1 /*
2 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/bytecodeAssembler.hpp"
27 #include "classfile/defaultMethods.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/allocation.hpp"
33 #include "memory/metadataFactory.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/signature.hpp"
37 #include "runtime/thread.hpp"
38 #include "oops/instanceKlass.hpp"
39 #include "oops/klass.hpp"
40 #include "oops/method.hpp"
41 #include "utilities/accessFlags.hpp"
42 #include "utilities/exceptions.hpp"
43 #include "utilities/ostream.hpp"
44 #include "utilities/pair.hpp"
45 #include "utilities/resourceHash.hpp"
46
47 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
48
49 // Because we use an iterative algorithm when iterating over the type
50 // hierarchy, we can't use traditional scoped objects which automatically do
51 // cleanup in the destructor when the scope is exited. PseudoScope (and
52 // PseudoScopeMark) provides a similar functionality, but for when you want a
53 // scoped object in non-stack memory (such as in resource memory, as we do
54 // here). You've just got to remember to call 'destroy()' on the scope when
55 // leaving it (and marks have to be explicitly added).
56 class PseudoScopeMark : public ResourceObj {
57 public:
58 virtual void destroy() = 0;
59 };
60
61 class PseudoScope : public ResourceObj {
62 private:
63 GrowableArray<PseudoScopeMark*> _marks;
64 public:
65
66 static PseudoScope* cast(void* data) {
67 return static_cast<PseudoScope*>(data);
68 }
69
70 void add_mark(PseudoScopeMark* psm) {
71 _marks.append(psm);
72 }
73
74 void destroy() {
75 for (int i = 0; i < _marks.length(); ++i) {
76 _marks.at(i)->destroy();
77 }
78 }
79 };
80
81 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
82 str->print("%s%s", name->as_C_string(), signature->as_C_string());
83 }
84
85 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
86 if (with_class) {
87 str->print("%s.", mo->klass_name()->as_C_string());
88 }
89 print_slot(str, mo->name(), mo->signature());
90 }
91
92 /**
93 * Perform a depth-first iteration over the class hierarchy, applying
94 * algorithmic logic as it goes.
95 *
96 * This class is one half of the inheritance hierarchy analysis mechanism.
97 * It is meant to be used in conjunction with another class, the algorithm,
98 * which is indicated by the ALGO template parameter. This class can be
99 * paired with any algorithm class that provides the required methods.
100 *
101 * This class contains all the mechanics for iterating over the class hierarchy
102 * starting at a particular root, without recursing (thus limiting stack growth
103 * from this point). It visits each superclass (if present) and superinterface
104 * in a depth-first manner, with callbacks to the ALGO class as each class is
105 * encountered (visit()), The algorithm can cut-off further exploration of a
106 * particular branch by returning 'false' from a visit() call.
107 *
108 * The ALGO class, must provide a visit() method, which each of which will be
109 * called once for each node in the inheritance tree during the iteration. In
110 * addition, it can provide a memory block via new_node_data(InstanceKlass*),
111 * which it can use for node-specific storage (and access via the
112 * current_data() and data_at_depth(int) methods).
113 *
114 * Bare minimum needed to be an ALGO class:
115 * class Algo : public HierarchyVisitor<Algo> {
116 * void* new_node_data(InstanceKlass* cls) { return NULL; }
117 * void free_node_data(void* data) { return; }
118 * bool visit() { return true; }
119 * };
120 */
121 template <class ALGO>
122 class HierarchyVisitor : StackObj {
123 private:
124
125 class Node : public ResourceObj {
126 public:
127 InstanceKlass* _class;
128 bool _super_was_visited;
129 int _interface_index;
130 void* _algorithm_data;
131
132 Node(InstanceKlass* cls, void* data, bool visit_super)
133 : _class(cls), _super_was_visited(!visit_super),
134 _interface_index(0), _algorithm_data(data) {}
135
136 int number_of_interfaces() { return _class->local_interfaces()->length(); }
137 int interface_index() { return _interface_index; }
138 void set_super_visited() { _super_was_visited = true; }
139 void increment_visited_interface() { ++_interface_index; }
140 void set_all_interfaces_visited() {
141 _interface_index = number_of_interfaces();
142 }
143 bool has_visited_super() { return _super_was_visited; }
144 bool has_visited_all_interfaces() {
145 return interface_index() >= number_of_interfaces();
146 }
147 InstanceKlass* interface_at(int index) {
148 return InstanceKlass::cast(_class->local_interfaces()->at(index));
149 }
150 InstanceKlass* next_super() { return _class->java_super(); }
151 InstanceKlass* next_interface() {
152 return interface_at(interface_index());
153 }
154 };
155
156 bool _cancelled;
157 GrowableArray<Node*> _path;
158
159 Node* current_top() const { return _path.top(); }
160 bool has_more_nodes() const { return !_path.is_empty(); }
161 void push(InstanceKlass* cls, void* data) {
162 assert(cls != NULL, "Requires a valid instance class");
163 Node* node = new Node(cls, data, has_super(cls));
164 _path.push(node);
165 }
166 void pop() { _path.pop(); }
167
168 void reset_iteration() {
169 _cancelled = false;
170 _path.clear();
171 }
172 bool is_cancelled() const { return _cancelled; }
173
174 // This code used to skip interface classes because their only
175 // superclass was j.l.Object which would be also covered by class
176 // superclass hierarchy walks. Now that the starting point can be
177 // an interface, we must ensure we catch j.l.Object as the super.
178 static bool has_super(InstanceKlass* cls) {
179 return cls->super() != NULL;
180 }
181
182 Node* node_at_depth(int i) const {
183 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
184 }
185
186 protected:
187
188 // Accessors available to the algorithm
189 int current_depth() const { return _path.length() - 1; }
190
191 InstanceKlass* class_at_depth(int i) {
192 Node* n = node_at_depth(i);
193 return n == NULL ? NULL : n->_class;
194 }
195 InstanceKlass* current_class() { return class_at_depth(0); }
196
197 void* data_at_depth(int i) {
198 Node* n = node_at_depth(i);
199 return n == NULL ? NULL : n->_algorithm_data;
200 }
201 void* current_data() { return data_at_depth(0); }
202
203 void cancel_iteration() { _cancelled = true; }
204
205 public:
206
207 void run(InstanceKlass* root) {
208 ALGO* algo = static_cast<ALGO*>(this);
209
210 reset_iteration();
211
212 void* algo_data = algo->new_node_data(root);
213 push(root, algo_data);
214 bool top_needs_visit = true;
215
216 do {
217 Node* top = current_top();
218 if (top_needs_visit) {
219 if (algo->visit() == false) {
220 // algorithm does not want to continue along this path. Arrange
221 // it so that this state is immediately popped off the stack
222 top->set_super_visited();
223 top->set_all_interfaces_visited();
224 }
225 top_needs_visit = false;
226 }
227
228 if (top->has_visited_super() && top->has_visited_all_interfaces()) {
229 algo->free_node_data(top->_algorithm_data);
230 pop();
231 } else {
232 InstanceKlass* next = NULL;
233 if (top->has_visited_super() == false) {
234 next = top->next_super();
235 top->set_super_visited();
236 } else {
237 next = top->next_interface();
238 top->increment_visited_interface();
239 }
240 assert(next != NULL, "Otherwise we shouldn't be here");
241 algo_data = algo->new_node_data(next);
242 push(next, algo_data);
243 top_needs_visit = true;
244 }
245 } while (!is_cancelled() && has_more_nodes());
246 }
247 };
248
249 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
250 private:
251 outputStream* _st;
252 public:
253 bool visit() {
254 InstanceKlass* cls = current_class();
255 streamIndentor si(_st, current_depth() * 2);
256 _st->indent().print_cr("%s", cls->name()->as_C_string());
257 return true;
258 }
259
260 void* new_node_data(InstanceKlass* cls) { return NULL; }
261 void free_node_data(void* data) { return; }
262
263 PrintHierarchy(outputStream* st = tty) : _st(st) {}
264 };
265
266 // Used to register InstanceKlass objects and all related metadata structures
267 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
268 // be deallocated by class redefinition while we're using them. The classes are
269 // de-registered when this goes out of scope.
270 //
271 // Once a class is registered, we need not bother with methodHandles or
272 // constantPoolHandles for it's associated metadata.
273 class KeepAliveRegistrar : public StackObj {
274 private:
275 Thread* _thread;
276 GrowableArray<ConstantPool*> _keep_alive;
277
278 public:
279 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
280 assert(thread == Thread::current(), "Must be current thread");
281 }
282
283 ~KeepAliveRegistrar() {
284 for (int i = _keep_alive.length() - 1; i >= 0; --i) {
285 ConstantPool* cp = _keep_alive.at(i);
286 int idx = _thread->metadata_handles()->find_from_end(cp);
287 assert(idx > 0, "Must be in the list");
288 _thread->metadata_handles()->remove_at(idx);
289 }
290 }
291
292 // Register a class as 'in-use' by the thread. It's fine to register a class
293 // multiple times (though perhaps inefficient)
294 void register_class(InstanceKlass* ik) {
295 ConstantPool* cp = ik->constants();
296 _keep_alive.push(cp);
297 _thread->metadata_handles()->push(cp);
298 }
299 };
300
301 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
302 private:
303 KeepAliveRegistrar* _registrar;
304
305 public:
306 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
307
308 void* new_node_data(InstanceKlass* cls) { return NULL; }
309 void free_node_data(void* data) { return; }
310
311 bool visit() {
312 _registrar->register_class(current_class());
313 return true;
314 }
315 };
316
317
318 // A method family contains a set of all methods that implement a single
319 // erased method. As members of the set are collected while walking over the
320 // hierarchy, they are tagged with a qualification state. The qualification
321 // state for an erased method is set to disqualified if there exists a path
322 // from the root of hierarchy to the method that contains an interleaving
323 // erased method defined in an interface.
324
325 class MethodFamily : public ResourceObj {
326 private:
327
328 GrowableArray<Pair<Method*,QualifiedState> > _members;
329 ResourceHashtable<Method*, int> _member_index;
330
331 Method* _selected_target; // Filled in later, if a unique target exists
332 Symbol* _exception_message; // If no unique target is found
333 Symbol* _exception_name; // If no unique target is found
334
335 bool contains_method(Method* method) {
336 int* lookup = _member_index.get(method);
337 return lookup != NULL;
338 }
339
340 void add_method(Method* method, QualifiedState state) {
341 Pair<Method*,QualifiedState> entry(method, state);
342 _member_index.put(method, _members.length());
343 _members.append(entry);
344 }
345
346 void disqualify_method(Method* method) {
347 int* index = _member_index.get(method);
348 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
349 _members.at(*index).second = DISQUALIFIED;
350 }
351
352 Symbol* generate_no_defaults_message(TRAPS) const;
353 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const;
354 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
355
356 public:
357
358 MethodFamily()
359 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {}
360
361 void set_target_if_empty(Method* m) {
362 if (_selected_target == NULL && !m->is_overpass()) {
363 _selected_target = m;
364 }
365 }
366
367 void record_qualified_method(Method* m) {
368 // If the method already exists in the set as qualified, this operation is
369 // redundant. If it already exists as disqualified, then we leave it as
370 // disqualfied. Thus we only add to the set if it's not already in the
371 // set.
372 if (!contains_method(m)) {
373 add_method(m, QUALIFIED);
374 }
375 }
376
377 void record_disqualified_method(Method* m) {
378 // If not in the set, add it as disqualified. If it's already in the set,
379 // then set the state to disqualified no matter what the previous state was.
380 if (!contains_method(m)) {
381 add_method(m, DISQUALIFIED);
382 } else {
383 disqualify_method(m);
384 }
385 }
386
387 bool has_target() const { return _selected_target != NULL; }
388 bool throws_exception() { return _exception_message != NULL; }
389
390 Method* get_selected_target() { return _selected_target; }
391 Symbol* get_exception_message() { return _exception_message; }
392 Symbol* get_exception_name() { return _exception_name; }
393
394 // Either sets the target or the exception error message
395 void determine_target(InstanceKlass* root, TRAPS) {
396 if (has_target() || throws_exception()) {
397 return;
398 }
399
400 // Qualified methods are maximally-specific methods
401 // These include public, instance concrete (=default) and abstract methods
402 GrowableArray<Method*> qualified_methods;
403 int num_defaults = 0;
404 int default_index = -1;
405 int qualified_index = -1;
406 for (int i = 0; i < _members.length(); ++i) {
407 Pair<Method*,QualifiedState> entry = _members.at(i);
408 if (entry.second == QUALIFIED) {
409 qualified_methods.append(entry.first);
410 qualified_index++;
411 if (entry.first->is_default_method()) {
412 num_defaults++;
413 default_index = qualified_index;
414
415 }
416 }
417 }
418
419 if (num_defaults == 0) {
420 // If the root klass has a static method with matching name and signature
421 // then do not generate an overpass method because it will hide the
422 // static method during resolution.
423 if (qualified_methods.length() == 0) {
424 _exception_message = generate_no_defaults_message(CHECK);
425 } else {
426 assert(root != NULL, "Null root class");
427 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK);
428 }
429 _exception_name = vmSymbols::java_lang_AbstractMethodError();
430
431 // If only one qualified method is default, select that
432 } else if (num_defaults == 1) {
433 _selected_target = qualified_methods.at(default_index);
434
435 } else if (num_defaults > 1) {
436 _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
437 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError();
438 LogTarget(Debug, defaultmethods) lt;
439 if (lt.is_enabled()) {
440 LogStream ls(lt);
441 _exception_message->print_value_on(&ls);
442 ls.cr();
443 }
444 }
445 }
446
447 bool contains_signature(Symbol* query) {
448 for (int i = 0; i < _members.length(); ++i) {
449 if (query == _members.at(i).first->signature()) {
450 return true;
451 }
452 }
453 return false;
454 }
455
456 void print_selected(outputStream* str, int indent) const {
457 assert(has_target(), "Should be called otherwise");
458 streamIndentor si(str, indent * 2);
459 str->indent().print("Selected method: ");
460 print_method(str, _selected_target);
461 Klass* method_holder = _selected_target->method_holder();
462 if (!method_holder->is_interface()) {
463 str->print(" : in superclass");
464 }
465 str->cr();
466 }
467
468 void print_exception(outputStream* str, int indent) {
469 assert(throws_exception(), "Should be called otherwise");
470 assert(_exception_name != NULL, "exception_name should be set");
471 streamIndentor si(str, indent * 2);
472 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string());
473 }
474 };
475
476 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
477 Symbol* s = SymbolTable::new_symbol("No qualifying defaults found", CHECK_NULL);
478 return s;
479 }
480
481 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const {
482 stringStream ss;
483 ss.print("Method ");
484 Symbol* name = method->name();
485 Symbol* signature = method->signature();
486 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length());
487 ss.print(".");
488 ss.write((const char*)name->bytes(), name->utf8_length());
489 ss.write((const char*)signature->bytes(), signature->utf8_length());
490 ss.print(" is abstract");
491 Symbol* s = SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
492 return s;
493 }
494
495 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
496 stringStream ss;
497 ss.print("Conflicting default methods:");
498 for (int i = 0; i < methods->length(); ++i) {
499 Method* method = methods->at(i);
500 Symbol* klass = method->klass_name();
501 Symbol* name = method->name();
502 ss.print(" ");
503 ss.write((const char*)klass->bytes(), klass->utf8_length());
504 ss.print(".");
505 ss.write((const char*)name->bytes(), name->utf8_length());
506 }
507 Symbol* s = SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
508 return s;
509 }
510
511
512 class StateRestorer;
513
514 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
515 // qualification state during hierarchy visitation, and applies that state
516 // when adding members to the MethodFamily
517 class StatefulMethodFamily : public ResourceObj {
518 friend class StateRestorer;
519 private:
520 QualifiedState _qualification_state;
521
522 void set_qualification_state(QualifiedState state) {
523 _qualification_state = state;
524 }
525
526 protected:
527 MethodFamily* _method_family;
528
529 public:
530 StatefulMethodFamily() {
531 _method_family = new MethodFamily();
532 _qualification_state = QUALIFIED;
533 }
534
535 StatefulMethodFamily(MethodFamily* mf) {
536 _method_family = mf;
537 _qualification_state = QUALIFIED;
538 }
539
540 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
541
542 MethodFamily* get_method_family() { return _method_family; }
543
544 StateRestorer* record_method_and_dq_further(Method* mo);
545 };
546
547 class StateRestorer : public PseudoScopeMark {
548 private:
549 StatefulMethodFamily* _method;
550 QualifiedState _state_to_restore;
551 public:
552 StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
553 : _method(dm), _state_to_restore(state) {}
554 ~StateRestorer() { destroy(); }
555 void restore_state() { _method->set_qualification_state(_state_to_restore); }
556 virtual void destroy() { restore_state(); }
557 };
558
559 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
560 StateRestorer* mark = new StateRestorer(this, _qualification_state);
561 if (_qualification_state == QUALIFIED) {
562 _method_family->record_qualified_method(mo);
563 } else {
564 _method_family->record_disqualified_method(mo);
565 }
566 // Everything found "above"??? this method in the hierarchy walk is set to
567 // disqualified
568 set_qualification_state(DISQUALIFIED);
569 return mark;
570 }
571
572 // Represents a location corresponding to a vtable slot for methods that
573 // neither the class nor any of it's ancestors provide an implementaion.
574 // Default methods may be present to fill this slot.
575 class EmptyVtableSlot : public ResourceObj {
576 private:
577 Symbol* _name;
578 Symbol* _signature;
579 int _size_of_parameters;
580 MethodFamily* _binding;
581
582 public:
583 EmptyVtableSlot(Method* method)
584 : _name(method->name()), _signature(method->signature()),
585 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
586
587 Symbol* name() const { return _name; }
588 Symbol* signature() const { return _signature; }
589 int size_of_parameters() const { return _size_of_parameters; }
590
591 void bind_family(MethodFamily* lm) { _binding = lm; }
592 bool is_bound() { return _binding != NULL; }
593 MethodFamily* get_binding() { return _binding; }
594
595 void print_on(outputStream* str) const {
596 print_slot(str, name(), signature());
597 }
598 };
599
600 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
601 bool found = false;
602 for (int j = 0; j < slots->length(); ++j) {
603 if (slots->at(j)->name() == m->name() &&
604 slots->at(j)->signature() == m->signature() ) {
605 found = true;
606 break;
607 }
608 }
609 return found;
610 }
611
612 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
613 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
614
615 assert(klass != NULL, "Must be valid class");
616
617 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
618
619 // All miranda methods are obvious candidates
620 for (int i = 0; i < mirandas->length(); ++i) {
621 Method* m = mirandas->at(i);
622 if (!already_in_vtable_slots(slots, m)) {
623 slots->append(new EmptyVtableSlot(m));
624 }
625 }
626
627 // Also any overpasses in our superclasses, that we haven't implemented.
628 // (can't use the vtable because it is not guaranteed to be initialized yet)
629 InstanceKlass* super = klass->java_super();
630 while (super != NULL) {
631 for (int i = 0; i < super->methods()->length(); ++i) {
632 Method* m = super->methods()->at(i);
633 if (m->is_overpass() || m->is_static()) {
634 // m is a method that would have been a miranda if not for the
635 // default method processing that occurred on behalf of our superclass,
636 // so it's a method we want to re-examine in this new context. That is,
637 // unless we have a real implementation of it in the current class.
638 Method* impl = klass->lookup_method(m->name(), m->signature());
639 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
640 if (!already_in_vtable_slots(slots, m)) {
641 slots->append(new EmptyVtableSlot(m));
642 }
643 }
644 }
645 }
646
647 // also any default methods in our superclasses
648 if (super->default_methods() != NULL) {
649 for (int i = 0; i < super->default_methods()->length(); ++i) {
650 Method* m = super->default_methods()->at(i);
651 // m is a method that would have been a miranda if not for the
652 // default method processing that occurred on behalf of our superclass,
653 // so it's a method we want to re-examine in this new context. That is,
654 // unless we have a real implementation of it in the current class.
655 Method* impl = klass->lookup_method(m->name(), m->signature());
656 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
657 if (!already_in_vtable_slots(slots, m)) {
658 slots->append(new EmptyVtableSlot(m));
659 }
660 }
661 }
662 }
663 super = super->java_super();
664 }
665
666 LogTarget(Debug, defaultmethods) lt;
667 if (lt.is_enabled()) {
668 lt.print("Slots that need filling:");
669 ResourceMark rm;
670 LogStream ls(lt);
671 streamIndentor si(&ls);
672 for (int i = 0; i < slots->length(); ++i) {
673 ls.indent();
674 slots->at(i)->print_on(&ls);
675 ls.cr();
676 }
677 }
678
679 return slots;
680 }
681
682 // Iterates over the superinterface type hierarchy looking for all methods
683 // with a specific erased signature.
684 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
685 private:
686 // Context data
687 Symbol* _method_name;
688 Symbol* _method_signature;
689 StatefulMethodFamily* _family;
690 bool _cur_class_is_interface;
691
692 public:
693 FindMethodsByErasedSig(Symbol* name, Symbol* signature, bool is_interf) :
694 _method_name(name), _method_signature(signature), _family(NULL),
695 _cur_class_is_interface(is_interf) {}
696
697 void get_discovered_family(MethodFamily** family) {
698 if (_family != NULL) {
699 *family = _family->get_method_family();
700 } else {
701 *family = NULL;
702 }
703 }
704
705 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
706 void free_node_data(void* node_data) {
707 PseudoScope::cast(node_data)->destroy();
708 }
709
710 // Find all methods on this hierarchy that match this
711 // method's erased (name, signature)
712 bool visit() {
713 PseudoScope* scope = PseudoScope::cast(current_data());
714 InstanceKlass* iklass = current_class();
715
716 Method* m = iklass->find_method(_method_name, _method_signature);
717 // Private interface methods are not candidates for default methods.
718 // invokespecial to private interface methods doesn't use default method logic.
719 // Private class methods are not candidates for default methods.
720 // Private methods do not override default methods, so need to perform
721 // default method inheritance without including private methods.
722 // The overpasses are your supertypes' errors, we do not include them.
723 // Non-public methods in java.lang.Object are not candidates for default
724 // methods.
725 // Future: take access controls into account for superclass methods
726 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() &&
727 (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) {
728 if (_family == NULL) {
729 _family = new StatefulMethodFamily();
730 }
731
732 if (iklass->is_interface()) {
733 StateRestorer* restorer = _family->record_method_and_dq_further(m);
734 scope->add_mark(restorer);
735 } else {
736 // This is the rule that methods in classes "win" (bad word) over
737 // methods in interfaces. This works because of single inheritance.
738 // Private methods in classes do not "win", they will be found
739 // first on searching, but overriding for invokevirtual needs
740 // to find default method candidates for the same signature
741 _family->set_target_if_empty(m);
742 }
743 }
744 return true;
745 }
746
747 };
748
749
750
751 static void create_defaults_and_exceptions(
752 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
753
754 static void generate_erased_defaults(
755 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
756 EmptyVtableSlot* slot, bool is_intf, TRAPS) {
757
758 // sets up a set of methods with the same exact erased signature
759 FindMethodsByErasedSig visitor(slot->name(), slot->signature(), is_intf);
760 visitor.run(klass);
761
762 MethodFamily* family;
763 visitor.get_discovered_family(&family);
764 if (family != NULL) {
765 family->determine_target(klass, CHECK);
766 slot->bind_family(family);
767 }
768 }
769
770 static void merge_in_new_methods(InstanceKlass* klass,
771 GrowableArray<Method*>* new_methods, TRAPS);
772 static void create_default_methods( InstanceKlass* klass,
773 GrowableArray<Method*>* new_methods, TRAPS);
774
775 // This is the guts of the default methods implementation. This is called just
776 // after the classfile has been parsed if some ancestor has default methods.
777 //
778 // First it finds any name/signature slots that need any implementation (either
779 // because they are miranda or a superclass's implementation is an overpass
780 // itself). For each slot, iterate over the hierarchy, to see if they contain a
781 // signature that matches the slot we are looking at.
782 //
783 // For each slot filled, we either record the default method candidate in the
784 // klass default_methods list or, only to handle exception cases, we create an
785 // overpass method that throws an exception and add it to the klass methods list.
786 // The JVM does not create bridges nor handle generic signatures here.
787 void DefaultMethods::generate_default_methods(
788 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
789 assert(klass != NULL, "invariant");
790
791 // This resource mark is the bound for all memory allocation that takes
792 // place during default method processing. After this goes out of scope,
793 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
794 // embedded resource mark under here as that memory can't be used outside
795 // whatever scope it's in.
796 ResourceMark rm(THREAD);
797
798 // Keep entire hierarchy alive for the duration of the computation
799 constantPoolHandle cp(THREAD, klass->constants());
800 KeepAliveRegistrar keepAlive(THREAD);
801 KeepAliveVisitor loadKeepAlive(&keepAlive);
802 loadKeepAlive.run(klass);
803
804 LogTarget(Debug, defaultmethods) lt;
805 if (lt.is_enabled()) {
806 ResourceMark rm;
807 lt.print("%s %s requires default method processing",
808 klass->is_interface() ? "Interface" : "Class",
809 klass->name()->as_klass_external_name());
810 LogStream ls(lt);
811 PrintHierarchy printer(&ls);
812 printer.run(klass);
813 }
814
815 GrowableArray<EmptyVtableSlot*>* empty_slots =
816 find_empty_vtable_slots(klass, mirandas, CHECK);
817
818 for (int i = 0; i < empty_slots->length(); ++i) {
819 EmptyVtableSlot* slot = empty_slots->at(i);
820 LogTarget(Debug, defaultmethods) lt;
821 if (lt.is_enabled()) {
822 LogStream ls(lt);
823 streamIndentor si(&ls, 2);
824 ls.indent().print("Looking for default methods for slot ");
825 slot->print_on(&ls);
826 ls.cr();
827 }
828 generate_erased_defaults(klass, empty_slots, slot, klass->is_interface(), CHECK);
829 }
830 log_debug(defaultmethods)("Creating defaults and overpasses...");
831 create_defaults_and_exceptions(empty_slots, klass, CHECK);
832 log_debug(defaultmethods)("Default method processing complete");
833 }
834
835 static int assemble_method_error(
836 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
837
838 Symbol* init = vmSymbols::object_initializer_name();
839 Symbol* sig = vmSymbols::string_void_signature();
840
841 BytecodeAssembler assem(buffer, cp);
842
843 assem._new(errorName);
844 assem.dup();
845 assem.load_string(message);
846 assem.invokespecial(errorName, init, sig);
847 assem.athrow();
848
849 return 3; // max stack size: [ exception, exception, string ]
850 }
851
852 static Method* new_method(
853 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
854 Symbol* sig, AccessFlags flags, int max_stack, int params,
855 ConstMethod::MethodType mt, TRAPS) {
856
857 address code_start = 0;
858 int code_length = 0;
859 InlineTableSizes sizes;
860
861 if (bytecodes != NULL && bytecodes->length() > 0) {
862 code_start = static_cast<address>(bytecodes->adr_at(0));
863 code_length = bytecodes->length();
864 }
865
866 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
867 code_length, flags, &sizes,
868 mt, CHECK_NULL);
869
870 m->set_constants(NULL); // This will get filled in later
871 m->set_name_index(cp->utf8(name));
872 m->set_signature_index(cp->utf8(sig));
873 ResultTypeFinder rtf(sig);
874 m->constMethod()->set_result_type(rtf.type());
875 m->set_size_of_parameters(params);
876 m->set_max_stack(max_stack);
877 m->set_max_locals(params);
878 m->constMethod()->set_stackmap_data(NULL);
879 m->set_code(code_start);
880
881 return m;
882 }
883
884 static void switchover_constant_pool(BytecodeConstantPool* bpool,
885 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
886
887 if (new_methods->length() > 0) {
888 ConstantPool* cp = bpool->create_constant_pool(CHECK);
889 if (cp != klass->constants()) {
890 // Copy resolved anonymous class into new constant pool.
891 if (klass->is_unsafe_anonymous()) {
892 cp->klass_at_put(klass->this_class_index(), klass);
893 }
894 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
895 klass->set_constants(cp);
896 cp->set_pool_holder(klass);
897
898 for (int i = 0; i < new_methods->length(); ++i) {
899 new_methods->at(i)->set_constants(cp);
900 }
901 for (int i = 0; i < klass->methods()->length(); ++i) {
902 Method* mo = klass->methods()->at(i);
903 mo->set_constants(cp);
904 }
905 }
906 }
907 }
908
909 // Create default_methods list for the current class.
910 // With the VM only processing erased signatures, the VM only
911 // creates an overpass in a conflict case or a case with no candidates.
912 // This allows virtual methods to override the overpass, but ensures
913 // that a local method search will find the exception rather than an abstract
914 // or default method that is not a valid candidate.
915 //
916 // Note that if overpass method are ever created that are not exception
917 // throwing methods then the loader constraint checking logic for vtable and
918 // itable creation needs to be changed to check loader constraints for the
919 // overpass methods that do not throw exceptions.
920 static void create_defaults_and_exceptions(
921 GrowableArray<EmptyVtableSlot*>* slots,
922 InstanceKlass* klass, TRAPS) {
923
924 GrowableArray<Method*> overpasses;
925 GrowableArray<Method*> defaults;
926 BytecodeConstantPool bpool(klass->constants());
927
928 for (int i = 0; i < slots->length(); ++i) {
929 EmptyVtableSlot* slot = slots->at(i);
930
931 if (slot->is_bound()) {
932 MethodFamily* method = slot->get_binding();
933 BytecodeBuffer buffer;
934
935 LogTarget(Debug, defaultmethods) lt;
936 if (lt.is_enabled()) {
937 ResourceMark rm(THREAD);
938 LogStream ls(lt);
939 ls.print("for slot: ");
940 slot->print_on(&ls);
941 ls.cr();
942 if (method->has_target()) {
943 method->print_selected(&ls, 1);
944 } else if (method->throws_exception()) {
945 method->print_exception(&ls, 1);
946 }
947 }
948
949 if (method->has_target()) {
950 Method* selected = method->get_selected_target();
951 if (selected->method_holder()->is_interface()) {
952 assert(!selected->is_private(), "pushing private interface method as default");
953 defaults.push(selected);
954 }
955 } else if (method->throws_exception()) {
956 int max_stack = assemble_method_error(&bpool, &buffer,
957 method->get_exception_name(), method->get_exception_message(), CHECK);
958 AccessFlags flags = accessFlags_from(
959 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
960 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
961 flags, max_stack, slot->size_of_parameters(),
962 ConstMethod::OVERPASS, CHECK);
963 // We push to the methods list:
964 // overpass methods which are exception throwing methods
965 if (m != NULL) {
966 overpasses.push(m);
967 }
968 }
969 }
970 }
971
972
973 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length());
974 log_debug(defaultmethods)("Created %d default methods", defaults.length());
975
976 if (overpasses.length() > 0) {
977 switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
978 merge_in_new_methods(klass, &overpasses, CHECK);
979 }
980 if (defaults.length() > 0) {
981 create_default_methods(klass, &defaults, CHECK);
982 }
983 }
984
985 static void create_default_methods( InstanceKlass* klass,
986 GrowableArray<Method*>* new_methods, TRAPS) {
987
988 int new_size = new_methods->length();
989 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>(
990 klass->class_loader_data(), new_size, NULL, CHECK);
991 for (int index = 0; index < new_size; index++ ) {
992 total_default_methods->at_put(index, new_methods->at(index));
993 }
994 Method::sort_methods(total_default_methods, false, false);
995
996 klass->set_default_methods(total_default_methods);
997 }
998
999 static void sort_methods(GrowableArray<Method*>* methods) {
1000 // Note that this must sort using the same key as is used for sorting
1001 // methods in InstanceKlass.
1002 bool sorted = true;
1003 for (int i = methods->length() - 1; i > 0; --i) {
1004 for (int j = 0; j < i; ++j) {
1005 Method* m1 = methods->at(j);
1006 Method* m2 = methods->at(j + 1);
1007 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
1008 methods->at_put(j, m2);
1009 methods->at_put(j + 1, m1);
1010 sorted = false;
1011 }
1012 }
1013 if (sorted) break;
1014 sorted = true;
1015 }
1016 #ifdef ASSERT
1017 uintptr_t prev = 0;
1018 for (int i = 0; i < methods->length(); ++i) {
1019 Method* mh = methods->at(i);
1020 uintptr_t nv = (uintptr_t)mh->name();
1021 assert(nv >= prev, "Incorrect overpass method ordering");
1022 prev = nv;
1023 }
1024 #endif
1025 }
1026
1027 static void merge_in_new_methods(InstanceKlass* klass,
1028 GrowableArray<Method*>* new_methods, TRAPS) {
1029
1030 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1031
1032 Array<Method*>* original_methods = klass->methods();
1033 Array<int>* original_ordering = klass->method_ordering();
1034 Array<int>* merged_ordering = Universe::the_empty_int_array();
1035
1036 int new_size = klass->methods()->length() + new_methods->length();
1037
1038 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1039 klass->class_loader_data(), new_size, NULL, CHECK);
1040
1041 // original_ordering might be empty if this class has no methods of its own
1042 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
1043 merged_ordering = MetadataFactory::new_array<int>(
1044 klass->class_loader_data(), new_size, CHECK);
1045 }
1046 int method_order_index = klass->methods()->length();
1047
1048 sort_methods(new_methods);
1049
1050 // Perform grand merge of existing methods and new methods
1051 int orig_idx = 0;
1052 int new_idx = 0;
1053
1054 for (int i = 0; i < new_size; ++i) {
1055 Method* orig_method = NULL;
1056 Method* new_method = NULL;
1057 if (orig_idx < original_methods->length()) {
1058 orig_method = original_methods->at(orig_idx);
1059 }
1060 if (new_idx < new_methods->length()) {
1061 new_method = new_methods->at(new_idx);
1062 }
1063
1064 if (orig_method != NULL &&
1065 (new_method == NULL || orig_method->name() < new_method->name())) {
1066 merged_methods->at_put(i, orig_method);
1067 original_methods->at_put(orig_idx, NULL);
1068 if (merged_ordering->length() > 0) {
1069 assert(original_ordering != NULL && original_ordering->length() > 0,
1070 "should have original order information for this method");
1071 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1072 }
1073 ++orig_idx;
1074 } else {
1075 merged_methods->at_put(i, new_method);
1076 if (merged_ordering->length() > 0) {
1077 merged_ordering->at_put(i, method_order_index++);
1078 }
1079 ++new_idx;
1080 }
1081 // update idnum for new location
1082 merged_methods->at(i)->set_method_idnum(i);
1083 merged_methods->at(i)->set_orig_method_idnum(i);
1084 }
1085
1086 // Verify correct order
1087 #ifdef ASSERT
1088 uintptr_t prev = 0;
1089 for (int i = 0; i < merged_methods->length(); ++i) {
1090 Method* mo = merged_methods->at(i);
1091 uintptr_t nv = (uintptr_t)mo->name();
1092 assert(nv >= prev, "Incorrect method ordering");
1093 prev = nv;
1094 }
1095 #endif
1096
1097 // Replace klass methods with new merged lists
1098 klass->set_methods(merged_methods);
1099 klass->set_initial_method_idnum(new_size);
1100 klass->set_method_ordering(merged_ordering);
1101
1102 // Free metadata
1103 ClassLoaderData* cld = klass->class_loader_data();
1104 if (original_methods->length() > 0) {
1105 MetadataFactory::free_array(cld, original_methods);
1106 }
1107 if (original_ordering != NULL && original_ordering->length() > 0) {
1108 MetadataFactory::free_array(cld, original_ordering);
1109 }
1110 }