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