1 /* 2 * Copyright (c) 2012, 2016, 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 "logging/log.hpp" 30 #include "memory/allocation.hpp" 31 #include "memory/metadataFactory.hpp" 32 #include "memory/resourceArea.hpp" 33 #include "runtime/handles.inline.hpp" 34 #include "runtime/signature.hpp" 35 #include "runtime/thread.hpp" 36 #include "oops/instanceKlass.hpp" 37 #include "oops/klass.hpp" 38 #include "oops/method.hpp" 39 #include "utilities/accessFlags.hpp" 40 #include "utilities/exceptions.hpp" 41 #include "utilities/ostream.hpp" 42 #include "utilities/pair.hpp" 43 #include "utilities/resourceHash.hpp" 44 45 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState; 46 47 // Because we use an iterative algorithm when iterating over the type 48 // hierarchy, we can't use traditional scoped objects which automatically do 49 // cleanup in the destructor when the scope is exited. PseudoScope (and 50 // PseudoScopeMark) provides a similar functionality, but for when you want a 51 // scoped object in non-stack memory (such as in resource memory, as we do 52 // here). You've just got to remember to call 'destroy()' on the scope when 53 // leaving it (and marks have to be explicitly added). 54 class PseudoScopeMark : public ResourceObj { 55 public: 56 virtual void destroy() = 0; 57 }; 58 59 class PseudoScope : public ResourceObj { 60 private: 61 GrowableArray<PseudoScopeMark*> _marks; 62 public: 63 64 static PseudoScope* cast(void* data) { 65 return static_cast<PseudoScope*>(data); 66 } 67 68 void add_mark(PseudoScopeMark* psm) { 69 _marks.append(psm); 70 } 71 72 void destroy() { 73 for (int i = 0; i < _marks.length(); ++i) { 74 _marks.at(i)->destroy(); 75 } 76 } 77 }; 78 79 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) { 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 if (with_class) { 85 str->print("%s.", mo->klass_name()->as_C_string()); 86 } 87 print_slot(str, mo->name(), mo->signature()); 88 } 89 90 /** 91 * Perform a depth-first iteration over the class hierarchy, applying 92 * algorithmic logic as it goes. 93 * 94 * This class is one half of the inheritance hierarchy analysis mechanism. 95 * It is meant to be used in conjunction with another class, the algorithm, 96 * which is indicated by the ALGO template parameter. This class can be 97 * paired with any algorithm class that provides the required methods. 98 * 99 * This class contains all the mechanics for iterating over the class hierarchy 100 * starting at a particular root, without recursing (thus limiting stack growth 101 * from this point). It visits each superclass (if present) and superinterface 102 * in a depth-first manner, with callbacks to the ALGO class as each class is 103 * encountered (visit()), The algorithm can cut-off further exploration of a 104 * particular branch by returning 'false' from a visit() call. 105 * 106 * The ALGO class, must provide a visit() method, which each of which will be 107 * called once for each node in the inheritance tree during the iteration. In 108 * addition, it can provide a memory block via new_node_data(InstanceKlass*), 109 * which it can use for node-specific storage (and access via the 110 * current_data() and data_at_depth(int) methods). 111 * 112 * Bare minimum needed to be an ALGO class: 113 * class Algo : public HierarchyVisitor<Algo> { 114 * void* new_node_data(InstanceKlass* cls) { return NULL; } 115 * void free_node_data(void* data) { return; } 116 * bool visit() { return true; } 117 * }; 118 */ 119 template <class ALGO> 120 class HierarchyVisitor : StackObj { 121 private: 122 123 class Node : public ResourceObj { 124 public: 125 InstanceKlass* _class; 126 bool _super_was_visited; 127 int _interface_index; 128 void* _algorithm_data; 129 130 Node(InstanceKlass* cls, void* data, bool visit_super) 131 : _class(cls), _super_was_visited(!visit_super), 132 _interface_index(0), _algorithm_data(data) {} 133 134 int number_of_interfaces() { return _class->local_interfaces()->length(); } 135 int interface_index() { return _interface_index; } 136 void set_super_visited() { _super_was_visited = true; } 137 void increment_visited_interface() { ++_interface_index; } 138 void set_all_interfaces_visited() { 139 _interface_index = number_of_interfaces(); 140 } 141 bool has_visited_super() { return _super_was_visited; } 142 bool has_visited_all_interfaces() { 143 return interface_index() >= number_of_interfaces(); 144 } 145 InstanceKlass* interface_at(int index) { 146 return InstanceKlass::cast(_class->local_interfaces()->at(index)); 147 } 148 InstanceKlass* next_super() { return _class->java_super(); } 149 InstanceKlass* next_interface() { 150 return interface_at(interface_index()); 151 } 152 }; 153 154 bool _cancelled; 155 GrowableArray<Node*> _path; 156 157 Node* current_top() const { return _path.top(); } 158 bool has_more_nodes() const { return !_path.is_empty(); } 159 void push(InstanceKlass* cls, void* data) { 160 assert(cls != NULL, "Requires a valid instance class"); 161 Node* node = new Node(cls, data, has_super(cls)); 162 _path.push(node); 163 } 164 void pop() { _path.pop(); } 165 166 void reset_iteration() { 167 _cancelled = false; 168 _path.clear(); 169 } 170 bool is_cancelled() const { return _cancelled; } 171 172 // This code used to skip interface classes because their only 173 // superclass was j.l.Object which would be also covered by class 174 // superclass hierarchy walks. Now that the starting point can be 175 // an interface, we must ensure we catch j.l.Object as the super. 176 static bool has_super(InstanceKlass* cls) { 177 return cls->super() != NULL; 178 } 179 180 Node* node_at_depth(int i) const { 181 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1); 182 } 183 184 protected: 185 186 // Accessors available to the algorithm 187 int current_depth() const { return _path.length() - 1; } 188 189 InstanceKlass* class_at_depth(int i) { 190 Node* n = node_at_depth(i); 191 return n == NULL ? NULL : n->_class; 192 } 193 InstanceKlass* current_class() { return class_at_depth(0); } 194 195 void* data_at_depth(int i) { 196 Node* n = node_at_depth(i); 197 return n == NULL ? NULL : n->_algorithm_data; 198 } 199 void* current_data() { return data_at_depth(0); } 200 201 void cancel_iteration() { _cancelled = true; } 202 203 public: 204 205 void run(InstanceKlass* root) { 206 ALGO* algo = static_cast<ALGO*>(this); 207 208 reset_iteration(); 209 210 void* algo_data = algo->new_node_data(root); 211 push(root, algo_data); 212 bool top_needs_visit = true; 213 214 do { 215 Node* top = current_top(); 216 if (top_needs_visit) { 217 if (algo->visit() == false) { 218 // algorithm does not want to continue along this path. Arrange 219 // it so that this state is immediately popped off the stack 220 top->set_super_visited(); 221 top->set_all_interfaces_visited(); 222 } 223 top_needs_visit = false; 224 } 225 226 if (top->has_visited_super() && top->has_visited_all_interfaces()) { 227 algo->free_node_data(top->_algorithm_data); 228 pop(); 229 } else { 230 InstanceKlass* next = NULL; 231 if (top->has_visited_super() == false) { 232 next = top->next_super(); 233 top->set_super_visited(); 234 } else { 235 next = top->next_interface(); 236 top->increment_visited_interface(); 237 } 238 assert(next != NULL, "Otherwise we shouldn't be here"); 239 algo_data = algo->new_node_data(next); 240 push(next, algo_data); 241 top_needs_visit = true; 242 } 243 } while (!is_cancelled() && has_more_nodes()); 244 } 245 }; 246 247 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> { 248 private: 249 outputStream* _st; 250 public: 251 bool visit() { 252 InstanceKlass* cls = current_class(); 253 streamIndentor si(_st, current_depth() * 2); 254 _st->indent().print_cr("%s", cls->name()->as_C_string()); 255 return true; 256 } 257 258 void* new_node_data(InstanceKlass* cls) { return NULL; } 259 void free_node_data(void* data) { return; } 260 261 PrintHierarchy(outputStream* st = tty) : _st(st) {} 262 }; 263 264 // Used to register InstanceKlass objects and all related metadata structures 265 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't 266 // be deallocated by class redefinition while we're using them. The classes are 267 // de-registered when this goes out of scope. 268 // 269 // Once a class is registered, we need not bother with methodHandles or 270 // constantPoolHandles for it's associated metadata. 271 class KeepAliveRegistrar : public StackObj { 272 private: 273 Thread* _thread; 274 GrowableArray<ConstantPool*> _keep_alive; 275 276 public: 277 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) { 278 assert(thread == Thread::current(), "Must be current thread"); 279 } 280 281 ~KeepAliveRegistrar() { 282 for (int i = _keep_alive.length() - 1; i >= 0; --i) { 283 ConstantPool* cp = _keep_alive.at(i); 284 int idx = _thread->metadata_handles()->find_from_end(cp); 285 assert(idx > 0, "Must be in the list"); 286 _thread->metadata_handles()->remove_at(idx); 287 } 288 } 289 290 // Register a class as 'in-use' by the thread. It's fine to register a class 291 // multiple times (though perhaps inefficient) 292 void register_class(InstanceKlass* ik) { 293 ConstantPool* cp = ik->constants(); 294 _keep_alive.push(cp); 295 _thread->metadata_handles()->push(cp); 296 } 297 }; 298 299 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> { 300 private: 301 KeepAliveRegistrar* _registrar; 302 303 public: 304 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {} 305 306 void* new_node_data(InstanceKlass* cls) { return NULL; } 307 void free_node_data(void* data) { return; } 308 309 bool visit() { 310 _registrar->register_class(current_class()); 311 return true; 312 } 313 }; 314 315 316 // A method family contains a set of all methods that implement a single 317 // erased method. As members of the set are collected while walking over the 318 // hierarchy, they are tagged with a qualification state. The qualification 319 // state for an erased method is set to disqualified if there exists a path 320 // from the root of hierarchy to the method that contains an interleaving 321 // erased method defined in an interface. 322 323 class MethodFamily : public ResourceObj { 324 private: 325 326 GrowableArray<Pair<Method*,QualifiedState> > _members; 327 ResourceHashtable<Method*, int> _member_index; 328 329 Method* _selected_target; // Filled in later, if a unique target exists 330 Symbol* _exception_message; // If no unique target is found 331 Symbol* _exception_name; // If no unique target is found 332 333 bool contains_method(Method* method) { 334 int* lookup = _member_index.get(method); 335 return lookup != NULL; 336 } 337 338 void add_method(Method* method, QualifiedState state) { 339 Pair<Method*,QualifiedState> entry(method, state); 340 _member_index.put(method, _members.length()); 341 _members.append(entry); 342 } 343 344 void disqualify_method(Method* method) { 345 int* index = _member_index.get(method); 346 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index"); 347 _members.at(*index).second = DISQUALIFIED; 348 } 349 350 Symbol* generate_no_defaults_message(TRAPS) const; 351 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const; 352 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const; 353 354 public: 355 356 MethodFamily() 357 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {} 358 359 void set_target_if_empty(Method* m) { 360 if (_selected_target == NULL && !m->is_overpass()) { 361 _selected_target = m; 362 } 363 } 364 365 void record_qualified_method(Method* m) { 366 // If the method already exists in the set as qualified, this operation is 367 // redundant. If it already exists as disqualified, then we leave it as 368 // disqualfied. Thus we only add to the set if it's not already in the 369 // set. 370 if (!contains_method(m)) { 371 add_method(m, QUALIFIED); 372 } 373 } 374 375 void record_disqualified_method(Method* m) { 376 // If not in the set, add it as disqualified. If it's already in the set, 377 // then set the state to disqualified no matter what the previous state was. 378 if (!contains_method(m)) { 379 add_method(m, DISQUALIFIED); 380 } else { 381 disqualify_method(m); 382 } 383 } 384 385 bool has_target() const { return _selected_target != NULL; } 386 bool throws_exception() { return _exception_message != NULL; } 387 388 Method* get_selected_target() { return _selected_target; } 389 Symbol* get_exception_message() { return _exception_message; } 390 Symbol* get_exception_name() { return _exception_name; } 391 392 // Either sets the target or the exception error message 393 void determine_target(InstanceKlass* root, TRAPS) { 394 if (has_target() || throws_exception()) { 395 return; 396 } 397 398 // Qualified methods are maximally-specific methods 399 // These include public, instance concrete (=default) and abstract methods 400 GrowableArray<Method*> qualified_methods; 401 int num_defaults = 0; 402 int default_index = -1; 403 int qualified_index = -1; 404 for (int i = 0; i < _members.length(); ++i) { 405 Pair<Method*,QualifiedState> entry = _members.at(i); 406 if (entry.second == QUALIFIED) { 407 qualified_methods.append(entry.first); 408 qualified_index++; 409 if (entry.first->is_default_method()) { 410 num_defaults++; 411 default_index = qualified_index; 412 413 } 414 } 415 } 416 417 if (num_defaults == 0) { 418 // If the root klass has a static method with matching name and signature 419 // then do not generate an overpass method because it will hide the 420 // static method during resolution. 421 if (qualified_methods.length() == 0) { 422 _exception_message = generate_no_defaults_message(CHECK); 423 } else { 424 assert(root != NULL, "Null root class"); 425 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK); 426 } 427 _exception_name = vmSymbols::java_lang_AbstractMethodError(); 428 429 // If only one qualified method is default, select that 430 } else if (num_defaults == 1) { 431 _selected_target = qualified_methods.at(default_index); 432 433 } else if (num_defaults > 1) { 434 _exception_message = generate_conflicts_message(&qualified_methods,CHECK); 435 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError(); 436 if (log_is_enabled(Debug, defaultmethods)) { 437 ResourceMark rm; 438 outputStream* logstream = Log(defaultmethods)::debug_stream(); 439 _exception_message->print_value_on(logstream); 440 logstream->cr(); 441 } 442 } 443 } 444 445 bool contains_signature(Symbol* query) { 446 for (int i = 0; i < _members.length(); ++i) { 447 if (query == _members.at(i).first->signature()) { 448 return true; 449 } 450 } 451 return false; 452 } 453 454 void print_selected(outputStream* str, int indent) const { 455 assert(has_target(), "Should be called otherwise"); 456 streamIndentor si(str, indent * 2); 457 str->indent().print("Selected method: "); 458 print_method(str, _selected_target); 459 Klass* method_holder = _selected_target->method_holder(); 460 if (!method_holder->is_interface()) { 461 str->print(" : in superclass"); 462 } 463 str->cr(); 464 } 465 466 void print_exception(outputStream* str, int indent) { 467 assert(throws_exception(), "Should be called otherwise"); 468 assert(_exception_name != NULL, "exception_name should be set"); 469 streamIndentor si(str, indent * 2); 470 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string()); 471 } 472 }; 473 474 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const { 475 return SymbolTable::new_symbol("No qualifying defaults found", THREAD); 476 } 477 478 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const { 479 stringStream ss; 480 ss.print("Method "); 481 Symbol* name = method->name(); 482 Symbol* signature = method->signature(); 483 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length()); 484 ss.print("."); 485 ss.write((const char*)name->bytes(), name->utf8_length()); 486 ss.write((const char*)signature->bytes(), signature->utf8_length()); 487 ss.print(" is abstract"); 488 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD); 489 } 490 491 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const { 492 stringStream ss; 493 ss.print("Conflicting default methods:"); 494 for (int i = 0; i < methods->length(); ++i) { 495 Method* method = methods->at(i); 496 Symbol* klass = method->klass_name(); 497 Symbol* name = method->name(); 498 ss.print(" "); 499 ss.write((const char*)klass->bytes(), klass->utf8_length()); 500 ss.print("."); 501 ss.write((const char*)name->bytes(), name->utf8_length()); 502 } 503 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD); 504 } 505 506 507 class StateRestorer; 508 509 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the 510 // qualification state during hierarchy visitation, and applies that state 511 // when adding members to the MethodFamily 512 class StatefulMethodFamily : public ResourceObj { 513 friend class StateRestorer; 514 private: 515 QualifiedState _qualification_state; 516 517 void set_qualification_state(QualifiedState state) { 518 _qualification_state = state; 519 } 520 521 protected: 522 MethodFamily* _method_family; 523 524 public: 525 StatefulMethodFamily() { 526 _method_family = new MethodFamily(); 527 _qualification_state = QUALIFIED; 528 } 529 530 StatefulMethodFamily(MethodFamily* mf) { 531 _method_family = mf; 532 _qualification_state = QUALIFIED; 533 } 534 535 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); } 536 537 MethodFamily* get_method_family() { return _method_family; } 538 539 StateRestorer* record_method_and_dq_further(Method* mo); 540 }; 541 542 class StateRestorer : public PseudoScopeMark { 543 private: 544 StatefulMethodFamily* _method; 545 QualifiedState _state_to_restore; 546 public: 547 StateRestorer(StatefulMethodFamily* dm, QualifiedState state) 548 : _method(dm), _state_to_restore(state) {} 549 ~StateRestorer() { destroy(); } 550 void restore_state() { _method->set_qualification_state(_state_to_restore); } 551 virtual void destroy() { restore_state(); } 552 }; 553 554 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) { 555 StateRestorer* mark = new StateRestorer(this, _qualification_state); 556 if (_qualification_state == QUALIFIED) { 557 _method_family->record_qualified_method(mo); 558 } else { 559 _method_family->record_disqualified_method(mo); 560 } 561 // Everything found "above"??? this method in the hierarchy walk is set to 562 // disqualified 563 set_qualification_state(DISQUALIFIED); 564 return mark; 565 } 566 567 // Represents a location corresponding to a vtable slot for methods that 568 // neither the class nor any of it's ancestors provide an implementaion. 569 // Default methods may be present to fill this slot. 570 class EmptyVtableSlot : public ResourceObj { 571 private: 572 Symbol* _name; 573 Symbol* _signature; 574 int _size_of_parameters; 575 MethodFamily* _binding; 576 577 public: 578 EmptyVtableSlot(Method* method) 579 : _name(method->name()), _signature(method->signature()), 580 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {} 581 582 Symbol* name() const { return _name; } 583 Symbol* signature() const { return _signature; } 584 int size_of_parameters() const { return _size_of_parameters; } 585 586 void bind_family(MethodFamily* lm) { _binding = lm; } 587 bool is_bound() { return _binding != NULL; } 588 MethodFamily* get_binding() { return _binding; } 589 590 void print_on(outputStream* str) const { 591 print_slot(str, name(), signature()); 592 } 593 }; 594 595 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) { 596 bool found = false; 597 for (int j = 0; j < slots->length(); ++j) { 598 if (slots->at(j)->name() == m->name() && 599 slots->at(j)->signature() == m->signature() ) { 600 found = true; 601 break; 602 } 603 } 604 return found; 605 } 606 607 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots( 608 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) { 609 610 assert(klass != NULL, "Must be valid class"); 611 612 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>(); 613 614 // All miranda methods are obvious candidates 615 for (int i = 0; i < mirandas->length(); ++i) { 616 Method* m = mirandas->at(i); 617 if (!already_in_vtable_slots(slots, m)) { 618 slots->append(new EmptyVtableSlot(m)); 619 } 620 } 621 622 // Also any overpasses in our superclasses, that we haven't implemented. 623 // (can't use the vtable because it is not guaranteed to be initialized yet) 624 InstanceKlass* super = klass->java_super(); 625 while (super != NULL) { 626 for (int i = 0; i < super->methods()->length(); ++i) { 627 Method* m = super->methods()->at(i); 628 if (m->is_overpass() || m->is_static()) { 629 // m is a method that would have been a miranda if not for the 630 // default method processing that occurred on behalf of our superclass, 631 // so it's a method we want to re-examine in this new context. That is, 632 // unless we have a real implementation of it in the current class. 633 Method* impl = klass->lookup_method(m->name(), m->signature()); 634 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 635 if (!already_in_vtable_slots(slots, m)) { 636 slots->append(new EmptyVtableSlot(m)); 637 } 638 } 639 } 640 } 641 642 // also any default methods in our superclasses 643 if (super->default_methods() != NULL) { 644 for (int i = 0; i < super->default_methods()->length(); ++i) { 645 Method* m = super->default_methods()->at(i); 646 // m is a method that would have been a miranda if not for the 647 // default method processing that occurred on behalf of our superclass, 648 // so it's a method we want to re-examine in this new context. That is, 649 // unless we have a real implementation of it in the current class. 650 Method* impl = klass->lookup_method(m->name(), m->signature()); 651 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 652 if (!already_in_vtable_slots(slots, m)) { 653 slots->append(new EmptyVtableSlot(m)); 654 } 655 } 656 } 657 } 658 super = super->java_super(); 659 } 660 661 if (log_is_enabled(Debug, defaultmethods)) { 662 log_debug(defaultmethods)("Slots that need filling:"); 663 ResourceMark rm; 664 outputStream* logstream = Log(defaultmethods)::debug_stream(); 665 streamIndentor si(logstream); 666 for (int i = 0; i < slots->length(); ++i) { 667 logstream->indent(); 668 slots->at(i)->print_on(logstream); 669 logstream->cr(); 670 } 671 } 672 673 return slots; 674 } 675 676 // Iterates over the superinterface type hierarchy looking for all methods 677 // with a specific erased signature. 678 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> { 679 private: 680 // Context data 681 Symbol* _method_name; 682 Symbol* _method_signature; 683 StatefulMethodFamily* _family; 684 685 public: 686 FindMethodsByErasedSig(Symbol* name, Symbol* signature) : 687 _method_name(name), _method_signature(signature), 688 _family(NULL) {} 689 690 void get_discovered_family(MethodFamily** family) { 691 if (_family != NULL) { 692 *family = _family->get_method_family(); 693 } else { 694 *family = NULL; 695 } 696 } 697 698 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); } 699 void free_node_data(void* node_data) { 700 PseudoScope::cast(node_data)->destroy(); 701 } 702 703 // Find all methods on this hierarchy that match this 704 // method's erased (name, signature) 705 bool visit() { 706 PseudoScope* scope = PseudoScope::cast(current_data()); 707 InstanceKlass* iklass = current_class(); 708 709 Method* m = iklass->find_method(_method_name, _method_signature); 710 // private interface methods are not candidates for default methods 711 // invokespecial to private interface methods doesn't use default method logic 712 // private class methods are not candidates for default methods, 713 // private methods do not override default methods, so need to perform 714 // default method inheritance without including private methods 715 // The overpasses are your supertypes' errors, we do not include them 716 // future: take access controls into account for superclass methods 717 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private()) { 718 if (_family == NULL) { 719 _family = new StatefulMethodFamily(); 720 } 721 722 if (iklass->is_interface()) { 723 StateRestorer* restorer = _family->record_method_and_dq_further(m); 724 scope->add_mark(restorer); 725 } else { 726 // This is the rule that methods in classes "win" (bad word) over 727 // methods in interfaces. This works because of single inheritance 728 // private methods in classes do not "win", they will be found 729 // first on searching, but overriding for invokevirtual needs 730 // to find default method candidates for the same signature 731 _family->set_target_if_empty(m); 732 } 733 } 734 return true; 735 } 736 737 }; 738 739 740 741 static void create_defaults_and_exceptions( 742 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS); 743 744 static void generate_erased_defaults( 745 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots, 746 EmptyVtableSlot* slot, TRAPS) { 747 748 // sets up a set of methods with the same exact erased signature 749 FindMethodsByErasedSig visitor(slot->name(), slot->signature()); 750 visitor.run(klass); 751 752 MethodFamily* family; 753 visitor.get_discovered_family(&family); 754 if (family != NULL) { 755 family->determine_target(klass, CHECK); 756 slot->bind_family(family); 757 } 758 } 759 760 static void merge_in_new_methods(InstanceKlass* klass, 761 GrowableArray<Method*>* new_methods, TRAPS); 762 static void create_default_methods( InstanceKlass* klass, 763 GrowableArray<Method*>* new_methods, TRAPS); 764 765 // This is the guts of the default methods implementation. This is called just 766 // after the classfile has been parsed if some ancestor has default methods. 767 // 768 // First if finds any name/signature slots that need any implementation (either 769 // because they are miranda or a superclass's implementation is an overpass 770 // itself). For each slot, iterate over the hierarchy, to see if they contain a 771 // signature that matches the slot we are looking at. 772 // 773 // For each slot filled, we generate an overpass method that either calls the 774 // unique default method candidate using invokespecial, or throws an exception 775 // (in the case of no default method candidates, or more than one valid 776 // candidate). These methods are then added to the class's method list. 777 // The JVM does not create bridges nor handle generic signatures here. 778 void DefaultMethods::generate_default_methods( 779 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) { 780 assert(klass != NULL, "invariant"); 781 782 // This resource mark is the bound for all memory allocation that takes 783 // place during default method processing. After this goes out of scope, 784 // all (Resource) objects' memory will be reclaimed. Be careful if adding an 785 // embedded resource mark under here as that memory can't be used outside 786 // whatever scope it's in. 787 ResourceMark rm(THREAD); 788 789 // Keep entire hierarchy alive for the duration of the computation 790 constantPoolHandle cp(THREAD, klass->constants()); 791 KeepAliveRegistrar keepAlive(THREAD); 792 KeepAliveVisitor loadKeepAlive(&keepAlive); 793 loadKeepAlive.run(klass); 794 795 if (log_is_enabled(Debug, defaultmethods)) { 796 ResourceMark rm; 797 log_debug(defaultmethods)("%s %s requires default method processing", 798 klass->is_interface() ? "Interface" : "Class", 799 klass->name()->as_klass_external_name()); 800 PrintHierarchy printer(Log(defaultmethods)::debug_stream()); 801 printer.run(klass); 802 } 803 804 GrowableArray<EmptyVtableSlot*>* empty_slots = 805 find_empty_vtable_slots(klass, mirandas, CHECK); 806 807 for (int i = 0; i < empty_slots->length(); ++i) { 808 EmptyVtableSlot* slot = empty_slots->at(i); 809 if (log_is_enabled(Debug, defaultmethods)) { 810 outputStream* logstream = Log(defaultmethods)::debug_stream(); 811 streamIndentor si(logstream, 2); 812 logstream->indent().print("Looking for default methods for slot "); 813 slot->print_on(logstream); 814 logstream->cr(); 815 } 816 generate_erased_defaults(klass, empty_slots, slot, CHECK); 817 } 818 log_debug(defaultmethods)("Creating defaults and overpasses..."); 819 create_defaults_and_exceptions(empty_slots, klass, CHECK); 820 log_debug(defaultmethods)("Default method processing complete"); 821 } 822 823 static int assemble_method_error( 824 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) { 825 826 Symbol* init = vmSymbols::object_initializer_name(); 827 Symbol* sig = vmSymbols::string_void_signature(); 828 829 BytecodeAssembler assem(buffer, cp); 830 831 assem._new(errorName); 832 assem.dup(); 833 assem.load_string(message); 834 assem.invokespecial(errorName, init, sig); 835 assem.athrow(); 836 837 return 3; // max stack size: [ exception, exception, string ] 838 } 839 840 static Method* new_method( 841 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name, 842 Symbol* sig, AccessFlags flags, int max_stack, int params, 843 ConstMethod::MethodType mt, TRAPS) { 844 845 address code_start = 0; 846 int code_length = 0; 847 InlineTableSizes sizes; 848 849 if (bytecodes != NULL && bytecodes->length() > 0) { 850 code_start = static_cast<address>(bytecodes->adr_at(0)); 851 code_length = bytecodes->length(); 852 } 853 854 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(), 855 code_length, flags, &sizes, 856 mt, CHECK_NULL); 857 858 m->set_constants(NULL); // This will get filled in later 859 m->set_name_index(cp->utf8(name)); 860 m->set_signature_index(cp->utf8(sig)); 861 ResultTypeFinder rtf(sig); 862 m->constMethod()->set_result_type(rtf.type()); 863 m->set_size_of_parameters(params); 864 m->set_max_stack(max_stack); 865 m->set_max_locals(params); 866 m->constMethod()->set_stackmap_data(NULL); 867 m->set_code(code_start); 868 869 return m; 870 } 871 872 static void switchover_constant_pool(BytecodeConstantPool* bpool, 873 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) { 874 875 if (new_methods->length() > 0) { 876 ConstantPool* cp = bpool->create_constant_pool(CHECK); 877 if (cp != klass->constants()) { 878 klass->class_loader_data()->add_to_deallocate_list(klass->constants()); 879 klass->set_constants(cp); 880 cp->set_pool_holder(klass); 881 882 for (int i = 0; i < new_methods->length(); ++i) { 883 new_methods->at(i)->set_constants(cp); 884 } 885 for (int i = 0; i < klass->methods()->length(); ++i) { 886 Method* mo = klass->methods()->at(i); 887 mo->set_constants(cp); 888 } 889 } 890 } 891 } 892 893 // Create default_methods list for the current class. 894 // With the VM only processing erased signatures, the VM only 895 // creates an overpass in a conflict case or a case with no candidates. 896 // This allows virtual methods to override the overpass, but ensures 897 // that a local method search will find the exception rather than an abstract 898 // or default method that is not a valid candidate. 899 static void create_defaults_and_exceptions( 900 GrowableArray<EmptyVtableSlot*>* slots, 901 InstanceKlass* klass, TRAPS) { 902 903 GrowableArray<Method*> overpasses; 904 GrowableArray<Method*> defaults; 905 BytecodeConstantPool bpool(klass->constants()); 906 907 for (int i = 0; i < slots->length(); ++i) { 908 EmptyVtableSlot* slot = slots->at(i); 909 910 if (slot->is_bound()) { 911 MethodFamily* method = slot->get_binding(); 912 BytecodeBuffer buffer; 913 914 if (log_is_enabled(Debug, defaultmethods)) { 915 ResourceMark rm(THREAD); 916 outputStream* logstream = Log(defaultmethods)::debug_stream(); 917 logstream->print("for slot: "); 918 slot->print_on(logstream); 919 logstream->cr(); 920 if (method->has_target()) { 921 method->print_selected(logstream, 1); 922 } else if (method->throws_exception()) { 923 method->print_exception(logstream, 1); 924 } 925 } 926 927 if (method->has_target()) { 928 Method* selected = method->get_selected_target(); 929 if (selected->method_holder()->is_interface()) { 930 assert(!selected->is_private(), "pushing private interface method as default"); 931 defaults.push(selected); 932 } 933 } else if (method->throws_exception()) { 934 int max_stack = assemble_method_error(&bpool, &buffer, 935 method->get_exception_name(), method->get_exception_message(), CHECK); 936 AccessFlags flags = accessFlags_from( 937 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE); 938 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(), 939 flags, max_stack, slot->size_of_parameters(), 940 ConstMethod::OVERPASS, CHECK); 941 // We push to the methods list: 942 // overpass methods which are exception throwing methods 943 if (m != NULL) { 944 overpasses.push(m); 945 } 946 } 947 } 948 } 949 950 951 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length()); 952 log_debug(defaultmethods)("Created %d default methods", defaults.length()); 953 954 if (overpasses.length() > 0) { 955 switchover_constant_pool(&bpool, klass, &overpasses, CHECK); 956 merge_in_new_methods(klass, &overpasses, CHECK); 957 } 958 if (defaults.length() > 0) { 959 create_default_methods(klass, &defaults, CHECK); 960 } 961 } 962 963 static void create_default_methods( InstanceKlass* klass, 964 GrowableArray<Method*>* new_methods, TRAPS) { 965 966 int new_size = new_methods->length(); 967 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>( 968 klass->class_loader_data(), new_size, NULL, CHECK); 969 for (int index = 0; index < new_size; index++ ) { 970 total_default_methods->at_put(index, new_methods->at(index)); 971 } 972 Method::sort_methods(total_default_methods, false, false); 973 974 klass->set_default_methods(total_default_methods); 975 } 976 977 static void sort_methods(GrowableArray<Method*>* methods) { 978 // Note that this must sort using the same key as is used for sorting 979 // methods in InstanceKlass. 980 bool sorted = true; 981 for (int i = methods->length() - 1; i > 0; --i) { 982 for (int j = 0; j < i; ++j) { 983 Method* m1 = methods->at(j); 984 Method* m2 = methods->at(j + 1); 985 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) { 986 methods->at_put(j, m2); 987 methods->at_put(j + 1, m1); 988 sorted = false; 989 } 990 } 991 if (sorted) break; 992 sorted = true; 993 } 994 #ifdef ASSERT 995 uintptr_t prev = 0; 996 for (int i = 0; i < methods->length(); ++i) { 997 Method* mh = methods->at(i); 998 uintptr_t nv = (uintptr_t)mh->name(); 999 assert(nv >= prev, "Incorrect overpass method ordering"); 1000 prev = nv; 1001 } 1002 #endif 1003 } 1004 1005 static void merge_in_new_methods(InstanceKlass* klass, 1006 GrowableArray<Method*>* new_methods, TRAPS) { 1007 1008 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS }; 1009 1010 Array<Method*>* original_methods = klass->methods(); 1011 Array<int>* original_ordering = klass->method_ordering(); 1012 Array<int>* merged_ordering = Universe::the_empty_int_array(); 1013 1014 int new_size = klass->methods()->length() + new_methods->length(); 1015 1016 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>( 1017 klass->class_loader_data(), new_size, NULL, CHECK); 1018 1019 // original_ordering might be empty if this class has no methods of its own 1020 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) { 1021 merged_ordering = MetadataFactory::new_array<int>( 1022 klass->class_loader_data(), new_size, CHECK); 1023 } 1024 int method_order_index = klass->methods()->length(); 1025 1026 sort_methods(new_methods); 1027 1028 // Perform grand merge of existing methods and new methods 1029 int orig_idx = 0; 1030 int new_idx = 0; 1031 1032 for (int i = 0; i < new_size; ++i) { 1033 Method* orig_method = NULL; 1034 Method* new_method = NULL; 1035 if (orig_idx < original_methods->length()) { 1036 orig_method = original_methods->at(orig_idx); 1037 } 1038 if (new_idx < new_methods->length()) { 1039 new_method = new_methods->at(new_idx); 1040 } 1041 1042 if (orig_method != NULL && 1043 (new_method == NULL || orig_method->name() < new_method->name())) { 1044 merged_methods->at_put(i, orig_method); 1045 original_methods->at_put(orig_idx, NULL); 1046 if (merged_ordering->length() > 0) { 1047 assert(original_ordering != NULL && original_ordering->length() > 0, 1048 "should have original order information for this method"); 1049 merged_ordering->at_put(i, original_ordering->at(orig_idx)); 1050 } 1051 ++orig_idx; 1052 } else { 1053 merged_methods->at_put(i, new_method); 1054 if (merged_ordering->length() > 0) { 1055 merged_ordering->at_put(i, method_order_index++); 1056 } 1057 ++new_idx; 1058 } 1059 // update idnum for new location 1060 merged_methods->at(i)->set_method_idnum(i); 1061 merged_methods->at(i)->set_orig_method_idnum(i); 1062 } 1063 1064 // Verify correct order 1065 #ifdef ASSERT 1066 uintptr_t prev = 0; 1067 for (int i = 0; i < merged_methods->length(); ++i) { 1068 Method* mo = merged_methods->at(i); 1069 uintptr_t nv = (uintptr_t)mo->name(); 1070 assert(nv >= prev, "Incorrect method ordering"); 1071 prev = nv; 1072 } 1073 #endif 1074 1075 // Replace klass methods with new merged lists 1076 klass->set_methods(merged_methods); 1077 klass->set_initial_method_idnum(new_size); 1078 klass->set_method_ordering(merged_ordering); 1079 1080 // Free metadata 1081 ClassLoaderData* cld = klass->class_loader_data(); 1082 if (original_methods->length() > 0) { 1083 MetadataFactory::free_array(cld, original_methods); 1084 } 1085 if (original_ordering != NULL && original_ordering->length() > 0) { 1086 MetadataFactory::free_array(cld, original_ordering); 1087 } 1088 }