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   Symbol* s = SymbolTable::new_symbol("No qualifying defaults found", CHECK_NULL);
 478   return s;
 479 }
 480 
 481 Symbol* MethodFamily::generate_method_message(Symbol *klass_name, Method* method, TRAPS) const {
 482   stringStream ss;
 483   ss.print("Method ");
 484   Symbol* name = method->name();
 485   Symbol* signature = method->signature();
 486   ss.write((const char*)klass_name->bytes(), klass_name->utf8_length());
 487   ss.print(".");
 488   ss.write((const char*)name->bytes(), name->utf8_length());
 489   ss.write((const char*)signature->bytes(), signature->utf8_length());
 490   ss.print(" is abstract");
 491   Symbol* s = SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
 492   return s;
 493 }
 494 
 495 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
 496   stringStream ss;
 497   ss.print("Conflicting default methods:");
 498   for (int i = 0; i < methods->length(); ++i) {
 499     Method* method = methods->at(i);
 500     Symbol* klass = method->klass_name();
 501     Symbol* name = method->name();
 502     ss.print(" ");
 503     ss.write((const char*)klass->bytes(), klass->utf8_length());
 504     ss.print(".");
 505     ss.write((const char*)name->bytes(), name->utf8_length());
 506   }
 507   Symbol* s = SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
 508   return s;
 509 }
 510 
 511 
 512 class StateRestorer;
 513 
 514 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
 515 // qualification state during hierarchy visitation, and applies that state
 516 // when adding members to the MethodFamily
 517 class StatefulMethodFamily : public ResourceObj {
 518   friend class StateRestorer;
 519  private:
 520   QualifiedState _qualification_state;
 521 
 522   void set_qualification_state(QualifiedState state) {
 523     _qualification_state = state;
 524   }
 525 
 526  protected:
 527   MethodFamily* _method_family;
 528 
 529  public:
 530   StatefulMethodFamily() {
 531    _method_family = new MethodFamily();
 532    _qualification_state = QUALIFIED;
 533   }
 534 
 535   StatefulMethodFamily(MethodFamily* mf) {
 536    _method_family = mf;
 537    _qualification_state = QUALIFIED;
 538   }
 539 
 540   void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
 541 
 542   MethodFamily* get_method_family() { return _method_family; }
 543 
 544   StateRestorer* record_method_and_dq_further(Method* mo);
 545 };
 546 
 547 class StateRestorer : public PseudoScopeMark {
 548  private:
 549   StatefulMethodFamily* _method;
 550   QualifiedState _state_to_restore;
 551  public:
 552   StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
 553       : _method(dm), _state_to_restore(state) {}
 554   ~StateRestorer() { destroy(); }
 555   void restore_state() { _method->set_qualification_state(_state_to_restore); }
 556   virtual void destroy() { restore_state(); }
 557 };
 558 
 559 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
 560   StateRestorer* mark = new StateRestorer(this, _qualification_state);
 561   if (_qualification_state == QUALIFIED) {
 562     _method_family->record_qualified_method(mo);
 563   } else {
 564     _method_family->record_disqualified_method(mo);
 565   }
 566   // Everything found "above"??? this method in the hierarchy walk is set to
 567   // disqualified
 568   set_qualification_state(DISQUALIFIED);
 569   return mark;
 570 }
 571 
 572 // Represents a location corresponding to a vtable slot for methods that
 573 // neither the class nor any of it's ancestors provide an implementaion.
 574 // Default methods may be present to fill this slot.
 575 class EmptyVtableSlot : public ResourceObj {
 576  private:
 577   Symbol* _name;
 578   Symbol* _signature;
 579   int _size_of_parameters;
 580   MethodFamily* _binding;
 581 
 582  public:
 583   EmptyVtableSlot(Method* method)
 584       : _name(method->name()), _signature(method->signature()),
 585         _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
 586 
 587   Symbol* name() const { return _name; }
 588   Symbol* signature() const { return _signature; }
 589   int size_of_parameters() const { return _size_of_parameters; }
 590 
 591   void bind_family(MethodFamily* lm) { _binding = lm; }
 592   bool is_bound() { return _binding != NULL; }
 593   MethodFamily* get_binding() { return _binding; }
 594 
 595   void print_on(outputStream* str) const {
 596     print_slot(str, name(), signature());
 597   }
 598 };
 599 
 600 static bool already_in_vtable_slots(GrowableArray<EmptyVtableSlot*>* slots, Method* m) {
 601   bool found = false;
 602   for (int j = 0; j < slots->length(); ++j) {
 603     if (slots->at(j)->name() == m->name() &&
 604         slots->at(j)->signature() == m->signature() ) {
 605       found = true;
 606       break;
 607     }
 608   }
 609   return found;
 610 }
 611 
 612 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
 613     InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
 614 
 615   assert(klass != NULL, "Must be valid class");
 616 
 617   GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
 618 
 619   // All miranda methods are obvious candidates
 620   for (int i = 0; i < mirandas->length(); ++i) {
 621     Method* m = mirandas->at(i);
 622     if (!already_in_vtable_slots(slots, m)) {
 623       slots->append(new EmptyVtableSlot(m));
 624     }
 625   }
 626 
 627   // Also any overpasses in our superclasses, that we haven't implemented.
 628   // (can't use the vtable because it is not guaranteed to be initialized yet)
 629   InstanceKlass* super = klass->java_super();
 630   while (super != NULL) {
 631     for (int i = 0; i < super->methods()->length(); ++i) {
 632       Method* m = super->methods()->at(i);
 633       if (m->is_overpass() || m->is_static()) {
 634         // m is a method that would have been a miranda if not for the
 635         // default method processing that occurred on behalf of our superclass,
 636         // so it's a method we want to re-examine in this new context.  That is,
 637         // unless we have a real implementation of it in the current class.
 638         Method* impl = klass->lookup_method(m->name(), m->signature());
 639         if (impl == NULL || impl->is_overpass() || impl->is_static()) {
 640           if (!already_in_vtable_slots(slots, m)) {
 641             slots->append(new EmptyVtableSlot(m));
 642           }
 643         }
 644       }
 645     }
 646 
 647     // also any default methods in our superclasses
 648     if (super->default_methods() != NULL) {
 649       for (int i = 0; i < super->default_methods()->length(); ++i) {
 650         Method* m = super->default_methods()->at(i);
 651         // m is a method that would have been a miranda if not for the
 652         // default method processing that occurred on behalf of our superclass,
 653         // so it's a method we want to re-examine in this new context.  That is,
 654         // unless we have a real implementation of it in the current class.
 655         Method* impl = klass->lookup_method(m->name(), m->signature());
 656         if (impl == NULL || impl->is_overpass() || impl->is_static()) {
 657           if (!already_in_vtable_slots(slots, m)) {
 658             slots->append(new EmptyVtableSlot(m));
 659           }
 660         }
 661       }
 662     }
 663     super = super->java_super();
 664   }
 665 
 666   LogTarget(Debug, defaultmethods) lt;
 667   if (lt.is_enabled()) {
 668     lt.print("Slots that need filling:");
 669     ResourceMark rm;
 670     LogStream ls(lt);
 671     streamIndentor si(&ls);
 672     for (int i = 0; i < slots->length(); ++i) {
 673       ls.indent();
 674       slots->at(i)->print_on(&ls);
 675       ls.cr();
 676     }
 677   }
 678 
 679   return slots;
 680 }
 681 
 682 // Iterates over the superinterface type hierarchy looking for all methods
 683 // with a specific erased signature.
 684 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
 685  private:
 686   // Context data
 687   Symbol* _method_name;
 688   Symbol* _method_signature;
 689   StatefulMethodFamily*  _family;
 690   bool _cur_class_is_interface;
 691 
 692  public:
 693   FindMethodsByErasedSig(Symbol* name, Symbol* signature, bool is_interf) :
 694       _method_name(name), _method_signature(signature), _family(NULL),
 695       _cur_class_is_interface(is_interf) {}
 696 
 697   void get_discovered_family(MethodFamily** family) {
 698       if (_family != NULL) {
 699         *family = _family->get_method_family();
 700       } else {
 701         *family = NULL;
 702       }
 703   }
 704 
 705   void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
 706   void free_node_data(void* node_data) {
 707     PseudoScope::cast(node_data)->destroy();
 708   }
 709 
 710   // Find all methods on this hierarchy that match this
 711   // method's erased (name, signature)
 712   bool visit() {
 713     PseudoScope* scope = PseudoScope::cast(current_data());
 714     InstanceKlass* iklass = current_class();
 715 
 716     Method* m = iklass->find_method(_method_name, _method_signature);
 717     // Private interface methods are not candidates for default methods.
 718     // invokespecial to private interface methods doesn't use default method logic.
 719     // Private class methods are not candidates for default methods.
 720     // Private methods do not override default methods, so need to perform
 721     // default method inheritance without including private methods.
 722     // The overpasses are your supertypes' errors, we do not include them.
 723     // Non-public methods in java.lang.Object are not candidates for default
 724     // methods.
 725     // Future: take access controls into account for superclass methods
 726     if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private() &&
 727      (!_cur_class_is_interface || !SystemDictionary::is_nonpublic_Object_method(m))) {
 728       if (_family == NULL) {
 729         _family = new StatefulMethodFamily();
 730       }
 731 
 732       if (iklass->is_interface()) {
 733         StateRestorer* restorer = _family->record_method_and_dq_further(m);
 734         scope->add_mark(restorer);
 735       } else {
 736         // This is the rule that methods in classes "win" (bad word) over
 737         // methods in interfaces. This works because of single inheritance.
 738         // Private methods in classes do not "win", they will be found
 739         // first on searching, but overriding for invokevirtual needs
 740         // to find default method candidates for the same signature
 741         _family->set_target_if_empty(m);
 742       }
 743     }
 744     return true;
 745   }
 746 
 747 };
 748 
 749 
 750 
 751 static void create_defaults_and_exceptions(
 752     GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
 753 
 754 static void generate_erased_defaults(
 755      InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
 756      EmptyVtableSlot* slot, bool is_intf, TRAPS) {
 757 
 758   // sets up a set of methods with the same exact erased signature
 759   FindMethodsByErasedSig visitor(slot->name(), slot->signature(), is_intf);
 760   visitor.run(klass);
 761 
 762   MethodFamily* family;
 763   visitor.get_discovered_family(&family);
 764   if (family != NULL) {
 765     family->determine_target(klass, CHECK);
 766     slot->bind_family(family);
 767   }
 768 }
 769 
 770 static void merge_in_new_methods(InstanceKlass* klass,
 771     GrowableArray<Method*>* new_methods, TRAPS);
 772 static void create_default_methods( InstanceKlass* klass,
 773     GrowableArray<Method*>* new_methods, TRAPS);
 774 
 775 // This is the guts of the default methods implementation.  This is called just
 776 // after the classfile has been parsed if some ancestor has default methods.
 777 //
 778 // First it finds any name/signature slots that need any implementation (either
 779 // because they are miranda or a superclass's implementation is an overpass
 780 // itself).  For each slot, iterate over the hierarchy, to see if they contain a
 781 // signature that matches the slot we are looking at.
 782 //
 783 // For each slot filled, we either record the default method candidate in the
 784 // klass default_methods list or, only to handle exception cases, we create an
 785 // overpass method that throws an exception and add it to the klass methods list.
 786 // The JVM does not create bridges nor handle generic signatures here.
 787 void DefaultMethods::generate_default_methods(
 788     InstanceKlass* klass, const GrowableArray<Method*>* mirandas, TRAPS) {
 789   assert(klass != NULL, "invariant");
 790 
 791   // This resource mark is the bound for all memory allocation that takes
 792   // place during default method processing.  After this goes out of scope,
 793   // all (Resource) objects' memory will be reclaimed.  Be careful if adding an
 794   // embedded resource mark under here as that memory can't be used outside
 795   // whatever scope it's in.
 796   ResourceMark rm(THREAD);
 797 
 798   // Keep entire hierarchy alive for the duration of the computation
 799   constantPoolHandle cp(THREAD, klass->constants());
 800   KeepAliveRegistrar keepAlive(THREAD);
 801   KeepAliveVisitor loadKeepAlive(&keepAlive);
 802   loadKeepAlive.run(klass);
 803 
 804   LogTarget(Debug, defaultmethods) lt;
 805   if (lt.is_enabled()) {
 806     ResourceMark rm;
 807     lt.print("%s %s requires default method processing",
 808              klass->is_interface() ? "Interface" : "Class",
 809              klass->name()->as_klass_external_name());
 810     LogStream ls(lt);
 811     PrintHierarchy printer(&ls);
 812     printer.run(klass);
 813   }
 814 
 815   GrowableArray<EmptyVtableSlot*>* empty_slots =
 816       find_empty_vtable_slots(klass, mirandas, CHECK);
 817 
 818   for (int i = 0; i < empty_slots->length(); ++i) {
 819     EmptyVtableSlot* slot = empty_slots->at(i);
 820     LogTarget(Debug, defaultmethods) lt;
 821     if (lt.is_enabled()) {
 822       LogStream ls(lt);
 823       streamIndentor si(&ls, 2);
 824       ls.indent().print("Looking for default methods for slot ");
 825       slot->print_on(&ls);
 826       ls.cr();
 827     }
 828     generate_erased_defaults(klass, empty_slots, slot, klass->is_interface(), CHECK);
 829   }
 830   log_debug(defaultmethods)("Creating defaults and overpasses...");
 831   create_defaults_and_exceptions(empty_slots, klass, CHECK);
 832   log_debug(defaultmethods)("Default method processing complete");
 833 }
 834 
 835 static int assemble_method_error(
 836     BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* errorName, Symbol* message, TRAPS) {
 837 
 838   Symbol* init = vmSymbols::object_initializer_name();
 839   Symbol* sig = vmSymbols::string_void_signature();
 840 
 841   BytecodeAssembler assem(buffer, cp);
 842 
 843   assem._new(errorName);
 844   assem.dup();
 845   assem.load_string(message);
 846   assem.invokespecial(errorName, init, sig);
 847   assem.athrow();
 848 
 849   return 3; // max stack size: [ exception, exception, string ]
 850 }
 851 
 852 static Method* new_method(
 853     BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
 854     Symbol* sig, AccessFlags flags, int max_stack, int params,
 855     ConstMethod::MethodType mt, TRAPS) {
 856 
 857   address code_start = 0;
 858   int code_length = 0;
 859   InlineTableSizes sizes;
 860 
 861   if (bytecodes != NULL && bytecodes->length() > 0) {
 862     code_start = static_cast<address>(bytecodes->adr_at(0));
 863     code_length = bytecodes->length();
 864   }
 865 
 866   Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
 867                                code_length, flags, &sizes,
 868                                mt, CHECK_NULL);
 869 
 870   m->set_constants(NULL); // This will get filled in later
 871   m->set_name_index(cp->utf8(name));
 872   m->set_signature_index(cp->utf8(sig));
 873   ResultTypeFinder rtf(sig);
 874   m->constMethod()->set_result_type(rtf.type());
 875   m->set_size_of_parameters(params);
 876   m->set_max_stack(max_stack);
 877   m->set_max_locals(params);
 878   m->constMethod()->set_stackmap_data(NULL);
 879   m->set_code(code_start);
 880 
 881   return m;
 882 }
 883 
 884 static void switchover_constant_pool(BytecodeConstantPool* bpool,
 885     InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
 886 
 887   if (new_methods->length() > 0) {
 888     ConstantPool* cp = bpool->create_constant_pool(CHECK);
 889     if (cp != klass->constants()) {
 890       // Copy resolved anonymous class into new constant pool.
 891       if (klass->is_unsafe_anonymous()) {
 892         cp->klass_at_put(klass->this_class_index(), klass);
 893       }
 894       klass->class_loader_data()->add_to_deallocate_list(klass->constants());
 895       klass->set_constants(cp);
 896       cp->set_pool_holder(klass);
 897 
 898       for (int i = 0; i < new_methods->length(); ++i) {
 899         new_methods->at(i)->set_constants(cp);
 900       }
 901       for (int i = 0; i < klass->methods()->length(); ++i) {
 902         Method* mo = klass->methods()->at(i);
 903         mo->set_constants(cp);
 904       }
 905     }
 906   }
 907 }
 908 
 909 // Create default_methods list for the current class.
 910 // With the VM only processing erased signatures, the VM only
 911 // creates an overpass in a conflict case or a case with no candidates.
 912 // This allows virtual methods to override the overpass, but ensures
 913 // that a local method search will find the exception rather than an abstract
 914 // or default method that is not a valid candidate.
 915 //
 916 // Note that if overpass method are ever created that are not exception
 917 // throwing methods then the loader constraint checking logic for vtable and
 918 // itable creation needs to be changed to check loader constraints for the
 919 // overpass methods that do not throw exceptions.
 920 static void create_defaults_and_exceptions(
 921     GrowableArray<EmptyVtableSlot*>* slots,
 922     InstanceKlass* klass, TRAPS) {
 923 
 924   GrowableArray<Method*> overpasses;
 925   GrowableArray<Method*> defaults;
 926   BytecodeConstantPool bpool(klass->constants());
 927 
 928   for (int i = 0; i < slots->length(); ++i) {
 929     EmptyVtableSlot* slot = slots->at(i);
 930 
 931     if (slot->is_bound()) {
 932       MethodFamily* method = slot->get_binding();
 933       BytecodeBuffer buffer;
 934 
 935       LogTarget(Debug, defaultmethods) lt;
 936       if (lt.is_enabled()) {
 937         ResourceMark rm(THREAD);
 938         LogStream ls(lt);
 939         ls.print("for slot: ");
 940         slot->print_on(&ls);
 941         ls.cr();
 942         if (method->has_target()) {
 943           method->print_selected(&ls, 1);
 944         } else if (method->throws_exception()) {
 945           method->print_exception(&ls, 1);
 946         }
 947       }
 948 
 949       if (method->has_target()) {
 950         Method* selected = method->get_selected_target();
 951         if (selected->method_holder()->is_interface()) {
 952           assert(!selected->is_private(), "pushing private interface method as default");
 953           defaults.push(selected);
 954         }
 955       } else if (method->throws_exception()) {
 956         int max_stack = assemble_method_error(&bpool, &buffer,
 957            method->get_exception_name(), method->get_exception_message(), CHECK);
 958         AccessFlags flags = accessFlags_from(
 959           JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
 960          Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
 961           flags, max_stack, slot->size_of_parameters(),
 962           ConstMethod::OVERPASS, CHECK);
 963         // We push to the methods list:
 964         // overpass methods which are exception throwing methods
 965         if (m != NULL) {
 966           overpasses.push(m);
 967         }
 968       }
 969     }
 970   }
 971 
 972 
 973   log_debug(defaultmethods)("Created %d overpass methods", overpasses.length());
 974   log_debug(defaultmethods)("Created %d default  methods", defaults.length());
 975 
 976   if (overpasses.length() > 0) {
 977     switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
 978     merge_in_new_methods(klass, &overpasses, CHECK);
 979   }
 980   if (defaults.length() > 0) {
 981     create_default_methods(klass, &defaults, CHECK);
 982   }
 983 }
 984 
 985 static void create_default_methods( InstanceKlass* klass,
 986     GrowableArray<Method*>* new_methods, TRAPS) {
 987 
 988   int new_size = new_methods->length();
 989   Array<Method*>* total_default_methods = MetadataFactory::new_array<Method*>(
 990       klass->class_loader_data(), new_size, NULL, CHECK);
 991   for (int index = 0; index < new_size; index++ ) {
 992     total_default_methods->at_put(index, new_methods->at(index));
 993   }
 994   Method::sort_methods(total_default_methods, false, false);
 995 
 996   klass->set_default_methods(total_default_methods);
 997 }
 998 
 999 static void sort_methods(GrowableArray<Method*>* methods) {
1000   // Note that this must sort using the same key as is used for sorting
1001   // methods in InstanceKlass.
1002   bool sorted = true;
1003   for (int i = methods->length() - 1; i > 0; --i) {
1004     for (int j = 0; j < i; ++j) {
1005       Method* m1 = methods->at(j);
1006       Method* m2 = methods->at(j + 1);
1007       if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
1008         methods->at_put(j, m2);
1009         methods->at_put(j + 1, m1);
1010         sorted = false;
1011       }
1012     }
1013     if (sorted) break;
1014     sorted = true;
1015   }
1016 #ifdef ASSERT
1017   uintptr_t prev = 0;
1018   for (int i = 0; i < methods->length(); ++i) {
1019     Method* mh = methods->at(i);
1020     uintptr_t nv = (uintptr_t)mh->name();
1021     assert(nv >= prev, "Incorrect overpass method ordering");
1022     prev = nv;
1023   }
1024 #endif
1025 }
1026 
1027 static void merge_in_new_methods(InstanceKlass* klass,
1028     GrowableArray<Method*>* new_methods, TRAPS) {
1029 
1030   enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
1031 
1032   Array<Method*>* original_methods = klass->methods();
1033   Array<int>* original_ordering = klass->method_ordering();
1034   Array<int>* merged_ordering = Universe::the_empty_int_array();
1035 
1036   int new_size = klass->methods()->length() + new_methods->length();
1037 
1038   Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
1039       klass->class_loader_data(), new_size, NULL, CHECK);
1040 
1041   // original_ordering might be empty if this class has no methods of its own
1042   if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
1043     merged_ordering = MetadataFactory::new_array<int>(
1044         klass->class_loader_data(), new_size, CHECK);
1045   }
1046   int method_order_index = klass->methods()->length();
1047 
1048   sort_methods(new_methods);
1049 
1050   // Perform grand merge of existing methods and new methods
1051   int orig_idx = 0;
1052   int new_idx = 0;
1053 
1054   for (int i = 0; i < new_size; ++i) {
1055     Method* orig_method = NULL;
1056     Method* new_method = NULL;
1057     if (orig_idx < original_methods->length()) {
1058       orig_method = original_methods->at(orig_idx);
1059     }
1060     if (new_idx < new_methods->length()) {
1061       new_method = new_methods->at(new_idx);
1062     }
1063 
1064     if (orig_method != NULL &&
1065         (new_method == NULL || orig_method->name() < new_method->name())) {
1066       merged_methods->at_put(i, orig_method);
1067       original_methods->at_put(orig_idx, NULL);
1068       if (merged_ordering->length() > 0) {
1069         assert(original_ordering != NULL && original_ordering->length() > 0,
1070                "should have original order information for this method");
1071         merged_ordering->at_put(i, original_ordering->at(orig_idx));
1072       }
1073       ++orig_idx;
1074     } else {
1075       merged_methods->at_put(i, new_method);
1076       if (merged_ordering->length() > 0) {
1077         merged_ordering->at_put(i, method_order_index++);
1078       }
1079       ++new_idx;
1080     }
1081     // update idnum for new location
1082     merged_methods->at(i)->set_method_idnum(i);
1083     merged_methods->at(i)->set_orig_method_idnum(i);
1084   }
1085 
1086   // Verify correct order
1087 #ifdef ASSERT
1088   uintptr_t prev = 0;
1089   for (int i = 0; i < merged_methods->length(); ++i) {
1090     Method* mo = merged_methods->at(i);
1091     uintptr_t nv = (uintptr_t)mo->name();
1092     assert(nv >= prev, "Incorrect method ordering");
1093     prev = nv;
1094   }
1095 #endif
1096 
1097   // Replace klass methods with new merged lists
1098   klass->set_methods(merged_methods);
1099   klass->set_initial_method_idnum(new_size);
1100   klass->set_method_ordering(merged_ordering);
1101 
1102   // Free metadata
1103   ClassLoaderData* cld = klass->class_loader_data();
1104   if (original_methods->length() > 0) {
1105     MetadataFactory::free_array(cld, original_methods);
1106   }
1107   if (original_ordering != NULL && original_ordering->length() > 0) {
1108     MetadataFactory::free_array(cld, original_ordering);
1109   }
1110 }
--- EOF ---