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 */
24
25 #include "precompiled.hpp"
26 #include "classfile/bytecodeAssembler.hpp"
27 #include "classfile/defaultMethods.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/metadataFactory.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "runtime/signature.hpp"
33 #include "runtime/thread.hpp"
34 #include "oops/instanceKlass.hpp"
35 #include "oops/klass.hpp"
36 #include "oops/method.hpp"
37 #include "utilities/accessFlags.hpp"
38 #include "utilities/exceptions.hpp"
39 #include "utilities/ostream.hpp"
40 #include "utilities/pair.hpp"
41 #include "utilities/resourceHash.hpp"
42
43 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
44
45 // Because we use an iterative algorithm when iterating over the type
46 // hierarchy, we can't use traditional scoped objects which automatically do
47 // cleanup in the destructor when the scope is exited. PseudoScope (and
48 // PseudoScopeMark) provides a similar functionality, but for when you want a
49 // scoped object in non-stack memory (such as in resource memory, as we do
50 // here). You've just got to remember to call 'destroy()' on the scope when
51 // leaving it (and marks have to be explicitly added).
52 class PseudoScopeMark : public ResourceObj {
53 public:
54 virtual void destroy() = 0;
55 };
56
57 class PseudoScope : public ResourceObj {
58 private:
59 GrowableArray<PseudoScopeMark*> _marks;
60 public:
61
62 static PseudoScope* cast(void* data) {
63 return static_cast<PseudoScope*>(data);
64 }
65
66 void add_mark(PseudoScopeMark* psm) {
67 _marks.append(psm);
68 }
69
70 void destroy() {
71 for (int i = 0; i < _marks.length(); ++i) {
72 _marks.at(i)->destroy();
73 }
74 }
75 };
76
77 #ifndef PRODUCT
78 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
79 ResourceMark rm;
80 str->print("%s%s", name->as_C_string(), signature->as_C_string());
81 }
82
83 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
84 ResourceMark rm;
85 if (with_class) {
86 str->print("%s.", mo->klass_name()->as_C_string());
87 }
88 print_slot(str, mo->name(), mo->signature());
89 }
90 #endif // ndef PRODUCT
91
92 /**
93 * Perform a depth-first iteration over the class hierarchy, applying
94 * algorithmic logic as it goes.
95 *
96 * This class is one half of the inheritance hierarchy analysis mechanism.
97 * It is meant to be used in conjunction with another class, the algorithm,
98 * which is indicated by the ALGO template parameter. This class can be
99 * paired with any algorithm class that provides the required methods.
100 *
101 * This class contains all the mechanics for iterating over the class hierarchy
102 * starting at a particular root, without recursing (thus limiting stack growth
103 * from this point). It visits each superclass (if present) and superinterface
104 * in a depth-first manner, with callbacks to the ALGO class as each class is
105 * encountered (visit()), The algorithm can cut-off further exploration of a
106 * particular branch by returning 'false' from a visit() call.
107 *
108 * The ALGO class, must provide a visit() method, which each of which will be
109 * called once for each node in the inheritance tree during the iteration. In
110 * addition, it can provide a memory block via new_node_data(InstanceKlass*),
111 * which it can use for node-specific storage (and access via the
112 * current_data() and data_at_depth(int) methods).
113 *
114 * Bare minimum needed to be an ALGO class:
115 * class Algo : public HierarchyVisitor<Algo> {
116 * void* new_node_data(InstanceKlass* cls) { return NULL; }
117 * void free_node_data(void* data) { return; }
118 * bool visit() { return true; }
119 * };
120 */
121 template <class ALGO>
122 class HierarchyVisitor : StackObj {
123 private:
124
125 class Node : public ResourceObj {
126 public:
127 InstanceKlass* _class;
128 bool _super_was_visited;
129 int _interface_index;
130 void* _algorithm_data;
131
132 Node(InstanceKlass* cls, void* data, bool visit_super)
133 : _class(cls), _super_was_visited(!visit_super),
134 _interface_index(0), _algorithm_data(data) {}
135
136 int number_of_interfaces() { return _class->local_interfaces()->length(); }
137 int interface_index() { return _interface_index; }
138 void set_super_visited() { _super_was_visited = true; }
139 void increment_visited_interface() { ++_interface_index; }
140 void set_all_interfaces_visited() {
141 _interface_index = number_of_interfaces();
142 }
143 bool has_visited_super() { return _super_was_visited; }
144 bool has_visited_all_interfaces() {
145 return interface_index() >= number_of_interfaces();
146 }
147 InstanceKlass* interface_at(int index) {
148 return InstanceKlass::cast(_class->local_interfaces()->at(index));
149 }
150 InstanceKlass* next_super() { return _class->java_super(); }
151 InstanceKlass* next_interface() {
152 return interface_at(interface_index());
153 }
154 };
155
156 bool _cancelled;
157 GrowableArray<Node*> _path;
158
159 Node* current_top() const { return _path.top(); }
160 bool has_more_nodes() const { return !_path.is_empty(); }
161 void push(InstanceKlass* cls, void* data) {
162 assert(cls != NULL, "Requires a valid instance class");
163 Node* node = new Node(cls, data, has_super(cls));
164 _path.push(node);
165 }
166 void pop() { _path.pop(); }
167
168 void reset_iteration() {
169 _cancelled = false;
170 _path.clear();
171 }
172 bool is_cancelled() const { return _cancelled; }
173
174 // This code used to skip interface classes because their only
175 // superclass was j.l.Object which would be also covered by class
176 // superclass hierarchy walks. Now that the starting point can be
177 // an interface, we must ensure we catch j.l.Object as the super.
178 static bool has_super(InstanceKlass* cls) {
179 return cls->super() != NULL;
180 }
181
182 Node* node_at_depth(int i) const {
183 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
184 }
185
186 protected:
187
188 // Accessors available to the algorithm
189 int current_depth() const { return _path.length() - 1; }
190
191 InstanceKlass* class_at_depth(int i) {
192 Node* n = node_at_depth(i);
193 return n == NULL ? NULL : n->_class;
194 }
195 InstanceKlass* current_class() { return class_at_depth(0); }
196
197 void* data_at_depth(int i) {
198 Node* n = node_at_depth(i);
199 return n == NULL ? NULL : n->_algorithm_data;
200 }
201 void* current_data() { return data_at_depth(0); }
202
203 void cancel_iteration() { _cancelled = true; }
204
205 public:
206
207 void run(InstanceKlass* root) {
208 ALGO* algo = static_cast<ALGO*>(this);
209
210 reset_iteration();
211
212 void* algo_data = algo->new_node_data(root);
213 push(root, algo_data);
214 bool top_needs_visit = true;
215
216 do {
217 Node* top = current_top();
218 if (top_needs_visit) {
219 if (algo->visit() == false) {
220 // algorithm does not want to continue along this path. Arrange
221 // it so that this state is immediately popped off the stack
222 top->set_super_visited();
223 top->set_all_interfaces_visited();
224 }
225 top_needs_visit = false;
226 }
227
228 if (top->has_visited_super() && top->has_visited_all_interfaces()) {
229 algo->free_node_data(top->_algorithm_data);
230 pop();
231 } else {
232 InstanceKlass* next = NULL;
233 if (top->has_visited_super() == false) {
234 next = top->next_super();
235 top->set_super_visited();
236 } else {
237 next = top->next_interface();
238 top->increment_visited_interface();
239 }
240 assert(next != NULL, "Otherwise we shouldn't be here");
241 algo_data = algo->new_node_data(next);
242 push(next, algo_data);
243 top_needs_visit = true;
244 }
245 } while (!is_cancelled() && has_more_nodes());
246 }
247 };
248
249 #ifndef PRODUCT
250 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
251 public:
252
253 bool visit() {
254 InstanceKlass* cls = current_class();
255 streamIndentor si(tty, current_depth() * 2);
256 tty->indent().print_cr("%s", cls->name()->as_C_string());
257 return true;
258 }
259
260 void* new_node_data(InstanceKlass* cls) { return NULL; }
261 void free_node_data(void* data) { return; }
262 };
263 #endif // ndef PRODUCT
264
265 // Used to register InstanceKlass objects and all related metadata structures
266 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
267 // be deallocated by class redefinition while we're using them. The classes are
268 // de-registered when this goes out of scope.
269 //
270 // Once a class is registered, we need not bother with methodHandles or
271 // constantPoolHandles for it's associated metadata.
272 class KeepAliveRegistrar : public StackObj {
273 private:
274 Thread* _thread;
275 GrowableArray<ConstantPool*> _keep_alive;
276
277 public:
278 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
279 assert(thread == Thread::current(), "Must be current thread");
280 }
281
282 ~KeepAliveRegistrar() {
283 for (int i = _keep_alive.length() - 1; i >= 0; --i) {
284 ConstantPool* cp = _keep_alive.at(i);
285 int idx = _thread->metadata_handles()->find_from_end(cp);
286 assert(idx > 0, "Must be in the list");
287 _thread->metadata_handles()->remove_at(idx);
288 }
289 }
290
291 // Register a class as 'in-use' by the thread. It's fine to register a class
292 // multiple times (though perhaps inefficient)
293 void register_class(InstanceKlass* ik) {
294 ConstantPool* cp = ik->constants();
295 _keep_alive.push(cp);
296 _thread->metadata_handles()->push(cp);
297 }
298 };
299
300 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
301 private:
302 KeepAliveRegistrar* _registrar;
303
304 public:
305 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
306
307 void* new_node_data(InstanceKlass* cls) { return NULL; }
308 void free_node_data(void* data) { return; }
309
310 bool visit() {
311 _registrar->register_class(current_class());
312 return true;
313 }
314 };
315
316
317 // A method family contains a set of all methods that implement a single
318 // erased method. As members of the set are collected while walking over the
319 // hierarchy, they are tagged with a qualification state. The qualification
320 // state for an erased method is set to disqualified if there exists a path
321 // from the root of hierarchy to the method that contains an interleaving
322 // erased method defined in an interface.
323
324 class MethodFamily : public ResourceObj {
325 private:
326
327 GrowableArray<Pair<Method*,QualifiedState> > _members;
328 ResourceHashtable<Method*, int> _member_index;
329
330 Method* _selected_target; // Filled in later, if a unique target exists
331 Symbol* _exception_message; // If no unique target is found
332 Symbol* _exception_name; // If no unique target is found
333
334 bool contains_method(Method* method) {
335 int* lookup = _member_index.get(method);
336 return lookup != NULL;
337 }
338
339 void add_method(Method* method, QualifiedState state) {
340 Pair<Method*,QualifiedState> entry(method, state);
341 _member_index.put(method, _members.length());
342 _members.append(entry);
343 }
344
345 void disqualify_method(Method* method) {
346 int* index = _member_index.get(method);
347 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
348 _members.at(*index).second = DISQUALIFIED;
349 }
350
351 Symbol* generate_no_defaults_message(TRAPS) const;
352 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
353
354 public:
355
356 MethodFamily()
357 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {}
358
359 void set_target_if_empty(Method* m) {
360 if (_selected_target == NULL && !m->is_overpass()) {
361 _selected_target = m;
362 }
363 }
364
365 void record_qualified_method(Method* m) {
366 // If the method already exists in the set as qualified, this operation is
367 // redundant. If it already exists as disqualified, then we leave it as
368 // disqualfied. Thus we only add to the set if it's not already in the
369 // set.
370 if (!contains_method(m)) {
371 add_method(m, QUALIFIED);
372 }
373 }
374
375 void record_disqualified_method(Method* m) {
376 // If not in the set, add it as disqualified. If it's already in the set,
377 // then set the state to disqualified no matter what the previous state was.
378 if (!contains_method(m)) {
379 add_method(m, DISQUALIFIED);
380 } else {
381 disqualify_method(m);
382 }
383 }
384
385 bool has_target() const { return _selected_target != NULL; }
386 bool throws_exception() { return _exception_message != NULL; }
387
388 Method* get_selected_target() { return _selected_target; }
389 Symbol* get_exception_message() { return _exception_message; }
390 Symbol* get_exception_name() { return _exception_name; }
391
392 // Either sets the target or the exception error message
393 void determine_target(InstanceKlass* root, TRAPS) {
394 if (has_target() || throws_exception()) {
395 return;
396 }
397
398 // Qualified methods are maximally-specific methods
399 // These include public, instance concrete (=default) and abstract methods
400 GrowableArray<Method*> qualified_methods;
401 int num_defaults = 0;
402 int default_index = -1;
403 int qualified_index = -1;
404 for (int i = 0; i < _members.length(); ++i) {
405 Pair<Method*,QualifiedState> entry = _members.at(i);
406 if (entry.second == QUALIFIED) {
407 qualified_methods.append(entry.first);
408 qualified_index++;
409 if (entry.first->is_default_method()) {
410 num_defaults++;
411 default_index = qualified_index;
412
413 }
414 }
415 }
416
417 if (qualified_methods.length() == 0) {
418 _exception_message = generate_no_defaults_message(CHECK);
419 _exception_name = vmSymbols::java_lang_AbstractMethodError();
420 // If only one qualified method is default, select that
421 } else if (num_defaults == 1) {
422 _selected_target = qualified_methods.at(default_index);
423 } else if (num_defaults > 1) {
424 _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
425 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError();
426 if (TraceDefaultMethods) {
427 _exception_message->print_value_on(tty);
428 tty->print_cr("");
429 }
430 }
431 // leave abstract methods alone, they will be found via normal search path
432 }
433
434 bool contains_signature(Symbol* query) {
435 for (int i = 0; i < _members.length(); ++i) {
436 if (query == _members.at(i).first->signature()) {
437 return true;
438 }
439 }
440 return false;
441 }
442
443 #ifndef PRODUCT
444 void print_sig_on(outputStream* str, Symbol* signature, int indent) const {
445 streamIndentor si(str, indent * 2);
446
447 str->indent().print_cr("Logical Method %s:", signature->as_C_string());
448
449 streamIndentor si2(str);
450 for (int i = 0; i < _members.length(); ++i) {
451 str->indent();
452 print_method(str, _members.at(i).first);
453 if (_members.at(i).second == DISQUALIFIED) {
454 str->print(" (disqualified)");
455 }
456 str->print_cr("");
457 }
458
459 if (_selected_target != NULL) {
460 print_selected(str, 1);
461 }
462 }
463
464 void print_selected(outputStream* str, int indent) const {
465 assert(has_target(), "Should be called otherwise");
466 streamIndentor si(str, indent * 2);
467 str->indent().print("Selected method: ");
468 print_method(str, _selected_target);
469 Klass* method_holder = _selected_target->method_holder();
470 if (!method_holder->is_interface()) {
471 tty->print(" : in superclass");
472 }
473 str->print_cr("");
474 }
475
476 void print_exception(outputStream* str, int indent) {
477 assert(throws_exception(), "Should be called otherwise");
478 assert(_exception_name != NULL, "exception_name should be set");
479 streamIndentor si(str, indent * 2);
480 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string());
481 }
482 #endif // ndef PRODUCT
483 };
484
485 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
486 return SymbolTable::new_symbol("No qualifying defaults found", CHECK_NULL);
487 }
488
489 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
490 stringStream ss;
491 ss.print("Conflicting default methods:");
492 for (int i = 0; i < methods->length(); ++i) {
493 Method* method = methods->at(i);
494 Symbol* klass = method->klass_name();
495 Symbol* name = method->name();
496 ss.print(" ");
497 ss.write((const char*)klass->bytes(), klass->utf8_length());
498 ss.print(".");
499 ss.write((const char*)name->bytes(), name->utf8_length());
500 }
501 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
502 }
503
504
505 class StateRestorer;
506
507 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
508 // qualification state during hierarchy visitation, and applies that state
509 // when adding members to the MethodFamily
510 class StatefulMethodFamily : public ResourceObj {
511 friend class StateRestorer;
512 private:
513 QualifiedState _qualification_state;
514
515 void set_qualification_state(QualifiedState state) {
516 _qualification_state = state;
517 }
518
519 protected:
520 MethodFamily* _method_family;
521
522 public:
523 StatefulMethodFamily() {
524 _method_family = new MethodFamily();
525 _qualification_state = QUALIFIED;
526 }
527
528 StatefulMethodFamily(MethodFamily* mf) {
529 _method_family = mf;
530 _qualification_state = QUALIFIED;
531 }
532
533 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
534
535 MethodFamily* get_method_family() { return _method_family; }
536
537 StateRestorer* record_method_and_dq_further(Method* mo);
538 };
539
540 class StateRestorer : public PseudoScopeMark {
541 private:
542 StatefulMethodFamily* _method;
543 QualifiedState _state_to_restore;
544 public:
545 StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
546 : _method(dm), _state_to_restore(state) {}
547 ~StateRestorer() { destroy(); }
548 void restore_state() { _method->set_qualification_state(_state_to_restore); }
549 virtual void destroy() { restore_state(); }
550 };
551
552 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
553 StateRestorer* mark = new StateRestorer(this, _qualification_state);
554 if (_qualification_state == QUALIFIED) {
555 _method_family->record_qualified_method(mo);
556 } else {
557 _method_family->record_disqualified_method(mo);
558 }
559 // Everything found "above"??? this method in the hierarchy walk is set to
560 // disqualified
561 set_qualification_state(DISQUALIFIED);
562 return mark;
563 }
564
565 // Represents a location corresponding to a vtable slot for methods that
566 // neither the class nor any of it's ancestors provide an implementaion.
567 // Default methods may be present to fill this slot.
568 class EmptyVtableSlot : public ResourceObj {
569 private:
570 Symbol* _name;
571 Symbol* _signature;
572 int _size_of_parameters;
573 MethodFamily* _binding;
574
575 public:
576 EmptyVtableSlot(Method* method)
577 : _name(method->name()), _signature(method->signature()),
578 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
579
580 Symbol* name() const { return _name; }
581 Symbol* signature() const { return _signature; }
582 int size_of_parameters() const { return _size_of_parameters; }
583
584 void bind_family(MethodFamily* lm) { _binding = lm; }
585 bool is_bound() { return _binding != NULL; }
586 MethodFamily* get_binding() { return _binding; }
587
588 #ifndef PRODUCT
589 void print_on(outputStream* str) const {
590 print_slot(str, name(), signature());
591 }
592 #endif // ndef PRODUCT
593 };
594
595 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
596 bool found = false;
597 for (int j = 0; j < slots->length(); ++j) {
598 if (slots->at(j)->name() == m->name() &&
599 slots->at(j)->signature() == m->signature() ) {
600 found = true;
601 break;
602 }
603 }
604 return found;
605 }
606
607 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
608 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
609
610 assert(klass != NULL, "Must be valid class");
611
612 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
613
614 // All miranda methods are obvious candidates
615 for (int i = 0; i < mirandas->length(); ++i) {
616 Method* m = mirandas->at(i);
617 if (!already_in_vtable_slots(slots, m)) {
618 slots->append(new EmptyVtableSlot(m));
619 }
620 }
621
622 // Also any overpasses in our superclasses, that we haven't implemented.
623 // (can't use the vtable because it is not guaranteed to be initialized yet)
624 InstanceKlass* super = klass->java_super();
625 while (super != NULL) {
626 for (int i = 0; i < super->methods()->length(); ++i) {
627 Method* m = super->methods()->at(i);
628 if (m->is_overpass() || m->is_static()) {
629 // m is a method that would have been a miranda if not for the
630 // default method processing that occurred on behalf of our superclass,
631 // so it's a method we want to re-examine in this new context. That is,
632 // unless we have a real implementation of it in the current class.
633 Method* impl = klass->lookup_method(m->name(), m->signature());
634 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
635 if (!already_in_vtable_slots(slots, m)) {
636 slots->append(new EmptyVtableSlot(m));
637 }
638 }
639 }
640 }
641
642 // also any default methods in our superclasses
643 if (super->default_methods() != NULL) {
644 for (int i = 0; i < super->default_methods()->length(); ++i) {
645 Method* m = super->default_methods()->at(i);
646 // m is a method that would have been a miranda if not for the
647 // default method processing that occurred on behalf of our superclass,
648 // so it's a method we want to re-examine in this new context. That is,
649 // unless we have a real implementation of it in the current class.
650 Method* impl = klass->lookup_method(m->name(), m->signature());
651 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
652 if (!already_in_vtable_slots(slots, m)) {
653 slots->append(new EmptyVtableSlot(m));
654 }
655 }
656 }
657 }
658 super = super->java_super();
659 }
660
661 #ifndef PRODUCT
662 if (TraceDefaultMethods) {
663 tty->print_cr("Slots that need filling:");
664 streamIndentor si(tty);
665 for (int i = 0; i < slots->length(); ++i) {
666 tty->indent();
667 slots->at(i)->print_on(tty);
668 tty->print_cr("");
669 }
670 }
671 #endif // ndef PRODUCT
672 return slots;
673 }
674
675 // Iterates over the superinterface type hierarchy looking for all methods
676 // with a specific erased signature.
677 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
678 private:
679 // Context data
680 Symbol* _method_name;
681 Symbol* _method_signature;
682 StatefulMethodFamily* _family;
683
684 public:
685 FindMethodsByErasedSig(Symbol* name, Symbol* signature) :
686 _method_name(name), _method_signature(signature),
687 _family(NULL) {}
688
689 void get_discovered_family(MethodFamily** family) {
690 if (_family != NULL) {
691 *family = _family->get_method_family();
692 } else {
693 *family = NULL;
694 }
695 }
696
697 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
698 void free_node_data(void* node_data) {
699 PseudoScope::cast(node_data)->destroy();
700 }
701
702 // Find all methods on this hierarchy that match this
703 // method's erased (name, signature)
704 bool visit() {
705 PseudoScope* scope = PseudoScope::cast(current_data());
706 InstanceKlass* iklass = current_class();
707
708 Method* m = iklass->find_method(_method_name, _method_signature);
709 // private interface methods are not candidates for default methods
710 // invokespecial to private interface methods doesn't use default method logic
711 // The overpasses are your supertypes' errors, we do not include them
712 // future: take access controls into account for superclass methods
713 if (m != NULL && !m->is_static() && !m->is_overpass() &&
714 (!iklass->is_interface() || m->is_public())) {
715 if (_family == NULL) {
716 _family = new StatefulMethodFamily();
717 }
718
719 if (iklass->is_interface()) {
720 StateRestorer* restorer = _family->record_method_and_dq_further(m);
721 scope->add_mark(restorer);
722 } else {
723 // This is the rule that methods in classes "win" (bad word) over
724 // methods in interfaces. This works because of single inheritance
725 _family->set_target_if_empty(m);
726 }
727 }
728 return true;
729 }
730
731 };
732
733
734
735 static void create_defaults_and_exceptions(
736 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
737
738 static void generate_erased_defaults(
739 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
740 EmptyVtableSlot* slot, TRAPS) {
741
742 // sets up a set of methods with the same exact erased signature
743 FindMethodsByErasedSig visitor(slot->name(), slot->signature());
744 visitor.run(klass);
745
746 MethodFamily* family;
747 visitor.get_discovered_family(&family);
748 if (family != NULL) {
749 family->determine_target(klass, CHECK);
750 slot->bind_family(family);
751 }
752 }
753
754 static void merge_in_new_methods(InstanceKlass* klass,
755 GrowableArray<Method*>* new_methods, TRAPS);
756 static void create_default_methods( InstanceKlass* klass,
757 GrowableArray<Method*>* new_methods, TRAPS);
758
759 // This is the guts of the default methods implementation. This is called just
760 // after the classfile has been parsed if some ancestor has default methods.
761 //
762 // First if finds any name/signature slots that need any implementation (either
763 // because they are miranda or a superclass's implementation is an overpass
764 // itself). For each slot, iterate over the hierarchy, to see if they contain a
765 // signature that matches the slot we are looking at.
766 //
767 // For each slot filled, we generate an overpass method that either calls the
768 // unique default method candidate using invokespecial, or throws an exception
769 // (in the case of no default method candidates, or more than one valid
770 // candidate). These methods are then added to the class's method list.
771 // The JVM does not create bridges nor handle generic signatures here.
772 void DefaultMethods::generate_default_methods(
773 InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
774
775 // This resource mark is the bound for all memory allocation that takes
776 // place during default method processing. After this goes out of scope,
777 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
778 // embedded resource mark under here as that memory can't be used outside
779 // whatever scope it's in.
780 ResourceMark rm(THREAD);
781
782 // Keep entire hierarchy alive for the duration of the computation
783 KeepAliveRegistrar keepAlive(THREAD);
784 KeepAliveVisitor loadKeepAlive(&keepAlive);
785 loadKeepAlive.run(klass);
786
787 #ifndef PRODUCT
788 if (TraceDefaultMethods) {
789 ResourceMark rm; // be careful with these!
790 tty->print_cr("%s %s requires default method processing",
791 klass->is_interface() ? "Interface" : "Class",
792 klass->name()->as_klass_external_name());
793 PrintHierarchy printer;
794 printer.run(klass);
795 }
796 #endif // ndef PRODUCT
797
798 GrowableArray<EmptyVtableSlot*>* empty_slots =
799 find_empty_vtable_slots(klass, mirandas, CHECK);
800
801 for (int i = 0; i < empty_slots->length(); ++i) {
802 EmptyVtableSlot* slot = empty_slots->at(i);
803 #ifndef PRODUCT
804 if (TraceDefaultMethods) {
805 streamIndentor si(tty, 2);
806 tty->indent().print("Looking for default methods for slot ");
807 slot->print_on(tty);
808 tty->print_cr("");
809 }
810 #endif // ndef PRODUCT
811
812 generate_erased_defaults(klass, empty_slots, slot, CHECK);
813 }
814 #ifndef PRODUCT
815 if (TraceDefaultMethods) {
816 tty->print_cr("Creating defaults and overpasses...");
817 }
818 #endif // ndef PRODUCT
819
820 create_defaults_and_exceptions(empty_slots, klass, CHECK);
821
822 #ifndef PRODUCT
823 if (TraceDefaultMethods) {
824 tty->print_cr("Default method processing complete");
825 }
826 #endif // ndef PRODUCT
827 }
828
829 static int assemble_method_error(
830 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
831
832 Symbol* init = vmSymbols::object_initializer_name();
833 Symbol* sig = vmSymbols::string_void_signature();
834
835 BytecodeAssembler assem(buffer, cp);
836
837 assem._new(errorName);
838 assem.dup();
839 assem.load_string(message);
840 assem.invokespecial(errorName, init, sig);
841 assem.athrow();
842
843 return 3; // max stack size: [ exception, exception, string ]
844 }
845
846 static Method* new_method(
847 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
848 Symbol* sig, AccessFlags flags, int max_stack, int params,
849 ConstMethod::MethodType mt, TRAPS) {
850
851 address code_start = 0;
852 int code_length = 0;
853 InlineTableSizes sizes;
854
855 if (bytecodes != NULL && bytecodes->length() > 0) {
856 code_start = static_cast<address>(bytecodes->adr_at(0));
857 code_length = bytecodes->length();
858 }
859
860 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
861 code_length, flags, &sizes,
862 mt, CHECK_NULL);
863
864 m->set_constants(NULL); // This will get filled in later
865 m->set_name_index(cp->utf8(name));
866 m->set_signature_index(cp->utf8(sig));
867 #ifdef CC_INTERP
868 ResultTypeFinder rtf(sig);
869 m->set_result_index(rtf.type());
870 #endif
871 m->set_size_of_parameters(params);
872 m->set_max_stack(max_stack);
873 m->set_max_locals(params);
874 m->constMethod()->set_stackmap_data(NULL);
875 m->set_code(code_start);
876
877 return m;
878 }
879
880 static void switchover_constant_pool(BytecodeConstantPool* bpool,
881 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
882
883 if (new_methods->length() > 0) {
884 ConstantPool* cp = bpool->create_constant_pool(CHECK);
885 if (cp != klass->constants()) {
886 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
887 klass->set_constants(cp);
888 cp->set_pool_holder(klass);
889
890 for (int i = 0; i < new_methods->length(); ++i) {
891 new_methods->at(i)->set_constants(cp);
892 }
893 for (int i = 0; i < klass->methods()->length(); ++i) {
894 Method* mo = klass->methods()->at(i);
895 mo->set_constants(cp);
896 }
897 }
898 }
899 }
900
901 // Create default_methods list for the current class.
902 // With the VM only processing erased signatures, the VM only
903 // creates an overpass in a conflict case or a case with no candidates.
904 // This allows virtual methods to override the overpass, but ensures
905 // that a local method search will find the exception rather than an abstract
906 // or default method that is not a valid candidate.
907 static void create_defaults_and_exceptions(
908 GrowableArray<EmptyVtableSlot*>* slots,
909 InstanceKlass* klass, TRAPS) {
910
911 GrowableArray<Method*> overpasses;
912 GrowableArray<Method*> defaults;
913 BytecodeConstantPool bpool(klass->constants());
914
915 for (int i = 0; i < slots->length(); ++i) {
916 EmptyVtableSlot* slot = slots->at(i);
917
918 if (slot->is_bound()) {
919 MethodFamily* method = slot->get_binding();
920 BytecodeBuffer buffer;
921
922 #ifndef PRODUCT
923 if (TraceDefaultMethods) {
924 tty->print("for slot: ");
925 slot->print_on(tty);
926 tty->print_cr("");
927 if (method->has_target()) {
928 method->print_selected(tty, 1);
929 } else if (method->throws_exception()) {
930 method->print_exception(tty, 1);
931 }
932 }
933 #endif // ndef PRODUCT
934
935 if (method->has_target()) {
936 Method* selected = method->get_selected_target();
937 if (selected->method_holder()->is_interface()) {
938 defaults.push(selected);
939 }
940 } else if (method->throws_exception()) {
941 int max_stack = assemble_method_error(&bpool, &buffer,
942 method->get_exception_name(), method->get_exception_message(), CHECK);
943 AccessFlags flags = accessFlags_from(
944 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
945 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
946 flags, max_stack, slot->size_of_parameters(),
947 ConstMethod::OVERPASS, CHECK);
948 // We push to the methods list:
949 // overpass methods which are exception throwing methods
950 if (m != NULL) {
951 overpasses.push(m);
952 }
953 }
954 }
955 }
956
957 #ifndef PRODUCT
958 if (TraceDefaultMethods) {
959 tty->print_cr("Created %d overpass methods", overpasses.length());
960 tty->print_cr("Created %d default methods", defaults.length());
961 }
962 #endif // ndef PRODUCT
963
964 if (overpasses.length() > 0) {
965 switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
966 merge_in_new_methods(klass, &overpasses, CHECK);
967 }
968 if (defaults.length() > 0) {
969 create_default_methods(klass, &defaults, CHECK);
970 }
971 }
972
973 static void create_default_methods( InstanceKlass* klass,
974 GrowableArray<Method*>* new_methods, TRAPS) {
975
976 int new_size = new_methods->length();
977 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>(
978 klass->class_loader_data(), new_size, NULL, CHECK);
979 for (int index = 0; index < new_size; index++ ) {
980 total_default_methods->at_put(index, new_methods->at(index));
981 }
982 Method::sort_methods(total_default_methods, false, false);
983
984 klass->set_default_methods(total_default_methods);
985 }
986
987 static void sort_methods(GrowableArray<Method*>* methods) {
988 // Note that this must sort using the same key as is used for sorting
989 // methods in InstanceKlass.
990 bool sorted = true;
991 for (int i = methods->length() - 1; i > 0; --i) {
992 for (int j = 0; j < i; ++j) {
993 Method* m1 = methods->at(j);
994 Method* m2 = methods->at(j + 1);
995 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
996 methods->at_put(j, m2);
997 methods->at_put(j + 1, m1);
998 sorted = false;
999 }
1000 }
1001 if (sorted) break;
1002 sorted = true;
1003 }
1004 #ifdef ASSERT
1005 uintptr_t prev = 0;
1006 for (int i = 0; i < methods->length(); ++i) {
1007 Method* mh = methods->at(i);
1008 uintptr_t nv = (uintptr_t)mh->name();
1009 assert(nv >= prev, "Incorrect overpass method ordering");
1010 prev = nv;
1011 }
1012 #endif
1013 }
1014
1015 static void merge_in_new_methods(InstanceKlass* klass,
1016 GrowableArray<Method*>* new_methods, TRAPS) {
1017
1018 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1019
1020 Array<Method*>* original_methods = klass->methods();
1021 Array<int>* original_ordering = klass->method_ordering();
1022 Array<int>* merged_ordering = Universe::the_empty_int_array();
1023
1024 int new_size = klass->methods()->length() + new_methods->length();
1025
1026 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1027 klass->class_loader_data(), new_size, NULL, CHECK);
1028
1029 if (original_ordering != NULL && original_ordering->length() > 0) {
1030 merged_ordering = MetadataFactory::new_array<int>(
1031 klass->class_loader_data(), new_size, CHECK);
1032 }
1033 int method_order_index = klass->methods()->length();
1034
1035 sort_methods(new_methods);
1036
1037 // Perform grand merge of existing methods and new methods
1038 int orig_idx = 0;
1039 int new_idx = 0;
1040
1041 for (int i = 0; i < new_size; ++i) {
1042 Method* orig_method = NULL;
1043 Method* new_method = NULL;
1044 if (orig_idx < original_methods->length()) {
1045 orig_method = original_methods->at(orig_idx);
1046 }
1047 if (new_idx < new_methods->length()) {
1048 new_method = new_methods->at(new_idx);
1049 }
1050
1051 if (orig_method != NULL &&
1052 (new_method == NULL || orig_method->name() < new_method->name())) {
1053 merged_methods->at_put(i, orig_method);
1054 original_methods->at_put(orig_idx, NULL);
1055 if (merged_ordering->length() > 0) {
1056 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1057 }
1058 ++orig_idx;
1059 } else {
1060 merged_methods->at_put(i, new_method);
1061 if (merged_ordering->length() > 0) {
1062 merged_ordering->at_put(i, method_order_index++);
1063 }
1064 ++new_idx;
1065 }
1066 // update idnum for new location
1067 merged_methods->at(i)->set_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
1085 ClassLoaderData* cld = klass->class_loader_data();
1086 if (original_methods ->length() > 0) {
1087 MetadataFactory::free_array(cld, original_methods);
1088 }
1089 if (original_ordering->length() > 0) {
1090 klass->set_method_ordering(merged_ordering);
1091 MetadataFactory::free_array(cld, original_ordering);
1092 }
1093 }