1 /* 2 * Copyright (c) 2012, 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 "classfile/bytecodeAssembler.hpp" 27 #include "classfile/defaultMethods.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "memory/allocation.hpp" 30 #include "memory/metadataFactory.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "runtime/signature.hpp" 33 #include "runtime/thread.hpp" 34 #include "oops/instanceKlass.hpp" 35 #include "oops/klass.hpp" 36 #include "oops/method.hpp" 37 #include "utilities/accessFlags.hpp" 38 #include "utilities/exceptions.hpp" 39 #include "utilities/ostream.hpp" 40 #include "utilities/pair.hpp" 41 #include "utilities/resourceHash.hpp" 42 43 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState; 44 45 // Because we use an iterative algorithm when iterating over the type 46 // hierarchy, we can't use traditional scoped objects which automatically do 47 // cleanup in the destructor when the scope is exited. PseudoScope (and 48 // PseudoScopeMark) provides a similar functionality, but for when you want a 49 // scoped object in non-stack memory (such as in resource memory, as we do 50 // here). You've just got to remember to call 'destroy()' on the scope when 51 // leaving it (and marks have to be explicitly added). 52 class PseudoScopeMark : public ResourceObj { 53 public: 54 virtual void destroy() = 0; 55 }; 56 57 class PseudoScope : public ResourceObj { 58 private: 59 GrowableArray<PseudoScopeMark*> _marks; 60 public: 61 62 static PseudoScope* cast(void* data) { 63 return static_cast<PseudoScope*>(data); 64 } 65 66 void add_mark(PseudoScopeMark* psm) { 67 _marks.append(psm); 68 } 69 70 void destroy() { 71 for (int i = 0; i < _marks.length(); ++i) { 72 _marks.at(i)->destroy(); 73 } 74 } 75 }; 76 77 #ifndef PRODUCT 78 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) { 79 ResourceMark rm; 80 str->print("%s%s", name->as_C_string(), signature->as_C_string()); 81 } 82 83 static void print_method(outputStream* str, Method* mo, bool with_class=true) { 84 ResourceMark rm; 85 if (with_class) { 86 str->print("%s.", mo->klass_name()->as_C_string()); 87 } 88 print_slot(str, mo->name(), mo->signature()); 89 } 90 #endif // ndef PRODUCT 91 92 /** 93 * Perform a depth-first iteration over the class hierarchy, applying 94 * algorithmic logic as it goes. 95 * 96 * This class is one half of the inheritance hierarchy analysis mechanism. 97 * It is meant to be used in conjunction with another class, the algorithm, 98 * which is indicated by the ALGO template parameter. This class can be 99 * paired with any algorithm class that provides the required methods. 100 * 101 * This class contains all the mechanics for iterating over the class hierarchy 102 * starting at a particular root, without recursing (thus limiting stack growth 103 * from this point). It visits each superclass (if present) and superinterface 104 * in a depth-first manner, with callbacks to the ALGO class as each class is 105 * encountered (visit()), The algorithm can cut-off further exploration of a 106 * particular branch by returning 'false' from a visit() call. 107 * 108 * The ALGO class, must provide a visit() method, which each of which will be 109 * called once for each node in the inheritance tree during the iteration. In 110 * addition, it can provide a memory block via new_node_data(InstanceKlass*), 111 * which it can use for node-specific storage (and access via the 112 * current_data() and data_at_depth(int) methods). 113 * 114 * Bare minimum needed to be an ALGO class: 115 * class Algo : public HierarchyVisitor<Algo> { 116 * void* new_node_data(InstanceKlass* cls) { return NULL; } 117 * void free_node_data(void* data) { return; } 118 * bool visit() { return true; } 119 * }; 120 */ 121 template <class ALGO> 122 class HierarchyVisitor : StackObj { 123 private: 124 125 class Node : public ResourceObj { 126 public: 127 InstanceKlass* _class; 128 bool _super_was_visited; 129 int _interface_index; 130 void* _algorithm_data; 131 132 Node(InstanceKlass* cls, void* data, bool visit_super) 133 : _class(cls), _super_was_visited(!visit_super), 134 _interface_index(0), _algorithm_data(data) {} 135 136 int number_of_interfaces() { return _class->local_interfaces()->length(); } 137 int interface_index() { return _interface_index; } 138 void set_super_visited() { _super_was_visited = true; } 139 void increment_visited_interface() { ++_interface_index; } 140 void set_all_interfaces_visited() { 141 _interface_index = number_of_interfaces(); 142 } 143 bool has_visited_super() { return _super_was_visited; } 144 bool has_visited_all_interfaces() { 145 return interface_index() >= number_of_interfaces(); 146 } 147 InstanceKlass* interface_at(int index) { 148 return InstanceKlass::cast(_class->local_interfaces()->at(index)); 149 } 150 InstanceKlass* next_super() { return _class->java_super(); } 151 InstanceKlass* next_interface() { 152 return interface_at(interface_index()); 153 } 154 }; 155 156 bool _cancelled; 157 GrowableArray<Node*> _path; 158 159 Node* current_top() const { return _path.top(); } 160 bool has_more_nodes() const { return !_path.is_empty(); } 161 void push(InstanceKlass* cls, void* data) { 162 assert(cls != NULL, "Requires a valid instance class"); 163 Node* node = new Node(cls, data, has_super(cls)); 164 _path.push(node); 165 } 166 void pop() { _path.pop(); } 167 168 void reset_iteration() { 169 _cancelled = false; 170 _path.clear(); 171 } 172 bool is_cancelled() const { return _cancelled; } 173 174 // This code used to skip interface classes because their only 175 // superclass was j.l.Object which would be also covered by class 176 // superclass hierarchy walks. Now that the starting point can be 177 // an interface, we must ensure we catch j.l.Object as the super. 178 static bool has_super(InstanceKlass* cls) { 179 return cls->super() != NULL; 180 } 181 182 Node* node_at_depth(int i) const { 183 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1); 184 } 185 186 protected: 187 188 // Accessors available to the algorithm 189 int current_depth() const { return _path.length() - 1; } 190 191 InstanceKlass* class_at_depth(int i) { 192 Node* n = node_at_depth(i); 193 return n == NULL ? NULL : n->_class; 194 } 195 InstanceKlass* current_class() { return class_at_depth(0); } 196 197 void* data_at_depth(int i) { 198 Node* n = node_at_depth(i); 199 return n == NULL ? NULL : n->_algorithm_data; 200 } 201 void* current_data() { return data_at_depth(0); } 202 203 void cancel_iteration() { _cancelled = true; } 204 205 public: 206 207 void run(InstanceKlass* root) { 208 ALGO* algo = static_cast<ALGO*>(this); 209 210 reset_iteration(); 211 212 void* algo_data = algo->new_node_data(root); 213 push(root, algo_data); 214 bool top_needs_visit = true; 215 216 do { 217 Node* top = current_top(); 218 if (top_needs_visit) { 219 if (algo->visit() == false) { 220 // algorithm does not want to continue along this path. Arrange 221 // it so that this state is immediately popped off the stack 222 top->set_super_visited(); 223 top->set_all_interfaces_visited(); 224 } 225 top_needs_visit = false; 226 } 227 228 if (top->has_visited_super() && top->has_visited_all_interfaces()) { 229 algo->free_node_data(top->_algorithm_data); 230 pop(); 231 } else { 232 InstanceKlass* next = NULL; 233 if (top->has_visited_super() == false) { 234 next = top->next_super(); 235 top->set_super_visited(); 236 } else { 237 next = top->next_interface(); 238 top->increment_visited_interface(); 239 } 240 assert(next != NULL, "Otherwise we shouldn't be here"); 241 algo_data = algo->new_node_data(next); 242 push(next, algo_data); 243 top_needs_visit = true; 244 } 245 } while (!is_cancelled() && has_more_nodes()); 246 } 247 }; 248 249 #ifndef PRODUCT 250 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> { 251 public: 252 253 bool visit() { 254 InstanceKlass* cls = current_class(); 255 streamIndentor si(tty, current_depth() * 2); 256 tty->indent().print_cr("%s", cls->name()->as_C_string()); 257 return true; 258 } 259 260 void* new_node_data(InstanceKlass* cls) { return NULL; } 261 void free_node_data(void* data) { return; } 262 }; 263 #endif // ndef PRODUCT 264 265 // Used to register InstanceKlass objects and all related metadata structures 266 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't 267 // be deallocated by class redefinition while we're using them. The classes are 268 // de-registered when this goes out of scope. 269 // 270 // Once a class is registered, we need not bother with methodHandles or 271 // constantPoolHandles for it's associated metadata. 272 class KeepAliveRegistrar : public StackObj { 273 private: 274 Thread* _thread; 275 GrowableArray<ConstantPool*> _keep_alive; 276 277 public: 278 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) { 279 assert(thread == Thread::current(), "Must be current thread"); 280 } 281 282 ~KeepAliveRegistrar() { 283 for (int i = _keep_alive.length() - 1; i >= 0; --i) { 284 ConstantPool* cp = _keep_alive.at(i); 285 int idx = _thread->metadata_handles()->find_from_end(cp); 286 assert(idx > 0, "Must be in the list"); 287 _thread->metadata_handles()->remove_at(idx); 288 } 289 } 290 291 // Register a class as 'in-use' by the thread. It's fine to register a class 292 // multiple times (though perhaps inefficient) 293 void register_class(InstanceKlass* ik) { 294 ConstantPool* cp = ik->constants(); 295 _keep_alive.push(cp); 296 _thread->metadata_handles()->push(cp); 297 } 298 }; 299 300 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> { 301 private: 302 KeepAliveRegistrar* _registrar; 303 304 public: 305 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {} 306 307 void* new_node_data(InstanceKlass* cls) { return NULL; } 308 void free_node_data(void* data) { return; } 309 310 bool visit() { 311 _registrar->register_class(current_class()); 312 return true; 313 } 314 }; 315 316 317 // A method family contains a set of all methods that implement a single 318 // erased method. As members of the set are collected while walking over the 319 // hierarchy, they are tagged with a qualification state. The qualification 320 // state for an erased method is set to disqualified if there exists a path 321 // from the root of hierarchy to the method that contains an interleaving 322 // erased method defined in an interface. 323 324 class MethodFamily : public ResourceObj { 325 private: 326 327 GrowableArray<Pair<Method*,QualifiedState> > _members; 328 ResourceHashtable<Method*, int> _member_index; 329 330 Method* _selected_target; // Filled in later, if a unique target exists 331 Symbol* _exception_message; // If no unique target is found 332 Symbol* _exception_name; // If no unique target is found 333 334 bool contains_method(Method* method) { 335 int* lookup = _member_index.get(method); 336 return lookup != NULL; 337 } 338 339 void add_method(Method* method, QualifiedState state) { 340 Pair<Method*,QualifiedState> entry(method, state); 341 _member_index.put(method, _members.length()); 342 _members.append(entry); 343 } 344 345 void disqualify_method(Method* method) { 346 int* index = _member_index.get(method); 347 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index"); 348 _members.at(*index).second = DISQUALIFIED; 349 } 350 351 Symbol* generate_no_defaults_message(TRAPS) const; 352 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const; 353 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const; 354 355 public: 356 357 MethodFamily() 358 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {} 359 360 void set_target_if_empty(Method* m) { 361 if (_selected_target == NULL && !m->is_overpass()) { 362 _selected_target = m; 363 } 364 } 365 366 void record_qualified_method(Method* m) { 367 // If the method already exists in the set as qualified, this operation is 368 // redundant. If it already exists as disqualified, then we leave it as 369 // disqualfied. Thus we only add to the set if it's not already in the 370 // set. 371 if (!contains_method(m)) { 372 add_method(m, QUALIFIED); 373 } 374 } 375 376 void record_disqualified_method(Method* m) { 377 // If not in the set, add it as disqualified. If it's already in the set, 378 // then set the state to disqualified no matter what the previous state was. 379 if (!contains_method(m)) { 380 add_method(m, DISQUALIFIED); 381 } else { 382 disqualify_method(m); 383 } 384 } 385 386 bool has_target() const { return _selected_target != NULL; } 387 bool throws_exception() { return _exception_message != NULL; } 388 389 Method* get_selected_target() { return _selected_target; } 390 Symbol* get_exception_message() { return _exception_message; } 391 Symbol* get_exception_name() { return _exception_name; } 392 393 // Either sets the target or the exception error message 394 void determine_target(InstanceKlass* root, TRAPS) { 395 if (has_target() || throws_exception()) { 396 return; 397 } 398 399 // Qualified methods are maximally-specific methods 400 // These include public, instance concrete (=default) and abstract methods 401 GrowableArray<Method*> qualified_methods; 402 int num_defaults = 0; 403 int default_index = -1; 404 int qualified_index = -1; 405 for (int i = 0; i < _members.length(); ++i) { 406 Pair<Method*,QualifiedState> entry = _members.at(i); 407 if (entry.second == QUALIFIED) { 408 qualified_methods.append(entry.first); 409 qualified_index++; 410 if (entry.first->is_default_method()) { 411 num_defaults++; 412 default_index = qualified_index; 413 414 } 415 } 416 } 417 418 if (num_defaults == 0) { 419 // If the root klass has a static method with matching name and signature 420 // then do not generate an overpass method because it will hide the 421 // static method during resolution. 422 if (qualified_methods.length() == 0) { 423 _exception_message = generate_no_defaults_message(CHECK); 424 } else { 425 assert(root != NULL, "Null root class"); 426 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK); 427 } 428 _exception_name = vmSymbols::java_lang_AbstractMethodError(); 429 430 // If only one qualified method is default, select that 431 } else if (num_defaults == 1) { 432 _selected_target = qualified_methods.at(default_index); 433 434 } else if (num_defaults > 1) { 435 _exception_message = generate_conflicts_message(&qualified_methods,CHECK); 436 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError(); 437 if (TraceDefaultMethods) { 438 _exception_message->print_value_on(tty); 439 tty->cr(); 440 } 441 } 442 } 443 444 bool contains_signature(Symbol* query) { 445 for (int i = 0; i < _members.length(); ++i) { 446 if (query == _members.at(i).first->signature()) { 447 return true; 448 } 449 } 450 return false; 451 } 452 453 #ifndef PRODUCT 454 void print_sig_on(outputStream* str, Symbol* signature, int indent) const { 455 streamIndentor si(str, indent * 2); 456 457 str->indent().print_cr("Logical Method %s:", signature->as_C_string()); 458 459 streamIndentor si2(str); 460 for (int i = 0; i < _members.length(); ++i) { 461 str->indent(); 462 print_method(str, _members.at(i).first); 463 if (_members.at(i).second == DISQUALIFIED) { 464 str->print(" (disqualified)"); 465 } 466 str->cr(); 467 } 468 469 if (_selected_target != NULL) { 470 print_selected(str, 1); 471 } 472 } 473 474 void print_selected(outputStream* str, int indent) const { 475 assert(has_target(), "Should be called otherwise"); 476 streamIndentor si(str, indent * 2); 477 str->indent().print("Selected method: "); 478 print_method(str, _selected_target); 479 Klass* method_holder = _selected_target->method_holder(); 480 if (!method_holder->is_interface()) { 481 tty->print(" : in superclass"); 482 } 483 str->cr(); 484 } 485 486 void print_exception(outputStream* str, int indent) { 487 assert(throws_exception(), "Should be called otherwise"); 488 assert(_exception_name != NULL, "exception_name should be set"); 489 streamIndentor si(str, indent * 2); 490 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string()); 491 } 492 #endif // ndef PRODUCT 493 }; 494 495 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const { 496 return SymbolTable::new_symbol("No qualifying defaults found", THREAD); 497 } 498 499 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const { 500 stringStream ss; 501 ss.print("Method "); 502 Symbol* name = method->name(); 503 Symbol* signature = method->signature(); 504 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length()); 505 ss.print("."); 506 ss.write((const char*)name->bytes(), name->utf8_length()); 507 ss.write((const char*)signature->bytes(), signature->utf8_length()); 508 ss.print(" is abstract"); 509 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL); 510 } 511 512 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const { 513 stringStream ss; 514 ss.print("Conflicting default methods:"); 515 for (int i = 0; i < methods->length(); ++i) { 516 Method* method = methods->at(i); 517 Symbol* klass = method->klass_name(); 518 Symbol* name = method->name(); 519 ss.print(" "); 520 ss.write((const char*)klass->bytes(), klass->utf8_length()); 521 ss.print("."); 522 ss.write((const char*)name->bytes(), name->utf8_length()); 523 } 524 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL); 525 } 526 527 528 class StateRestorer; 529 530 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the 531 // qualification state during hierarchy visitation, and applies that state 532 // when adding members to the MethodFamily 533 class StatefulMethodFamily : public ResourceObj { 534 friend class StateRestorer; 535 private: 536 QualifiedState _qualification_state; 537 538 void set_qualification_state(QualifiedState state) { 539 _qualification_state = state; 540 } 541 542 protected: 543 MethodFamily* _method_family; 544 545 public: 546 StatefulMethodFamily() { 547 _method_family = new MethodFamily(); 548 _qualification_state = QUALIFIED; 549 } 550 551 StatefulMethodFamily(MethodFamily* mf) { 552 _method_family = mf; 553 _qualification_state = QUALIFIED; 554 } 555 556 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); } 557 558 MethodFamily* get_method_family() { return _method_family; } 559 560 StateRestorer* record_method_and_dq_further(Method* mo); 561 }; 562 563 class StateRestorer : public PseudoScopeMark { 564 private: 565 StatefulMethodFamily* _method; 566 QualifiedState _state_to_restore; 567 public: 568 StateRestorer(StatefulMethodFamily* dm, QualifiedState state) 569 : _method(dm), _state_to_restore(state) {} 570 ~StateRestorer() { destroy(); } 571 void restore_state() { _method->set_qualification_state(_state_to_restore); } 572 virtual void destroy() { restore_state(); } 573 }; 574 575 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) { 576 StateRestorer* mark = new StateRestorer(this, _qualification_state); 577 if (_qualification_state == QUALIFIED) { 578 _method_family->record_qualified_method(mo); 579 } else { 580 _method_family->record_disqualified_method(mo); 581 } 582 // Everything found "above"??? this method in the hierarchy walk is set to 583 // disqualified 584 set_qualification_state(DISQUALIFIED); 585 return mark; 586 } 587 588 // Represents a location corresponding to a vtable slot for methods that 589 // neither the class nor any of it's ancestors provide an implementaion. 590 // Default methods may be present to fill this slot. 591 class EmptyVtableSlot : public ResourceObj { 592 private: 593 Symbol* _name; 594 Symbol* _signature; 595 int _size_of_parameters; 596 MethodFamily* _binding; 597 598 public: 599 EmptyVtableSlot(Method* method) 600 : _name(method->name()), _signature(method->signature()), 601 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {} 602 603 Symbol* name() const { return _name; } 604 Symbol* signature() const { return _signature; } 605 int size_of_parameters() const { return _size_of_parameters; } 606 607 void bind_family(MethodFamily* lm) { _binding = lm; } 608 bool is_bound() { return _binding != NULL; } 609 MethodFamily* get_binding() { return _binding; } 610 611 #ifndef PRODUCT 612 void print_on(outputStream* str) const { 613 print_slot(str, name(), signature()); 614 } 615 #endif // ndef PRODUCT 616 }; 617 618 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) { 619 bool found = false; 620 for (int j = 0; j < slots->length(); ++j) { 621 if (slots->at(j)->name() == m->name() && 622 slots->at(j)->signature() == m->signature() ) { 623 found = true; 624 break; 625 } 626 } 627 return found; 628 } 629 630 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots( 631 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) { 632 633 assert(klass != NULL, "Must be valid class"); 634 635 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>(); 636 637 // All miranda methods are obvious candidates 638 for (int i = 0; i < mirandas->length(); ++i) { 639 Method* m = mirandas->at(i); 640 if (!already_in_vtable_slots(slots, m)) { 641 slots->append(new EmptyVtableSlot(m)); 642 } 643 } 644 645 // Also any overpasses in our superclasses, that we haven't implemented. 646 // (can't use the vtable because it is not guaranteed to be initialized yet) 647 InstanceKlass* super = klass->java_super(); 648 while (super != NULL) { 649 for (int i = 0; i < super->methods()->length(); ++i) { 650 Method* m = super->methods()->at(i); 651 if (m->is_overpass() || m->is_static()) { 652 // m is a method that would have been a miranda if not for the 653 // default method processing that occurred on behalf of our superclass, 654 // so it's a method we want to re-examine in this new context. That is, 655 // unless we have a real implementation of it in the current class. 656 Method* impl = klass->lookup_method(m->name(), m->signature()); 657 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 658 if (!already_in_vtable_slots(slots, m)) { 659 slots->append(new EmptyVtableSlot(m)); 660 } 661 } 662 } 663 } 664 665 // also any default methods in our superclasses 666 if (super->default_methods() != NULL) { 667 for (int i = 0; i < super->default_methods()->length(); ++i) { 668 Method* m = super->default_methods()->at(i); 669 // m is a method that would have been a miranda if not for the 670 // default method processing that occurred on behalf of our superclass, 671 // so it's a method we want to re-examine in this new context. That is, 672 // unless we have a real implementation of it in the current class. 673 Method* impl = klass->lookup_method(m->name(), m->signature()); 674 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 675 if (!already_in_vtable_slots(slots, m)) { 676 slots->append(new EmptyVtableSlot(m)); 677 } 678 } 679 } 680 } 681 super = super->java_super(); 682 } 683 684 #ifndef PRODUCT 685 if (TraceDefaultMethods) { 686 tty->print_cr("Slots that need filling:"); 687 streamIndentor si(tty); 688 for (int i = 0; i < slots->length(); ++i) { 689 tty->indent(); 690 slots->at(i)->print_on(tty); 691 tty->cr(); 692 } 693 } 694 #endif // ndef PRODUCT 695 return slots; 696 } 697 698 // Iterates over the superinterface type hierarchy looking for all methods 699 // with a specific erased signature. 700 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> { 701 private: 702 // Context data 703 Symbol* _method_name; 704 Symbol* _method_signature; 705 StatefulMethodFamily* _family; 706 707 public: 708 FindMethodsByErasedSig(Symbol* name, Symbol* signature) : 709 _method_name(name), _method_signature(signature), 710 _family(NULL) {} 711 712 void get_discovered_family(MethodFamily** family) { 713 if (_family != NULL) { 714 *family = _family->get_method_family(); 715 } else { 716 *family = NULL; 717 } 718 } 719 720 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); } 721 void free_node_data(void* node_data) { 722 PseudoScope::cast(node_data)->destroy(); 723 } 724 725 // Find all methods on this hierarchy that match this 726 // method's erased (name, signature) 727 bool visit() { 728 PseudoScope* scope = PseudoScope::cast(current_data()); 729 InstanceKlass* iklass = current_class(); 730 731 Method* m = iklass->find_method(_method_name, _method_signature); 732 // private interface methods are not candidates for default methods 733 // invokespecial to private interface methods doesn't use default method logic 734 // private class methods are not candidates for default methods, 735 // private methods do not override default methods, so need to perform 736 // default method inheritance without including private methods 737 // The overpasses are your supertypes' errors, we do not include them 738 // future: take access controls into account for superclass methods 739 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private()) { 740 if (_family == NULL) { 741 _family = new StatefulMethodFamily(); 742 } 743 744 if (iklass->is_interface()) { 745 StateRestorer* restorer = _family->record_method_and_dq_further(m); 746 scope->add_mark(restorer); 747 } else { 748 // This is the rule that methods in classes "win" (bad word) over 749 // methods in interfaces. This works because of single inheritance 750 // private methods in classes do not "win", they will be found 751 // first on searching, but overriding for invokevirtual needs 752 // to find default method candidates for the same signature 753 _family->set_target_if_empty(m); 754 } 755 } 756 return true; 757 } 758 759 }; 760 761 762 763 static void create_defaults_and_exceptions( 764 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS); 765 766 static void generate_erased_defaults( 767 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots, 768 EmptyVtableSlot* slot, TRAPS) { 769 770 // sets up a set of methods with the same exact erased signature 771 FindMethodsByErasedSig visitor(slot->name(), slot->signature()); 772 visitor.run(klass); 773 774 MethodFamily* family; 775 visitor.get_discovered_family(&family); 776 if (family != NULL) { 777 family->determine_target(klass, CHECK); 778 slot->bind_family(family); 779 } 780 } 781 782 static void merge_in_new_methods(InstanceKlass* klass, 783 GrowableArray<Method*>* new_methods, TRAPS); 784 static void create_default_methods( InstanceKlass* klass, 785 GrowableArray<Method*>* new_methods, TRAPS); 786 787 // This is the guts of the default methods implementation. This is called just 788 // after the classfile has been parsed if some ancestor has default methods. 789 // 790 // First if finds any name/signature slots that need any implementation (either 791 // because they are miranda or a superclass's implementation is an overpass 792 // itself). For each slot, iterate over the hierarchy, to see if they contain a 793 // signature that matches the slot we are looking at. 794 // 795 // For each slot filled, we generate an overpass method that either calls the 796 // unique default method candidate using invokespecial, or throws an exception 797 // (in the case of no default method candidates, or more than one valid 798 // candidate). These methods are then added to the class's method list. 799 // The JVM does not create bridges nor handle generic signatures here. 800 void DefaultMethods::generate_default_methods( 801 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) { 802 803 // This resource mark is the bound for all memory allocation that takes 804 // place during default method processing. After this goes out of scope, 805 // all (Resource) objects' memory will be reclaimed. Be careful if adding an 806 // embedded resource mark under here as that memory can't be used outside 807 // whatever scope it's in. 808 ResourceMark rm(THREAD); 809 810 // Keep entire hierarchy alive for the duration of the computation 811 KeepAliveRegistrar keepAlive(THREAD); 812 KeepAliveVisitor loadKeepAlive(&keepAlive); 813 loadKeepAlive.run(klass); 814 815 #ifndef PRODUCT 816 if (TraceDefaultMethods) { 817 ResourceMark rm; // be careful with these! 818 tty->print_cr("%s %s requires default method processing", 819 klass->is_interface() ? "Interface" : "Class", 820 klass->name()->as_klass_external_name()); 821 PrintHierarchy printer; 822 printer.run(klass); 823 } 824 #endif // ndef PRODUCT 825 826 GrowableArray<EmptyVtableSlot*>* empty_slots = 827 find_empty_vtable_slots(klass, mirandas, CHECK); 828 829 for (int i = 0; i < empty_slots->length(); ++i) { 830 EmptyVtableSlot* slot = empty_slots->at(i); 831 #ifndef PRODUCT 832 if (TraceDefaultMethods) { 833 streamIndentor si(tty, 2); 834 tty->indent().print("Looking for default methods for slot "); 835 slot->print_on(tty); 836 tty->cr(); 837 } 838 #endif // ndef PRODUCT 839 840 generate_erased_defaults(klass, empty_slots, slot, CHECK); 841 } 842 #ifndef PRODUCT 843 if (TraceDefaultMethods) { 844 tty->print_cr("Creating defaults and overpasses..."); 845 } 846 #endif // ndef PRODUCT 847 848 create_defaults_and_exceptions(empty_slots, klass, CHECK); 849 850 #ifndef PRODUCT 851 if (TraceDefaultMethods) { 852 tty->print_cr("Default method processing complete"); 853 } 854 #endif // ndef PRODUCT 855 } 856 857 static int assemble_method_error( 858 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) { 859 860 Symbol* init = vmSymbols::object_initializer_name(); 861 Symbol* sig = vmSymbols::string_void_signature(); 862 863 BytecodeAssembler assem(buffer, cp); 864 865 assem._new(errorName); 866 assem.dup(); 867 assem.load_string(message); 868 assem.invokespecial(errorName, init, sig); 869 assem.athrow(); 870 871 return 3; // max stack size: [ exception, exception, string ] 872 } 873 874 static Method* new_method( 875 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name, 876 Symbol* sig, AccessFlags flags, int max_stack, int params, 877 ConstMethod::MethodType mt, TRAPS) { 878 879 address code_start = 0; 880 int code_length = 0; 881 InlineTableSizes sizes; 882 883 if (bytecodes != NULL && bytecodes->length() > 0) { 884 code_start = static_cast<address>(bytecodes->adr_at(0)); 885 code_length = bytecodes->length(); 886 } 887 888 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(), 889 code_length, flags, &sizes, 890 mt, CHECK_NULL); 891 892 m->set_constants(NULL); // This will get filled in later 893 m->set_name_index(cp->utf8(name)); 894 m->set_signature_index(cp->utf8(sig)); 895 ResultTypeFinder rtf(sig); 896 m->constMethod()->set_result_type(rtf.type()); 897 m->set_size_of_parameters(params); 898 m->set_max_stack(max_stack); 899 m->set_max_locals(params); 900 m->constMethod()->set_stackmap_data(NULL); 901 m->set_code(code_start); 902 903 return m; 904 } 905 906 static void switchover_constant_pool(BytecodeConstantPool* bpool, 907 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) { 908 909 if (new_methods->length() > 0) { 910 ConstantPool* cp = bpool->create_constant_pool(CHECK); 911 if (cp != klass->constants()) { 912 klass->class_loader_data()->add_to_deallocate_list(klass->constants()); 913 klass->set_constants(cp); 914 cp->set_pool_holder(klass); 915 916 for (int i = 0; i < new_methods->length(); ++i) { 917 new_methods->at(i)->set_constants(cp); 918 } 919 for (int i = 0; i < klass->methods()->length(); ++i) { 920 Method* mo = klass->methods()->at(i); 921 mo->set_constants(cp); 922 } 923 } 924 } 925 } 926 927 // Create default_methods list for the current class. 928 // With the VM only processing erased signatures, the VM only 929 // creates an overpass in a conflict case or a case with no candidates. 930 // This allows virtual methods to override the overpass, but ensures 931 // that a local method search will find the exception rather than an abstract 932 // or default method that is not a valid candidate. 933 static void create_defaults_and_exceptions( 934 GrowableArray<EmptyVtableSlot*>* slots, 935 InstanceKlass* klass, TRAPS) { 936 937 GrowableArray<Method*> overpasses; 938 GrowableArray<Method*> defaults; 939 BytecodeConstantPool bpool(klass->constants()); 940 941 for (int i = 0; i < slots->length(); ++i) { 942 EmptyVtableSlot* slot = slots->at(i); 943 944 if (slot->is_bound()) { 945 MethodFamily* method = slot->get_binding(); 946 BytecodeBuffer buffer; 947 948 #ifndef PRODUCT 949 if (TraceDefaultMethods) { 950 tty->print("for slot: "); 951 slot->print_on(tty); 952 tty->cr(); 953 if (method->has_target()) { 954 method->print_selected(tty, 1); 955 } else if (method->throws_exception()) { 956 method->print_exception(tty, 1); 957 } 958 } 959 #endif // ndef PRODUCT 960 961 if (method->has_target()) { 962 Method* selected = method->get_selected_target(); 963 if (selected->method_holder()->is_interface()) { 964 defaults.push(selected); 965 } 966 } else if (method->throws_exception()) { 967 int max_stack = assemble_method_error(&bpool, &buffer, 968 method->get_exception_name(), method->get_exception_message(), CHECK); 969 AccessFlags flags = accessFlags_from( 970 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE); 971 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(), 972 flags, max_stack, slot->size_of_parameters(), 973 ConstMethod::OVERPASS, CHECK); 974 // We push to the methods list: 975 // overpass methods which are exception throwing methods 976 if (m != NULL) { 977 overpasses.push(m); 978 } 979 } 980 } 981 } 982 983 #ifndef PRODUCT 984 if (TraceDefaultMethods) { 985 tty->print_cr("Created %d overpass methods", overpasses.length()); 986 tty->print_cr("Created %d default methods", defaults.length()); 987 } 988 #endif // ndef PRODUCT 989 990 if (overpasses.length() > 0) { 991 switchover_constant_pool(&bpool, klass, &overpasses, CHECK); 992 merge_in_new_methods(klass, &overpasses, CHECK); 993 } 994 if (defaults.length() > 0) { 995 create_default_methods(klass, &defaults, CHECK); 996 } 997 } 998 999 static void create_default_methods( InstanceKlass* klass, 1000 GrowableArray<Method*>* new_methods, TRAPS) { 1001 1002 int new_size = new_methods->length(); 1003 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>( 1004 klass->class_loader_data(), new_size, NULL, CHECK); 1005 for (int index = 0; index < new_size; index++ ) { 1006 total_default_methods->at_put(index, new_methods->at(index)); 1007 } 1008 Method::sort_methods(total_default_methods, false, false); 1009 1010 klass->set_default_methods(total_default_methods); 1011 } 1012 1013 static void sort_methods(GrowableArray<Method*>* methods) { 1014 // Note that this must sort using the same key as is used for sorting 1015 // methods in InstanceKlass. 1016 bool sorted = true; 1017 for (int i = methods->length() - 1; i > 0; --i) { 1018 for (int j = 0; j < i; ++j) { 1019 Method* m1 = methods->at(j); 1020 Method* m2 = methods->at(j + 1); 1021 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) { 1022 methods->at_put(j, m2); 1023 methods->at_put(j + 1, m1); 1024 sorted = false; 1025 } 1026 } 1027 if (sorted) break; 1028 sorted = true; 1029 } 1030 #ifdef ASSERT 1031 uintptr_t prev = 0; 1032 for (int i = 0; i < methods->length(); ++i) { 1033 Method* mh = methods->at(i); 1034 uintptr_t nv = (uintptr_t)mh->name(); 1035 assert(nv >= prev, "Incorrect overpass method ordering"); 1036 prev = nv; 1037 } 1038 #endif 1039 } 1040 1041 static void merge_in_new_methods(InstanceKlass* klass, 1042 GrowableArray<Method*>* new_methods, TRAPS) { 1043 1044 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS }; 1045 1046 Array<Method*>* original_methods = klass->methods(); 1047 Array<int>* original_ordering = klass->method_ordering(); 1048 Array<int>* merged_ordering = Universe::the_empty_int_array(); 1049 1050 int new_size = klass->methods()->length() + new_methods->length(); 1051 1052 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>( 1053 klass->class_loader_data(), new_size, NULL, CHECK); 1054 1055 // original_ordering might be empty if this class has no methods of its own 1056 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) { 1057 merged_ordering = MetadataFactory::new_array<int>( 1058 klass->class_loader_data(), new_size, CHECK); 1059 } 1060 int method_order_index = klass->methods()->length(); 1061 1062 sort_methods(new_methods); 1063 1064 // Perform grand merge of existing methods and new methods 1065 int orig_idx = 0; 1066 int new_idx = 0; 1067 1068 for (int i = 0; i < new_size; ++i) { 1069 Method* orig_method = NULL; 1070 Method* new_method = NULL; 1071 if (orig_idx < original_methods->length()) { 1072 orig_method = original_methods->at(orig_idx); 1073 } 1074 if (new_idx < new_methods->length()) { 1075 new_method = new_methods->at(new_idx); 1076 } 1077 1078 if (orig_method != NULL && 1079 (new_method == NULL || orig_method->name() < new_method->name())) { 1080 merged_methods->at_put(i, orig_method); 1081 original_methods->at_put(orig_idx, NULL); 1082 if (merged_ordering->length() > 0) { 1083 assert(original_ordering != NULL && original_ordering->length() > 0, 1084 "should have original order information for this method"); 1085 merged_ordering->at_put(i, original_ordering->at(orig_idx)); 1086 } 1087 ++orig_idx; 1088 } else { 1089 merged_methods->at_put(i, new_method); 1090 if (merged_ordering->length() > 0) { 1091 merged_ordering->at_put(i, method_order_index++); 1092 } 1093 ++new_idx; 1094 } 1095 // update idnum for new location 1096 merged_methods->at(i)->set_method_idnum(i); 1097 merged_methods->at(i)->set_orig_method_idnum(i); 1098 } 1099 1100 // Verify correct order 1101 #ifdef ASSERT 1102 uintptr_t prev = 0; 1103 for (int i = 0; i < merged_methods->length(); ++i) { 1104 Method* mo = merged_methods->at(i); 1105 uintptr_t nv = (uintptr_t)mo->name(); 1106 assert(nv >= prev, "Incorrect method ordering"); 1107 prev = nv; 1108 } 1109 #endif 1110 1111 // Replace klass methods with new merged lists 1112 klass->set_methods(merged_methods); 1113 klass->set_initial_method_idnum(new_size); 1114 klass->set_method_ordering(merged_ordering); 1115 1116 // Free metadata 1117 ClassLoaderData* cld = klass->class_loader_data(); 1118 if (original_methods->length() > 0) { 1119 MetadataFactory::free_array(cld, original_methods); 1120 } 1121 if (original_ordering != NULL && original_ordering->length() > 0) { 1122 MetadataFactory::free_array(cld, original_ordering); 1123 } 1124 }