1 /*
   2  * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/bytecodeAssembler.hpp"
  27 #include "classfile/defaultMethods.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logStream.hpp"
  32 #include "memory/allocation.hpp"
  33 #include "memory/metadataFactory.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "runtime/handles.inline.hpp"
  36 #include "runtime/signature.hpp"
  37 #include "runtime/thread.hpp"
  38 #include "oops/instanceKlass.hpp"
  39 #include "oops/klass.hpp"
  40 #include "oops/method.hpp"
  41 #include "utilities/accessFlags.hpp"
  42 #include "utilities/exceptions.hpp"
  43 #include "utilities/ostream.hpp"
  44 #include "utilities/pair.hpp"
  45 #include "utilities/resourceHash.hpp"
  46 
  47 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
  48 
  49 // Because we use an iterative algorithm when iterating over the type
  50 // hierarchy, we can't use traditional scoped objects which automatically do
  51 // cleanup in the destructor when the scope is exited.  PseudoScope (and
  52 // PseudoScopeMark) provides a similar functionality, but for when you want a
  53 // scoped object in non-stack memory (such as in resource memory, as we do
  54 // here).  You've just got to remember to call 'destroy()' on the scope when
  55 // leaving it (and marks have to be explicitly added).
  56 class PseudoScopeMark : public ResourceObj {
  57  public:
  58   virtual void destroy() = 0;
  59 };
  60 
  61 class PseudoScope : public ResourceObj {
  62  private:
  63   GrowableArray<PseudoScopeMark*> _marks;
  64  public:
  65 
  66   static PseudoScope* cast(void* data) {
  67     return static_cast<PseudoScope*>(data);
  68   }
  69 
  70   void add_mark(PseudoScopeMark* psm) {
  71    _marks.append(psm);
  72   }
  73 
  74   void destroy() {
  75     for (int i = 0; i < _marks.length(); ++i) {
  76       _marks.at(i)->destroy();
  77     }
  78   }
  79 };
  80 
  81 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
  82   str->print("%s%s", name->as_C_string(), signature->as_C_string());
  83 }
  84 
  85 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
  86   if (with_class) {
  87     str->print("%s.", mo->klass_name()->as_C_string());
  88   }
  89   print_slot(str, mo->name(), mo->signature());
  90 }
  91 
  92 /**
  93  * Perform a depth-first iteration over the class hierarchy, applying
  94  * algorithmic logic as it goes.
  95  *
  96  * This class is one half of the inheritance hierarchy analysis mechanism.
  97  * It is meant to be used in conjunction with another class, the algorithm,
  98  * which is indicated by the ALGO template parameter.  This class can be
  99  * paired with any algorithm class that provides the required methods.
 100  *
 101  * This class contains all the mechanics for iterating over the class hierarchy
 102  * starting at a particular root, without recursing (thus limiting stack growth
 103  * from this point).  It visits each superclass (if present) and superinterface
 104  * in a depth-first manner, with callbacks to the ALGO class as each class is
 105  * encountered (visit()), The algorithm can cut-off further exploration of a
 106  * particular branch by returning 'false' from a visit() call.
 107  *
 108  * The ALGO class, must provide a visit() method, which each of which will be
 109  * called once for each node in the inheritance tree during the iteration.  In
 110  * addition, it can provide a memory block via new_node_data(InstanceKlass*),
 111  * which it can use for node-specific storage (and access via the
 112  * current_data() and data_at_depth(int) methods).
 113  *
 114  * Bare minimum needed to be an ALGO class:
 115  * class Algo : public HierarchyVisitor<Algo> {
 116  *   void* new_node_data(InstanceKlass* cls) { return NULL; }
 117  *   void free_node_data(void* data) { return; }
 118  *   bool visit() { return true; }
 119  * };
 120  */
 121 template <class ALGO>
 122 class HierarchyVisitor : StackObj {
 123  private:
 124 
 125   class Node : public ResourceObj {
 126    public:
 127     InstanceKlass* _class;
 128     bool _super_was_visited;
 129     int _interface_index;
 130     void* _algorithm_data;
 131 
 132     Node(InstanceKlass* cls, void* data, bool visit_super)
 133         : _class(cls), _super_was_visited(!visit_super),
 134           _interface_index(0), _algorithm_data(data) {}
 135 
 136     int number_of_interfaces() { return _class->local_interfaces()->length(); }
 137     int interface_index() { return _interface_index; }
 138     void set_super_visited() { _super_was_visited = true; }
 139     void increment_visited_interface() { ++_interface_index; }
 140     void set_all_interfaces_visited() {
 141       _interface_index = number_of_interfaces();
 142     }
 143     bool has_visited_super() { return _super_was_visited; }
 144     bool has_visited_all_interfaces() {
 145       return interface_index() >= number_of_interfaces();
 146     }
 147     InstanceKlass* interface_at(int index) {
 148       return InstanceKlass::cast(_class->local_interfaces()->at(index));
 149     }
 150     InstanceKlass* next_super() { return _class->java_super(); }
 151     InstanceKlass* next_interface() {
 152       return interface_at(interface_index());
 153     }
 154   };
 155 
 156   bool _cancelled;
 157   GrowableArray<Node*> _path;
 158 
 159   Node* current_top() const { return _path.top(); }
 160   bool has_more_nodes() const { return !_path.is_empty(); }
 161   void push(InstanceKlass* cls, void* data) {
 162     assert(cls != NULL, "Requires a valid instance class");
 163     Node* node = new Node(cls, data, has_super(cls));
 164     _path.push(node);
 165   }
 166   void pop() { _path.pop(); }
 167 
 168   void reset_iteration() {
 169     _cancelled = false;
 170     _path.clear();
 171   }
 172   bool is_cancelled() const { return _cancelled; }
 173 
 174   // This code used to skip interface classes because their only
 175   // superclass was j.l.Object which would be also covered by class
 176   // superclass hierarchy walks. Now that the starting point can be
 177   // an interface, we must ensure we catch j.l.Object as the super.
 178   static bool has_super(InstanceKlass* cls) {
 179     return cls->super() != NULL;
 180   }
 181 
 182   Node* node_at_depth(int i) const {
 183     return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
 184   }
 185 
 186  protected:
 187 
 188   // Accessors available to the algorithm
 189   int current_depth() const { return _path.length() - 1; }
 190 
 191   InstanceKlass* class_at_depth(int i) {
 192     Node* n = node_at_depth(i);
 193     return n == NULL ? NULL : n->_class;
 194   }
 195   InstanceKlass* current_class() { return class_at_depth(0); }
 196 
 197   void* data_at_depth(int i) {
 198     Node* n = node_at_depth(i);
 199     return n == NULL ? NULL : n->_algorithm_data;
 200   }
 201   void* current_data() { return data_at_depth(0); }
 202 
 203   void cancel_iteration() { _cancelled = true; }
 204 
 205  public:
 206 
 207   void run(InstanceKlass* root) {
 208     ALGO* algo = static_cast<ALGO*>(this);
 209 
 210     reset_iteration();
 211 
 212     void* algo_data = algo->new_node_data(root);
 213     push(root, algo_data);
 214     bool top_needs_visit = true;
 215 
 216     do {
 217       Node* top = current_top();
 218       if (top_needs_visit) {
 219         if (algo->visit() == false) {
 220           // algorithm does not want to continue along this path.  Arrange
 221           // it so that this state is immediately popped off the stack
 222           top->set_super_visited();
 223           top->set_all_interfaces_visited();
 224         }
 225         top_needs_visit = false;
 226       }
 227 
 228       if (top->has_visited_super() && top->has_visited_all_interfaces()) {
 229         algo->free_node_data(top->_algorithm_data);
 230         pop();
 231       } else {
 232         InstanceKlass* next = NULL;
 233         if (top->has_visited_super() == false) {
 234           next = top->next_super();
 235           top->set_super_visited();
 236         } else {
 237           next = top->next_interface();
 238           top->increment_visited_interface();
 239         }
 240         assert(next != NULL, "Otherwise we shouldn't be here");
 241         algo_data = algo->new_node_data(next);
 242         push(next, algo_data);
 243         top_needs_visit = true;
 244       }
 245     } while (!is_cancelled() && has_more_nodes());
 246   }
 247 };
 248 
 249 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
 250  private:
 251    outputStream* _st;
 252  public:
 253   bool visit() {
 254     InstanceKlass* cls = current_class();
 255     streamIndentor si(_st, current_depth() * 2);
 256     _st->indent().print_cr("%s", cls->name()->as_C_string());
 257     return true;
 258   }
 259 
 260   void* new_node_data(InstanceKlass* cls) { return NULL; }
 261   void free_node_data(void* data) { return; }
 262 
 263   PrintHierarchy(outputStream* st = tty) : _st(st) {}
 264 };
 265 
 266 // Used to register InstanceKlass objects and all related metadata structures
 267 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
 268 // be deallocated by class redefinition while we're using them.  The classes are
 269 // de-registered when this goes out of scope.
 270 //
 271 // Once a class is registered, we need not bother with methodHandles or
 272 // constantPoolHandles for it's associated metadata.
 273 class KeepAliveRegistrar : public StackObj {
 274  private:
 275   Thread* _thread;
 276   GrowableArray<ConstantPool*> _keep_alive;
 277 
 278  public:
 279   KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
 280     assert(thread == Thread::current(), "Must be current thread");
 281   }
 282 
 283   ~KeepAliveRegistrar() {
 284     for (int i = _keep_alive.length() - 1; i >= 0; --i) {
 285       ConstantPool* cp = _keep_alive.at(i);
 286       int idx = _thread->metadata_handles()->find_from_end(cp);
 287       assert(idx > 0, "Must be in the list");
 288       _thread->metadata_handles()->remove_at(idx);
 289     }
 290   }
 291 
 292   // Register a class as 'in-use' by the thread.  It's fine to register a class
 293   // multiple times (though perhaps inefficient)
 294   void register_class(InstanceKlass* ik) {
 295     ConstantPool* cp = ik->constants();
 296     _keep_alive.push(cp);
 297     _thread->metadata_handles()->push(cp);
 298   }
 299 };
 300 
 301 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
 302  private:
 303   KeepAliveRegistrar* _registrar;
 304 
 305  public:
 306   KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
 307 
 308   void* new_node_data(InstanceKlass* cls) { return NULL; }
 309   void free_node_data(void* data) { return; }
 310 
 311   bool visit() {
 312     _registrar->register_class(current_class());
 313     return true;
 314   }
 315 };
 316 
 317 
 318 // A method family contains a set of all methods that implement a single
 319 // erased method. As members of the set are collected while walking over the
 320 // hierarchy, they are tagged with a qualification state.  The qualification
 321 // state for an erased method is set to disqualified if there exists a path
 322 // from the root of hierarchy to the method that contains an interleaving
 323 // erased method defined in an interface.
 324 
 325 class MethodFamily : public ResourceObj {
 326  private:
 327 
 328   GrowableArray<Pair<Method*,QualifiedState> > _members;
 329   ResourceHashtable<Method*, int> _member_index;
 330 
 331   Method* _selected_target;  // Filled in later, if a unique target exists
 332   Symbol* _exception_message; // If no unique target is found
 333   Symbol* _exception_name;    // If no unique target is found
 334 
 335   bool contains_method(Method* method) {
 336     int* lookup = _member_index.get(method);
 337     return lookup != NULL;
 338   }
 339 
 340   void add_method(Method* method, QualifiedState state) {
 341     Pair<Method*,QualifiedState> entry(method, state);
 342     _member_index.put(method, _members.length());
 343     _members.append(entry);
 344   }
 345 
 346   void disqualify_method(Method* method) {
 347     int* index = _member_index.get(method);
 348     guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
 349     _members.at(*index).second = DISQUALIFIED;
 350   }
 351 
 352   Symbol* generate_no_defaults_message(TRAPS) const;
 353   Symbol* generate_method_message(Symbol *klass_name, Method* method, TRAPS) const;
 354   Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
 355 
 356  public:
 357 
 358   MethodFamily()
 359       : _selected_target(NULL), _exception_message(NULL), _exception_name(NULL) {}
 360 
 361   void set_target_if_empty(Method* m) {
 362     if (_selected_target == NULL && !m->is_overpass()) {
 363       _selected_target = m;
 364     }
 365   }
 366 
 367   void record_qualified_method(Method* m) {
 368     // If the method already exists in the set as qualified, this operation is
 369     // redundant.  If it already exists as disqualified, then we leave it as
 370     // disqualfied.  Thus we only add to the set if it's not already in the
 371     // set.
 372     if (!contains_method(m)) {
 373       add_method(m, QUALIFIED);
 374     }
 375   }
 376 
 377   void record_disqualified_method(Method* m) {
 378     // If not in the set, add it as disqualified.  If it's already in the set,
 379     // then set the state to disqualified no matter what the previous state was.
 380     if (!contains_method(m)) {
 381       add_method(m, DISQUALIFIED);
 382     } else {
 383       disqualify_method(m);
 384     }
 385   }
 386 
 387   bool has_target() const { return _selected_target != NULL; }
 388   bool throws_exception() { return _exception_message != NULL; }
 389 
 390   Method* get_selected_target() { return _selected_target; }
 391   Symbol* get_exception_message() { return _exception_message; }
 392   Symbol* get_exception_name() { return _exception_name; }
 393 
 394   // Either sets the target or the exception error message
 395   void determine_target(InstanceKlass* root, TRAPS) {
 396     if (has_target() || throws_exception()) {
 397       return;
 398     }
 399 
 400     // Qualified methods are maximally-specific methods
 401     // These include public, instance concrete (=default) and abstract methods
 402     GrowableArray<Method*> qualified_methods;
 403     int num_defaults = 0;
 404     int default_index = -1;
 405     int qualified_index = -1;
 406     for (int i = 0; i < _members.length(); ++i) {
 407       Pair<Method*,QualifiedState> entry = _members.at(i);
 408       if (entry.second == QUALIFIED) {
 409         qualified_methods.append(entry.first);
 410         qualified_index++;
 411         if (entry.first->is_default_method()) {
 412           num_defaults++;
 413           default_index = qualified_index;
 414 
 415         }
 416       }
 417     }
 418 
 419     if (num_defaults == 0) {
 420       // If the root klass has a static method with matching name and signature
 421       // then do not generate an overpass method because it will hide the
 422       // static method during resolution.
 423       if (qualified_methods.length() == 0) {
 424         _exception_message = generate_no_defaults_message(CHECK);
 425       } else {
 426         assert(root != NULL, "Null root class");
 427         _exception_message = generate_method_message(root->name(), qualified_methods.at(0), CHECK);
 428       }
 429       _exception_name = vmSymbols::java_lang_AbstractMethodError();
 430 
 431     // If only one qualified method is default, select that
 432     } else if (num_defaults == 1) {
 433         _selected_target = qualified_methods.at(default_index);
 434 
 435     } else if (num_defaults > 1) {
 436       _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
 437       _exception_name = vmSymbols::java_lang_IncompatibleClassChangeError();
 438       LogTarget(Debug, defaultmethods) lt;
 439       if (lt.is_enabled()) {
 440         LogStream ls(lt);
 441         _exception_message->print_value_on(&ls);
 442         ls.cr();
 443       }
 444     }
 445   }
 446 
 447   bool contains_signature(Symbol* query) {
 448     for (int i = 0; i < _members.length(); ++i) {
 449       if (query == _members.at(i).first->signature()) {
 450         return true;
 451       }
 452     }
 453     return false;
 454   }
 455 
 456   void print_selected(outputStream* str, int indent) const {
 457     assert(has_target(), "Should be called otherwise");
 458     streamIndentor si(str, indent * 2);
 459     str->indent().print("Selected method: ");
 460     print_method(str, _selected_target);
 461     Klass* method_holder = _selected_target->method_holder();
 462     if (!method_holder->is_interface()) {
 463       str->print(" : in superclass");
 464     }
 465     str->cr();
 466   }
 467 
 468   void print_exception(outputStream* str, int indent) {
 469     assert(throws_exception(), "Should be called otherwise");
 470     assert(_exception_name != NULL, "exception_name should be set");
 471     streamIndentor si(str, indent * 2);
 472     str->indent().print_cr("%s: %s", _exception_name->as_C_string(), _exception_message->as_C_string());
 473   }
 474 };
 475 
 476 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
 477   return SymbolTable::new_symbol("No qualifying defaults found", THREAD);

 478 }
 479 
 480 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const {
 481   stringStream ss;
 482   ss.print("Method ");
 483   Symbol* name = method->name();
 484   Symbol* signature = method->signature();
 485   ss.write((const char*)klass_name->bytes(), klass_name->utf8_length());
 486   ss.print(".");
 487   ss.write((const char*)name->bytes(), name->utf8_length());
 488   ss.write((const char*)signature->bytes(), signature->utf8_length());
 489   ss.print(" is abstract");
 490   return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD);

 491 }
 492 
 493 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
 494   stringStream ss;
 495   ss.print("Conflicting default methods:");
 496   for (int i = 0; i < methods->length(); ++i) {
 497     Method* method = methods->at(i);
 498     Symbol* klass = method->klass_name();
 499     Symbol* name = method->name();
 500     ss.print(" ");
 501     ss.write((const char*)klass->bytes(), klass->utf8_length());
 502     ss.print(".");
 503     ss.write((const char*)name->bytes(), name->utf8_length());
 504   }
 505   return SymbolTable::new_symbol(ss.base(), (int)ss.size(), THREAD);

 506 }
 507 
 508 
 509 class StateRestorer;
 510 
 511 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
 512 // qualification state during hierarchy visitation, and applies that state
 513 // when adding members to the MethodFamily
 514 class StatefulMethodFamily : public ResourceObj {
 515   friend class StateRestorer;
 516  private:
 517   QualifiedState _qualification_state;
 518 
 519   void set_qualification_state(QualifiedState state) {
 520     _qualification_state = state;
 521   }
 522 
 523  protected:
 524   MethodFamily* _method_family;
 525 
 526  public:
 527   StatefulMethodFamily() {
 528    _method_family = new MethodFamily();
 529    _qualification_state = QUALIFIED;
 530   }
 531 
 532   StatefulMethodFamily(MethodFamily* mf) {
 533    _method_family = mf;
 534    _qualification_state = QUALIFIED;
 535   }
 536 
 537   void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
 538 
 539   MethodFamily* get_method_family() { return _method_family; }
 540 
 541   StateRestorer* record_method_and_dq_further(Method* mo);
 542 };
 543 
 544 class StateRestorer : public PseudoScopeMark {
 545  private:
 546   StatefulMethodFamily* _method;
 547   QualifiedState _state_to_restore;
 548  public:
 549   StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
 550       : _method(dm), _state_to_restore(state) {}
 551   ~StateRestorer() { destroy(); }
 552   void restore_state() { _method->set_qualification_state(_state_to_restore); }
 553   virtual void destroy() { restore_state(); }
 554 };
 555 
 556 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
 557   StateRestorer* mark = new StateRestorer(this, _qualification_state);
 558   if (_qualification_state == QUALIFIED) {
 559     _method_family->record_qualified_method(mo);
 560   } else {
 561     _method_family->record_disqualified_method(mo);
 562   }
 563   // Everything found "above"??? this method in the hierarchy walk is set to
 564   // disqualified
 565   set_qualification_state(DISQUALIFIED);
 566   return mark;
 567 }
 568 
 569 // Represents a location corresponding to a vtable slot for methods that
 570 // neither the class nor any of it's ancestors provide an implementaion.
 571 // Default methods may be present to fill this slot.
 572 class EmptyVtableSlot : public ResourceObj {
 573  private:
 574   Symbol* _name;
 575   Symbol* _signature;
 576   int _size_of_parameters;
 577   MethodFamily* _binding;
 578 
 579  public:
 580   EmptyVtableSlot(Method* method)
 581       : _name(method->name()), _signature(method->signature()),
 582         _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
 583 
 584   Symbol* name() const { return _name; }
 585   Symbol* signature() const { return _signature; }
 586   int size_of_parameters() const { return _size_of_parameters; }
 587 
 588   void bind_family(MethodFamily* lm) { _binding = lm; }
 589   bool is_bound() { return _binding != NULL; }
 590   MethodFamily* get_binding() { return _binding; }
 591 
 592   void print_on(outputStream* str) const {
 593     print_slot(str, name(), signature());
 594   }
 595 };
 596 
 597 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
 598   bool found = false;
 599   for (int j = 0; j < slots->length(); ++j) {
 600     if (slots->at(j)->name() == m->name() &&
 601         slots->at(j)->signature() == m->signature() ) {
 602       found = true;
 603       break;
 604     }
 605   }
 606   return found;
 607 }
 608 
 609 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
 610     InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
 611 
 612   assert(klass != NULL, "Must be valid class");
 613 
 614   GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
 615 
 616   // All miranda methods are obvious candidates
 617   for (int i = 0; i < mirandas->length(); ++i) {
 618     Method* m = mirandas->at(i);
 619     if (!already_in_vtable_slots(slots, m)) {
 620       slots->append(new EmptyVtableSlot(m));
 621     }
 622   }
 623 
 624   // Also any overpasses in our superclasses, that we haven't implemented.
 625   // (can't use the vtable because it is not guaranteed to be initialized yet)
 626   InstanceKlass* super = klass->java_super();
 627   while (super != NULL) {
 628     for (int i = 0; i < super->methods()->length(); ++i) {
 629       Method* m = super->methods()->at(i);
 630       if (m->is_overpass() || m->is_static()) {
 631         // m is a method that would have been a miranda if not for the
 632         // default method processing that occurred on behalf of our superclass,
 633         // so it's a method we want to re-examine in this new context.  That is,
 634         // unless we have a real implementation of it in the current class.
 635         Method* impl = klass->lookup_method(m->name(), m->signature());
 636         if (impl == NULL || impl->is_overpass() || impl->is_static()) {
 637           if (!already_in_vtable_slots(slots, m)) {
 638             slots->append(new EmptyVtableSlot(m));
 639           }
 640         }
 641       }
 642     }
 643 
 644     // also any default methods in our superclasses
 645     if (super->default_methods() != NULL) {
 646       for (int i = 0; i < super->default_methods()->length(); ++i) {
 647         Method* m = super->default_methods()->at(i);
 648         // m is a method that would have been a miranda if not for the
 649         // default method processing that occurred on behalf of our superclass,
 650         // so it's a method we want to re-examine in this new context.  That is,
 651         // unless we have a real implementation of it in the current class.
 652         Method* impl = klass->lookup_method(m->name(), m->signature());
 653         if (impl == NULL || impl->is_overpass() || impl->is_static()) {
 654           if (!already_in_vtable_slots(slots, m)) {
 655             slots->append(new EmptyVtableSlot(m));
 656           }
 657         }
 658       }
 659     }
 660     super = super->java_super();
 661   }
 662 
 663   LogTarget(Debug, defaultmethods) lt;
 664   if (lt.is_enabled()) {
 665     lt.print("Slots that need filling:");
 666     ResourceMark rm;
 667     LogStream ls(lt);
 668     streamIndentor si(&ls);
 669     for (int i = 0; i < slots->length(); ++i) {
 670       ls.indent();
 671       slots->at(i)->print_on(&ls);
 672       ls.cr();
 673     }
 674   }
 675 
 676   return slots;
 677 }
 678 
 679 // Iterates over the superinterface type hierarchy looking for all methods
 680 // with a specific erased signature.
 681 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
 682  private:
 683   // Context data
 684   Symbol* _method_name;
 685   Symbol* _method_signature;
 686   StatefulMethodFamily*  _family;
 687   bool _cur_class_is_interface;
 688 
 689  public:
 690   FindMethodsByErasedSig(Symbol* name, Symbol* signature, bool is_interf) :
 691       _method_name(name), _method_signature(signature), _family(NULL),
 692       _cur_class_is_interface(is_interf) {}
 693 
 694   void get_discovered_family(MethodFamily** family) {
 695       if (_family != NULL) {
 696         *family = _family->get_method_family();
 697       } else {
 698         *family = NULL;
 699       }
 700   }
 701 
 702   void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
 703   void free_node_data(void* node_data) {
 704     PseudoScope::cast(node_data)->destroy();
 705   }
 706 
 707   // Find all methods on this hierarchy that match this
 708   // method's erased (name, signature)
 709   bool visit() {
 710     PseudoScope* scope = PseudoScope::cast(current_data());
 711     InstanceKlass* iklass = current_class();
 712 
 713     Method* m = iklass->find_method(_method_name, _method_signature);
 714     // Private interface methods are not candidates for default methods.
 715     // invokespecial to private interface methods doesn't use default method logic.
 716     // Private class methods are not candidates for default methods.
 717     // Private methods do not override default methods, so need to perform
 718     // default method inheritance without including private methods.
 719     // The overpasses are your supertypes' errors, we do not include them.
 720     // Non-public methods in java.lang.Object are not candidates for default
 721     // methods.
 722     // Future: take access controls into account for superclass methods
 723     if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() &&
 724      (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) {
 725       if (_family == NULL) {
 726         _family = new StatefulMethodFamily();
 727       }
 728 
 729       if (iklass->is_interface()) {
 730         StateRestorer* restorer = _family->record_method_and_dq_further(m);
 731         scope->add_mark(restorer);
 732       } else {
 733         // This is the rule that methods in classes "win" (bad word) over
 734         // methods in interfaces. This works because of single inheritance.
 735         // Private methods in classes do not "win", they will be found
 736         // first on searching, but overriding for invokevirtual needs
 737         // to find default method candidates for the same signature
 738         _family->set_target_if_empty(m);
 739       }
 740     }
 741     return true;
 742   }
 743 
 744 };
 745 
 746 
 747 
 748 static void create_defaults_and_exceptions(
 749     GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
 750 
 751 static void generate_erased_defaults(
 752      InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
 753      EmptyVtableSlot* slot, bool is_intf, TRAPS) {
 754 
 755   // sets up a set of methods with the same exact erased signature
 756   FindMethodsByErasedSig visitor(slot->name(), slot->signature(), is_intf);
 757   visitor.run(klass);
 758 
 759   MethodFamily* family;
 760   visitor.get_discovered_family(&family);
 761   if (family != NULL) {
 762     family->determine_target(klass, CHECK);
 763     slot->bind_family(family);
 764   }
 765 }
 766 
 767 static void merge_in_new_methods(InstanceKlass* klass,
 768     GrowableArray<Method*>* new_methods, TRAPS);
 769 static void create_default_methods( InstanceKlass* klass,
 770     GrowableArray<Method*>* new_methods, TRAPS);
 771 
 772 // This is the guts of the default methods implementation.  This is called just
 773 // after the classfile has been parsed if some ancestor has default methods.
 774 //
 775 // First it finds any name/signature slots that need any implementation (either
 776 // because they are miranda or a superclass's implementation is an overpass
 777 // itself).  For each slot, iterate over the hierarchy, to see if they contain a
 778 // signature that matches the slot we are looking at.
 779 //
 780 // For each slot filled, we either record the default method candidate in the
 781 // klass default_methods list or, only to handle exception cases, we create an
 782 // overpass method that throws an exception and add it to the klass methods list.
 783 // The JVM does not create bridges nor handle generic signatures here.
 784 void DefaultMethods::generate_default_methods(
 785     InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
 786   assert(klass != NULL, "invariant");
 787 
 788   // This resource mark is the bound for all memory allocation that takes
 789   // place during default method processing.  After this goes out of scope,
 790   // all (Resource) objects' memory will be reclaimed.  Be careful if adding an
 791   // embedded resource mark under here as that memory can't be used outside
 792   // whatever scope it's in.
 793   ResourceMark rm(THREAD);
 794 
 795   // Keep entire hierarchy alive for the duration of the computation
 796   constantPoolHandle cp(THREAD, klass->constants());
 797   KeepAliveRegistrar keepAlive(THREAD);
 798   KeepAliveVisitor loadKeepAlive(&keepAlive);
 799   loadKeepAlive.run(klass);
 800 
 801   LogTarget(Debug, defaultmethods) lt;
 802   if (lt.is_enabled()) {
 803     ResourceMark rm;
 804     lt.print("%s %s requires default method processing",
 805              klass->is_interface() ? "Interface" : "Class",
 806              klass->name()->as_klass_external_name());
 807     LogStream ls(lt);
 808     PrintHierarchy printer(&ls);
 809     printer.run(klass);
 810   }
 811 
 812   GrowableArray<EmptyVtableSlot*>* empty_slots =
 813       find_empty_vtable_slots(klass, mirandas, CHECK);
 814 
 815   for (int i = 0; i < empty_slots->length(); ++i) {
 816     EmptyVtableSlot* slot = empty_slots->at(i);
 817     LogTarget(Debug, defaultmethods) lt;
 818     if (lt.is_enabled()) {
 819       LogStream ls(lt);
 820       streamIndentor si(&ls, 2);
 821       ls.indent().print("Looking for default methods for slot ");
 822       slot->print_on(&ls);
 823       ls.cr();
 824     }
 825     generate_erased_defaults(klass, empty_slots, slot, klass->is_interface(), CHECK);
 826   }
 827   log_debug(defaultmethods)("Creating defaults and overpasses...");
 828   create_defaults_and_exceptions(empty_slots, klass, CHECK);
 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, false, 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 }
--- EOF ---