1 /*
2 * Copyright (c) 2012, 2019, 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 _visited_object;
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 if (cls == SystemDictionary::Object_klass()) {
165 _visited_object = true;
166 }
167 _path.push(node);
168 }
169 void pop() { _path.pop(); }
170
171 void reset_iteration() {
172 _path.clear();
173 }
174
175 // This code used to skip interface classes because their only
176 // superclass was j.l.Object which would be also covered by class
177 // superclass hierarchy walks. Now that the starting point can be
178 // an interface, we must ensure we catch j.l.Object as the super.
179 bool has_super(InstanceKlass* cls) {
180 return cls->super() != NULL && (!_visited_object || !cls->is_interface());
181 }
182
183 Node* node_at_depth(int i) const {
184 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
185 }
186
187 protected:
188
189 // Accessors available to the algorithm
190 int current_depth() const { return _path.length() - 1; }
191
192 InstanceKlass* class_at_depth(int i) {
193 Node* n = node_at_depth(i);
194 return n == NULL ? NULL : n->_class;
195 }
196 InstanceKlass* current_class() { return class_at_depth(0); }
197
198 void* data_at_depth(int i) {
199 Node* n = node_at_depth(i);
200 return n == NULL ? NULL : n->_algorithm_data;
201 }
202 void* current_data() { return data_at_depth(0); }
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 (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 && super != SystemDictionary::Object_klass()) {
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() && vmSymbols::class_initializer_name() != m->name())) {
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 if (!already_in_vtable_slots(slots, m)) {
635 Method* impl = klass->lookup_method(m->name(), m->signature());
636 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
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 if (!already_in_vtable_slots(slots, m)) {
652 Method* impl = klass->lookup_method(m->name(), m->signature());
653 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
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 bool _cur_class_is_interface;
687
688 public:
689 FindMethodsByErasedSig(Symbol* name, Symbol* signature, bool is_interf) :
690 _method_name(name), _method_signature(signature), _family(NULL),
691 _cur_class_is_interface(is_interf) {}
692
693 void get_discovered_family(MethodFamily** family) {
694 if (_family != NULL) {
695 *family = _family->get_method_family();
696 } else {
697 *family = NULL;
698 }
699 }
700
701 void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
702 void free_node_data(void* node_data) {
703 PseudoScope::cast(node_data)->destroy();
704 }
705
706 // Find all methods on this hierarchy that match this
707 // method's erased (name, signature)
708 bool visit() {
709 PseudoScope* scope = PseudoScope::cast(current_data());
710 InstanceKlass* iklass = current_class();
711
712 Method* m = iklass->find_method(_method_name, _method_signature);
713 // Private interface methods are not candidates for default methods.
714 // invokespecial to private interface methods doesn't use default method logic.
715 // Private class methods are not candidates for default methods.
716 // Private methods do not override default methods, so need to perform
717 // default method inheritance without including private methods.
718 // The overpasses are your supertypes' errors, we do not include them.
719 // Non-public methods in java.lang.Object are not candidates for default
720 // methods.
721 // Future: take access controls into account for superclass methods
722 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() &&
723 (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) {
724 if (_family == NULL) {
725 _family = new StatefulMethodFamily();
726 }
727
728 if (iklass->is_interface()) {
729 StateRestorer* restorer = _family->record_method_and_dq_further(m);
730 scope->add_mark(restorer);
731 } else {
732 // This is the rule that methods in classes "win" (bad word) over
733 // methods in interfaces. This works because of single inheritance.
734 // Private methods in classes do not "win", they will be found
735 // first on searching, but overriding for invokevirtual needs
736 // to find default method candidates for the same signature
737 _family->set_target_if_empty(m);
738 }
739 }
740 return true;
741 }
742
743 };
744
745
746
747 static void create_defaults_and_exceptions(
748 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
749
750 static void generate_erased_defaults(
751 InstanceKlass* klass, EmptyVtableSlot* slot, bool is_intf, TRAPS) {
752
753 // sets up a set of methods with the same exact erased signature
754 FindMethodsByErasedSig visitor(slot->name(), slot->signature(), is_intf);
755 visitor.run(klass);
756
757 MethodFamily* family;
758 visitor.get_discovered_family(&family);
759 if (family != NULL) {
760 family->determine_target(klass, CHECK);
761 slot->bind_family(family);
762 }
763 }
764
765 static void merge_in_new_methods(InstanceKlass* klass,
766 GrowableArray<Method*>* new_methods, TRAPS);
767 static void create_default_methods( InstanceKlass* klass,
768 GrowableArray<Method*>* new_methods, TRAPS);
769
770 // This is the guts of the default methods implementation. This is called just
771 // after the classfile has been parsed if some ancestor has default methods.
772 //
773 // First it finds any name/signature slots that need any implementation (either
774 // because they are miranda or a superclass's implementation is an overpass
775 // itself). For each slot, iterate over the hierarchy, to see if they contain a
776 // signature that matches the slot we are looking at.
777 //
778 // For each slot filled, we either record the default method candidate in the
779 // klass default_methods list or, only to handle exception cases, we create an
780 // overpass method that throws an exception and add it to the klass methods list.
781 // The JVM does not create bridges nor handle generic signatures here.
782 void DefaultMethods::generate_default_methods(
783 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
784 assert(klass != NULL, "invariant");
785
786 // This resource mark is the bound for all memory allocation that takes
787 // place during default method processing. After this goes out of scope,
788 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
789 // embedded resource mark under here as that memory can't be used outside
790 // whatever scope it's in.
791 ResourceMark rm(THREAD);
792
793 // Keep entire hierarchy alive for the duration of the computation
794 constantPoolHandle cp(THREAD, klass->constants());
795 KeepAliveRegistrar keepAlive(THREAD);
796 KeepAliveVisitor loadKeepAlive(&keepAlive);
797 loadKeepAlive.run(klass);
798
799 LogTarget(Debug, defaultmethods) lt;
800 if (lt.is_enabled()) {
801 ResourceMark rm;
802 lt.print("%s %s requires default method processing",
803 klass->is_interface() ? "Interface" : "Class",
804 klass->name()->as_klass_external_name());
805 LogStream ls(lt);
806 PrintHierarchy printer(&ls);
807 printer.run(klass);
808 }
809
810 GrowableArray<EmptyVtableSlot*>* empty_slots =
811 find_empty_vtable_slots(klass, mirandas, CHECK);
812
813 if (empty_slots->length() > 0) {
814 for (int i = 0; i < empty_slots->length(); ++i) {
815 EmptyVtableSlot* slot = empty_slots->at(i);
816 LogTarget(Debug, defaultmethods) lt;
817 if (lt.is_enabled()) {
818 LogStream ls(lt);
819 streamIndentor si(&ls, 2);
820 ls.indent().print("Looking for default methods for slot ");
821 slot->print_on(&ls);
822 ls.cr();
823 }
824 generate_erased_defaults(klass, slot, klass->is_interface(), CHECK);
825 }
826 log_debug(defaultmethods)("Creating defaults and overpasses...");
827 create_defaults_and_exceptions(empty_slots, klass, CHECK);
828 }
829 log_debug(defaultmethods)("Default method processing complete");
830 }
831
832 static int assemble_method_error(
833 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
834
835 Symbol* init = vmSymbols::object_initializer_name();
836 Symbol* sig = vmSymbols::string_void_signature();
837
838 BytecodeAssembler assem(buffer, cp);
839
840 assem._new(errorName);
841 assem.dup();
842 assem.load_string(message);
843 assem.invokespecial(errorName, init, sig);
844 assem.athrow();
845
846 return 3; // max stack size: [ exception, exception, string ]
847 }
848
849 static Method* new_method(
850 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
851 Symbol* sig, AccessFlags flags, int max_stack, int params,
852 ConstMethod::MethodType mt, TRAPS) {
853
854 address code_start = 0;
855 int code_length = 0;
856 InlineTableSizes sizes;
857
858 if (bytecodes != NULL && bytecodes->length() > 0) {
859 code_start = static_cast<address>(bytecodes->adr_at(0));
860 code_length = bytecodes->length();
861 }
862
863 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
864 code_length, flags, &sizes,
865 mt, CHECK_NULL);
866
867 m->set_constants(NULL); // This will get filled in later
868 m->set_name_index(cp->utf8(name));
869 m->set_signature_index(cp->utf8(sig));
870 ResultTypeFinder rtf(sig);
871 m->constMethod()->set_result_type(rtf.type());
872 m->set_size_of_parameters(params);
873 m->set_max_stack(max_stack);
874 m->set_max_locals(params);
875 m->constMethod()->set_stackmap_data(NULL);
876 m->set_code(code_start);
877
878 return m;
879 }
880
881 static void switchover_constant_pool(BytecodeConstantPool* bpool,
882 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
883
884 if (new_methods->length() > 0) {
885 ConstantPool* cp = bpool->create_constant_pool(CHECK);
886 if (cp != klass->constants()) {
887 // Copy resolved anonymous class into new constant pool.
888 if (klass->is_unsafe_anonymous()) {
889 cp->klass_at_put(klass->this_class_index(), klass);
890 }
891 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
892 klass->set_constants(cp);
893 cp->set_pool_holder(klass);
894
895 for (int i = 0; i < new_methods->length(); ++i) {
896 new_methods->at(i)->set_constants(cp);
897 }
898 for (int i = 0; i < klass->methods()->length(); ++i) {
899 Method* mo = klass->methods()->at(i);
900 mo->set_constants(cp);
901 }
902 }
903 }
904 }
905
906 // Create default_methods list for the current class.
907 // With the VM only processing erased signatures, the VM only
908 // creates an overpass in a conflict case or a case with no candidates.
909 // This allows virtual methods to override the overpass, but ensures
910 // that a local method search will find the exception rather than an abstract
911 // or default method that is not a valid candidate.
912 //
913 // Note that if overpass method are ever created that are not exception
914 // throwing methods then the loader constraint checking logic for vtable and
915 // itable creation needs to be changed to check loader constraints for the
916 // overpass methods that do not throw exceptions.
917 static void create_defaults_and_exceptions(
918 GrowableArray<EmptyVtableSlot*>* slots,
919 InstanceKlass* klass, TRAPS) {
920
921 GrowableArray<Method*> overpasses;
922 GrowableArray<Method*> defaults;
923 BytecodeConstantPool bpool(klass->constants());
924
925 for (int i = 0; i < slots->length(); ++i) {
926 EmptyVtableSlot* slot = slots->at(i);
927
928 if (slot->is_bound()) {
929 MethodFamily* method = slot->get_binding();
930 BytecodeBuffer buffer;
931
932 LogTarget(Debug, defaultmethods) lt;
933 if (lt.is_enabled()) {
934 ResourceMark rm(THREAD);
935 LogStream ls(lt);
936 ls.print("for slot: ");
937 slot->print_on(&ls);
938 ls.cr();
939 if (method->has_target()) {
940 method->print_selected(&ls, 1);
941 } else if (method->throws_exception()) {
942 method->print_exception(&ls, 1);
943 }
944 }
945
946 if (method->has_target()) {
947 Method* selected = method->get_selected_target();
948 if (selected->method_holder()->is_interface()) {
949 assert(!selected->is_private(), "pushing private interface method as default");
950 defaults.push(selected);
951 }
952 } else if (method->throws_exception()) {
953 int max_stack = assemble_method_error(&bpool, &buffer,
954 method->get_exception_name(), method->get_exception_message(), CHECK);
955 AccessFlags flags = accessFlags_from(
956 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
957 Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
958 flags, max_stack, slot->size_of_parameters(),
959 ConstMethod::OVERPASS, CHECK);
960 // We push to the methods list:
961 // overpass methods which are exception throwing methods
962 if (m != NULL) {
963 overpasses.push(m);
964 }
965 }
966 }
967 }
968
969
970 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length());
971 log_debug(defaultmethods)("Created %d default methods", defaults.length());
972
973 if (overpasses.length() > 0) {
974 switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
975 merge_in_new_methods(klass, &overpasses, CHECK);
976 }
977 if (defaults.length() > 0) {
978 create_default_methods(klass, &defaults, CHECK);
979 }
980 }
981
982 static void create_default_methods( InstanceKlass* klass,
983 GrowableArray<Method*>* new_methods, TRAPS) {
984
985 int new_size = new_methods->length();
986 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>(
987 klass->class_loader_data(), new_size, NULL, CHECK);
988 for (int index = 0; index < new_size; index++ ) {
989 total_default_methods->at_put(index, new_methods->at(index));
990 }
991 Method::sort_methods(total_default_methods, /*set_idnums=*/false);
992
993 klass->set_default_methods(total_default_methods);
994 }
995
996 static void sort_methods(GrowableArray<Method*>* methods) {
997 // Note that this must sort using the same key as is used for sorting
998 // methods in InstanceKlass.
999 bool sorted = true;
1000 for (int i = methods->length() - 1; i > 0; --i) {
1001 for (int j = 0; j < i; ++j) {
1002 Method* m1 = methods->at(j);
1003 Method* m2 = methods->at(j + 1);
1004 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
1005 methods->at_put(j, m2);
1006 methods->at_put(j + 1, m1);
1007 sorted = false;
1008 }
1009 }
1010 if (sorted) break;
1011 sorted = true;
1012 }
1013 #ifdef ASSERT
1014 uintptr_t prev = 0;
1015 for (int i = 0; i < methods->length(); ++i) {
1016 Method* mh = methods->at(i);
1017 uintptr_t nv = (uintptr_t)mh->name();
1018 assert(nv >= prev, "Incorrect overpass method ordering");
1019 prev = nv;
1020 }
1021 #endif
1022 }
1023
1024 static void merge_in_new_methods(InstanceKlass* klass,
1025 GrowableArray<Method*>* new_methods, TRAPS) {
1026
1027 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1028
1029 Array<Method*>* original_methods = klass->methods();
1030 Array<int>* original_ordering = klass->method_ordering();
1031 Array<int>* merged_ordering = Universe::the_empty_int_array();
1032
1033 int new_size = klass->methods()->length() + new_methods->length();
1034
1035 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1036 klass->class_loader_data(), new_size, NULL, CHECK);
1037
1038 // original_ordering might be empty if this class has no methods of its own
1039 if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
1040 merged_ordering = MetadataFactory::new_array<int>(
1041 klass->class_loader_data(), new_size, CHECK);
1042 }
1043 int method_order_index = klass->methods()->length();
1044
1045 sort_methods(new_methods);
1046
1047 // Perform grand merge of existing methods and new methods
1048 int orig_idx = 0;
1049 int new_idx = 0;
1050
1051 for (int i = 0; i < new_size; ++i) {
1052 Method* orig_method = NULL;
1053 Method* new_method = NULL;
1054 if (orig_idx < original_methods->length()) {
1055 orig_method = original_methods->at(orig_idx);
1056 }
1057 if (new_idx < new_methods->length()) {
1058 new_method = new_methods->at(new_idx);
1059 }
1060
1061 if (orig_method != NULL &&
1062 (new_method == NULL || orig_method->name() < new_method->name())) {
1063 merged_methods->at_put(i, orig_method);
1064 original_methods->at_put(orig_idx, NULL);
1065 if (merged_ordering->length() > 0) {
1066 assert(original_ordering != NULL && original_ordering->length() > 0,
1067 "should have original order information for this method");
1068 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1069 }
1070 ++orig_idx;
1071 } else {
1072 merged_methods->at_put(i, new_method);
1073 if (merged_ordering->length() > 0) {
1074 merged_ordering->at_put(i, method_order_index++);
1075 }
1076 ++new_idx;
1077 }
1078 // update idnum for new location
1079 merged_methods->at(i)->set_method_idnum(i);
1080 merged_methods->at(i)->set_orig_method_idnum(i);
1081 }
1082
1083 // Verify correct order
1084 #ifdef ASSERT
1085 uintptr_t prev = 0;
1086 for (int i = 0; i < merged_methods->length(); ++i) {
1087 Method* mo = merged_methods->at(i);
1088 uintptr_t nv = (uintptr_t)mo->name();
1089 assert(nv >= prev, "Incorrect method ordering");
1090 prev = nv;
1091 }
1092 #endif
1093
1094 // Replace klass methods with new merged lists
1095 klass->set_methods(merged_methods);
1096 klass->set_initial_method_idnum(new_size);
1097 klass->set_method_ordering(merged_ordering);
1098
1099 // Free metadata
1100 ClassLoaderData* cld = klass->class_loader_data();
1101 if (original_methods->length() > 0) {
1102 MetadataFactory::free_array(cld, original_methods);
1103 }
1104 if (original_ordering != NULL && original_ordering->length() > 0) {
1105 MetadataFactory::free_array(cld, original_ordering);
1106 }
1107 }