1 /*
2 * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/bytecodeAssembler.hpp"
27 #include "classfile/defaultMethods.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "logging/log.hpp"
30 #include "logging/logStream.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/metadataFactory.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/signature.hpp"
36 #include "runtime/thread.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/klass.hpp"
39 #include "oops/method.hpp"
40 #include "utilities/accessFlags.hpp"
41 #include "utilities/exceptions.hpp"
42 #include "utilities/ostream.hpp"
43 #include "utilities/pair.hpp"
44 #include "utilities/resourceHash.hpp"
45
46 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
47
48 // Because we use an iterative algorithm when iterating over the type
49 // hierarchy, we can't use traditional scoped objects which automatically do
50 // cleanup in the destructor when the scope is exited. PseudoScope (and
51 // PseudoScopeMark) provides a similar functionality, but for when you want a
52 // scoped object in non-stack memory (such as in resource memory, as we do
53 // here). You've just got to remember to call 'destroy()' on the scope when
54 // leaving it (and marks have to be explicitly added).
55 class PseudoScopeMark : public ResourceObj {
56 public:
57 virtual void destroy() = 0;
58 };
59
60 class PseudoScope : public ResourceObj {
61 private:
62 GrowableArray<PseudoScopeMark*> _marks;
63 public:
64
65 static PseudoScope* cast(void* data) {
66 return static_cast<PseudoScope*>(data);
67 }
68
69 void add_mark(PseudoScopeMark* psm) {
70 _marks.append(psm);
71 }
72
73 void destroy() {
74 for (int i = 0; i < _marks.length(); ++i) {
75 _marks.at(i)->destroy();
76 }
77 }
78 };
79
80 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
81 str->print("%s%s", name->as_C_string(), signature->as_C_string());
82 }
83
84 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
85 if (with_class) {
86 str->print("%s.", mo->klass_name()->as_C_string());
87 }
88 print_slot(str, mo->name(), mo->signature());
89 }
90
91 /**
92 * Perform a depth-first iteration over the class hierarchy, applying
93 * algorithmic logic as it goes.
94 *
95 * This class is one half of the inheritance hierarchy analysis mechanism.
96 * It is meant to be used in conjunction with another class, the algorithm,
97 * which is indicated by the ALGO template parameter. This class can be
98 * paired with any algorithm class that provides the required methods.
99 *
100 * This class contains all the mechanics for iterating over the class hierarchy
101 * starting at a particular root, without recursing (thus limiting stack growth
102 * from this point). It visits each superclass (if present) and superinterface
103 * in a depth-first manner, with callbacks to the ALGO class as each class is
104 * encountered (visit()), The algorithm can cut-off further exploration of a
105 * particular branch by returning 'false' from a visit() call.
106 *
107 * The ALGO class, must provide a visit() method, which each of which will be
108 * called once for each node in the inheritance tree during the iteration. In
109 * addition, it can provide a memory block via new_node_data(InstanceKlass*),
110 * which it can use for node-specific storage (and access via the
111 * current_data() and data_at_depth(int) methods).
112 *
113 * Bare minimum needed to be an ALGO class:
114 * class Algo : public HierarchyVisitor<Algo> {
115 * void* new_node_data(InstanceKlass* cls) { return NULL; }
116 * void free_node_data(void* data) { return; }
117 * bool visit() { return true; }
118 * };
119 */
120 template <class ALGO>
121 class HierarchyVisitor : StackObj {
122 private:
123
124 class Node : public ResourceObj {
125 public:
126 InstanceKlass* _class;
127 bool _super_was_visited;
128 int _interface_index;
129 void* _algorithm_data;
130
131 Node(InstanceKlass* cls, void* data, bool visit_super)
132 : _class(cls), _super_was_visited(!visit_super),
133 _interface_index(0), _algorithm_data(data) {}
134
135 int number_of_interfaces() { return _class->local_interfaces()->length(); }
136 int interface_index() { return _interface_index; }
137 void set_super_visited() { _super_was_visited = true; }
138 void increment_visited_interface() { ++_interface_index; }
139 void set_all_interfaces_visited() {
140 _interface_index = number_of_interfaces();
141 }
142 bool has_visited_super() { return _super_was_visited; }
143 bool has_visited_all_interfaces() {
144 return interface_index() >= number_of_interfaces();
145 }
146 InstanceKlass* interface_at(int index) {
147 return InstanceKlass::cast(_class->local_interfaces()->at(index));
148 }
149 InstanceKlass* next_super() { return _class->java_super(); }
150 InstanceKlass* next_interface() {
151 return interface_at(interface_index());
152 }
153 };
154
155 bool _cancelled;
156 GrowableArray<Node*> _path;
157
158 Node* current_top() const { return _path.top(); }
159 bool has_more_nodes() const { return !_path.is_empty(); }
160 void push(InstanceKlass* cls, void* data) {
161 assert(cls != NULL, "Requires a valid instance class");
162 Node* node = new Node(cls, data, has_super(cls));
163 _path.push(node);
164 }
165 void pop() { _path.pop(); }
166
167 void reset_iteration() {
168 _cancelled = false;
169 _path.clear();
170 }
171 bool is_cancelled() const { return _cancelled; }
172
173 // This code used to skip interface classes because their only
174 // superclass was j.l.Object which would be also covered by class
175 // superclass hierarchy walks. Now that the starting point can be
176 // an interface, we must ensure we catch j.l.Object as the super.
177 static bool has_super(InstanceKlass* cls) {
178 return cls->super() != NULL;
179 }
180
181 Node* node_at_depth(int i) const {
182 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
183 }
184
185 protected:
186
187 // Accessors available to the algorithm
188 int current_depth() const { return _path.length() - 1; }
189
190 InstanceKlass* class_at_depth(int i) {
191 Node* n = node_at_depth(i);
192 return n == NULL ? NULL : n->_class;
193 }
194 InstanceKlass* current_class() { return class_at_depth(0); }
195
196 void* data_at_depth(int i) {
197 Node* n = node_at_depth(i);
198 return n == NULL ? NULL : n->_algorithm_data;
199 }
200 void* current_data() { return data_at_depth(0); }
201
202 void cancel_iteration() { _cancelled = true; }
203
204 public:
205
206 void run(InstanceKlass* root) {
207 ALGO* algo = static_cast<ALGO*>(this);
208
209 reset_iteration();
210
211 void* algo_data = algo->new_node_data(root);
212 push(root, algo_data);
213 bool top_needs_visit = true;
214
215 do {
216 Node* top = current_top();
217 if (top_needs_visit) {
218 if (algo->visit() == false) {
219 // algorithm does not want to continue along this path. Arrange
220 // it so that this state is immediately popped off the stack
221 top->set_super_visited();
222 top->set_all_interfaces_visited();
223 }
224 top_needs_visit = false;
225 }
226
227 if (top->has_visited_super() && top->has_visited_all_interfaces()) {
228 algo->free_node_data(top->_algorithm_data);
229 pop();
230 } else {
231 InstanceKlass* next = NULL;
232 if (top->has_visited_super() == false) {
233 next = top->next_super();
234 top->set_super_visited();
235 } else {
236 next = top->next_interface();
237 top->increment_visited_interface();
238 }
239 assert(next != NULL, "Otherwise we shouldn't be here");
240 algo_data = algo->new_node_data(next);
241 push(next, algo_data);
242 top_needs_visit = true;
243 }
244 } while (!is_cancelled() && has_more_nodes());
245 }
246 };
247
248 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
249 private:
250 outputStream* _st;
251 public:
252 bool visit() {
253 InstanceKlass* cls = current_class();
254 streamIndentor si(_st, current_depth() * 2);
255 _st->indent().print_cr("%s", cls->name()->as_C_string());
256 return true;
257 }
258
259 void* new_node_data(InstanceKlass* cls) { return NULL; }
260 void free_node_data(void* data) { return; }
261
262 PrintHierarchy(outputStream* st = tty) : _st(st) {}
263 };
264
265 // Used to register InstanceKlass objects and all related metadata structures
266 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
267 // be deallocated by class redefinition while we're using them. The classes are
268 // de-registered when this goes out of scope.
269 //
270 // Once a class is registered, we need not bother with methodHandles or
271 // constantPoolHandles for it's associated metadata.
272 class KeepAliveRegistrar : public StackObj {
273 private:
274 Thread* _thread;
275 GrowableArray<ConstantPool*> _keep_alive;
276
277 public:
278 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
279 assert(thread == Thread::current(), "Must be current thread");
280 }
281
282 ~KeepAliveRegistrar() {
283 for (int i = _keep_alive.length() - 1; i >= 0; --i) {
284 ConstantPool* cp = _keep_alive.at(i);
285 int idx = _thread->metadata_handles()->find_from_end(cp);
286 assert(idx > 0, "Must be in the list");
287 _thread->metadata_handles()->remove_at(idx);
288 }
289 }
290
291 // Register a class as 'in-use' by the thread. It's fine to register a class
292 // multiple times (though perhaps inefficient)
293 void register_class(InstanceKlass* ik) {
294 ConstantPool* cp = ik->constants();
295 _keep_alive.push(cp);
296 _thread->metadata_handles()->push(cp);
297 }
298 };
299
300 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
301 private:
302 KeepAliveRegistrar* _registrar;
303
304 public:
305 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
306
307 void* new_node_data(InstanceKlass* cls) { return NULL; }
308 void free_node_data(void* data) { return; }
309
310 bool visit() {
311 _registrar->register_class(current_class());
312 return true;
313 }
314 };
315
316
317 // A method family contains a set of all methods that implement a single
318 // erased method. As members of the set are collected while walking over the
319 // hierarchy, they are tagged with a qualification state. The qualification
320 // state for an erased method is set to disqualified if there exists a path
321 // from the root of hierarchy to the method that contains an interleaving
322 // erased method defined in an interface.
323
324 class MethodFamily : public ResourceObj {
325 private:
326
327 GrowableArray<Pair<Method*,QualifiedState> > _members;
328 ResourceHashtable<Method*, int> _member_index;
329
330 Method* _selected_target; // Filled in later, if a unique target exists
331 Symbol* _exception_message; // If no unique target is found
332 Symbol* _exception_name; // If no unique target is found
333
334 bool contains_method(Method* method) {
335 int* lookup = _member_index.get(method);
336 return lookup != NULL;
337 }
338
339 void add_method(Method* method, QualifiedState state) {
340 Pair<Method*,QualifiedState> entry(method, state);
341 _member_index.put(method, _members.length());
342 _members.append(entry);
343 }
344
345 void disqualify_method(Method* method) {
346 int* index = _member_index.get(method);
347 guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
348 _members.at(*index).second = DISQUALIFIED;
349 }
350
351 Symbol* generate_no_defaults_message(TRAPS) const;
352 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const;
353 Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
354
355 public:
356
357 MethodFamily()
358 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {}
359
360 void set_target_if_empty(Method* m) {
361 if (_selected_target == NULL && !m->is_overpass()) {
362 _selected_target = m;
363 }
364 }
365
366 void record_qualified_method(Method* m) {
367 // If the method already exists in the set as qualified, this operation is
368 // redundant. If it already exists as disqualified, then we leave it as
369 // disqualfied. Thus we only add to the set if it's not already in the
370 // set.
371 if (!contains_method(m)) {
372 add_method(m, QUALIFIED);
373 }
374 }
375
376 void record_disqualified_method(Method* m) {
377 // If not in the set, add it as disqualified. If it's already in the set,
378 // then set the state to disqualified no matter what the previous state was.
379 if (!contains_method(m)) {
380 add_method(m, DISQUALIFIED);
381 } else {
382 disqualify_method(m);
383 }
384 }
385
386 bool has_target() const { return _selected_target != NULL; }
387 bool throws_exception() { return _exception_message != NULL; }
388
389 Method* get_selected_target() { return _selected_target; }
390 Symbol* get_exception_message() { return _exception_message; }
391 Symbol* get_exception_name() { return _exception_name; }
392
393 // Either sets the target or the exception error message
394 void determine_target(InstanceKlass* root, TRAPS) {
395 if (has_target() || throws_exception()) {
396 return;
397 }
398
399 // Qualified methods are maximally-specific methods
400 // These include public, instance concrete (=default) and abstract methods
401 GrowableArray<Method*> qualified_methods;
402 int num_defaults = 0;
403 int default_index = -1;
404 int qualified_index = -1;
405 for (int i = 0; i < _members.length(); ++i) {
406 Pair<Method*,QualifiedState> entry = _members.at(i);
407 if (entry.second == QUALIFIED) {
408 qualified_methods.append(entry.first);
409 qualified_index++;
410 if (entry.first->is_default_method()) {
411 num_defaults++;
412 default_index = qualified_index;
413
414 }
415 }
416 }
417
418 if (num_defaults == 0) {
419 // If the root klass has a static method with matching name and signature
420 // then do not generate an overpass method because it will hide the
421 // static method during resolution.
422 if (qualified_methods.length() == 0) {
423 _exception_message = generate_no_defaults_message(CHECK);
424 } else {
425 assert(root != NULL, "Null root class");
426 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK);
427 }
428 _exception_name = vmSymbols::java_lang_AbstractMethodError();
429
430 // If only one qualified method is default, select that
431 } else if (num_defaults == 1) {
432 _selected_target = qualified_methods.at(default_index);
433
434 } else if (num_defaults > 1) {
435 _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
436 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError();
437 LogTarget(Debug, defaultmethods) lt;
438 if (lt.is_enabled()) {
439 LogStream ls(lt);
440 _exception_message->print_value_on(&ls);
441 ls.cr();
442 }
443 }
444 }
445
446 bool contains_signature(Symbol* query) {
447 for (int i = 0; i < _members.length(); ++i) {
448 if (query == _members.at(i).first->signature()) {
449 return true;
450 }
451 }
452 return false;
453 }
454
455 void print_selected(outputStream* str, int indent) const {
456 assert(has_target(), "Should be called otherwise");
457 streamIndentor si(str, indent * 2);
458 str->indent().print("Selected method: ");
459 print_method(str, _selected_target);
460 Klass* method_holder = _selected_target->method_holder();
461 if (!method_holder->is_interface()) {
462 str->print(" : in superclass");
463 }
464 str->cr();
465 }
466
467 void print_exception(outputStream* str, int indent) {
468 assert(throws_exception(), "Should be called otherwise");
469 assert(_exception_name != NULL, "exception_name should be set");
470 streamIndentor si(str, indent * 2);
471 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string());
472 }
473 };
474
475 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
476 return SymbolTable::new_symbol("No qualifying defaults found", THREAD);
477 }
478
479 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const {
480 stringStream ss;
481 ss.print("Method ");
482 Symbol* name = method->name();
483 Symbol* signature = method->signature();
484 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length());
485 ss.print(".");
486 ss.write((const char*)name->bytes(), name->utf8_length());
487 ss.write((const char*)signature->bytes(), signature->utf8_length());
488 ss.print(" is abstract");
489 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD);
490 }
491
492 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
493 stringStream ss;
494 ss.print("Conflicting default methods:");
495 for (int i = 0; i < methods->length(); ++i) {
496 Method* method = methods->at(i);
497 Symbol* klass = method->klass_name();
498 Symbol* name = method->name();
499 ss.print(" ");
500 ss.write((const char*)klass->bytes(), klass->utf8_length());
501 ss.print(".");
502 ss.write((const char*)name->bytes(), name->utf8_length());
503 }
504 return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD);
505 }
506
507
508 class StateRestorer;
509
510 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
511 // qualification state during hierarchy visitation, and applies that state
512 // when adding members to the MethodFamily
513 class StatefulMethodFamily : public ResourceObj {
514 friend class StateRestorer;
515 private:
516 QualifiedState _qualification_state;
517
518 void set_qualification_state(QualifiedState state) {
519 _qualification_state = state;
520 }
521
522 protected:
523 MethodFamily* _method_family;
524
525 public:
526 StatefulMethodFamily() {
527 _method_family = new MethodFamily();
528 _qualification_state = QUALIFIED;
529 }
530
531 StatefulMethodFamily(MethodFamily* mf) {
532 _method_family = mf;
533 _qualification_state = QUALIFIED;
534 }
535
536 void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
537
538 MethodFamily* get_method_family() { return _method_family; }
539
540 StateRestorer* record_method_and_dq_further(Method* mo);
541 };
542
543 class StateRestorer : public PseudoScopeMark {
544 private:
545 StatefulMethodFamily* _method;
546 QualifiedState _state_to_restore;
547 public:
548 StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
549 : _method(dm), _state_to_restore(state) {}
550 ~StateRestorer() { destroy(); }
551 void restore_state() { _method->set_qualification_state(_state_to_restore); }
552 virtual void destroy() { restore_state(); }
553 };
554
555 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
556 StateRestorer* mark = new StateRestorer(this, _qualification_state);
557 if (_qualification_state == QUALIFIED) {
558 _method_family->record_qualified_method(mo);
559 } else {
560 _method_family->record_disqualified_method(mo);
561 }
562 // Everything found "above"??? this method in the hierarchy walk is set to
563 // disqualified
564 set_qualification_state(DISQUALIFIED);
565 return mark;
566 }
567
568 // Represents a location corresponding to a vtable slot for methods that
569 // neither the class nor any of it's ancestors provide an implementaion.
570 // Default methods may be present to fill this slot.
571 class EmptyVtableSlot : public ResourceObj {
572 private:
573 Symbol* _name;
574 Symbol* _signature;
575 int _size_of_parameters;
576 MethodFamily* _binding;
577
578 public:
579 EmptyVtableSlot(Method* method)
580 : _name(method->name()), _signature(method->signature()),
581 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
582
583 Symbol* name() const { return _name; }
584 Symbol* signature() const { return _signature; }
585 int size_of_parameters() const { return _size_of_parameters; }
586
587 void bind_family(MethodFamily* lm) { _binding = lm; }
588 bool is_bound() { return _binding != NULL; }
589 MethodFamily* get_binding() { return _binding; }
590
591 void print_on(outputStream* str) const {
592 print_slot(str, name(), signature());
593 }
594 };
595
596 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
597 bool found = false;
598 for (int j = 0; j < slots->length(); ++j) {
599 if (slots->at(j)->name() == m->name() &&
600 slots->at(j)->signature() == m->signature() ) {
601 found = true;
602 break;
603 }
604 }
605 return found;
606 }
607
608 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
609 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
610
611 assert(klass != NULL, "Must be valid class");
612
613 GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
614
615 // All miranda methods are obvious candidates
616 for (int i = 0; i < mirandas->length(); ++i) {
617 Method* m = mirandas->at(i);
618 if (!already_in_vtable_slots(slots, m)) {
619 slots->append(new EmptyVtableSlot(m));
620 }
621 }
622
623 // Also any overpasses in our superclasses, that we haven't implemented.
624 // (can't use the vtable because it is not guaranteed to be initialized yet)
625 InstanceKlass* super = klass->java_super();
626 while (super != NULL) {
627 for (int i = 0; i < super->methods()->length(); ++i) {
628 Method* m = super->methods()->at(i);
629 if (m->is_overpass() || m->is_static()) {
630 // m is a method that would have been a miranda if not for the
631 // default method processing that occurred on behalf of our superclass,
632 // so it's a method we want to re-examine in this new context. That is,
633 // unless we have a real implementation of it in the current class.
634 Method* impl = klass->lookup_method(m->name(), m->signature());
635 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
636 if (!already_in_vtable_slots(slots, m)) {
637 slots->append(new EmptyVtableSlot(m));
638 }
639 }
640 }
641 }
642
643 // also any default methods in our superclasses
644 if (super->default_methods() != NULL) {
645 for (int i = 0; i < super->default_methods()->length(); ++i) {
646 Method* m = super->default_methods()->at(i);
647 // m is a method that would have been a miranda if not for the
648 // default method processing that occurred on behalf of our superclass,
649 // so it's a method we want to re-examine in this new context. That is,
650 // unless we have a real implementation of it in the current class.
651 Method* impl = klass->lookup_method(m->name(), m->signature());
652 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
653 if (!already_in_vtable_slots(slots, m)) {
654 slots->append(new EmptyVtableSlot(m));
655 }
656 }
657 }
658 }
659 super = super->java_super();
660 }
661
662 LogTarget(Debug, defaultmethods) lt;
663 if (lt.is_enabled()) {
664 lt.print("Slots that need filling:");
665 ResourceMark rm;
666 LogStream ls(lt);
667 streamIndentor si(&ls);
668 for (int i = 0; i < slots->length(); ++i) {
669 ls.indent();
670 slots->at(i)->print_on(&ls);
671 ls.cr();
672 }
673 }
674
675 return slots;
676 }
677
678 // Iterates over the superinterface type hierarchy looking for all methods
679 // with a specific erased signature.
680 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
681 private:
682 // Context data
683 Symbol* _method_name;
684 Symbol* _method_signature;
685 StatefulMethodFamily* _family;
686
687 public:
688 FindMethodsByErasedSig(Symbol* name, Symbol* signature) :
689 _method_name(name), _method_signature(signature),
690 _family(NULL) {}
691
692 void get_discovered_family(MethodFamily** family) {
693 if (_family != NULL) {
694 *family = _family->get_method_family();
695 } else {
696 *family = NULL;
697 }
698 }
699
700 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
701 void free_node_data(void* node_data) {
702 PseudoScope::cast(node_data)->destroy();
703 }
704
705 // Find all methods on this hierarchy that match this
706 // method's erased (name, signature)
707 bool visit() {
708 PseudoScope* scope = PseudoScope::cast(current_data());
709 InstanceKlass* iklass = current_class();
710
711 Method* m = iklass->find_method(_method_name, _method_signature);
712 // private interface methods are not candidates for default methods
713 // invokespecial to private interface methods doesn't use default method logic
714 // private class methods are not candidates for default methods,
715 // private methods do not override default methods, so need to perform
716 // default method inheritance without including private methods
717 // The overpasses are your supertypes' errors, we do not include them
718 // future: take access controls into account for superclass methods
719 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private()) {
720 if (_family == NULL) {
721 _family = new StatefulMethodFamily();
722 }
723
724 if (iklass->is_interface()) {
725 StateRestorer* restorer = _family->record_method_and_dq_further(m);
726 scope->add_mark(restorer);
727 } else {
728 // This is the rule that methods in classes "win" (bad word) over
729 // methods in interfaces. This works because of single inheritance
730 // private methods in classes do not "win", they will be found
731 // first on searching, but overriding for invokevirtual needs
732 // to find default method candidates for the same signature
733 _family->set_target_if_empty(m);
734 }
735 }
736 return true;
737 }
738
739 };
740
741
742
743 static void create_defaults_and_exceptions(
744 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
745
746 static void generate_erased_defaults(
747 InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
748 EmptyVtableSlot* slot, TRAPS) {
749
750 // sets up a set of methods with the same exact erased signature
751 FindMethodsByErasedSig visitor(slot->name(), slot->signature());
752 visitor.run(klass);
753
754 MethodFamily* family;
755 visitor.get_discovered_family(&family);
756 if (family != NULL) {
757 family->determine_target(klass, CHECK);
758 slot->bind_family(family);
759 }
760 }
761
762 static void merge_in_new_methods(InstanceKlass* klass,
763 GrowableArray<Method*>* new_methods, TRAPS);
764 static void create_default_methods( InstanceKlass* klass,
765 GrowableArray<Method*>* new_methods, TRAPS);
766
767 // This is the guts of the default methods implementation. This is called just
768 // after the classfile has been parsed if some ancestor has default methods.
769 //
770 // First it finds any name/signature slots that need any implementation (either
771 // because they are miranda or a superclass's implementation is an overpass
772 // itself). For each slot, iterate over the hierarchy, to see if they contain a
773 // signature that matches the slot we are looking at.
774 //
775 // For each slot filled, we either record the default method candidate in the
776 // klass default_methods list or, only to handle exception cases, we create an
777 // overpass method that throws an exception and add it to the klass methods list.
778 // The JVM does not create bridges nor handle generic signatures here.
779 void DefaultMethods::generate_default_methods(
780 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
781 assert(klass != NULL, "invariant");
782
783 // This resource mark is the bound for all memory allocation that takes
784 // place during default method processing. After this goes out of scope,
785 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
786 // embedded resource mark under here as that memory can't be used outside
787 // whatever scope it's in.
788 ResourceMark rm(THREAD);
789
790 // Keep entire hierarchy alive for the duration of the computation
791 constantPoolHandle cp(THREAD, klass->constants());
792 KeepAliveRegistrar keepAlive(THREAD);
793 KeepAliveVisitor loadKeepAlive(&keepAlive);
794 loadKeepAlive.run(klass);
795
796 LogTarget(Debug, defaultmethods) lt;
797 if (lt.is_enabled()) {
798 ResourceMark rm;
799 lt.print("%s %s requires default method processing",
800 klass->is_interface() ? "Interface" : "Class",
801 klass->name()->as_klass_external_name());
802 LogStream ls(lt);
803 PrintHierarchy printer(&ls);
804 printer.run(klass);
805 }
806
807 GrowableArray<EmptyVtableSlot*>* empty_slots =
808 find_empty_vtable_slots(klass, mirandas, CHECK);
809
810 for (int i = 0; i < empty_slots->length(); ++i) {
811 EmptyVtableSlot* slot = empty_slots->at(i);
812 LogTarget(Debug, defaultmethods) lt;
813 if (lt.is_enabled()) {
814 LogStream ls(lt);
815 streamIndentor si(&ls, 2);
816 ls.indent().print("Looking for default methods for slot ");
817 slot->print_on(&ls);
818 ls.cr();
819 }
820 generate_erased_defaults(klass, empty_slots, slot, CHECK);
821 }
822 log_debug(defaultmethods)("Creating defaults and overpasses...");
823 create_defaults_and_exceptions(empty_slots, klass, CHECK);
824 log_debug(defaultmethods)("Default method processing complete");
825 }
826
827 static int assemble_method_error(
828 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
829
830 Symbol* init = vmSymbols::object_initializer_name();
831 Symbol* sig = vmSymbols::string_void_signature();
832
833 BytecodeAssembler assem(buffer, cp);
834
835 assem._new(errorName);
836 assem.dup();
837 assem.load_string(message);
838 assem.invokespecial(errorName, init, sig);
839 assem.athrow();
840
841 return 3; // max stack size: [ exception, exception, string ]
842 }
843
844 static Method* new_method(
845 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
846 Symbol* sig, AccessFlags flags, int max_stack, int params,
847 ConstMethod::MethodType mt, TRAPS) {
848
849 address code_start = 0;
850 int code_length = 0;
851 InlineTableSizes sizes;
852
853 if (bytecodes != NULL && bytecodes->length() > 0) {
854 code_start = static_cast<address>(bytecodes->adr_at(0));
855 code_length = bytecodes->length();
856 }
857
858 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
859 code_length, flags, &sizes,
860 mt, CHECK_NULL);
861
862 m->set_constants(NULL); // This will get filled in later
863 m->set_name_index(cp->utf8(name));
864 m->set_signature_index(cp->utf8(sig));
865 ResultTypeFinder rtf(sig);
866 m->constMethod()->set_result_type(rtf.type());
867 m->set_size_of_parameters(params);
868 m->set_max_stack(max_stack);
869 m->set_max_locals(params);
870 m->constMethod()->set_stackmap_data(NULL);
871 m->set_code(code_start);
872
873 return m;
874 }
875
876 static void switchover_constant_pool(BytecodeConstantPool* bpool,
877 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
878
879 if (new_methods->length() > 0) {
880 ConstantPool* cp = bpool->create_constant_pool(CHECK);
881 if (cp != klass->constants()) {
882 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
883 klass->set_constants(cp);
884 cp->set_pool_holder(klass);
885
886 for (int i = 0; i < new_methods->length(); ++i) {
887 new_methods->at(i)->set_constants(cp);
888 }
889 for (int i = 0; i < klass->methods()->length(); ++i) {
890 Method* mo = klass->methods()->at(i);
891 mo->set_constants(cp);
892 }
893 }
894 }
895 }
896
897 // Create default_methods list for the current class.
898 // With the VM only processing erased signatures, the VM only
899 // creates an overpass in a conflict case or a case with no candidates.
900 // This allows virtual methods to override the overpass, but ensures
901 // that a local method search will find the exception rather than an abstract
902 // or default method that is not a valid candidate.
903 //
904 // Note that if overpass method are ever created that are not exception
905 // throwing methods then the loader constraint checking logic for vtable and
906 // itable creation needs to be changed to check loader constraints for the
907 // overpass methods that do not throw exceptions.
908 static void create_defaults_and_exceptions(
909 GrowableArray<EmptyVtableSlot*>* slots,
910 InstanceKlass* klass, TRAPS) {
911
912 GrowableArray<Method*> overpasses;
913 GrowableArray<Method*> defaults;
914 BytecodeConstantPool bpool(klass->constants());
915
916 for (int i = 0; i < slots->length(); ++i) {
917 EmptyVtableSlot* slot = slots->at(i);
918
919 if (slot->is_bound()) {
920 MethodFamily* method = slot->get_binding();
921 BytecodeBuffer buffer;
922
923 LogTarget(Debug, defaultmethods) lt;
924 if (lt.is_enabled()) {
925 ResourceMark rm(THREAD);
926 LogStream ls(lt);
927 ls.print("for slot: ");
928 slot->print_on(&ls);
929 ls.cr();
930 if (method->has_target()) {
931 method->print_selected(&ls, 1);
932 } else if (method->throws_exception()) {
933 method->print_exception(&ls, 1);
934 }
935 }
936
937 if (method->has_target()) {
938 Method* selected = method->get_selected_target();
939 if (selected->method_holder()->is_interface()) {
940 assert(!selected->is_private(), "pushing private interface method as default");
941 defaults.push(selected);
942 }
943 } else if (method->throws_exception()) {
944 int max_stack = assemble_method_error(&bpool, &buffer,
945 method->get_exception_name(), method->get_exception_message(), CHECK);
946 AccessFlags flags = accessFlags_from(
947 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
948 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
949 flags, max_stack, slot->size_of_parameters(),
950 ConstMethod::OVERPASS, CHECK);
951 // We push to the methods list:
952 // overpass methods which are exception throwing methods
953 if (m != NULL) {
954 overpasses.push(m);
955 }
956 }
957 }
958 }
959
960
961 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length());
962 log_debug(defaultmethods)("Created %d default methods", defaults.length());
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 // original_ordering might be empty if this class has no methods of its own
1030 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
1031 merged_ordering = MetadataFactory::new_array<int>(
1032 klass->class_loader_data(), new_size, CHECK);
1033 }
1034 int method_order_index = klass->methods()->length();
1035
1036 sort_methods(new_methods);
1037
1038 // Perform grand merge of existing methods and new methods
1039 int orig_idx = 0;
1040 int new_idx = 0;
1041
1042 for (int i = 0; i < new_size; ++i) {
1043 Method* orig_method = NULL;
1044 Method* new_method = NULL;
1045 if (orig_idx < original_methods->length()) {
1046 orig_method = original_methods->at(orig_idx);
1047 }
1048 if (new_idx < new_methods->length()) {
1049 new_method = new_methods->at(new_idx);
1050 }
1051
1052 if (orig_method != NULL &&
1053 (new_method == NULL || orig_method->name() < new_method->name())) {
1054 merged_methods->at_put(i, orig_method);
1055 original_methods->at_put(orig_idx, NULL);
1056 if (merged_ordering->length() > 0) {
1057 assert(original_ordering != NULL && original_ordering->length() > 0,
1058 "should have original order information for this method");
1059 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1060 }
1061 ++orig_idx;
1062 } else {
1063 merged_methods->at_put(i, new_method);
1064 if (merged_ordering->length() > 0) {
1065 merged_ordering->at_put(i, method_order_index++);
1066 }
1067 ++new_idx;
1068 }
1069 // update idnum for new location
1070 merged_methods->at(i)->set_method_idnum(i);
1071 merged_methods->at(i)->set_orig_method_idnum(i);
1072 }
1073
1074 // Verify correct order
1075 #ifdef ASSERT
1076 uintptr_t prev = 0;
1077 for (int i = 0; i < merged_methods->length(); ++i) {
1078 Method* mo = merged_methods->at(i);
1079 uintptr_t nv = (uintptr_t)mo->name();
1080 assert(nv >= prev, "Incorrect method ordering");
1081 prev = nv;
1082 }
1083 #endif
1084
1085 // Replace klass methods with new merged lists
1086 klass->set_methods(merged_methods);
1087 klass->set_initial_method_idnum(new_size);
1088 klass->set_method_ordering(merged_ordering);
1089
1090 // Free metadata
1091 ClassLoaderData* cld = klass->class_loader_data();
1092 if (original_methods->length() > 0) {
1093 MetadataFactory::free_array(cld, original_methods);
1094 }
1095 if (original_ordering != NULL && original_ordering->length() > 0) {
1096 MetadataFactory::free_array(cld, original_ordering);
1097 }
1098 }