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