1 /* 2 * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/bytecodeAssembler.hpp" 27 #include "classfile/defaultMethods.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "logging/log.hpp" 31 #include "logging/logStream.hpp" 32 #include "memory/allocation.hpp" 33 #include "memory/metadataFactory.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "runtime/handles.inline.hpp" 36 #include "runtime/signature.hpp" 37 #include "runtime/thread.hpp" 38 #include "oops/instanceKlass.hpp" 39 #include "oops/klass.hpp" 40 #include "oops/method.hpp" 41 #include "utilities/accessFlags.hpp" 42 #include "utilities/exceptions.hpp" 43 #include "utilities/ostream.hpp" 44 #include "utilities/pair.hpp" 45 #include "utilities/resourceHash.hpp" 46 47 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState; 48 49 // Because we use an iterative algorithm when iterating over the type 50 // hierarchy, we can't use traditional scoped objects which automatically do 51 // cleanup in the destructor when the scope is exited. PseudoScope (and 52 // PseudoScopeMark) provides a similar functionality, but for when you want a 53 // scoped object in non-stack memory (such as in resource memory, as we do 54 // here). You've just got to remember to call 'destroy()' on the scope when 55 // leaving it (and marks have to be explicitly added). 56 class PseudoScopeMark : public ResourceObj { 57 public: 58 virtual void destroy() = 0; 59 }; 60 61 class PseudoScope : public ResourceObj { 62 private: 63 GrowableArray<PseudoScopeMark*> _marks; 64 public: 65 66 static PseudoScope* cast(void* data) { 67 return static_cast<PseudoScope*>(data); 68 } 69 70 void add_mark(PseudoScopeMark* psm) { 71 _marks.append(psm); 72 } 73 74 void destroy() { 75 for (int i = 0; i < _marks.length(); ++i) { 76 _marks.at(i)->destroy(); 77 } 78 } 79 }; 80 81 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) { 82 str->print("%s%s", name->as_C_string(), signature->as_C_string()); 83 } 84 85 static void print_method(outputStream* str, Method* mo, bool with_class=true) { 86 if (with_class) { 87 str->print("%s.", mo->klass_name()->as_C_string()); 88 } 89 print_slot(str, mo->name(), mo->signature()); 90 } 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 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> { 250 private: 251 outputStream* _st; 252 public: 253 bool visit() { 254 InstanceKlass* cls = current_class(); 255 streamIndentor si(_st, current_depth() * 2); 256 _st->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 PrintHierarchy(outputStream* st = tty) : _st(st) {} 264 }; 265 266 // Used to register InstanceKlass objects and all related metadata structures 267 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't 268 // be deallocated by class redefinition while we're using them. The classes are 269 // de-registered when this goes out of scope. 270 // 271 // Once a class is registered, we need not bother with methodHandles or 272 // constantPoolHandles for it's associated metadata. 273 class KeepAliveRegistrar : public StackObj { 274 private: 275 Thread* _thread; 276 GrowableArray<ConstantPool*> _keep_alive; 277 278 public: 279 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) { 280 assert(thread == Thread::current(), "Must be current thread"); 281 } 282 283 ~KeepAliveRegistrar() { 284 for (int i = _keep_alive.length() - 1; i >= 0; --i) { 285 ConstantPool* cp = _keep_alive.at(i); 286 int idx = _thread->metadata_handles()->find_from_end(cp); 287 assert(idx > 0, "Must be in the list"); 288 _thread->metadata_handles()->remove_at(idx); 289 } 290 } 291 292 // Register a class as 'in-use' by the thread. It's fine to register a class 293 // multiple times (though perhaps inefficient) 294 void register_class(InstanceKlass* ik) { 295 ConstantPool* cp = ik->constants(); 296 _keep_alive.push(cp); 297 _thread->metadata_handles()->push(cp); 298 } 299 }; 300 301 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> { 302 private: 303 KeepAliveRegistrar* _registrar; 304 305 public: 306 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {} 307 308 void* new_node_data(InstanceKlass* cls) { return NULL; } 309 void free_node_data(void* data) { return; } 310 311 bool visit() { 312 _registrar->register_class(current_class()); 313 return true; 314 } 315 }; 316 317 318 // A method family contains a set of all methods that implement a single 319 // erased method. As members of the set are collected while walking over the 320 // hierarchy, they are tagged with a qualification state. The qualification 321 // state for an erased method is set to disqualified if there exists a path 322 // from the root of hierarchy to the method that contains an interleaving 323 // erased method defined in an interface. 324 325 class MethodFamily : public ResourceObj { 326 private: 327 328 GrowableArray<Pair<Method*,QualifiedState> > _members; 329 ResourceHashtable<Method*, int> _member_index; 330 331 Method* _selected_target; // Filled in later, if a unique target exists 332 Symbol* _exception_message; // If no unique target is found 333 Symbol* _exception_name; // If no unique target is found 334 335 bool contains_method(Method* method) { 336 int* lookup = _member_index.get(method); 337 return lookup != NULL; 338 } 339 340 void add_method(Method* method, QualifiedState state) { 341 Pair<Method*,QualifiedState> entry(method, state); 342 _member_index.put(method, _members.length()); 343 _members.append(entry); 344 } 345 346 void disqualify_method(Method* method) { 347 int* index = _member_index.get(method); 348 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index"); 349 _members.at(*index).second = DISQUALIFIED; 350 } 351 352 Symbol* generate_no_defaults_message(TRAPS) const; 353 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const; 354 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const; 355 356 public: 357 358 MethodFamily() 359 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {} 360 361 void set_target_if_empty(Method* m) { 362 if (_selected_target == NULL && !m->is_overpass()) { 363 _selected_target = m; 364 } 365 } 366 367 void record_qualified_method(Method* m) { 368 // If the method already exists in the set as qualified, this operation is 369 // redundant. If it already exists as disqualified, then we leave it as 370 // disqualfied. Thus we only add to the set if it's not already in the 371 // set. 372 if (!contains_method(m)) { 373 add_method(m, QUALIFIED); 374 } 375 } 376 377 void record_disqualified_method(Method* m) { 378 // If not in the set, add it as disqualified. If it's already in the set, 379 // then set the state to disqualified no matter what the previous state was. 380 if (!contains_method(m)) { 381 add_method(m, DISQUALIFIED); 382 } else { 383 disqualify_method(m); 384 } 385 } 386 387 bool has_target() const { return _selected_target != NULL; } 388 bool throws_exception() { return _exception_message != NULL; } 389 390 Method* get_selected_target() { return _selected_target; } 391 Symbol* get_exception_message() { return _exception_message; } 392 Symbol* get_exception_name() { return _exception_name; } 393 394 // Either sets the target or the exception error message 395 void determine_target(InstanceKlass* root, TRAPS) { 396 if (has_target() || throws_exception()) { 397 return; 398 } 399 400 // Qualified methods are maximally-specific methods 401 // These include public, instance concrete (=default) and abstract methods 402 GrowableArray<Method*> qualified_methods; 403 int num_defaults = 0; 404 int default_index = -1; 405 int qualified_index = -1; 406 for (int i = 0; i < _members.length(); ++i) { 407 Pair<Method*,QualifiedState> entry = _members.at(i); 408 if (entry.second == QUALIFIED) { 409 qualified_methods.append(entry.first); 410 qualified_index++; 411 if (entry.first->is_default_method()) { 412 num_defaults++; 413 default_index = qualified_index; 414 415 } 416 } 417 } 418 419 if (num_defaults == 0) { 420 // If the root klass has a static method with matching name and signature 421 // then do not generate an overpass method because it will hide the 422 // static method during resolution. 423 if (qualified_methods.length() == 0) { 424 _exception_message = generate_no_defaults_message(CHECK); 425 } else { 426 assert(root != NULL, "Null root class"); 427 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK); 428 } 429 _exception_name = vmSymbols::java_lang_AbstractMethodError(); 430 431 // If only one qualified method is default, select that 432 } else if (num_defaults == 1) { 433 _selected_target = qualified_methods.at(default_index); 434 435 } else if (num_defaults > 1) { 436 _exception_message = generate_conflicts_message(&qualified_methods,CHECK); 437 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError(); 438 LogTarget(Debug, defaultmethods) lt; 439 if (lt.is_enabled()) { 440 LogStream ls(lt); 441 _exception_message->print_value_on(&ls); 442 ls.cr(); 443 } 444 } 445 } 446 447 bool contains_signature(Symbol* query) { 448 for (int i = 0; i < _members.length(); ++i) { 449 if (query == _members.at(i).first->signature()) { 450 return true; 451 } 452 } 453 return false; 454 } 455 456 void print_selected(outputStream* str, int indent) const { 457 assert(has_target(), "Should be called otherwise"); 458 streamIndentor si(str, indent * 2); 459 str->indent().print("Selected method: "); 460 print_method(str, _selected_target); 461 Klass* method_holder = _selected_target->method_holder(); 462 if (!method_holder->is_interface()) { 463 str->print(" : in superclass"); 464 } 465 str->cr(); 466 } 467 468 void print_exception(outputStream* str, int indent) { 469 assert(throws_exception(), "Should be called otherwise"); 470 assert(_exception_name != NULL, "exception_name should be set"); 471 streamIndentor si(str, indent * 2); 472 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string()); 473 } 474 }; 475 476 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const { 477 return SymbolTable::new_symbol("No qualifying defaults found", THREAD); 478 } 479 480 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const { 481 stringStream ss; 482 ss.print("Method "); 483 Symbol* name = method->name(); 484 Symbol* signature = method->signature(); 485 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length()); 486 ss.print("."); 487 ss.write((const char*)name->bytes(), name->utf8_length()); 488 ss.write((const char*)signature->bytes(), signature->utf8_length()); 489 ss.print(" is abstract"); 490 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD); 491 } 492 493 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const { 494 stringStream ss; 495 ss.print("Conflicting default methods:"); 496 for (int i = 0; i < methods->length(); ++i) { 497 Method* method = methods->at(i); 498 Symbol* klass = method->klass_name(); 499 Symbol* name = method->name(); 500 ss.print(" "); 501 ss.write((const char*)klass->bytes(), klass->utf8_length()); 502 ss.print("."); 503 ss.write((const char*)name->bytes(), name->utf8_length()); 504 } 505 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD); 506 } 507 508 509 class StateRestorer; 510 511 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the 512 // qualification state during hierarchy visitation, and applies that state 513 // when adding members to the MethodFamily 514 class StatefulMethodFamily : public ResourceObj { 515 friend class StateRestorer; 516 private: 517 QualifiedState _qualification_state; 518 519 void set_qualification_state(QualifiedState state) { 520 _qualification_state = state; 521 } 522 523 protected: 524 MethodFamily* _method_family; 525 526 public: 527 StatefulMethodFamily() { 528 _method_family = new MethodFamily(); 529 _qualification_state = QUALIFIED; 530 } 531 532 StatefulMethodFamily(MethodFamily* mf) { 533 _method_family = mf; 534 _qualification_state = QUALIFIED; 535 } 536 537 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); } 538 539 MethodFamily* get_method_family() { return _method_family; } 540 541 StateRestorer* record_method_and_dq_further(Method* mo); 542 }; 543 544 class StateRestorer : public PseudoScopeMark { 545 private: 546 StatefulMethodFamily* _method; 547 QualifiedState _state_to_restore; 548 public: 549 StateRestorer(StatefulMethodFamily* dm, QualifiedState state) 550 : _method(dm), _state_to_restore(state) {} 551 ~StateRestorer() { destroy(); } 552 void restore_state() { _method->set_qualification_state(_state_to_restore); } 553 virtual void destroy() { restore_state(); } 554 }; 555 556 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) { 557 StateRestorer* mark = new StateRestorer(this, _qualification_state); 558 if (_qualification_state == QUALIFIED) { 559 _method_family->record_qualified_method(mo); 560 } else { 561 _method_family->record_disqualified_method(mo); 562 } 563 // Everything found "above"??? this method in the hierarchy walk is set to 564 // disqualified 565 set_qualification_state(DISQUALIFIED); 566 return mark; 567 } 568 569 // Represents a location corresponding to a vtable slot for methods that 570 // neither the class nor any of it's ancestors provide an implementaion. 571 // Default methods may be present to fill this slot. 572 class EmptyVtableSlot : public ResourceObj { 573 private: 574 Symbol* _name; 575 Symbol* _signature; 576 int _size_of_parameters; 577 MethodFamily* _binding; 578 579 public: 580 EmptyVtableSlot(Method* method) 581 : _name(method->name()), _signature(method->signature()), 582 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {} 583 584 Symbol* name() const { return _name; } 585 Symbol* signature() const { return _signature; } 586 int size_of_parameters() const { return _size_of_parameters; } 587 588 void bind_family(MethodFamily* lm) { _binding = lm; } 589 bool is_bound() { return _binding != NULL; } 590 MethodFamily* get_binding() { return _binding; } 591 592 void print_on(outputStream* str) const { 593 print_slot(str, name(), signature()); 594 } 595 }; 596 597 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) { 598 bool found = false; 599 for (int j = 0; j < slots->length(); ++j) { 600 if (slots->at(j)->name() == m->name() && 601 slots->at(j)->signature() == m->signature() ) { 602 found = true; 603 break; 604 } 605 } 606 return found; 607 } 608 609 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots( 610 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) { 611 612 assert(klass != NULL, "Must be valid class"); 613 614 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>(); 615 616 // All miranda methods are obvious candidates 617 for (int i = 0; i < mirandas->length(); ++i) { 618 Method* m = mirandas->at(i); 619 if (!already_in_vtable_slots(slots, m)) { 620 slots->append(new EmptyVtableSlot(m)); 621 } 622 } 623 624 // Also any overpasses in our superclasses, that we haven't implemented. 625 // (can't use the vtable because it is not guaranteed to be initialized yet) 626 InstanceKlass* super = klass->java_super(); 627 while (super != NULL) { 628 for (int i = 0; i < super->methods()->length(); ++i) { 629 Method* m = super->methods()->at(i); 630 if (m->is_overpass() || m->is_static()) { 631 // m is a method that would have been a miranda if not for the 632 // default method processing that occurred on behalf of our superclass, 633 // so it's a method we want to re-examine in this new context. That is, 634 // unless we have a real implementation of it in the current class. 635 Method* impl = klass->lookup_method(m->name(), m->signature()); 636 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 637 if (!already_in_vtable_slots(slots, m)) { 638 slots->append(new EmptyVtableSlot(m)); 639 } 640 } 641 } 642 } 643 644 // also any default methods in our superclasses 645 if (super->default_methods() != NULL) { 646 for (int i = 0; i < super->default_methods()->length(); ++i) { 647 Method* m = super->default_methods()->at(i); 648 // m is a method that would have been a miranda if not for the 649 // default method processing that occurred on behalf of our superclass, 650 // so it's a method we want to re-examine in this new context. That is, 651 // unless we have a real implementation of it in the current class. 652 Method* impl = klass->lookup_method(m->name(), m->signature()); 653 if (impl == NULL || impl->is_overpass() || impl->is_static()) { 654 if (!already_in_vtable_slots(slots, m)) { 655 slots->append(new EmptyVtableSlot(m)); 656 } 657 } 658 } 659 } 660 super = super->java_super(); 661 } 662 663 LogTarget(Debug, defaultmethods) lt; 664 if (lt.is_enabled()) { 665 lt.print("Slots that need filling:"); 666 ResourceMark rm; 667 LogStream ls(lt); 668 streamIndentor si(&ls); 669 for (int i = 0; i < slots->length(); ++i) { 670 ls.indent(); 671 slots->at(i)->print_on(&ls); 672 ls.cr(); 673 } 674 } 675 676 return slots; 677 } 678 679 // Iterates over the superinterface type hierarchy looking for all methods 680 // with a specific erased signature. 681 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> { 682 private: 683 // Context data 684 Symbol* _method_name; 685 Symbol* _method_signature; 686 StatefulMethodFamily* _family; 687 bool _cur_class_is_interface; 688 689 public: 690 FindMethodsByErasedSig(Symbol* name, Symbol* signature, bool is_interf) : 691 _method_name(name), _method_signature(signature), _cur_class_is_interface(is_interf), 692 _family(NULL) {} 693 694 void get_discovered_family(MethodFamily** family) { 695 if (_family != NULL) { 696 *family = _family->get_method_family(); 697 } else { 698 *family = NULL; 699 } 700 } 701 702 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); } 703 void free_node_data(void* node_data) { 704 PseudoScope::cast(node_data)->destroy(); 705 } 706 707 // Find all methods on this hierarchy that match this 708 // method's erased (name, signature) 709 bool visit() { 710 PseudoScope* scope = PseudoScope::cast(current_data()); 711 InstanceKlass* iklass = current_class(); 712 713 Method* m = iklass->find_method(_method_name, _method_signature); 714 // Private interface methods are not candidates for default methods. 715 // invokespecial to private interface methods doesn't use default method logic. 716 // Private class methods are not candidates for default methods. 717 // Private methods do not override default methods, so need to perform 718 // default method inheritance without including private methods. 719 // The overpasses are your supertypes' errors, we do not include them. 720 // Non-public methods in java.lang.Object are not candidates for default 721 // methods. 722 // Future: take access controls into account for superclass methods 723 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() && 724 (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) { 725 if (_family == NULL) { 726 _family = new StatefulMethodFamily(); 727 } 728 729 if (iklass->is_interface()) { 730 StateRestorer* restorer = _family->record_method_and_dq_further(m); 731 scope->add_mark(restorer); 732 } else { 733 // This is the rule that methods in classes "win" (bad word) over 734 // methods in interfaces. This works because of single inheritance. 735 // Private methods in classes do not "win", they will be found 736 // first on searching, but overriding for invokevirtual needs 737 // to find default method candidates for the same signature 738 _family->set_target_if_empty(m); 739 } 740 } 741 return true; 742 } 743 744 }; 745 746 747 748 static void create_defaults_and_exceptions( 749 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS); 750 751 static void generate_erased_defaults( 752 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots, 753 EmptyVtableSlot* slot, bool is_intf, TRAPS) { 754 755 // sets up a set of methods with the same exact erased signature 756 FindMethodsByErasedSig visitor(slot->name(), slot->signature(), is_intf); 757 visitor.run(klass); 758 759 MethodFamily* family; 760 visitor.get_discovered_family(&family); 761 if (family != NULL) { 762 family->determine_target(klass, CHECK); 763 slot->bind_family(family); 764 } 765 } 766 767 static void merge_in_new_methods(InstanceKlass* klass, 768 GrowableArray<Method*>* new_methods, TRAPS); 769 static void create_default_methods( InstanceKlass* klass, 770 GrowableArray<Method*>* new_methods, TRAPS); 771 772 // This is the guts of the default methods implementation. This is called just 773 // after the classfile has been parsed if some ancestor has default methods. 774 // 775 // First it finds any name/signature slots that need any implementation (either 776 // because they are miranda or a superclass's implementation is an overpass 777 // itself). For each slot, iterate over the hierarchy, to see if they contain a 778 // signature that matches the slot we are looking at. 779 // 780 // For each slot filled, we either record the default method candidate in the 781 // klass default_methods list or, only to handle exception cases, we create an 782 // overpass method that throws an exception and add it to the klass methods list. 783 // The JVM does not create bridges nor handle generic signatures here. 784 void DefaultMethods::generate_default_methods( 785 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) { 786 assert(klass != NULL, "invariant"); 787 788 // This resource mark is the bound for all memory allocation that takes 789 // place during default method processing. After this goes out of scope, 790 // all (Resource) objects' memory will be reclaimed. Be careful if adding an 791 // embedded resource mark under here as that memory can't be used outside 792 // whatever scope it's in. 793 ResourceMark rm(THREAD); 794 795 // Keep entire hierarchy alive for the duration of the computation 796 constantPoolHandle cp(THREAD, klass->constants()); 797 KeepAliveRegistrar keepAlive(THREAD); 798 KeepAliveVisitor loadKeepAlive(&keepAlive); 799 loadKeepAlive.run(klass); 800 801 LogTarget(Debug, defaultmethods) lt; 802 if (lt.is_enabled()) { 803 ResourceMark rm; 804 lt.print("%s %s requires default method processing", 805 klass->is_interface() ? "Interface" : "Class", 806 klass->name()->as_klass_external_name()); 807 LogStream ls(lt); 808 PrintHierarchy printer(&ls); 809 printer.run(klass); 810 } 811 812 GrowableArray<EmptyVtableSlot*>* empty_slots = 813 find_empty_vtable_slots(klass, mirandas, CHECK); 814 815 for (int i = 0; i < empty_slots->length(); ++i) { 816 EmptyVtableSlot* slot = empty_slots->at(i); 817 LogTarget(Debug, defaultmethods) lt; 818 if (lt.is_enabled()) { 819 LogStream ls(lt); 820 streamIndentor si(&ls, 2); 821 ls.indent().print("Looking for default methods for slot "); 822 slot->print_on(&ls); 823 ls.cr(); 824 } 825 generate_erased_defaults(klass, empty_slots, slot, klass->is_interface(), CHECK); 826 } 827 log_debug(defaultmethods)("Creating defaults and overpasses..."); 828 create_defaults_and_exceptions(empty_slots, klass, CHECK); 829 log_debug(defaultmethods)("Default method processing complete"); 830 } 831 832 static int assemble_method_error( 833 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) { 834 835 Symbol* init = vmSymbols::object_initializer_name(); 836 Symbol* sig = vmSymbols::string_void_signature(); 837 838 BytecodeAssembler assem(buffer, cp); 839 840 assem._new(errorName); 841 assem.dup(); 842 assem.load_string(message); 843 assem.invokespecial(errorName, init, sig); 844 assem.athrow(); 845 846 return 3; // max stack size: [ exception, exception, string ] 847 } 848 849 static Method* new_method( 850 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name, 851 Symbol* sig, AccessFlags flags, int max_stack, int params, 852 ConstMethod::MethodType mt, TRAPS) { 853 854 address code_start = 0; 855 int code_length = 0; 856 InlineTableSizes sizes; 857 858 if (bytecodes != NULL && bytecodes->length() > 0) { 859 code_start = static_cast<address>(bytecodes->adr_at(0)); 860 code_length = bytecodes->length(); 861 } 862 863 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(), 864 code_length, flags, &sizes, 865 mt, CHECK_NULL); 866 867 m->set_constants(NULL); // This will get filled in later 868 m->set_name_index(cp->utf8(name)); 869 m->set_signature_index(cp->utf8(sig)); 870 ResultTypeFinder rtf(sig); 871 m->constMethod()->set_result_type(rtf.type()); 872 m->set_size_of_parameters(params); 873 m->set_max_stack(max_stack); 874 m->set_max_locals(params); 875 m->constMethod()->set_stackmap_data(NULL); 876 m->set_code(code_start); 877 878 return m; 879 } 880 881 static void switchover_constant_pool(BytecodeConstantPool* bpool, 882 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) { 883 884 if (new_methods->length() > 0) { 885 ConstantPool* cp = bpool->create_constant_pool(CHECK); 886 if (cp != klass->constants()) { 887 klass->class_loader_data()->add_to_deallocate_list(klass->constants()); 888 klass->set_constants(cp); 889 cp->set_pool_holder(klass); 890 891 for (int i = 0; i < new_methods->length(); ++i) { 892 new_methods->at(i)->set_constants(cp); 893 } 894 for (int i = 0; i < klass->methods()->length(); ++i) { 895 Method* mo = klass->methods()->at(i); 896 mo->set_constants(cp); 897 } 898 } 899 } 900 } 901 902 // Create default_methods list for the current class. 903 // With the VM only processing erased signatures, the VM only 904 // creates an overpass in a conflict case or a case with no candidates. 905 // This allows virtual methods to override the overpass, but ensures 906 // that a local method search will find the exception rather than an abstract 907 // or default method that is not a valid candidate. 908 // 909 // Note that if overpass method are ever created that are not exception 910 // throwing methods then the loader constraint checking logic for vtable and 911 // itable creation needs to be changed to check loader constraints for the 912 // overpass methods that do not throw exceptions. 913 static void create_defaults_and_exceptions( 914 GrowableArray<EmptyVtableSlot*>* slots, 915 InstanceKlass* klass, TRAPS) { 916 917 GrowableArray<Method*> overpasses; 918 GrowableArray<Method*> defaults; 919 BytecodeConstantPool bpool(klass->constants()); 920 921 for (int i = 0; i < slots->length(); ++i) { 922 EmptyVtableSlot* slot = slots->at(i); 923 924 if (slot->is_bound()) { 925 MethodFamily* method = slot->get_binding(); 926 BytecodeBuffer buffer; 927 928 LogTarget(Debug, defaultmethods) lt; 929 if (lt.is_enabled()) { 930 ResourceMark rm(THREAD); 931 LogStream ls(lt); 932 ls.print("for slot: "); 933 slot->print_on(&ls); 934 ls.cr(); 935 if (method->has_target()) { 936 method->print_selected(&ls, 1); 937 } else if (method->throws_exception()) { 938 method->print_exception(&ls, 1); 939 } 940 } 941 942 if (method->has_target()) { 943 Method* selected = method->get_selected_target(); 944 if (selected->method_holder()->is_interface()) { 945 assert(!selected->is_private(), "pushing private interface method as default"); 946 defaults.push(selected); 947 } 948 } else if (method->throws_exception()) { 949 int max_stack = assemble_method_error(&bpool, &buffer, 950 method->get_exception_name(), method->get_exception_message(), CHECK); 951 AccessFlags flags = accessFlags_from( 952 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE); 953 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(), 954 flags, max_stack, slot->size_of_parameters(), 955 ConstMethod::OVERPASS, CHECK); 956 // We push to the methods list: 957 // overpass methods which are exception throwing methods 958 if (m != NULL) { 959 overpasses.push(m); 960 } 961 } 962 } 963 } 964 965 966 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length()); 967 log_debug(defaultmethods)("Created %d default methods", defaults.length()); 968 969 if (overpasses.length() > 0) { 970 switchover_constant_pool(&bpool, klass, &overpasses, CHECK); 971 merge_in_new_methods(klass, &overpasses, CHECK); 972 } 973 if (defaults.length() > 0) { 974 create_default_methods(klass, &defaults, CHECK); 975 } 976 } 977 978 static void create_default_methods( InstanceKlass* klass, 979 GrowableArray<Method*>* new_methods, TRAPS) { 980 981 int new_size = new_methods->length(); 982 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>( 983 klass->class_loader_data(), new_size, NULL, CHECK); 984 for (int index = 0; index < new_size; index++ ) { 985 total_default_methods->at_put(index, new_methods->at(index)); 986 } 987 Method::sort_methods(total_default_methods, false, false); 988 989 klass->set_default_methods(total_default_methods); 990 } 991 992 static void sort_methods(GrowableArray<Method*>* methods) { 993 // Note that this must sort using the same key as is used for sorting 994 // methods in InstanceKlass. 995 bool sorted = true; 996 for (int i = methods->length() - 1; i > 0; --i) { 997 for (int j = 0; j < i; ++j) { 998 Method* m1 = methods->at(j); 999 Method* m2 = methods->at(j + 1); 1000 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) { 1001 methods->at_put(j, m2); 1002 methods->at_put(j + 1, m1); 1003 sorted = false; 1004 } 1005 } 1006 if (sorted) break; 1007 sorted = true; 1008 } 1009 #ifdef ASSERT 1010 uintptr_t prev = 0; 1011 for (int i = 0; i < methods->length(); ++i) { 1012 Method* mh = methods->at(i); 1013 uintptr_t nv = (uintptr_t)mh->name(); 1014 assert(nv >= prev, "Incorrect overpass method ordering"); 1015 prev = nv; 1016 } 1017 #endif 1018 } 1019 1020 static void merge_in_new_methods(InstanceKlass* klass, 1021 GrowableArray<Method*>* new_methods, TRAPS) { 1022 1023 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS }; 1024 1025 Array<Method*>* original_methods = klass->methods(); 1026 Array<int>* original_ordering = klass->method_ordering(); 1027 Array<int>* merged_ordering = Universe::the_empty_int_array(); 1028 1029 int new_size = klass->methods()->length() + new_methods->length(); 1030 1031 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>( 1032 klass->class_loader_data(), new_size, NULL, CHECK); 1033 1034 // original_ordering might be empty if this class has no methods of its own 1035 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) { 1036 merged_ordering = MetadataFactory::new_array<int>( 1037 klass->class_loader_data(), new_size, CHECK); 1038 } 1039 int method_order_index = klass->methods()->length(); 1040 1041 sort_methods(new_methods); 1042 1043 // Perform grand merge of existing methods and new methods 1044 int orig_idx = 0; 1045 int new_idx = 0; 1046 1047 for (int i = 0; i < new_size; ++i) { 1048 Method* orig_method = NULL; 1049 Method* new_method = NULL; 1050 if (orig_idx < original_methods->length()) { 1051 orig_method = original_methods->at(orig_idx); 1052 } 1053 if (new_idx < new_methods->length()) { 1054 new_method = new_methods->at(new_idx); 1055 } 1056 1057 if (orig_method != NULL && 1058 (new_method == NULL || orig_method->name() < new_method->name())) { 1059 merged_methods->at_put(i, orig_method); 1060 original_methods->at_put(orig_idx, NULL); 1061 if (merged_ordering->length() > 0) { 1062 assert(original_ordering != NULL && original_ordering->length() > 0, 1063 "should have original order information for this method"); 1064 merged_ordering->at_put(i, original_ordering->at(orig_idx)); 1065 } 1066 ++orig_idx; 1067 } else { 1068 merged_methods->at_put(i, new_method); 1069 if (merged_ordering->length() > 0) { 1070 merged_ordering->at_put(i, method_order_index++); 1071 } 1072 ++new_idx; 1073 } 1074 // update idnum for new location 1075 merged_methods->at(i)->set_method_idnum(i); 1076 merged_methods->at(i)->set_orig_method_idnum(i); 1077 } 1078 1079 // Verify correct order 1080 #ifdef ASSERT 1081 uintptr_t prev = 0; 1082 for (int i = 0; i < merged_methods->length(); ++i) { 1083 Method* mo = merged_methods->at(i); 1084 uintptr_t nv = (uintptr_t)mo->name(); 1085 assert(nv >= prev, "Incorrect method ordering"); 1086 prev = nv; 1087 } 1088 #endif 1089 1090 // Replace klass methods with new merged lists 1091 klass->set_methods(merged_methods); 1092 klass->set_initial_method_idnum(new_size); 1093 klass->set_method_ordering(merged_ordering); 1094 1095 // Free metadata 1096 ClassLoaderData* cld = klass->class_loader_data(); 1097 if (original_methods->length() > 0) { 1098 MetadataFactory::free_array(cld, original_methods); 1099 } 1100 if (original_ordering != NULL && original_ordering->length() > 0) { 1101 MetadataFactory::free_array(cld, original_ordering); 1102 } 1103 }