Thu, 26 Sep 2013 12:18:21 +0200
Merge
1 /*
2 * Copyright (c) 2012, 2013, 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 */
25 #include "precompiled.hpp"
26 #include "classfile/bytecodeAssembler.hpp"
27 #include "classfile/defaultMethods.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/metadataFactory.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "runtime/signature.hpp"
33 #include "runtime/thread.hpp"
34 #include "oops/instanceKlass.hpp"
35 #include "oops/klass.hpp"
36 #include "oops/method.hpp"
37 #include "utilities/accessFlags.hpp"
38 #include "utilities/exceptions.hpp"
39 #include "utilities/ostream.hpp"
40 #include "utilities/pair.hpp"
41 #include "utilities/resourceHash.hpp"
43 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
45 // Because we use an iterative algorithm when iterating over the type
46 // hierarchy, we can't use traditional scoped objects which automatically do
47 // cleanup in the destructor when the scope is exited. PseudoScope (and
48 // PseudoScopeMark) provides a similar functionality, but for when you want a
49 // scoped object in non-stack memory (such as in resource memory, as we do
50 // here). You've just got to remember to call 'destroy()' on the scope when
51 // leaving it (and marks have to be explicitly added).
52 class PseudoScopeMark : public ResourceObj {
53 public:
54 virtual void destroy() = 0;
55 };
57 class PseudoScope : public ResourceObj {
58 private:
59 GrowableArray<PseudoScopeMark*> _marks;
60 public:
62 static PseudoScope* cast(void* data) {
63 return static_cast<PseudoScope*>(data);
64 }
66 void add_mark(PseudoScopeMark* psm) {
67 _marks.append(psm);
68 }
70 void destroy() {
71 for (int i = 0; i < _marks.length(); ++i) {
72 _marks.at(i)->destroy();
73 }
74 }
75 };
77 #ifndef PRODUCT
78 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
79 ResourceMark rm;
80 str->print("%s%s", name->as_C_string(), signature->as_C_string());
81 }
83 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
84 ResourceMark rm;
85 if (with_class) {
86 str->print("%s.", mo->klass_name()->as_C_string());
87 }
88 print_slot(str, mo->name(), mo->signature());
89 }
90 #endif // ndef PRODUCT
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:
125 class Node : public ResourceObj {
126 public:
127 InstanceKlass* _class;
128 bool _super_was_visited;
129 int _interface_index;
130 void* _algorithm_data;
132 Node(InstanceKlass* cls, void* data, bool visit_super)
133 : _class(cls), _super_was_visited(!visit_super),
134 _interface_index(0), _algorithm_data(data) {}
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 };
156 bool _cancelled;
157 GrowableArray<Node*> _path;
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(); }
168 void reset_iteration() {
169 _cancelled = false;
170 _path.clear();
171 }
172 bool is_cancelled() const { return _cancelled; }
174 static bool has_super(InstanceKlass* cls) {
175 return cls->super() != NULL && !cls->is_interface();
176 }
178 Node* node_at_depth(int i) const {
179 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
180 }
182 protected:
184 // Accessors available to the algorithm
185 int current_depth() const { return _path.length() - 1; }
187 InstanceKlass* class_at_depth(int i) {
188 Node* n = node_at_depth(i);
189 return n == NULL ? NULL : n->_class;
190 }
191 InstanceKlass* current_class() { return class_at_depth(0); }
193 void* data_at_depth(int i) {
194 Node* n = node_at_depth(i);
195 return n == NULL ? NULL : n->_algorithm_data;
196 }
197 void* current_data() { return data_at_depth(0); }
199 void cancel_iteration() { _cancelled = true; }
201 public:
203 void run(InstanceKlass* root) {
204 ALGO* algo = static_cast<ALGO*>(this);
206 reset_iteration();
208 void* algo_data = algo->new_node_data(root);
209 push(root, algo_data);
210 bool top_needs_visit = true;
212 do {
213 Node* top = current_top();
214 if (top_needs_visit) {
215 if (algo->visit() == false) {
216 // algorithm does not want to continue along this path. Arrange
217 // it so that this state is immediately popped off the stack
218 top->set_super_visited();
219 top->set_all_interfaces_visited();
220 }
221 top_needs_visit = false;
222 }
224 if (top->has_visited_super() && top->has_visited_all_interfaces()) {
225 algo->free_node_data(top->_algorithm_data);
226 pop();
227 } else {
228 InstanceKlass* next = NULL;
229 if (top->has_visited_super() == false) {
230 next = top->next_super();
231 top->set_super_visited();
232 } else {
233 next = top->next_interface();
234 top->increment_visited_interface();
235 }
236 assert(next != NULL, "Otherwise we shouldn't be here");
237 algo_data = algo->new_node_data(next);
238 push(next, algo_data);
239 top_needs_visit = true;
240 }
241 } while (!is_cancelled() && has_more_nodes());
242 }
243 };
245 #ifndef PRODUCT
246 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
247 public:
249 bool visit() {
250 InstanceKlass* cls = current_class();
251 streamIndentor si(tty, current_depth() * 2);
252 tty->indent().print_cr("%s", cls->name()->as_C_string());
253 return true;
254 }
256 void* new_node_data(InstanceKlass* cls) { return NULL; }
257 void free_node_data(void* data) { return; }
258 };
259 #endif // ndef PRODUCT
261 // Used to register InstanceKlass objects and all related metadata structures
262 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
263 // be deallocated by class redefinition while we're using them. The classes are
264 // de-registered when this goes out of scope.
265 //
266 // Once a class is registered, we need not bother with methodHandles or
267 // constantPoolHandles for it's associated metadata.
268 class KeepAliveRegistrar : public StackObj {
269 private:
270 Thread* _thread;
271 GrowableArray<ConstantPool*> _keep_alive;
273 public:
274 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
275 assert(thread == Thread::current(), "Must be current thread");
276 }
278 ~KeepAliveRegistrar() {
279 for (int i = _keep_alive.length() - 1; i >= 0; --i) {
280 ConstantPool* cp = _keep_alive.at(i);
281 int idx = _thread->metadata_handles()->find_from_end(cp);
282 assert(idx > 0, "Must be in the list");
283 _thread->metadata_handles()->remove_at(idx);
284 }
285 }
287 // Register a class as 'in-use' by the thread. It's fine to register a class
288 // multiple times (though perhaps inefficient)
289 void register_class(InstanceKlass* ik) {
290 ConstantPool* cp = ik->constants();
291 _keep_alive.push(cp);
292 _thread->metadata_handles()->push(cp);
293 }
294 };
296 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
297 private:
298 KeepAliveRegistrar* _registrar;
300 public:
301 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
303 void* new_node_data(InstanceKlass* cls) { return NULL; }
304 void free_node_data(void* data) { return; }
306 bool visit() {
307 _registrar->register_class(current_class());
308 return true;
309 }
310 };
313 // A method family contains a set of all methods that implement a single
314 // erased method. As members of the set are collected while walking over the
315 // hierarchy, they are tagged with a qualification state. The qualification
316 // state for an erased method is set to disqualified if there exists a path
317 // from the root of hierarchy to the method that contains an interleaving
318 // erased method defined in an interface.
320 class MethodFamily : public ResourceObj {
321 private:
323 GrowableArray<Pair<Method*,QualifiedState> > _members;
324 ResourceHashtable<Method*, int> _member_index;
326 Method* _selected_target; // Filled in later, if a unique target exists
327 Symbol* _exception_message; // If no unique target is found
329 bool contains_method(Method* method) {
330 int* lookup = _member_index.get(method);
331 return lookup != NULL;
332 }
334 void add_method(Method* method, QualifiedState state) {
335 Pair<Method*,QualifiedState> entry(method, state);
336 _member_index.put(method, _members.length());
337 _members.append(entry);
338 }
340 void disqualify_method(Method* method) {
341 int* index = _member_index.get(method);
342 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
343 _members.at(*index).second = DISQUALIFIED;
344 }
346 Symbol* generate_no_defaults_message(TRAPS) const;
347 Symbol* generate_abstract_method_message(Method* method, TRAPS) const;
348 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
350 public:
352 MethodFamily()
353 : _selected_target(NULL), _exception_message(NULL) {}
355 void set_target_if_empty(Method* m) {
356 if (_selected_target == NULL && !m->is_overpass()) {
357 _selected_target = m;
358 }
359 }
361 void record_qualified_method(Method* m) {
362 // If the method already exists in the set as qualified, this operation is
363 // redundant. If it already exists as disqualified, then we leave it as
364 // disqualfied. Thus we only add to the set if it's not already in the
365 // set.
366 if (!contains_method(m)) {
367 add_method(m, QUALIFIED);
368 }
369 }
371 void record_disqualified_method(Method* m) {
372 // If not in the set, add it as disqualified. If it's already in the set,
373 // then set the state to disqualified no matter what the previous state was.
374 if (!contains_method(m)) {
375 add_method(m, DISQUALIFIED);
376 } else {
377 disqualify_method(m);
378 }
379 }
381 bool has_target() const { return _selected_target != NULL; }
382 bool throws_exception() { return _exception_message != NULL; }
384 Method* get_selected_target() { return _selected_target; }
385 Symbol* get_exception_message() { return _exception_message; }
387 // Either sets the target or the exception error message
388 void determine_target(InstanceKlass* root, TRAPS) {
389 if (has_target() || throws_exception()) {
390 return;
391 }
393 GrowableArray<Method*> qualified_methods;
394 for (int i = 0; i < _members.length(); ++i) {
395 Pair<Method*,QualifiedState> entry = _members.at(i);
396 if (entry.second == QUALIFIED) {
397 qualified_methods.append(entry.first);
398 }
399 }
401 if (qualified_methods.length() == 0) {
402 _exception_message = generate_no_defaults_message(CHECK);
403 } else if (qualified_methods.length() == 1) {
404 Method* method = qualified_methods.at(0);
405 if (method->is_abstract()) {
406 _exception_message = generate_abstract_method_message(method, CHECK);
407 } else {
408 _selected_target = qualified_methods.at(0);
409 }
410 } else {
411 _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
412 }
414 assert((has_target() ^ throws_exception()) == 1,
415 "One and only one must be true");
416 }
418 bool contains_signature(Symbol* query) {
419 for (int i = 0; i < _members.length(); ++i) {
420 if (query == _members.at(i).first->signature()) {
421 return true;
422 }
423 }
424 return false;
425 }
427 #ifndef PRODUCT
428 void print_sig_on(outputStream* str, Symbol* signature, int indent) const {
429 streamIndentor si(str, indent * 2);
431 str->indent().print_cr("Logical Method %s:", signature->as_C_string());
433 streamIndentor si2(str);
434 for (int i = 0; i < _members.length(); ++i) {
435 str->indent();
436 print_method(str, _members.at(i).first);
437 if (_members.at(i).second == DISQUALIFIED) {
438 str->print(" (disqualified)");
439 }
440 str->print_cr("");
441 }
443 if (_selected_target != NULL) {
444 print_selected(str, 1);
445 }
446 }
448 void print_selected(outputStream* str, int indent) const {
449 assert(has_target(), "Should be called otherwise");
450 streamIndentor si(str, indent * 2);
451 str->indent().print("Selected method: ");
452 print_method(str, _selected_target);
453 Klass* method_holder = _selected_target->method_holder();
454 if (!method_holder->is_interface()) {
455 tty->print(" : in superclass");
456 }
457 str->print_cr("");
458 }
460 void print_exception(outputStream* str, int indent) {
461 assert(throws_exception(), "Should be called otherwise");
462 streamIndentor si(str, indent * 2);
463 str->indent().print_cr("%s", _exception_message->as_C_string());
464 }
465 #endif // ndef PRODUCT
466 };
468 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
469 return SymbolTable::new_symbol("No qualifying defaults found", CHECK_NULL);
470 }
472 Symbol* MethodFamily::generate_abstract_method_message(Method* method, TRAPS) const {
473 Symbol* klass = method->klass_name();
474 Symbol* name = method->name();
475 Symbol* sig = method->signature();
476 stringStream ss;
477 ss.print("Method ");
478 ss.write((const char*)klass->bytes(), klass->utf8_length());
479 ss.print(".");
480 ss.write((const char*)name->bytes(), name->utf8_length());
481 ss.write((const char*)sig->bytes(), sig->utf8_length());
482 ss.print(" is abstract");
483 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
484 }
486 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
487 stringStream ss;
488 ss.print("Conflicting default methods:");
489 for (int i = 0; i < methods->length(); ++i) {
490 Method* method = methods->at(i);
491 Symbol* klass = method->klass_name();
492 Symbol* name = method->name();
493 ss.print(" ");
494 ss.write((const char*)klass->bytes(), klass->utf8_length());
495 ss.print(".");
496 ss.write((const char*)name->bytes(), name->utf8_length());
497 }
498 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
499 }
502 class StateRestorer;
504 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
505 // qualification state during hierarchy visitation, and applies that state
506 // when adding members to the MethodFamily
507 class StatefulMethodFamily : public ResourceObj {
508 friend class StateRestorer;
509 private:
510 QualifiedState _qualification_state;
512 void set_qualification_state(QualifiedState state) {
513 _qualification_state = state;
514 }
516 protected:
517 MethodFamily* _method_family;
519 public:
520 StatefulMethodFamily() {
521 _method_family = new MethodFamily();
522 _qualification_state = QUALIFIED;
523 }
525 StatefulMethodFamily(MethodFamily* mf) {
526 _method_family = mf;
527 _qualification_state = QUALIFIED;
528 }
530 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
532 MethodFamily* get_method_family() { return _method_family; }
534 StateRestorer* record_method_and_dq_further(Method* mo);
535 };
537 class StateRestorer : public PseudoScopeMark {
538 private:
539 StatefulMethodFamily* _method;
540 QualifiedState _state_to_restore;
541 public:
542 StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
543 : _method(dm), _state_to_restore(state) {}
544 ~StateRestorer() { destroy(); }
545 void restore_state() { _method->set_qualification_state(_state_to_restore); }
546 virtual void destroy() { restore_state(); }
547 };
549 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
550 StateRestorer* mark = new StateRestorer(this, _qualification_state);
551 if (_qualification_state == QUALIFIED) {
552 _method_family->record_qualified_method(mo);
553 } else {
554 _method_family->record_disqualified_method(mo);
555 }
556 // Everything found "above"??? this method in the hierarchy walk is set to
557 // disqualified
558 set_qualification_state(DISQUALIFIED);
559 return mark;
560 }
562 // Represents a location corresponding to a vtable slot for methods that
563 // neither the class nor any of it's ancestors provide an implementaion.
564 // Default methods may be present to fill this slot.
565 class EmptyVtableSlot : public ResourceObj {
566 private:
567 Symbol* _name;
568 Symbol* _signature;
569 int _size_of_parameters;
570 MethodFamily* _binding;
572 public:
573 EmptyVtableSlot(Method* method)
574 : _name(method->name()), _signature(method->signature()),
575 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
577 Symbol* name() const { return _name; }
578 Symbol* signature() const { return _signature; }
579 int size_of_parameters() const { return _size_of_parameters; }
581 void bind_family(MethodFamily* lm) { _binding = lm; }
582 bool is_bound() { return _binding != NULL; }
583 MethodFamily* get_binding() { return _binding; }
585 #ifndef PRODUCT
586 void print_on(outputStream* str) const {
587 print_slot(str, name(), signature());
588 }
589 #endif // ndef PRODUCT
590 };
592 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
593 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
595 assert(klass != NULL, "Must be valid class");
597 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
599 // All miranda methods are obvious candidates
600 for (int i = 0; i < mirandas->length(); ++i) {
601 EmptyVtableSlot* slot = new EmptyVtableSlot(mirandas->at(i));
602 slots->append(slot);
603 }
605 // Also any overpasses in our superclasses, that we haven't implemented.
606 // (can't use the vtable because it is not guaranteed to be initialized yet)
607 InstanceKlass* super = klass->java_super();
608 while (super != NULL) {
609 for (int i = 0; i < super->methods()->length(); ++i) {
610 Method* m = super->methods()->at(i);
611 if (m->is_overpass()) {
612 // m is a method that would have been a miranda if not for the
613 // default method processing that occurred on behalf of our superclass,
614 // so it's a method we want to re-examine in this new context. That is,
615 // unless we have a real implementation of it in the current class.
616 Method* impl = klass->lookup_method(m->name(), m->signature());
617 if (impl == NULL || impl->is_overpass()) {
618 slots->append(new EmptyVtableSlot(m));
619 }
620 }
621 }
622 super = super->java_super();
623 }
625 #ifndef PRODUCT
626 if (TraceDefaultMethods) {
627 tty->print_cr("Slots that need filling:");
628 streamIndentor si(tty);
629 for (int i = 0; i < slots->length(); ++i) {
630 tty->indent();
631 slots->at(i)->print_on(tty);
632 tty->print_cr("");
633 }
634 }
635 #endif // ndef PRODUCT
636 return slots;
637 }
639 // Iterates over the superinterface type hierarchy looking for all methods
640 // with a specific erased signature.
641 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
642 private:
643 // Context data
644 Symbol* _method_name;
645 Symbol* _method_signature;
646 StatefulMethodFamily* _family;
648 public:
649 FindMethodsByErasedSig(Symbol* name, Symbol* signature) :
650 _method_name(name), _method_signature(signature),
651 _family(NULL) {}
653 void get_discovered_family(MethodFamily** family) {
654 if (_family != NULL) {
655 *family = _family->get_method_family();
656 } else {
657 *family = NULL;
658 }
659 }
661 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
662 void free_node_data(void* node_data) {
663 PseudoScope::cast(node_data)->destroy();
664 }
666 // Find all methods on this hierarchy that match this
667 // method's erased (name, signature)
668 bool visit() {
669 PseudoScope* scope = PseudoScope::cast(current_data());
670 InstanceKlass* iklass = current_class();
672 Method* m = iklass->find_method(_method_name, _method_signature);
673 if (m != NULL) {
674 if (_family == NULL) {
675 _family = new StatefulMethodFamily();
676 }
678 if (iklass->is_interface()) {
679 StateRestorer* restorer = _family->record_method_and_dq_further(m);
680 scope->add_mark(restorer);
681 } else {
682 // This is the rule that methods in classes "win" (bad word) over
683 // methods in interfaces. This works because of single inheritance
684 _family->set_target_if_empty(m);
685 }
686 }
687 return true;
688 }
690 };
694 static void create_overpasses(
695 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
697 static void generate_erased_defaults(
698 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
699 EmptyVtableSlot* slot, TRAPS) {
701 // sets up a set of methods with the same exact erased signature
702 FindMethodsByErasedSig visitor(slot->name(), slot->signature());
703 visitor.run(klass);
705 MethodFamily* family;
706 visitor.get_discovered_family(&family);
707 if (family != NULL) {
708 family->determine_target(klass, CHECK);
709 slot->bind_family(family);
710 }
711 }
713 static void merge_in_new_methods(InstanceKlass* klass,
714 GrowableArray<Method*>* new_methods, TRAPS);
716 // This is the guts of the default methods implementation. This is called just
717 // after the classfile has been parsed if some ancestor has default methods.
718 //
719 // First if finds any name/signature slots that need any implementation (either
720 // because they are miranda or a superclass's implementation is an overpass
721 // itself). For each slot, iterate over the hierarchy, to see if they contain a
722 // signature that matches the slot we are looking at.
723 //
724 // For each slot filled, we generate an overpass method that either calls the
725 // unique default method candidate using invokespecial, or throws an exception
726 // (in the case of no default method candidates, or more than one valid
727 // candidate). These methods are then added to the class's method list.
728 // The JVM does not create bridges nor handle generic signatures here.
729 void DefaultMethods::generate_default_methods(
730 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
732 // This resource mark is the bound for all memory allocation that takes
733 // place during default method processing. After this goes out of scope,
734 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
735 // embedded resource mark under here as that memory can't be used outside
736 // whatever scope it's in.
737 ResourceMark rm(THREAD);
739 // Keep entire hierarchy alive for the duration of the computation
740 KeepAliveRegistrar keepAlive(THREAD);
741 KeepAliveVisitor loadKeepAlive(&keepAlive);
742 loadKeepAlive.run(klass);
744 #ifndef PRODUCT
745 if (TraceDefaultMethods) {
746 ResourceMark rm; // be careful with these!
747 tty->print_cr("Class %s requires default method processing",
748 klass->name()->as_klass_external_name());
749 PrintHierarchy printer;
750 printer.run(klass);
751 }
752 #endif // ndef PRODUCT
754 GrowableArray<EmptyVtableSlot*>* empty_slots =
755 find_empty_vtable_slots(klass, mirandas, CHECK);
757 for (int i = 0; i < empty_slots->length(); ++i) {
758 EmptyVtableSlot* slot = empty_slots->at(i);
759 #ifndef PRODUCT
760 if (TraceDefaultMethods) {
761 streamIndentor si(tty, 2);
762 tty->indent().print("Looking for default methods for slot ");
763 slot->print_on(tty);
764 tty->print_cr("");
765 }
766 #endif // ndef PRODUCT
768 generate_erased_defaults(klass, empty_slots, slot, CHECK);
769 }
770 #ifndef PRODUCT
771 if (TraceDefaultMethods) {
772 tty->print_cr("Creating overpasses...");
773 }
774 #endif // ndef PRODUCT
776 create_overpasses(empty_slots, klass, CHECK);
778 #ifndef PRODUCT
779 if (TraceDefaultMethods) {
780 tty->print_cr("Default method processing complete");
781 }
782 #endif // ndef PRODUCT
783 }
785 /**
786 * Interface inheritance rules were used to find a unique default method
787 * candidate for the resolved class. This
788 * method is only viable if it would also be in the set of default method
789 * candidates if we ran a full analysis on the current class.
790 *
791 * The only reason that the method would not be in the set of candidates for
792 * the current class is if that there's another matching method
793 * which is "more specific" than the found method -- i.e., one could find a
794 * path in the interface hierarchy in which the matching method appears
795 * before we get to '_target'.
796 *
797 * In order to determine this, we examine all of the implemented
798 * interfaces. If we find path that leads to the '_target' interface, then
799 * we examine that path to see if there are any methods that would shadow
800 * the selected method along that path.
801 */
802 class ShadowChecker : public HierarchyVisitor<ShadowChecker> {
803 protected:
804 Thread* THREAD;
806 InstanceKlass* _target;
808 Symbol* _method_name;
809 InstanceKlass* _method_holder;
810 bool _found_shadow;
813 public:
815 ShadowChecker(Thread* thread, Symbol* name, InstanceKlass* holder,
816 InstanceKlass* target)
817 : THREAD(thread), _method_name(name), _method_holder(holder),
818 _target(target), _found_shadow(false) {}
820 void* new_node_data(InstanceKlass* cls) { return NULL; }
821 void free_node_data(void* data) { return; }
823 bool visit() {
824 InstanceKlass* ik = current_class();
825 if (ik == _target && current_depth() == 1) {
826 return false; // This was the specified super -- no need to search it
827 }
828 if (ik == _method_holder || ik == _target) {
829 // We found a path that should be examined to see if it shadows _method
830 if (path_has_shadow()) {
831 _found_shadow = true;
832 cancel_iteration();
833 }
834 return false; // no need to continue up hierarchy
835 }
836 return true;
837 }
839 virtual bool path_has_shadow() = 0;
840 bool found_shadow() { return _found_shadow; }
841 };
843 // Used for Invokespecial.
844 // Invokespecial is allowed to invoke a concrete interface method
845 // and can be used to disambuiguate among qualified candidates,
846 // which are methods in immediate superinterfaces,
847 // but may not be used to invoke a candidate that would be shadowed
848 // from the perspective of the caller.
849 // Invokespecial is also used in the overpass generation today
850 // We re-run the shadowchecker because we can't distinguish this case,
851 // but it should return the same answer, since the overpass target
852 // is now the invokespecial caller.
853 class ErasedShadowChecker : public ShadowChecker {
854 private:
855 bool path_has_shadow() {
857 for (int i = current_depth() - 1; i > 0; --i) {
858 InstanceKlass* ik = class_at_depth(i);
860 if (ik->is_interface()) {
861 int end;
862 int start = ik->find_method_by_name(_method_name, &end);
863 if (start != -1) {
864 return true;
865 }
866 }
867 }
868 return false;
869 }
870 public:
872 ErasedShadowChecker(Thread* thread, Symbol* name, InstanceKlass* holder,
873 InstanceKlass* target)
874 : ShadowChecker(thread, name, holder, target) {}
875 };
877 // Find the unique qualified candidate from the perspective of the super_class
878 // which is the resolved_klass, which must be an immediate superinterface
879 // of klass
880 Method* find_erased_super_default(InstanceKlass* current_class, InstanceKlass* super_class, Symbol* method_name, Symbol* sig, TRAPS) {
882 FindMethodsByErasedSig visitor(method_name, sig);
883 visitor.run(super_class); // find candidates from resolved_klass
885 MethodFamily* family;
886 visitor.get_discovered_family(&family);
888 if (family != NULL) {
889 family->determine_target(current_class, CHECK_NULL); // get target from current_class
891 if (family->has_target()) {
892 Method* target = family->get_selected_target();
893 InstanceKlass* holder = InstanceKlass::cast(target->method_holder());
895 // Verify that the identified method is valid from the context of
896 // the current class, which is the caller class for invokespecial
897 // link resolution, i.e. ensure there it is not shadowed.
898 // You can use invokespecial to disambiguate interface methods, but
899 // you can not use it to skip over an interface method that would shadow it.
900 ErasedShadowChecker checker(THREAD, target->name(), holder, super_class);
901 checker.run(current_class);
903 if (checker.found_shadow()) {
904 #ifndef PRODUCT
905 if (TraceDefaultMethods) {
906 tty->print_cr(" Only candidate found was shadowed.");
907 }
908 #endif // ndef PRODUCT
909 THROW_MSG_(vmSymbols::java_lang_AbstractMethodError(),
910 "Accessible default method not found", NULL);
911 } else {
912 #ifndef PRODUCT
913 if (TraceDefaultMethods) {
914 family->print_sig_on(tty, target->signature(), 1);
915 }
916 #endif // ndef PRODUCT
917 return target;
918 }
919 } else {
920 assert(family->throws_exception(), "must have target or throw");
921 THROW_MSG_(vmSymbols::java_lang_AbstractMethodError(),
922 family->get_exception_message()->as_C_string(), NULL);
923 }
924 } else {
925 // no method found
926 ResourceMark rm(THREAD);
927 THROW_MSG_(vmSymbols::java_lang_NoSuchMethodError(),
928 Method::name_and_sig_as_C_string(current_class,
929 method_name, sig), NULL);
930 }
931 }
932 // This is called during linktime when we find an invokespecial call that
933 // refers to a direct superinterface. It indicates that we should find the
934 // default method in the hierarchy of that superinterface, and if that method
935 // would have been a candidate from the point of view of 'this' class, then we
936 // return that method.
937 // This logic assumes that the super is a direct superclass of the caller
938 Method* DefaultMethods::find_super_default(
939 Klass* cls, Klass* super, Symbol* method_name, Symbol* sig, TRAPS) {
941 ResourceMark rm(THREAD);
943 assert(cls != NULL && super != NULL, "Need real classes");
945 InstanceKlass* current_class = InstanceKlass::cast(cls);
946 InstanceKlass* super_class = InstanceKlass::cast(super);
948 // Keep entire hierarchy alive for the duration of the computation
949 KeepAliveRegistrar keepAlive(THREAD);
950 KeepAliveVisitor loadKeepAlive(&keepAlive);
951 loadKeepAlive.run(current_class); // get hierarchy from current class
953 #ifndef PRODUCT
954 if (TraceDefaultMethods) {
955 tty->print_cr("Finding super default method %s.%s%s from %s",
956 super_class->name()->as_C_string(),
957 method_name->as_C_string(), sig->as_C_string(),
958 current_class->name()->as_C_string());
959 }
960 #endif // ndef PRODUCT
962 assert(super_class->is_interface(), "only call for default methods");
964 Method* target = NULL;
965 target = find_erased_super_default(current_class, super_class,
966 method_name, sig, CHECK_NULL);
968 #ifndef PRODUCT
969 if (target != NULL) {
970 if (TraceDefaultMethods) {
971 tty->print(" Returning ");
972 print_method(tty, target, true);
973 tty->print_cr("");
974 }
975 }
976 #endif // ndef PRODUCT
977 return target;
978 }
980 #ifndef PRODUCT
981 // Return true is broad type is a covariant return of narrow type
982 static bool covariant_return_type(BasicType narrow, BasicType broad) {
983 if (narrow == broad) {
984 return true;
985 }
986 if (broad == T_OBJECT) {
987 return true;
988 }
989 return false;
990 }
991 #endif // ndef PRODUCT
993 static int assemble_redirect(
994 BytecodeConstantPool* cp, BytecodeBuffer* buffer,
995 Symbol* incoming, Method* target, TRAPS) {
997 BytecodeAssembler assem(buffer, cp);
999 SignatureStream in(incoming, true);
1000 SignatureStream out(target->signature(), true);
1001 u2 parameter_count = 0;
1003 assem.aload(parameter_count++); // load 'this'
1005 while (!in.at_return_type()) {
1006 assert(!out.at_return_type(), "Parameter counts do not match");
1007 BasicType bt = in.type();
1008 assert(out.type() == bt, "Parameter types are not compatible");
1009 assem.load(bt, parameter_count);
1010 if (in.is_object() && in.as_symbol(THREAD) != out.as_symbol(THREAD)) {
1011 assem.checkcast(out.as_symbol(THREAD));
1012 } else if (bt == T_LONG || bt == T_DOUBLE) {
1013 ++parameter_count; // longs and doubles use two slots
1014 }
1015 ++parameter_count;
1016 in.next();
1017 out.next();
1018 }
1019 assert(out.at_return_type(), "Parameter counts do not match");
1020 assert(covariant_return_type(out.type(), in.type()), "Return types are not compatible");
1022 if (parameter_count == 1 && (in.type() == T_LONG || in.type() == T_DOUBLE)) {
1023 ++parameter_count; // need room for return value
1024 }
1025 if (target->method_holder()->is_interface()) {
1026 assem.invokespecial(target);
1027 } else {
1028 assem.invokevirtual(target);
1029 }
1031 if (in.is_object() && in.as_symbol(THREAD) != out.as_symbol(THREAD)) {
1032 assem.checkcast(in.as_symbol(THREAD));
1033 }
1034 assem._return(in.type());
1035 return parameter_count;
1036 }
1038 static int assemble_abstract_method_error(
1039 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* message, TRAPS) {
1041 Symbol* errorName = vmSymbols::java_lang_AbstractMethodError();
1042 Symbol* init = vmSymbols::object_initializer_name();
1043 Symbol* sig = vmSymbols::string_void_signature();
1045 BytecodeAssembler assem(buffer, cp);
1047 assem._new(errorName);
1048 assem.dup();
1049 assem.load_string(message);
1050 assem.invokespecial(errorName, init, sig);
1051 assem.athrow();
1053 return 3; // max stack size: [ exception, exception, string ]
1054 }
1056 static Method* new_method(
1057 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
1058 Symbol* sig, AccessFlags flags, int max_stack, int params,
1059 ConstMethod::MethodType mt, TRAPS) {
1061 address code_start = 0;
1062 int code_length = 0;
1063 InlineTableSizes sizes;
1065 if (bytecodes != NULL && bytecodes->length() > 0) {
1066 code_start = static_cast<address>(bytecodes->adr_at(0));
1067 code_length = bytecodes->length();
1068 }
1070 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
1071 code_length, flags, &sizes,
1072 mt, CHECK_NULL);
1074 m->set_constants(NULL); // This will get filled in later
1075 m->set_name_index(cp->utf8(name));
1076 m->set_signature_index(cp->utf8(sig));
1077 #ifdef CC_INTERP
1078 ResultTypeFinder rtf(sig);
1079 m->set_result_index(rtf.type());
1080 #endif
1081 m->set_size_of_parameters(params);
1082 m->set_max_stack(max_stack);
1083 m->set_max_locals(params);
1084 m->constMethod()->set_stackmap_data(NULL);
1085 m->set_code(code_start);
1086 m->set_force_inline(true);
1088 return m;
1089 }
1091 static void switchover_constant_pool(BytecodeConstantPool* bpool,
1092 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
1094 if (new_methods->length() > 0) {
1095 ConstantPool* cp = bpool->create_constant_pool(CHECK);
1096 if (cp != klass->constants()) {
1097 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
1098 klass->set_constants(cp);
1099 cp->set_pool_holder(klass);
1101 for (int i = 0; i < new_methods->length(); ++i) {
1102 new_methods->at(i)->set_constants(cp);
1103 }
1104 for (int i = 0; i < klass->methods()->length(); ++i) {
1105 Method* mo = klass->methods()->at(i);
1106 mo->set_constants(cp);
1107 }
1108 }
1109 }
1110 }
1112 // A "bridge" is a method created by javac to bridge the gap between
1113 // an implementation and a generically-compatible, but different, signature.
1114 // Bridges have actual bytecode implementation in classfiles.
1115 // An "overpass", on the other hand, performs the same function as a bridge
1116 // but does not occur in a classfile; the VM creates overpass itself,
1117 // when it needs a path to get from a call site to an default method, and
1118 // a bridge doesn't exist.
1119 static void create_overpasses(
1120 GrowableArray<EmptyVtableSlot*>* slots,
1121 InstanceKlass* klass, TRAPS) {
1123 GrowableArray<Method*> overpasses;
1124 BytecodeConstantPool bpool(klass->constants());
1126 for (int i = 0; i < slots->length(); ++i) {
1127 EmptyVtableSlot* slot = slots->at(i);
1129 if (slot->is_bound()) {
1130 MethodFamily* method = slot->get_binding();
1131 int max_stack = 0;
1132 BytecodeBuffer buffer;
1134 #ifndef PRODUCT
1135 if (TraceDefaultMethods) {
1136 tty->print("for slot: ");
1137 slot->print_on(tty);
1138 tty->print_cr("");
1139 if (method->has_target()) {
1140 method->print_selected(tty, 1);
1141 } else {
1142 method->print_exception(tty, 1);
1143 }
1144 }
1145 #endif // ndef PRODUCT
1146 if (method->has_target()) {
1147 Method* selected = method->get_selected_target();
1148 if (selected->method_holder()->is_interface()) {
1149 max_stack = assemble_redirect(
1150 &bpool, &buffer, slot->signature(), selected, CHECK);
1151 }
1152 } else if (method->throws_exception()) {
1153 max_stack = assemble_abstract_method_error(
1154 &bpool, &buffer, method->get_exception_message(), CHECK);
1155 }
1156 if (max_stack != 0) {
1157 AccessFlags flags = accessFlags_from(
1158 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
1159 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
1160 flags, max_stack, slot->size_of_parameters(),
1161 ConstMethod::OVERPASS, CHECK);
1162 if (m != NULL) {
1163 overpasses.push(m);
1164 }
1165 }
1166 }
1167 }
1169 #ifndef PRODUCT
1170 if (TraceDefaultMethods) {
1171 tty->print_cr("Created %d overpass methods", overpasses.length());
1172 }
1173 #endif // ndef PRODUCT
1175 switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
1176 merge_in_new_methods(klass, &overpasses, CHECK);
1177 }
1179 static void sort_methods(GrowableArray<Method*>* methods) {
1180 // Note that this must sort using the same key as is used for sorting
1181 // methods in InstanceKlass.
1182 bool sorted = true;
1183 for (int i = methods->length() - 1; i > 0; --i) {
1184 for (int j = 0; j < i; ++j) {
1185 Method* m1 = methods->at(j);
1186 Method* m2 = methods->at(j + 1);
1187 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
1188 methods->at_put(j, m2);
1189 methods->at_put(j + 1, m1);
1190 sorted = false;
1191 }
1192 }
1193 if (sorted) break;
1194 sorted = true;
1195 }
1196 #ifdef ASSERT
1197 uintptr_t prev = 0;
1198 for (int i = 0; i < methods->length(); ++i) {
1199 Method* mh = methods->at(i);
1200 uintptr_t nv = (uintptr_t)mh->name();
1201 assert(nv >= prev, "Incorrect overpass method ordering");
1202 prev = nv;
1203 }
1204 #endif
1205 }
1207 static void merge_in_new_methods(InstanceKlass* klass,
1208 GrowableArray<Method*>* new_methods, TRAPS) {
1210 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1212 Array<Method*>* original_methods = klass->methods();
1213 Array<int>* original_ordering = klass->method_ordering();
1214 Array<int>* merged_ordering = Universe::the_empty_int_array();
1216 int new_size = klass->methods()->length() + new_methods->length();
1218 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1219 klass->class_loader_data(), new_size, NULL, CHECK);
1221 if (original_ordering != NULL && original_ordering->length() > 0) {
1222 merged_ordering = MetadataFactory::new_array<int>(
1223 klass->class_loader_data(), new_size, CHECK);
1224 }
1225 int method_order_index = klass->methods()->length();
1227 sort_methods(new_methods);
1229 // Perform grand merge of existing methods and new methods
1230 int orig_idx = 0;
1231 int new_idx = 0;
1233 for (int i = 0; i < new_size; ++i) {
1234 Method* orig_method = NULL;
1235 Method* new_method = NULL;
1236 if (orig_idx < original_methods->length()) {
1237 orig_method = original_methods->at(orig_idx);
1238 }
1239 if (new_idx < new_methods->length()) {
1240 new_method = new_methods->at(new_idx);
1241 }
1243 if (orig_method != NULL &&
1244 (new_method == NULL || orig_method->name() < new_method->name())) {
1245 merged_methods->at_put(i, orig_method);
1246 original_methods->at_put(orig_idx, NULL);
1247 if (merged_ordering->length() > 0) {
1248 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1249 }
1250 ++orig_idx;
1251 } else {
1252 merged_methods->at_put(i, new_method);
1253 if (merged_ordering->length() > 0) {
1254 merged_ordering->at_put(i, method_order_index++);
1255 }
1256 ++new_idx;
1257 }
1258 // update idnum for new location
1259 merged_methods->at(i)->set_method_idnum(i);
1260 }
1262 // Verify correct order
1263 #ifdef ASSERT
1264 uintptr_t prev = 0;
1265 for (int i = 0; i < merged_methods->length(); ++i) {
1266 Method* mo = merged_methods->at(i);
1267 uintptr_t nv = (uintptr_t)mo->name();
1268 assert(nv >= prev, "Incorrect method ordering");
1269 prev = nv;
1270 }
1271 #endif
1273 // Replace klass methods with new merged lists
1274 klass->set_methods(merged_methods);
1275 klass->set_initial_method_idnum(new_size);
1277 ClassLoaderData* cld = klass->class_loader_data();
1278 MetadataFactory::free_array(cld, original_methods);
1279 if (original_ordering->length() > 0) {
1280 klass->set_method_ordering(merged_ordering);
1281 MetadataFactory::free_array(cld, original_ordering);
1282 }
1283 }