark rm; 1145 LogTarget(Trace, itables) lt; 1146 LogStream ls(lt); 1147 assert(m != NULL, "methods can never be null"); 1148 const char* sig = m->name_and_sig_as_C_string(); 1149 if (m->has_vtable_index()) { 1150 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1151 } else { 1152 ls.print("itable index %d for method: %s, flags: ", ime_num, sig); 1153 } 1154 m->print_linkage_flags(&ls); 1155 ls.cr(); 1156 } 1157 if (!m->has_vtable_index()) { 1158 // A shared method could have an initialized itable_index that 1159 // is < 0. 1160 assert(m->vtable_index() == Method::pending_itable_index || 1161 m->is_shared(), 1162 "set by initialize_vtable"); 1163 m->set_itable_index(ime_num); 1164 // Progress to next itable entry 1165 ime_num++; 1166 } 1167 } 1168 } 1169 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1170 return ime_num; 1171 } 1172 1173 int klassItable::method_count_for_interface(Klass* interf) { 1174 assert(interf->is_instance_klass(), "must be"); 1175 assert(interf->is_interface(), "must be"); 1176 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1177 int nof_methods = methods->length(); 1178 int length = 0; 1179 while (nof_methods > 0) { 1180 Method* m = methods->at(nof_methods-1); 1181 if (m->has_itable_index()) { 1182 length = m->itable_index() + 1; 1183 break; 1184 } 1185 nof_methods -= 1; 1186 } 1187 #ifdef ASSERT 1188 int nof_methods_copy = nof_methods; 1189 while (nof_methods_copy > 0) { 1190 Method* mm = methods->at(--nof_methods_copy); 1191 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1192 } 1193 #endif //ASSERT 1194 // return the rightmost itable index, plus one; or 0 if no methods have 1195 // itable indices 1196 return length; 1197 } 1198 1199 1200 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) { 1201 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1202 int nof_methods = methods->length(); 1203 HandleMark hm; 1204 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader()); 1205 1206 int ime_count = method_count_for_interface(interf); 1207 for (int i = 0; i < nof_methods; i++) { 1208 Method* m = methods->at(i); 1209 methodHandle target; 1210 if (m->has_itable_index()) { 1211 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1212 // to correctly enforce loader constraints for interface method inheritance 1213 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1214 } 1215 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) { 1216 assert(target == NULL || !target->is_overpass() || target->is_public(), 1217 "Non-public overpass method!"); 1218 // Entry does not resolve. Leave it empty for AbstractMethodError or other error. 1219 if (!(target == NULL) && !target->is_public()) { 1220 // Stuff an IllegalAccessError throwing method in there instead. 1221 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1222 initialize(Universe::throw_illegal_access_error()); 1223 } 1224 } else { 1225 // Entry did resolve, check loader constraints before initializing 1226 // if checkconstraints requested 1227 if (checkconstraints) { 1228 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1229 if (!oopDesc::equals(method_holder_loader(), interface_loader())) { 1230 ResourceMark rm(THREAD); 1231 Symbol* failed_type_symbol = 1232 SystemDictionary::check_signature_loaders(m->signature(), 1233 method_holder_loader, 1234 interface_loader, 1235 true, CHECK); 1236 if (failed_type_symbol != NULL) { 1237 const char* msg = "loader constraint violation in interface itable" 1238 " initialization for class %s: when selecting method \"%s\" the" 1239 " class loader (instance of %s) for super interface %s, and the class" 1240 " loader (instance of %s) of the selected method's type, %s have" 1241 " different Class objects for the type %s used in the signature"; 1242 char* current = _klass->name()->as_C_string(); 1243 char* sig = m->name_and_sig_as_C_string(); 1244 const char* loader1 = SystemDictionary::loader_name(interface_loader()); 1245 char* iface = InstanceKlass::cast(interf)->name()->as_C_string(); 1246 const char* loader2 = SystemDictionary::loader_name(method_holder_loader()); 1247 char* mclass = target()->method_holder()->name()->as_C_string(); 1248 char* failed_type_name = failed_type_symbol->as_C_string(); 1249 size_t buflen = strlen(msg) + strlen(current) + strlen(sig) + 1250 strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) + 1251 strlen(failed_type_name); 1252 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1253 jio_snprintf(buf, buflen, msg, current, sig, loader1, iface, 1254 loader2, mclass, failed_type_name); 1255 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1256 } 1257 } 1258 } 1259 1260 // ime may have moved during GC so recalculate address 1261 int ime_num = m->itable_index(); 1262 assert(ime_num < ime_count, "oob"); 1263 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target()); 1264 if (log_develop_is_enabled(Trace, itables)) { 1265 ResourceMark rm(THREAD); 1266 if (target() != NULL) { 1267 LogTarget(Trace, itables) lt; 1268 LogStream ls(lt); 1269 char* sig = target()->name_and_sig_as_C_string(); 1270 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1271 interf->internal_name(), ime_num, sig, 1272 target()->method_holder()->internal_name()); 1273 ls.print("target_method flags: "); 1274 target()->print_linkage_flags(&ls); 1275 ls.cr(); 1276 } 1277 } 1278 } 1279 } 1280 } 1281 1282 #if INCLUDE_JVMTI 1283 // search the itable for uses of either obsolete or EMCP methods 1284 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1285 1286 itableMethodEntry* ime = method_entry(0); 1287 for (int i = 0; i < _size_method_table; i++, ime++) { 1288 Method* old_method = ime->method(); 1289 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1290 continue; // skip uninteresting entries 1291 } 1292 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1293 1294 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1295 1296 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1297 assert(old_method != new_method, "sanity check"); 1298 1299 ime->initialize(new_method); 1300 1301 if (log_is_enabled(Info, redefine, class, update)) { 1302 ResourceMark rm; 1303 if (!(*trace_name_printed)) { 1304 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1305 *trace_name_printed = true; 1306 } 1307 log_trace(redefine, class, update, itables) 1308 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string()); 1309 } 1310 } 1311 } 1312 1313 // an itable should never contain old or obsolete methods 1314 bool klassItable::check_no_old_or_obsolete_entries() { 1315 itableMethodEntry* ime = method_entry(0); 1316 for (int i = 0; i < _size_method_table; i++) { 1317 Method* m = ime->method(); 1318 if (m != NULL && 1319 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1320 return false; 1321 } 1322 ime++; 1323 } 1324 return true; 1325 } 1326 1327 void klassItable::dump_itable() { 1328 itableMethodEntry* ime = method_entry(0); 1329 tty->print_cr("itable dump --"); 1330 for (int i = 0; i < _size_method_table; i++) { 1331 Method* m = ime->method(); 1332 if (m != NULL) { 1333 tty->print(" (%5d) ", i); 1334 m->access_flags().print_on(tty); 1335 if (m->is_default_method()) { 1336 tty->print("default "); 1337 } 1338 tty->print(" -- "); 1339 m->print_name(tty); 1340 tty->cr(); 1341 } 1342 ime++; 1343 } 1344 } 1345 #endif // INCLUDE_JVMTI 1346 1347 // Setup 1348 class InterfaceVisiterClosure : public StackObj { 1349 public: 1350 virtual void doit(Klass* intf, int method_count) = 0; 1351 }; 1352 1353 // Visit all interfaces with at least one itable method 1354 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1355 // Handle array argument 1356 for(int i = 0; i < transitive_intf->length(); i++) { 1357 Klass* intf = transitive_intf->at(i); 1358 assert(intf->is_interface(), "sanity check"); 1359 1360 // Find no. of itable methods 1361 int method_count = 0; 1362 // method_count = klassItable::method_count_for_interface(intf); 1363 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1364 if (methods->length() > 0) { 1365 for (int i = methods->length(); --i >= 0; ) { 1366 if (interface_method_needs_itable_index(methods->at(i))) { 1367 method_count++; 1368 } 1369 } 1370 } 1371 1372 // Visit all interfaces which either have any methods or can participate in receiver type check. 1373 // We do not bother to count methods in transitive interfaces, although that would allow us to skip 1374 // this step in the rare case of a zero-method interface extending another zero-method interface. 1375 if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 0) { 1376 blk->doit(intf, method_count); 1377 } 1378 } 1379 } 1380 1381 class CountInterfacesClosure : public InterfaceVisiterClosure { 1382 private: 1383 int _nof_methods; 1384 int _nof_interfaces; 1385 public: 1386 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1387 1388 int nof_methods() const { return _nof_methods; } 1389 int nof_interfaces() const { return _nof_interfaces; } 1390 1391 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1392 }; 1393 1394 class SetupItableClosure : public InterfaceVisiterClosure { 1395 private: 1396 itableOffsetEntry* _offset_entry; 1397 itableMethodEntry* _method_entry; 1398 address _klass_begin; 1399 public: 1400 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1401 _klass_begin = klass_begin; 1402 _offset_entry = offset_entry; 1403 _method_entry = method_entry; 1404 } 1405 1406 itableMethodEntry* method_entry() const { return _method_entry; } 1407 1408 void doit(Klass* intf, int method_count) { 1409 int offset = ((address)_method_entry) - _klass_begin; 1410 _offset_entry->initialize(intf, offset); 1411 _offset_entry++; 1412 _method_entry += method_count; 1413 } 1414 }; 1415 1416 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1417 // Count no of interfaces and total number of interface methods 1418 CountInterfacesClosure cic; 1419 visit_all_interfaces(transitive_interfaces, &cic); 1420 1421 // There's alway an extra itable entry so we can null-terminate it. 1422 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1423 1424 // Statistics 1425 update_stats(itable_size * wordSize); 1426 1427 return itable_size; 1428 } 1429 1430 1431 // Fill out offset table and interface klasses into the itable space 1432 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1433 if (klass->itable_length() == 0) return; 1434 assert(!klass->is_interface(), "Should have zero length itable"); 1435 1436 // Count no of interfaces and total number of interface methods 1437 CountInterfacesClosure cic; 1438 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1439 int nof_methods = cic.nof_methods(); 1440 int nof_interfaces = cic.nof_interfaces(); 1441 1442 // Add one extra entry so we can null-terminate the table 1443 nof_interfaces++; 1444 1445 assert(compute_itable_size(klass->transitive_interfaces()) == 1446 calc_itable_size(nof_interfaces, nof_methods), 1447 "mismatch calculation of itable size"); 1448 1449 // Fill-out offset table 1450 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1451 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1452 intptr_t* end = klass->end_of_itable(); 1453 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1454 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1455 1456 // Visit all interfaces and initialize itable offset table 1457 SetupItableClosure sic((address)klass, ioe, ime); 1458 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1459 1460 #ifdef ASSERT 1461 ime = sic.method_entry(); 1462 oop* v = (oop*) klass->end_of_itable(); 1463 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1464 #endif 1465 } 1466 1467 1468 // inverse to itable_index 1469 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1470 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1471 assert(intf->verify_itable_index(itable_index), ""); 1472 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1473 1474 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1475 return NULL; // help caller defend against bad indices 1476 1477 int index = itable_index; 1478 Method* m = methods->at(index); 1479 int index2 = -1; 1480 while (!m->has_itable_index() || 1481 (index2 = m->itable_index()) != itable_index) { 1482 assert(index2 < itable_index, "monotonic"); 1483 if (++index == methods->length()) 1484 return NULL; 1485 m = methods->at(index); 1486 } 1487 assert(m->itable_index() == itable_index, "correct inverse"); 1488 1489 return m; 1490 } 1491 1492 void klassVtable::verify(outputStream* st, bool forced) { 1493 // make sure table is initialized 1494 if (!Universe::is_fully_initialized()) return; 1495 #ifndef PRODUCT 1496 // avoid redundant verifies 1497 if (!forced && _verify_count == Universe::verify_count()) return; 1498 _verify_count = Universe::verify_count(); 1499 #endif 1500 oop* end_of_obj = (oop*)_klass + _klass->size(); 1501 oop* end_of_vtable = (oop *)&table()[_length]; 1502 if (end_of_vtable > end_of_obj) { 1503 fatal("klass %s: klass object too short (vtable extends beyond end)", 1504 _klass->internal_name()); 1505 } 1506 1507 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1508 // verify consistency with superKlass vtable 1509 Klass* super = _klass->super(); 1510 if (super != NULL) { 1511 InstanceKlass* sk = InstanceKlass::cast(super); 1512 klassVtable vt = sk->vtable(); 1513 for (int i = 0; i < vt.length(); i++) { 1514 verify_against(st, &vt, i); 1515 } 1516 } 1517 } 1518 1519 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1520 vtableEntry* vte = &vt->table()[index]; 1521 if (vte->method()->name() != table()[index].method()->name() || 1522 vte->method()->signature() != table()[index].method()->signature()) { 1523 fatal("mismatched name/signature of vtable entries"); 1524 } 1525 } 1526 1527 #ifndef PRODUCT 1528 void klassVtable::print() { 1529 ResourceMark rm; 1530 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1531 for (int i = 0; i < length(); i++) { 1532 table()[i].print(); 1533 tty->cr(); 1534 } 1535 } 1536 #endif 1537 1538 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1539 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1540 Klass* vtklass = vt->klass(); 1541 if (vtklass->is_instance_klass() && 1542 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1543 assert(method() != NULL, "must have set method"); 1544 } 1545 if (method() != NULL) { 1546 method()->verify(); 1547 // we sub_type, because it could be a miranda method 1548 if (!vtklass->is_subtype_of(method()->method_holder())) { 1549 #ifndef PRODUCT 1550 print(); 1551 #endif 1552 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1553 } 1554 } 1555 } 1556 1557 #ifndef PRODUCT 1558 1559 void vtableEntry::print() { 1560 ResourceMark rm; 1561 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1562 if (Verbose) { 1563 tty->print("m " PTR_FORMAT " ", p2i(method())); 1564 } 1565 } 1566 1567 class VtableStats : AllStatic { 1568 public: 1569 static int no_klasses; // # classes with vtables 1570 static int no_array_klasses; // # array classes 1571 static int no_instance_klasses; // # instanceKlasses 1572 static int sum_of_vtable_len; // total # of vtable entries 1573 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1574 static int fixed; // total fixed overhead in bytes 1575 static int filler; // overhead caused by filler bytes 1576 static int entries; // total bytes consumed by vtable entries 1577 static int array_entries; // total bytes consumed by array vtable entries 1578 1579 static void do_class(Klass* k) { 1580 Klass* kl = k; 1581 klassVtable vt = kl->vtable(); 1582 no_klasses++; 1583 if (kl->is_instance_klass()) { 1584 no_instance_klasses++; 1585 kl->array_klasses_do(do_class); 1586 } 1587 if (kl->is_array_klass()) { 1588 no_array_klasses++; 1589 sum_of_array_vtable_len += vt.length(); 1590 } 1591 sum_of_vtable_len += vt.length(); 1592 } 1593 1594 static void compute() { 1595 ClassLoaderDataGraph::classes_do(do_class); 1596 fixed = no_klasses * oopSize; // vtable length 1597 // filler size is a conservative approximation 1598 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1599 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1600 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1601 } 1602 }; 1603 1604 int VtableStats::no_klasses = 0; 1605 int VtableStats::no_array_klasses = 0; 1606 int VtableStats::no_instance_klasses = 0; 1607 int VtableStats::sum_of_vtable_len = 0; 1608 int VtableStats::sum_of_array_vtable_len = 0; 1609 int VtableStats::fixed = 0; 1610 int VtableStats::filler = 0; 1611 int VtableStats::entries = 0; 1612 int VtableStats::array_entries = 0; 1613 1614 void klassVtable::print_statistics() { 1615 ResourceMark rm; 1616 HandleMark hm; 1617 VtableStats::compute(); 1618 tty->print_cr("vtable statistics:"); 1619 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1620 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1621 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1622 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1623 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1624 tty->print_cr("%6d bytes total", total); 1625 } 1626 1627 int klassItable::_total_classes; // Total no. of classes with itables 1628 long klassItable::_total_size; // Total no. of bytes used for itables 1629 1630 void klassItable::print_statistics() { 1631 tty->print_cr("itable statistics:"); 1632 tty->print_cr("%6d classes with itables", _total_classes); 1633 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes); 1634 } 1635 1636 #endif // PRODUCT