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