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 "memory/universe.hpp"
36 #include "runtime/handles.inline.hpp"
37 #include "runtime/signature.hpp"
38 #include "runtime/thread.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/klass.hpp"
41 #include "oops/method.hpp"
42 #include "utilities/accessFlags.hpp"
43 #include "utilities/exceptions.hpp"
44 #include "utilities/ostream.hpp"
45 #include "utilities/pair.hpp"
46 #include "utilities/resourceHash.hpp"
47
48 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
49
50 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
51 str->print("%s%s", name->as_C_string(), signature->as_C_string());
52 }
53
54 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
55 if (with_class) {
56 str->print("%s.", mo->klass_name()->as_C_string());
57 }
58 print_slot(str, mo->name(), mo->signature());
59 }
60
61 /**
62 * Perform a depth-first iteration over the class hierarchy, applying
63 * algorithmic logic as it goes.
64 *
65 * This class is one half of the inheritance hierarchy analysis mechanism.
66 * It is meant to be used in conjunction with another class, the algorithm,
67 * which is indicated by the ALGO template parameter. This class can be
68 * paired with any algorithm class that provides the required methods.
69 *
70 * This class contains all the mechanics for iterating over the class hierarchy
71 * starting at a particular root, without recursing (thus limiting stack growth
72 * from this point). It visits each superclass (if present) and superinterface
73 * in a depth-first manner, with callbacks to the ALGO class as each class is
74 * encountered (visit()), The algorithm can cut-off further exploration of a
75 * particular branch by returning 'false' from a visit() call.
76 *
77 * The ALGO class, must provide a visit() method, which each of which will be
78 * called once for each node in the inheritance tree during the iteration. In
79 * addition, it can provide a memory block via new_node_data(), which it can
80 * use for node-specific storage (and access via the current_data() and
81 * data_at_depth(int) methods).
82 *
83 * Bare minimum needed to be an ALGO class:
84 * class Algo : public HierarchyVisitor<Algo> {
85 * void* new_node_data() { return NULL; }
86 * void free_node_data(void* data) { return; }
87 * bool visit() { return true; }
88 * };
89 */
90 template <class ALGO>
91 class HierarchyVisitor : StackObj {
92 private:
93
94 class Node : public ResourceObj {
95 public:
96 InstanceKlass* _class;
97 bool _super_was_visited;
98 int _interface_index;
99 void* _algorithm_data;
100
101 Node(InstanceKlass* cls, void* data, bool visit_super)
102 : _class(cls), _super_was_visited(!visit_super),
103 _interface_index(0), _algorithm_data(data) {}
104
105 void update(InstanceKlass* cls, void* data, bool visit_super) {
106 _class = cls;
107 _super_was_visited = !visit_super;
108 _interface_index = 0;
109 _algorithm_data = data;
110 }
111 int number_of_interfaces() { return _class->local_interfaces()->length(); }
112 int interface_index() { return _interface_index; }
113 void set_super_visited() { _super_was_visited = true; }
114 void increment_visited_interface() { ++_interface_index; }
115 void set_all_interfaces_visited() {
116 _interface_index = number_of_interfaces();
117 }
118 bool has_visited_super() { return _super_was_visited; }
119 bool has_visited_all_interfaces() {
120 return interface_index() >= number_of_interfaces();
121 }
122 InstanceKlass* interface_at(int index) {
123 return _class->local_interfaces()->at(index);
124 }
125 InstanceKlass* next_super() { return _class->java_super(); }
126 InstanceKlass* next_interface() {
127 return interface_at(interface_index());
128 }
129 };
130
131 bool _visited_Object;
132
133 GrowableArray<Node*> _path;
134 GrowableArray<Node*> _free_nodes;
135
136 Node* current_top() const { return _path.top(); }
137 bool has_more_nodes() const { return _path.length() > 0; }
138 void push(InstanceKlass* cls, ALGO* algo) {
139 assert(cls != NULL, "Requires a valid instance class");
140 if (cls == SystemDictionary::Object_klass()) {
141 _visited_Object = true;
142 }
143 void* data = algo->new_node_data();
144 Node* node;
145 if (_free_nodes.is_empty()) { // Add a new node
146 node = new Node(cls, data, has_super(cls));
147 } else { // Reuse existing node and data
148 node = _free_nodes.pop();
149 node->update(cls, data, has_super(cls));
150 }
151 _path.push(node);
152 }
153 void pop() {
154 Node* node = _path.pop();
155 // Make the node available for reuse
156 _free_nodes.push(node);
157 }
158
159 // Since the starting point can be an interface, we must ensure we catch
160 // j.l.Object as the super once in those cases. The _visited_Object flag
161 // only ensures we don't then repeatedly enqueue Object for each interface
162 // in the class hierarchy.
163 bool has_super(InstanceKlass* cls) {
164 return cls->super() != NULL && (!_visited_Object || !cls->is_interface());
165 }
166
167 Node* node_at_depth(int i) const {
168 return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
169 }
170
171 protected:
172
173 // Resets the visitor
174 void reset() {
175 _visited_Object = false;
176 }
177
178 // Accessors available to the algorithm
179 int current_depth() const { return _path.length() - 1; }
180
181 InstanceKlass* class_at_depth(int i) {
182 Node* n = node_at_depth(i);
183 return n == NULL ? NULL : n->_class;
184 }
185 InstanceKlass* current_class() { return class_at_depth(0); }
186
187 void* data_at_depth(int i) {
188 Node* n = node_at_depth(i);
189 return n == NULL ? NULL : n->_algorithm_data;
190 }
191 void* current_data() { return data_at_depth(0); }
192
193 public:
194 HierarchyVisitor() : _visited_Object(false), _path() {}
195
196 void run(InstanceKlass* root) {
197 ALGO* algo = static_cast<ALGO*>(this);
198
199 push(root, algo);
200 bool top_needs_visit = true;
201 do {
202 Node* top = current_top();
203 if (top_needs_visit) {
204 if (algo->visit() == false) {
205 // algorithm does not want to continue along this path. Arrange
206 // it so that this state is immediately popped off the stack
207 top->set_super_visited();
208 top->set_all_interfaces_visited();
209 }
210 top_needs_visit = false;
211 }
212
213 if (top->has_visited_super() && top->has_visited_all_interfaces()) {
214 algo->free_node_data(top->_algorithm_data);
215 pop();
216 } else {
217 InstanceKlass* next = NULL;
218 if (top->has_visited_super() == false) {
219 next = top->next_super();
220 top->set_super_visited();
221 } else {
222 next = top->next_interface();
223 top->increment_visited_interface();
224 }
225 assert(next != NULL, "Otherwise we shouldn't be here");
226 push(next, algo);
227 top_needs_visit = true;
228 }
229 } while (has_more_nodes());
230 }
231 };
232
233 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
234 private:
235 outputStream* _st;
236 public:
237 bool visit() {
238 InstanceKlass* cls = current_class();
239 streamIndentor si(_st, current_depth() * 2);
240 _st->indent().print_cr("%s", cls->name()->as_C_string());
241 return true;
242 }
243
244 void* new_node_data() { return NULL; }
245 void free_node_data(void* data) { return; }
246
247 PrintHierarchy(outputStream* st = tty) : _st(st) {}
248 };
249
250 // Used to register InstanceKlass objects and all related metadata structures
251 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
252 // be deallocated by class redefinition while we're using them. The classes are
253 // de-registered when this goes out of scope.
254 //
255 // Once a class is registered, we need not bother with methodHandles or
256 // constantPoolHandles for it's associated metadata.
257 class KeepAliveRegistrar : public StackObj {
258 private:
259 Thread* _thread;
260 GrowableArray<ConstantPool*> _keep_alive;
261
262 public:
263 KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(6) {
264 assert(thread == Thread::current(), "Must be current thread");
265 }
266
267 ~KeepAliveRegistrar() {
268 for (int i = _keep_alive.length() - 1; i >= 0; --i) {
269 ConstantPool* cp = _keep_alive.at(i);
270 int idx = _thread->metadata_handles()->find_from_end(cp);
271 assert(idx > 0, "Must be in the list");
272 _thread->metadata_handles()->remove_at(idx);
273 }
274 }
275
276 // Register a class as 'in-use' by the thread. It's fine to register a class
277 // multiple times (though perhaps inefficient)
278 void register_class(InstanceKlass* ik) {
279 ConstantPool* cp = ik->constants();
280 _keep_alive.push(cp);
281 _thread->metadata_handles()->push(cp);
282 }
283 };
284
285 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
286 private:
287 KeepAliveRegistrar* _registrar;
288
289 public:
290 KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
291
292 void* new_node_data() { return NULL; }
293 void free_node_data(void* data) { return; }
294
295 bool visit() {
296 _registrar->register_class(current_class());
297 return true;
298 }
299 };
300
301
302 // A method family contains a set of all methods that implement a single
303 // erased method. As members of the set are collected while walking over the
304 // hierarchy, they are tagged with a qualification state. The qualification
305 // state for an erased method is set to disqualified if there exists a path
306 // from the root of hierarchy to the method that contains an interleaving
307 // erased method defined in an interface.
308
309 class MethodState {
310 public:
311 Method* _method;
312 QualifiedState _state;
313
314 MethodState() : _method(NULL), _state(DISQUALIFIED) {}
315 MethodState(Method* method, QualifiedState state) : _method(method), _state(state) {}
316 };
317
318 class MethodFamily : public ResourceObj {
319 private:
320
321 GrowableArray<MethodState> _members;
322
323 Method* _selected_target; // Filled in later, if a unique target exists
324 Symbol* _exception_message; // If no unique target is found
325 Symbol* _exception_name; // If no unique target is found
326
327 MethodState* find_method(Method* method) {
328 for (int i = 0; i < _members.length(); i++) {
329 if (_members.at(i)._method == method) {
330 return &_members.at(i);
331 }
332 }
333 return NULL;
334 }
335
336 void add_method(Method* method, QualifiedState state) {
337 MethodState method_state(method, state);
338 _members.append(method_state);
339 }
340
341 Symbol* generate_no_defaults_message(TRAPS) const;
342 Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const;
343 Symbol* generate_conflicts_message(GrowableArray<MethodState>* methods, TRAPS) const;
344
345 public:
346
347 MethodFamily()
348 : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {}
349
350 void set_target_if_empty(Method* m) {
351 if (_selected_target == NULL && !m->is_overpass()) {
352 _selected_target = m;
353 }
354 }
355
356 void record_method(Method* m, QualifiedState state) {
357 // If not in the set, add it. If it's already in the set, then leave it
358 // as is if state is qualified, or set it to disqualified if state is
359 // disqualified.
360 MethodState* method_state = find_method(m);
361 if (method_state == NULL) {
362 add_method(m, state);
363 } else if (state == DISQUALIFIED) {
364 method_state->_state = DISQUALIFIED;
365 }
366 }
367
368 bool has_target() const { return _selected_target != NULL; }
369 bool throws_exception() { return _exception_message != NULL; }
370
371 Method* get_selected_target() { return _selected_target; }
372 Symbol* get_exception_message() { return _exception_message; }
373 Symbol* get_exception_name() { return _exception_name; }
374
375 // Either sets the target or the exception error message
376 void determine_target_or_set_exception_message(InstanceKlass* root, TRAPS) {
377 if (has_target() || throws_exception()) {
378 return;
379 }
380
381 // Qualified methods are maximally-specific methods
382 // These include public, instance concrete (=default) and abstract methods
383 int num_defaults = 0;
384 int default_index = -1;
385 for (int i = 0; i < _members.length(); i++) {
386 MethodState &member = _members.at(i);
387 if (member._state == QUALIFIED) {
388 if (member._method->is_default_method()) {
389 num_defaults++;
390 default_index = i;
391 }
392 }
393 }
394
395 if (num_defaults == 1) {
396 assert(_members.at(default_index)._state == QUALIFIED, "");
397 _selected_target = _members.at(default_index)._method;
398 } else {
399 generate_and_set_exception_message(root, num_defaults, default_index, CHECK);
400 }
401 }
402
403 void generate_and_set_exception_message(InstanceKlass* root, int num_defaults, int default_index, TRAPS) {
404 assert(num_defaults != 1, "invariant - should've been handled calling method");
405
406 GrowableArray<Method*> qualified_methods;
407 for (int i = 0; i < _members.length(); i++) {
408 MethodState& member = _members.at(i);
409 if (member._state == QUALIFIED) {
410 qualified_methods.push(member._method);
411 }
412 }
413 if (num_defaults == 0) {
414 // If the root klass has a static method with matching name and signature
415 // then do not generate an overpass method because it will hide the
416 // static method during resolution.
417 if (qualified_methods.length() == 0) {
418 _exception_message = generate_no_defaults_message(CHECK);
419 } else {
420 assert(root != NULL, "Null root class");
421 _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK);
422 }
423 _exception_name = vmSymbols::java_lang_AbstractMethodError();
424 } else {
425 _exception_message = generate_conflicts_message(&_members,CHECK);
426 _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError();
427 LogTarget(Debug, defaultmethods) lt;
428 if (lt.is_enabled()) {
429 LogStream ls(lt);
430 _exception_message->print_value_on(&ls);
431 ls.cr();
432 }
433 }
434 }
435
436 void print_selected(outputStream* str, int indent) const {
437 assert(has_target(), "Should be called otherwise");
438 streamIndentor si(str, indent * 2);
439 str->indent().print("Selected method: ");
440 print_method(str, _selected_target);
441 Klass* method_holder = _selected_target->method_holder();
442 if (!method_holder->is_interface()) {
443 str->print(" : in superclass");
444 }
445 str->cr();
446 }
447
448 void print_exception(outputStream* str, int indent) {
449 assert(throws_exception(), "Should be called otherwise");
450 assert(_exception_name != NULL, "exception_name should be set");
451 streamIndentor si(str, indent * 2);
452 str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string());
453 }
454 };
455
456 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
457 return SymbolTable::new_symbol("No qualifying defaults found");
458 }
459
460 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const {
461 stringStream ss;
462 ss.print("Method ");
463 Symbol* name = method->name();
464 Symbol* signature = method->signature();
465 ss.write((const char*)klass_name->bytes(), klass_name->utf8_length());
466 ss.print(".");
467 ss.write((const char*)name->bytes(), name->utf8_length());
468 ss.write((const char*)signature->bytes(), signature->utf8_length());
469 ss.print(" is abstract");
470 return SymbolTable::new_symbol(ss.base(), (int)ss.size());
471 }
472
473 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<MethodState>* methods, TRAPS) const {
474 stringStream ss;
475 ss.print("Conflicting default methods:");
476 for (int i = 0; i < methods->length(); ++i) {
477 Method *method = methods->at(i)._method;
478 Symbol *klass = method->klass_name();
479 Symbol *name = method->name();
480 ss.print(" ");
481 ss.write((const char*) klass->bytes(), klass->utf8_length());
482 ss.print(".");
483 ss.write((const char*) name->bytes(), name->utf8_length());
484 }
485 return SymbolTable::new_symbol(ss.base(), (int)ss.size());
486 }
487
488
489 class StateRestorerScope;
490
491 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
492 // qualification state during hierarchy visitation, and applies that state
493 // when adding members to the MethodFamily
494 class StatefulMethodFamily : public ResourceObj {
495 friend class StateRestorer;
496 private:
497 QualifiedState _qualification_state;
498
499 void set_qualification_state(QualifiedState state) {
500 _qualification_state = state;
501 }
502
503 protected:
504 MethodFamily _method_family;
505
506 public:
507 StatefulMethodFamily() {
508 _qualification_state = QUALIFIED;
509 }
510
511 void set_target_if_empty(Method* m) { _method_family.set_target_if_empty(m); }
512
513 MethodFamily* get_method_family() { return &_method_family; }
514
515 void record_method_and_dq_further(StateRestorerScope* scope, Method* mo);
516 };
517
518 // Because we use an iterative algorithm when iterating over the type
519 // hierarchy, we can't use traditional scoped objects which automatically do
520 // cleanup in the destructor when the scope is exited. StateRestorerScope (and
521 // StateRestorer) provides a similar functionality, but for when you want a
522 // scoped object in non-stack memory (such as in resource memory, as we do
523 // here). You've just got to remember to call 'restore_state()' on the scope when
524 // leaving it (and marks have to be explicitly added). The scope is reusable after
525 // 'restore_state()' has been called.
526 class StateRestorer : public ResourceObj {
527 public:
528 StatefulMethodFamily* _method;
529 QualifiedState _state_to_restore;
530
531 StateRestorer() : _method(NULL), _state_to_restore(DISQUALIFIED) {}
532
533 void restore_state() { _method->set_qualification_state(_state_to_restore); }
534 };
535
536 class StateRestorerScope : public ResourceObj {
537 private:
538 GrowableArray<StateRestorer*> _marks;
539 GrowableArray<StateRestorer*>* _free_list; // Shared between scopes
540 public:
541 StateRestorerScope(GrowableArray<StateRestorer*>* free_list) : _marks(), _free_list(free_list) {}
542
543 static StateRestorerScope* cast(void* data) {
544 return static_cast<StateRestorerScope*>(data);
545 }
546
547 void mark(StatefulMethodFamily* family, QualifiedState qualification_state) {
548 StateRestorer* restorer;
549 if (!_free_list->is_empty()) {
550 restorer = _free_list->pop();
551 } else {
552 restorer = new StateRestorer();
553 }
554 restorer->_method = family;
555 restorer->_state_to_restore = qualification_state;
556 _marks.append(restorer);
557 }
558
559 #ifdef ASSERT
560 bool is_empty() {
561 return _marks.is_empty();
562 }
563 #endif
564
565 void restore_state() {
566 while(!_marks.is_empty()) {
567 StateRestorer* restorer = _marks.pop();
568 restorer->restore_state();
569 _free_list->push(restorer);
570 }
571 }
572 };
573
574 void StatefulMethodFamily::record_method_and_dq_further(StateRestorerScope* scope, Method* mo) {
575 scope->mark(this, _qualification_state);
576 _method_family.record_method(mo, _qualification_state);
577
578 // Everything found "above"??? this method in the hierarchy walk is set to
579 // disqualified
580 set_qualification_state(DISQUALIFIED);
581 }
582
583 // Represents a location corresponding to a vtable slot for methods that
584 // neither the class nor any of it's ancestors provide an implementaion.
585 // Default methods may be present to fill this slot.
586 class EmptyVtableSlot : public ResourceObj {
587 private:
588 Symbol* _name;
589 Symbol* _signature;
590 int _size_of_parameters;
591 MethodFamily* _binding;
592
593 public:
594 EmptyVtableSlot(Method* method)
595 : _name(method->name()), _signature(method->signature()),
596 _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
597
598 Symbol* name() const { return _name; }
599 Symbol* signature() const { return _signature; }
600 int size_of_parameters() const { return _size_of_parameters; }
601
602 void bind_family(MethodFamily* lm) { _binding = lm; }
603 bool is_bound() { return _binding != NULL; }
604 MethodFamily* get_binding() { return _binding; }
605
606 void print_on(outputStream* str) const {
607 print_slot(str, name(), signature());
608 }
609 };
610
611 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
612 bool found = false;
613 for (int j = 0; j < slots->length(); ++j) {
614 if (slots->at(j)->name() == m->name() &&
615 slots->at(j)->signature() == m->signature() ) {
616 found = true;
617 break;
618 }
619 }
620 return found;
621 }
622
623 static void find_empty_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots,
624 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
625
626 assert(klass != NULL, "Must be valid class");
627
628 // All miranda methods are obvious candidates
629 for (int i = 0; i < mirandas->length(); ++i) {
630 Method* m = mirandas->at(i);
631 if (!already_in_vtable_slots(slots, m)) {
632 slots->append(new EmptyVtableSlot(m));
633 }
634 }
635
636 // Also any overpasses in our superclasses, that we haven't implemented.
637 // (can't use the vtable because it is not guaranteed to be initialized yet)
638 InstanceKlass* super = klass->java_super();
639 while (super != NULL) {
640 for (int i = 0; i < super->methods()->length(); ++i) {
641 Method* m = super->methods()->at(i);
642 if (m->is_overpass() || m->is_static()) {
643 // m is a method that would have been a miranda if not for the
644 // default method processing that occurred on behalf of our superclass,
645 // so it's a method we want to re-examine in this new context. That is,
646 // unless we have a real implementation of it in the current class.
647 if (!already_in_vtable_slots(slots, m)) {
648 Method *impl = klass->lookup_method(m->name(), m->signature());
649 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
650 slots->append(new EmptyVtableSlot(m));
651 }
652 }
653 }
654 }
655
656 // also any default methods in our superclasses
657 if (super->default_methods() != NULL) {
658 for (int i = 0; i < super->default_methods()->length(); ++i) {
659 Method* m = super->default_methods()->at(i);
660 // m is a method that would have been a miranda if not for the
661 // default method processing that occurred on behalf of our superclass,
662 // so it's a method we want to re-examine in this new context. That is,
663 // unless we have a real implementation of it in the current class.
664 if (!already_in_vtable_slots(slots, m)) {
665 Method* impl = klass->lookup_method(m->name(), m->signature());
666 if (impl == NULL || impl->is_overpass() || impl->is_static()) {
667 slots->append(new EmptyVtableSlot(m));
668 }
669 }
670 }
671 }
672 super = super->java_super();
673 }
674
675 LogTarget(Debug, defaultmethods) lt;
676 if (lt.is_enabled()) {
677 lt.print("Slots that need filling:");
678 ResourceMark rm;
679 LogStream ls(lt);
680 streamIndentor si(&ls);
681 for (int i = 0; i < slots->length(); ++i) {
682 ls.indent();
683 slots->at(i)->print_on(&ls);
684 ls.cr();
685 }
686 }
687 }
688
689 // Iterates over the superinterface type hierarchy looking for all methods
690 // with a specific erased signature.
691 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
692 private:
693 // Context data
694 Symbol* _method_name;
695 Symbol* _method_signature;
696 StatefulMethodFamily* _family;
697 bool _cur_class_is_interface;
698 // Free lists, used as an optimization
699 GrowableArray<StateRestorerScope*> _free_scopes;
700 GrowableArray<StateRestorer*> _free_restorers;
701 public:
702 FindMethodsByErasedSig() : _free_scopes(6), _free_restorers(6) {};
703
704 void prepare(Symbol* name, Symbol* signature, bool is_interf) {
705 reset();
706 _method_name = name;
707 _method_signature = signature;
708 _family = NULL;
709 _cur_class_is_interface = is_interf;
710 }
711
712 void get_discovered_family(MethodFamily** family) {
713 if (_family != NULL) {
714 *family = _family->get_method_family();
715 } else {
716 *family = NULL;
717 }
718 }
719
720 void* new_node_data() {
721 if (!_free_scopes.is_empty()) {
722 StateRestorerScope* free_scope = _free_scopes.pop();
723 assert(free_scope->is_empty(), "StateRestorerScope::_marks array not empty");
724 return free_scope;
725 }
726 return new StateRestorerScope(&_free_restorers);
727 }
728 void free_node_data(void* node_data) {
729 StateRestorerScope* scope = StateRestorerScope::cast(node_data);
730 scope->restore_state();
731 // Reuse scopes
732 _free_scopes.push(scope);
733 }
734
735 // Find all methods on this hierarchy that match this
736 // method's erased (name, signature)
737 bool visit() {
738 StateRestorerScope* scope = StateRestorerScope::cast(current_data());
739 InstanceKlass* iklass = current_class();
740
741 Method* m = iklass->find_method(_method_name, _method_signature);
742 // Private interface methods are not candidates for default methods.
743 // invokespecial to private interface methods doesn't use default method logic.
744 // Private class methods are not candidates for default methods.
745 // Private methods do not override default methods, so need to perform
746 // default method inheritance without including private methods.
747 // The overpasses are your supertypes' errors, we do not include them.
748 // Non-public methods in java.lang.Object are not candidates for default
749 // methods.
750 // Future: take access controls into account for superclass methods
751 if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() &&
752 (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) {
753 if (_family == NULL) {
754 _family = new StatefulMethodFamily();
755 }
756
757 if (iklass->is_interface()) {
758 _family->record_method_and_dq_further(scope, m);
759 } else {
760 // This is the rule that methods in classes "win" (bad word) over
761 // methods in interfaces. This works because of single inheritance.
762 // Private methods in classes do not "win", they will be found
763 // first on searching, but overriding for invokevirtual needs
764 // to find default method candidates for the same signature
765 _family->set_target_if_empty(m);
766 }
767 }
768 return true;
769 }
770
771 };
772
773
774
775 static void create_defaults_and_exceptions(
776 GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
777
778 static void generate_erased_defaults(
779 FindMethodsByErasedSig* visitor,
780 InstanceKlass* klass, EmptyVtableSlot* slot, bool is_intf, TRAPS) {
781
782 // the visitor needs to be initialized or re-initialized before use
783 // - this facilitates reusing the same visitor instance on multiple
784 // generation passes as an optimization
785 visitor->prepare(slot->name(), slot->signature(), is_intf);
786 // sets up a set of methods with the same exact erased signature
787 visitor->run(klass);
788
789 MethodFamily* family;
790 visitor->get_discovered_family(&family);
791 if (family != NULL) {
792 family->determine_target_or_set_exception_message(klass, CHECK);
793 slot->bind_family(family);
794 }
795 }
796
797 static void merge_in_new_methods(InstanceKlass* klass,
798 GrowableArray<Method*>* new_methods, TRAPS);
799 static void create_default_methods( InstanceKlass* klass,
800 GrowableArray<Method*>* new_methods, TRAPS);
801
802 // This is the guts of the default methods implementation. This is called just
803 // after the classfile has been parsed if some ancestor has default methods.
804 //
805 // First it finds any name/signature slots that need any implementation (either
806 // because they are miranda or a superclass's implementation is an overpass
807 // itself). For each slot, iterate over the hierarchy, to see if they contain a
808 // signature that matches the slot we are looking at.
809 //
810 // For each slot filled, we either record the default method candidate in the
811 // klass default_methods list or, only to handle exception cases, we create an
812 // overpass method that throws an exception and add it to the klass methods list.
813 // The JVM does not create bridges nor handle generic signatures here.
814 void DefaultMethods::generate_default_methods(
815 InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
816 assert(klass != NULL, "invariant");
817 assert(klass != SystemDictionary::Object_klass(), "Shouldn't be called for Object");
818
819 // This resource mark is the bound for all memory allocation that takes
820 // place during default method processing. After this goes out of scope,
821 // all (Resource) objects' memory will be reclaimed. Be careful if adding an
822 // embedded resource mark under here as that memory can't be used outside
823 // whatever scope it's in.
824 ResourceMark rm(THREAD);
825
826 // Keep entire hierarchy alive for the duration of the computation
827 constantPoolHandle cp(THREAD, klass->constants());
828 KeepAliveRegistrar keepAlive(THREAD);
829 KeepAliveVisitor loadKeepAlive(&keepAlive);
830 loadKeepAlive.run(klass);
831
832 LogTarget(Debug, defaultmethods) lt;
833 if (lt.is_enabled()) {
834 ResourceMark rm;
835 lt.print("%s %s requires default method processing",
836 klass->is_interface() ? "Interface" : "Class",
837 klass->name()->as_klass_external_name());
838 LogStream ls(lt);
839 PrintHierarchy printer(&ls);
840 printer.run(klass);
841 }
842
843 GrowableArray<EmptyVtableSlot*> empty_slots;
844 find_empty_vtable_slots(&empty_slots, klass, mirandas, CHECK);
845
846 if (empty_slots.length() > 0) {
847 FindMethodsByErasedSig findMethodsByErasedSig;
848 for (int i = 0; i < empty_slots.length(); ++i) {
849 EmptyVtableSlot* slot = empty_slots.at(i);
850 LogTarget(Debug, defaultmethods) lt;
851 if (lt.is_enabled()) {
852 LogStream ls(lt);
853 streamIndentor si(&ls, 2);
854 ls.indent().print("Looking for default methods for slot ");
855 slot->print_on(&ls);
856 ls.cr();
857 }
858 generate_erased_defaults(&findMethodsByErasedSig, klass, slot, klass->is_interface(), CHECK);
859 }
860 log_debug(defaultmethods)("Creating defaults and overpasses...");
861 create_defaults_and_exceptions(&empty_slots, klass, CHECK);
862 }
863 log_debug(defaultmethods)("Default method processing complete");
864 }
865
866 static int assemble_method_error(
867 BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
868
869 Symbol* init = vmSymbols::object_initializer_name();
870 Symbol* sig = vmSymbols::string_void_signature();
871
872 BytecodeAssembler assem(buffer, cp);
873
874 assem._new(errorName);
875 assem.dup();
876 assem.load_string(message);
877 assem.invokespecial(errorName, init, sig);
878 assem.athrow();
879
880 return 3; // max stack size: [ exception, exception, string ]
881 }
882
883 static Method* new_method(
884 BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
885 Symbol* sig, AccessFlags flags, int max_stack, int params,
886 ConstMethod::MethodType mt, TRAPS) {
887
888 address code_start = 0;
889 int code_length = 0;
890 InlineTableSizes sizes;
891
892 if (bytecodes != NULL && bytecodes->length() > 0) {
893 code_start = static_cast<address>(bytecodes->adr_at(0));
894 code_length = bytecodes->length();
895 }
896
897 Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
898 code_length, flags, &sizes,
899 mt, CHECK_NULL);
900
901 m->set_constants(NULL); // This will get filled in later
902 m->set_name_index(cp->utf8(name));
903 m->set_signature_index(cp->utf8(sig));
904 ResultTypeFinder rtf(sig);
905 m->constMethod()->set_result_type(rtf.type());
906 m->set_size_of_parameters(params);
907 m->set_max_stack(max_stack);
908 m->set_max_locals(params);
909 m->constMethod()->set_stackmap_data(NULL);
910 m->set_code(code_start);
911
912 return m;
913 }
914
915 static void switchover_constant_pool(BytecodeConstantPool* bpool,
916 InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
917
918 if (new_methods->length() > 0) {
919 ConstantPool* cp = bpool->create_constant_pool(CHECK);
920 if (cp != klass->constants()) {
921 // Copy resolved anonymous class into new constant pool.
922 if (klass->is_unsafe_anonymous()) {
923 cp->klass_at_put(klass->this_class_index(), klass);
924 }
925 klass->class_loader_data()->add_to_deallocate_list(klass->constants());
926 klass->set_constants(cp);
927 cp->set_pool_holder(klass);
928
929 for (int i = 0; i < new_methods->length(); ++i) {
930 new_methods->at(i)->set_constants(cp);
931 }
932 for (int i = 0; i < klass->methods()->length(); ++i) {
933 Method* mo = klass->methods()->at(i);
934 mo->set_constants(cp);
935 }
936 }
937 }
938 }
939
940 // Create default_methods list for the current class.
941 // With the VM only processing erased signatures, the VM only
942 // creates an overpass in a conflict case or a case with no candidates.
943 // This allows virtual methods to override the overpass, but ensures
944 // that a local method search will find the exception rather than an abstract
945 // or default method that is not a valid candidate.
946 //
947 // Note that if overpass method are ever created that are not exception
948 // throwing methods then the loader constraint checking logic for vtable and
949 // itable creation needs to be changed to check loader constraints for the
950 // overpass methods that do not throw exceptions.
951 static void create_defaults_and_exceptions(GrowableArray<EmptyVtableSlot*>* slots,
952 InstanceKlass* klass, TRAPS) {
953
954 GrowableArray<Method*> overpasses;
955 GrowableArray<Method*> defaults;
956 BytecodeConstantPool bpool(klass->constants());
957
958 BytecodeBuffer* buffer = NULL; // Lazily create a reusable buffer
959 for (int i = 0; i < slots->length(); ++i) {
960 EmptyVtableSlot* slot = slots->at(i);
961
962 if (slot->is_bound()) {
963 MethodFamily* method = slot->get_binding();
964
965 LogTarget(Debug, defaultmethods) lt;
966 if (lt.is_enabled()) {
967 ResourceMark rm(THREAD);
968 LogStream ls(lt);
969 ls.print("for slot: ");
970 slot->print_on(&ls);
971 ls.cr();
972 if (method->has_target()) {
973 method->print_selected(&ls, 1);
974 } else if (method->throws_exception()) {
975 method->print_exception(&ls, 1);
976 }
977 }
978
979 if (method->has_target()) {
980 Method* selected = method->get_selected_target();
981 if (selected->method_holder()->is_interface()) {
982 assert(!selected->is_private(), "pushing private interface method as default");
983 defaults.push(selected);
984 }
985 } else if (method->throws_exception()) {
986 if (buffer == NULL) {
987 buffer = new BytecodeBuffer();
988 } else {
989 buffer->clear();
990 }
991 int max_stack = assemble_method_error(&bpool, buffer,
992 method->get_exception_name(), method->get_exception_message(), CHECK);
993 AccessFlags flags = accessFlags_from(
994 JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
995 Method* m = new_method(&bpool, buffer, slot->name(), slot->signature(),
996 flags, max_stack, slot->size_of_parameters(),
997 ConstMethod::OVERPASS, CHECK);
998 // We push to the methods list:
999 // overpass methods which are exception throwing methods
1000 if (m != NULL) {
1001 overpasses.push(m);
1002 }
1003 }
1004 }
1005 }
1006
1007
1008 log_debug(defaultmethods)("Created %d overpass methods", overpasses.length());
1009 log_debug(defaultmethods)("Created %d default methods", defaults.length());
1010
1011 if (overpasses.length() > 0) {
1012 switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
1013 merge_in_new_methods(klass, &overpasses, CHECK);
1014 }
1015 if (defaults.length() > 0) {
1016 create_default_methods(klass, &defaults, CHECK);
1017 }
1018 }
1019
1020 static void create_default_methods(InstanceKlass* klass,
1021 GrowableArray<Method*>* new_methods, TRAPS) {
1022
1023 int new_size = new_methods->length();
1024 Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>(
1025 klass->class_loader_data(), new_size, NULL, CHECK);
1026 for (int index = 0; index < new_size; index++ ) {
1027 total_default_methods->at_put(index, new_methods->at(index));
1028 }
1029 Method::sort_methods(total_default_methods, /*set_idnums=*/false);
1030
1031 klass->set_default_methods(total_default_methods);
1032 }
1033
1034 static void sort_methods(GrowableArray<Method*>* methods) {
1035 // Note that this must sort using the same key as is used for sorting
1036 // methods in InstanceKlass.
1037 bool sorted = true;
1038 for (int i = methods->length() - 1; i > 0; --i) {
1039 for (int j = 0; j < i; ++j) {
1040 Method* m1 = methods->at(j);
1041 Method* m2 = methods->at(j + 1);
1042 if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
1043 methods->at_put(j, m2);
1044 methods->at_put(j + 1, m1);
1045 sorted = false;
1046 }
1047 }
1048 if (sorted) break;
1049 sorted = true;
1050 }
1051 #ifdef ASSERT
1052 uintptr_t prev = 0;
1053 for (int i = 0; i < methods->length(); ++i) {
1054 Method* mh = methods->at(i);
1055 uintptr_t nv = (uintptr_t)mh->name();
1056 assert(nv >= prev, "Incorrect overpass method ordering");
1057 prev = nv;
1058 }
1059 #endif
1060 }
1061
1062 static void merge_in_new_methods(InstanceKlass* klass,
1063 GrowableArray<Method*>* new_methods, TRAPS) {
1064
1065 enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1066
1067 Array<Method*>* original_methods = klass->methods();
1068 Array<int>* original_ordering = klass->method_ordering();
1069 Array<int>* merged_ordering = Universe::the_empty_int_array();
1070
1071 int new_size = klass->methods()->length() + new_methods->length();
1072
1073 Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1074 klass->class_loader_data(), new_size, NULL, CHECK);
1075
1076 // original_ordering might be empty if this class has no methods of its own
1077 if (JvmtiExport::can_maintain_original_method_order() || Arguments::is_dumping_archive()) {
1078 merged_ordering = MetadataFactory::new_array<int>(
1079 klass->class_loader_data(), new_size, CHECK);
1080 }
1081 int method_order_index = klass->methods()->length();
1082
1083 sort_methods(new_methods);
1084
1085 // Perform grand merge of existing methods and new methods
1086 int orig_idx = 0;
1087 int new_idx = 0;
1088
1089 for (int i = 0; i < new_size; ++i) {
1090 Method* orig_method = NULL;
1091 Method* new_method = NULL;
1092 if (orig_idx < original_methods->length()) {
1093 orig_method = original_methods->at(orig_idx);
1094 }
1095 if (new_idx < new_methods->length()) {
1096 new_method = new_methods->at(new_idx);
1097 }
1098
1099 if (orig_method != NULL &&
1100 (new_method == NULL || orig_method->name() < new_method->name())) {
1101 merged_methods->at_put(i, orig_method);
1102 original_methods->at_put(orig_idx, NULL);
1103 if (merged_ordering->length() > 0) {
1104 assert(original_ordering != NULL && original_ordering->length() > 0,
1105 "should have original order information for this method");
1106 merged_ordering->at_put(i, original_ordering->at(orig_idx));
1107 }
1108 ++orig_idx;
1109 } else {
1110 merged_methods->at_put(i, new_method);
1111 if (merged_ordering->length() > 0) {
1112 merged_ordering->at_put(i, method_order_index++);
1113 }
1114 ++new_idx;
1115 }
1116 // update idnum for new location
1117 merged_methods->at(i)->set_method_idnum(i);
1118 merged_methods->at(i)->set_orig_method_idnum(i);
1119 }
1120
1121 // Verify correct order
1122 #ifdef ASSERT
1123 uintptr_t prev = 0;
1124 for (int i = 0; i < merged_methods->length(); ++i) {
1125 Method* mo = merged_methods->at(i);
1126 uintptr_t nv = (uintptr_t)mo->name();
1127 assert(nv >= prev, "Incorrect method ordering");
1128 prev = nv;
1129 }
1130 #endif
1131
1132 // Replace klass methods with new merged lists
1133 klass->set_methods(merged_methods);
1134 klass->set_initial_method_idnum(new_size);
1135 klass->set_method_ordering(merged_ordering);
1136
1137 // Free metadata
1138 ClassLoaderData* cld = klass->class_loader_data();
1139 if (original_methods->length() > 0) {
1140 MetadataFactory::free_array(cld, original_methods);
1141 }
1142 if (original_ordering != NULL && original_ordering->length() > 0) {
1143 MetadataFactory::free_array(cld, original_ordering);
1144 }
1145 }