jdk8-mips64-public/hotspot: src/share/vm/classfile/defaultMethods.cpp@91b93f523ec6 (annotated)

src/share/vm/classfile/defaultMethods.cpp@91b93f523ec6 (annotated)

src/share/vm/classfile/defaultMethods.cpp

Mon, 26 Aug 2013 11:35:25 -0400

author: acorn
date: Mon, 26 Aug 2013 11:35:25 -0400
changeset 5599: 91b93f523ec6
parent 5377: 50257d6f5aaa
child 5608: 915cc4f3fb15
permissions: -rw-r--r--

8012294: remove generic handling for default methods
Reviewed-by: kamg, coleenp

 /*
  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/bytecodeAssembler.hpp"
 #include "classfile/defaultMethods.hpp"
 #include "classfile/symbolTable.hpp"
 #include "memory/allocation.hpp"
 #include "memory/metadataFactory.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/signature.hpp"
 #include "runtime/thread.hpp"
 #include "oops/instanceKlass.hpp"
 #include "oops/klass.hpp"
 #include "oops/method.hpp"
 #include "utilities/accessFlags.hpp"
 #include "utilities/exceptions.hpp"
 #include "utilities/ostream.hpp"
 #include "utilities/pair.hpp"
 #include "utilities/resourceHash.hpp"
 typedef enum { QUALIFIED, DISQUALIFIED } QualifiedState;
 // Because we use an iterative algorithm when iterating over the type
 // hierarchy, we can't use traditional scoped objects which automatically do
 // cleanup in the destructor when the scope is exited.  PseudoScope (and
 // PseudoScopeMark) provides a similar functionality, but for when you want a
 // scoped object in non-stack memory (such as in resource memory, as we do
 // here).  You've just got to remember to call 'destroy()' on the scope when
 // leaving it (and marks have to be explicitly added).
 class PseudoScopeMark : public ResourceObj {
  public:
   virtual void destroy() = 0;
 };
 class PseudoScope : public ResourceObj {
  private:
   GrowableArray<PseudoScopeMark*> _marks;
  public:
   static PseudoScope* cast(void* data) {
     return static_cast<PseudoScope*>(data);
   }
   void add_mark(PseudoScopeMark* psm) {
    _marks.append(psm);
   }
   void destroy() {
     for (int i = 0; i < _marks.length(); ++i) {
       _marks.at(i)->destroy();
     }
   }
 };
 #ifndef PRODUCT
 static void print_slot(outputStream* str, Symbol* name, Symbol* signature) {
   ResourceMark rm;
   str->print("%s%s", name->as_C_string(), signature->as_C_string());
 }
 static void print_method(outputStream* str, Method* mo, bool with_class=true) {
   ResourceMark rm;
   if (with_class) {
     str->print("%s.", mo->klass_name()->as_C_string());
   }
   print_slot(str, mo->name(), mo->signature());
 }
 #endif // ndef PRODUCT
 /**
  * Perform a depth-first iteration over the class hierarchy, applying
  * algorithmic logic as it goes.
  *
  * This class is one half of the inheritance hierarchy analysis mechanism.
  * It is meant to be used in conjunction with another class, the algorithm,
  * which is indicated by the ALGO template parameter.  This class can be
  * paired with any algorithm class that provides the required methods.
  *
  * This class contains all the mechanics for iterating over the class hierarchy
  * starting at a particular root, without recursing (thus limiting stack growth
  * from this point).  It visits each superclass (if present) and superinterface
  * in a depth-first manner, with callbacks to the ALGO class as each class is
  * encountered (visit()), The algorithm can cut-off further exploration of a
  * particular branch by returning 'false' from a visit() call.
  *
  * The ALGO class, must provide a visit() method, which each of which will be
  * called once for each node in the inheritance tree during the iteration.  In
  * addition, it can provide a memory block via new_node_data(InstanceKlass*),
  * which it can use for node-specific storage (and access via the
  * current_data() and data_at_depth(int) methods).
  *
  * Bare minimum needed to be an ALGO class:
  * class Algo : public HierarchyVisitor<Algo> {
  *   void* new_node_data(InstanceKlass* cls) { return NULL; }
  *   void free_node_data(void* data) { return; }
  *   bool visit() { return true; }
  * };
  */
 template <class ALGO>
 class HierarchyVisitor : StackObj {
  private:
   class Node : public ResourceObj {
    public:
     InstanceKlass* _class;
     bool _super_was_visited;
     int _interface_index;
     void* _algorithm_data;
     Node(InstanceKlass* cls, void* data, bool visit_super)
         : _class(cls), _super_was_visited(!visit_super),
           _interface_index(0), _algorithm_data(data) {}
     int number_of_interfaces() { return _class->local_interfaces()->length(); }
     int interface_index() { return _interface_index; }
     void set_super_visited() { _super_was_visited = true; }
     void increment_visited_interface() { ++_interface_index; }
     void set_all_interfaces_visited() {
       _interface_index = number_of_interfaces();
     }
     bool has_visited_super() { return _super_was_visited; }
     bool has_visited_all_interfaces() {
       return interface_index() >= number_of_interfaces();
     }
     InstanceKlass* interface_at(int index) {
       return InstanceKlass::cast(_class->local_interfaces()->at(index));
     }
     InstanceKlass* next_super() { return _class->java_super(); }
     InstanceKlass* next_interface() {
       return interface_at(interface_index());
     }
   };
   bool _cancelled;
   GrowableArray<Node*> _path;
   Node* current_top() const { return _path.top(); }
   bool has_more_nodes() const { return !_path.is_empty(); }
   void push(InstanceKlass* cls, void* data) {
     assert(cls != NULL, "Requires a valid instance class");
     Node* node = new Node(cls, data, has_super(cls));
     _path.push(node);
   }
   void pop() { _path.pop(); }
   void reset_iteration() {
     _cancelled = false;
     _path.clear();
   }
   bool is_cancelled() const { return _cancelled; }
   static bool has_super(InstanceKlass* cls) {
     return cls->super() != NULL && !cls->is_interface();
   }
   Node* node_at_depth(int i) const {
     return (i >= _path.length()) ? NULL : _path.at(_path.length() - i - 1);
   }
  protected:
   // Accessors available to the algorithm
   int current_depth() const { return _path.length() - 1; }
   InstanceKlass* class_at_depth(int i) {
     Node* n = node_at_depth(i);
     return n == NULL ? NULL : n->_class;
   }
   InstanceKlass* current_class() { return class_at_depth(0); }
   void* data_at_depth(int i) {
     Node* n = node_at_depth(i);
     return n == NULL ? NULL : n->_algorithm_data;
   }
   void* current_data() { return data_at_depth(0); }
   void cancel_iteration() { _cancelled = true; }
  public:
   void run(InstanceKlass* root) {
     ALGO* algo = static_cast<ALGO*>(this);
     reset_iteration();
     void* algo_data = algo->new_node_data(root);
     push(root, algo_data);
     bool top_needs_visit = true;
     do {
       Node* top = current_top();
       if (top_needs_visit) {
         if (algo->visit() == false) {
           // algorithm does not want to continue along this path.  Arrange
           // it so that this state is immediately popped off the stack
           top->set_super_visited();
           top->set_all_interfaces_visited();
         }
         top_needs_visit = false;
       }
       if (top->has_visited_super() && top->has_visited_all_interfaces()) {
         algo->free_node_data(top->_algorithm_data);
         pop();
       } else {
         InstanceKlass* next = NULL;
         if (top->has_visited_super() == false) {
           next = top->next_super();
           top->set_super_visited();
         } else {
           next = top->next_interface();
           top->increment_visited_interface();
         }
         assert(next != NULL, "Otherwise we shouldn't be here");
         algo_data = algo->new_node_data(next);
         push(next, algo_data);
         top_needs_visit = true;
       }
     } while (!is_cancelled() && has_more_nodes());
   }
 };
 #ifndef PRODUCT
 class PrintHierarchy : public HierarchyVisitor<PrintHierarchy> {
  public:
   bool visit() {
     InstanceKlass* cls = current_class();
     streamIndentor si(tty, current_depth() * 2);
     tty->indent().print_cr("%s", cls->name()->as_C_string());
     return true;
   }
   void* new_node_data(InstanceKlass* cls) { return NULL; }
   void free_node_data(void* data) { return; }
 };
 #endif // ndef PRODUCT
 // Used to register InstanceKlass objects and all related metadata structures
 // (Methods, ConstantPools) as "in-use" by the current thread so that they can't
 // be deallocated by class redefinition while we're using them.  The classes are
 // de-registered when this goes out of scope.
 //
 // Once a class is registered, we need not bother with methodHandles or
 // constantPoolHandles for it's associated metadata.
 class KeepAliveRegistrar : public StackObj {
  private:
   Thread* _thread;
   GrowableArray<ConstantPool*> _keep_alive;
  public:
   KeepAliveRegistrar(Thread* thread) : _thread(thread), _keep_alive(20) {
     assert(thread == Thread::current(), "Must be current thread");
   }
   ~KeepAliveRegistrar() {
     for (int i = _keep_alive.length() - 1; i >= 0; --i) {
       ConstantPool* cp = _keep_alive.at(i);
       int idx = _thread->metadata_handles()->find_from_end(cp);
       assert(idx > 0, "Must be in the list");
       _thread->metadata_handles()->remove_at(idx);
     }
   }
   // Register a class as 'in-use' by the thread.  It's fine to register a class
   // multiple times (though perhaps inefficient)
   void register_class(InstanceKlass* ik) {
     ConstantPool* cp = ik->constants();
     _keep_alive.push(cp);
     _thread->metadata_handles()->push(cp);
   }
 };
 class KeepAliveVisitor : public HierarchyVisitor<KeepAliveVisitor> {
  private:
   KeepAliveRegistrar* _registrar;
  public:
   KeepAliveVisitor(KeepAliveRegistrar* registrar) : _registrar(registrar) {}
   void* new_node_data(InstanceKlass* cls) { return NULL; }
   void free_node_data(void* data) { return; }
   bool visit() {
     _registrar->register_class(current_class());
     return true;
   }
 };
 // A method family contains a set of all methods that implement a single
 // erased method. As members of the set are collected while walking over the
 // hierarchy, they are tagged with a qualification state.  The qualification
 // state for an erased method is set to disqualified if there exists a path
 // from the root of hierarchy to the method that contains an interleaving
 // erased method defined in an interface.
 class MethodFamily : public ResourceObj {
  private:
   GrowableArray<Pair<Method*,QualifiedState> > _members;
   ResourceHashtable<Method*, int> _member_index;
   Method* _selected_target;  // Filled in later, if a unique target exists
   Symbol* _exception_message; // If no unique target is found
   bool contains_method(Method* method) {
     int* lookup = _member_index.get(method);
     return lookup != NULL;
   }
   void add_method(Method* method, QualifiedState state) {
     Pair<Method*,QualifiedState> entry(method, state);
     _member_index.put(method, _members.length());
     _members.append(entry);
   }
   void disqualify_method(Method* method) {
     int* index = _member_index.get(method);
     guarantee(index != NULL && *index >= 0 && *index < _members.length(), "bad index");
     _members.at(*index).second = DISQUALIFIED;
   }
   Symbol* generate_no_defaults_message(TRAPS) const;
   Symbol* generate_abstract_method_message(Method* method, TRAPS) const;
   Symbol* generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const;
  public:
   MethodFamily()
       : _selected_target(NULL), _exception_message(NULL) {}
   void set_target_if_empty(Method* m) {
     if (_selected_target == NULL && !m->is_overpass()) {
       _selected_target = m;
     }
   }
   void record_qualified_method(Method* m) {
     // If the method already exists in the set as qualified, this operation is
     // redundant.  If it already exists as disqualified, then we leave it as
     // disqualfied.  Thus we only add to the set if it's not already in the
     // set.
     if (!contains_method(m)) {
       add_method(m, QUALIFIED);
     }
   }
   void record_disqualified_method(Method* m) {
     // If not in the set, add it as disqualified.  If it's already in the set,
     // then set the state to disqualified no matter what the previous state was.
     if (!contains_method(m)) {
       add_method(m, DISQUALIFIED);
     } else {
       disqualify_method(m);
     }
   }
   bool has_target() const { return _selected_target != NULL; }
   bool throws_exception() { return _exception_message != NULL; }
   Method* get_selected_target() { return _selected_target; }
   Symbol* get_exception_message() { return _exception_message; }
   // Either sets the target or the exception error message
   void determine_target(InstanceKlass* root, TRAPS) {
     if (has_target() || throws_exception()) {
       return;
     }
     GrowableArray<Method*> qualified_methods;
     for (int i = 0; i < _members.length(); ++i) {
       Pair<Method*,QualifiedState> entry = _members.at(i);
       if (entry.second == QUALIFIED) {
         qualified_methods.append(entry.first);
       }
     }
     if (qualified_methods.length() == 0) {
       _exception_message = generate_no_defaults_message(CHECK);
     } else if (qualified_methods.length() == 1) {
       Method* method = qualified_methods.at(0);
       if (method->is_abstract()) {
         _exception_message = generate_abstract_method_message(method, CHECK);
       } else {
         _selected_target = qualified_methods.at(0);
       }
     } else {
       _exception_message = generate_conflicts_message(&qualified_methods,CHECK);
     }
     assert((has_target() ^ throws_exception()) == 1,
            "One and only one must be true");
   }
   bool contains_signature(Symbol* query) {
     for (int i = 0; i < _members.length(); ++i) {
       if (query == _members.at(i).first->signature()) {
         return true;
       }
     }
     return false;
   }
 #ifndef PRODUCT
   void print_sig_on(outputStream* str, Symbol* signature, int indent) const {
     streamIndentor si(str, indent * 2);
     str->indent().print_cr("Logical Method %s:", signature->as_C_string());
     streamIndentor si2(str);
     for (int i = 0; i < _members.length(); ++i) {
       str->indent();
       print_method(str, _members.at(i).first);
       if (_members.at(i).second == DISQUALIFIED) {
         str->print(" (disqualified)");
       }
       str->print_cr("");
     }
     if (_selected_target != NULL) {
       print_selected(str, 1);
     }
   }
   void print_selected(outputStream* str, int indent) const {
     assert(has_target(), "Should be called otherwise");
     streamIndentor si(str, indent * 2);
     str->indent().print("Selected method: ");
     print_method(str, _selected_target);
     str->print_cr("");
   }
   void print_exception(outputStream* str, int indent) {
     assert(throws_exception(), "Should be called otherwise");
     streamIndentor si(str, indent * 2);
     str->indent().print_cr("%s", _exception_message->as_C_string());
   }
 #endif // ndef PRODUCT
 };
 Symbol* MethodFamily::generate_no_defaults_message(TRAPS) const {
   return SymbolTable::new_symbol("No qualifying defaults found", CHECK_NULL);
 }
 Symbol* MethodFamily::generate_abstract_method_message(Method* method, TRAPS) const {
   Symbol* klass = method->klass_name();
   Symbol* name = method->name();
   Symbol* sig = method->signature();
   stringStream ss;
   ss.print("Method ");
   ss.write((const char*)klass->bytes(), klass->utf8_length());
   ss.print(".");
   ss.write((const char*)name->bytes(), name->utf8_length());
   ss.write((const char*)sig->bytes(), sig->utf8_length());
   ss.print(" is abstract");
   return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
 }
 Symbol* MethodFamily::generate_conflicts_message(GrowableArray<Method*>* methods, TRAPS) const {
   stringStream ss;
   ss.print("Conflicting default methods:");
   for (int i = 0; i < methods->length(); ++i) {
     Method* method = methods->at(i);
     Symbol* klass = method->klass_name();
     Symbol* name = method->name();
     ss.print(" ");
     ss.write((const char*)klass->bytes(), klass->utf8_length());
     ss.print(".");
     ss.write((const char*)name->bytes(), name->utf8_length());
   }
   return SymbolTable::new_symbol(ss.base(), (int)ss.size(), CHECK_NULL);
 }
 class StateRestorer;
 // StatefulMethodFamily is a wrapper around a MethodFamily that maintains the
 // qualification state during hierarchy visitation, and applies that state
 // when adding members to the MethodFamily
 class StatefulMethodFamily : public ResourceObj {
   friend class StateRestorer;
  private:
   QualifiedState _qualification_state;
   void set_qualification_state(QualifiedState state) {
     _qualification_state = state;
   }
  protected:
   MethodFamily* _method_family;
  public:
   StatefulMethodFamily() {
    _method_family = new MethodFamily();
    _qualification_state = QUALIFIED;
   }
   StatefulMethodFamily(MethodFamily* mf) {
    _method_family = mf;
    _qualification_state = QUALIFIED;
   }
   void set_target_if_empty(Method* m) { _method_family->set_target_if_empty(m); }
   MethodFamily* get_method_family() { return _method_family; }
   StateRestorer* record_method_and_dq_further(Method* mo);
 };
 class StateRestorer : public PseudoScopeMark {
  private:
   StatefulMethodFamily* _method;
   QualifiedState _state_to_restore;
  public:
   StateRestorer(StatefulMethodFamily* dm, QualifiedState state)
       : _method(dm), _state_to_restore(state) {}
   ~StateRestorer() { destroy(); }
   void restore_state() { _method->set_qualification_state(_state_to_restore); }
   virtual void destroy() { restore_state(); }
 };
 StateRestorer* StatefulMethodFamily::record_method_and_dq_further(Method* mo) {
   StateRestorer* mark = new StateRestorer(this, _qualification_state);
   if (_qualification_state == QUALIFIED) {
     _method_family->record_qualified_method(mo);
   } else {
     _method_family->record_disqualified_method(mo);
   }
   // Everything found "above"??? this method in the hierarchy walk is set to
   // disqualified
   set_qualification_state(DISQUALIFIED);
   return mark;
 }
 // Represents a location corresponding to a vtable slot for methods that
 // neither the class nor any of it's ancestors provide an implementaion.
 // Default methods may be present to fill this slot.
 class EmptyVtableSlot : public ResourceObj {
  private:
   Symbol* _name;
   Symbol* _signature;
   int _size_of_parameters;
   MethodFamily* _binding;
  public:
   EmptyVtableSlot(Method* method)
       : _name(method->name()), _signature(method->signature()),
         _size_of_parameters(method->size_of_parameters()), _binding(NULL) {}
   Symbol* name() const { return _name; }
   Symbol* signature() const { return _signature; }
   int size_of_parameters() const { return _size_of_parameters; }
   void bind_family(MethodFamily* lm) { _binding = lm; }
   bool is_bound() { return _binding != NULL; }
   MethodFamily* get_binding() { return _binding; }
 #ifndef PRODUCT
   void print_on(outputStream* str) const {
     print_slot(str, name(), signature());
   }
 #endif // ndef PRODUCT
 };
 static GrowableArray<EmptyVtableSlot*>* find_empty_vtable_slots(
     InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
   assert(klass != NULL, "Must be valid class");
   GrowableArray<EmptyVtableSlot*>* slots = new GrowableArray<EmptyVtableSlot*>();
   // All miranda methods are obvious candidates
   for (int i = 0; i < mirandas->length(); ++i) {
     EmptyVtableSlot* slot = new EmptyVtableSlot(mirandas->at(i));
     slots->append(slot);
   }
   // Also any overpasses in our superclasses, that we haven't implemented.
   // (can't use the vtable because it is not guaranteed to be initialized yet)
   InstanceKlass* super = klass->java_super();
   while (super != NULL) {
     for (int i = 0; i < super->methods()->length(); ++i) {
       Method* m = super->methods()->at(i);
       if (m->is_overpass()) {
         // m is a method that would have been a miranda if not for the
         // default method processing that occurred on behalf of our superclass,
         // so it's a method we want to re-examine in this new context.  That is,
         // unless we have a real implementation of it in the current class.
         Method* impl = klass->lookup_method(m->name(), m->signature());
         if (impl == NULL || impl->is_overpass()) {
           slots->append(new EmptyVtableSlot(m));
         }
       }
     }
     super = super->java_super();
   }
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     tty->print_cr("Slots that need filling:");
     streamIndentor si(tty);
     for (int i = 0; i < slots->length(); ++i) {
       tty->indent();
       slots->at(i)->print_on(tty);
       tty->print_cr("");
     }
   }
 #endif // ndef PRODUCT
   return slots;
 }
 // Iterates over the superinterface type hierarchy looking for all methods
 // with a specific erased signature.
 class FindMethodsByErasedSig : public HierarchyVisitor<FindMethodsByErasedSig> {
  private:
   // Context data
   Symbol* _method_name;
   Symbol* _method_signature;
   StatefulMethodFamily*  _family;
  public:
   FindMethodsByErasedSig(Symbol* name, Symbol* signature) :
       _method_name(name), _method_signature(signature),
       _family(NULL) {}
   void get_discovered_family(MethodFamily** family) {
       if (_family != NULL) {
         *family = _family->get_method_family();
       } else {
         *family = NULL;
       }
   }
   void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); }
   void free_node_data(void* node_data) {
     PseudoScope::cast(node_data)->destroy();
   }
   // Find all methods on this hierarchy that match this
   // method's erased (name, signature)
   bool visit() {
     PseudoScope* scope = PseudoScope::cast(current_data());
     InstanceKlass* iklass = current_class();
     Method* m = iklass->find_method(_method_name, _method_signature);
     if (m != NULL) {
       if (_family == NULL) {
         _family = new StatefulMethodFamily();
       }
       if (iklass->is_interface()) {
         StateRestorer* restorer = _family->record_method_and_dq_further(m);
         scope->add_mark(restorer);
       } else {
         // This is the rule that methods in classes "win" (bad word) over
         // methods in interfaces. This works because of single inheritance
         _family->set_target_if_empty(m);
       }
     }
     return true;
   }
 };
 static void create_overpasses(
     GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, TRAPS);
 static void generate_erased_defaults(
      InstanceKlass* klass, GrowableArray<EmptyVtableSlot*>* empty_slots,
      EmptyVtableSlot* slot, TRAPS) {
   // sets up a set of methods with the same exact erased signature
   FindMethodsByErasedSig visitor(slot->name(), slot->signature());
   visitor.run(klass);
   MethodFamily* family;
   visitor.get_discovered_family(&family);
   if (family != NULL) {
     family->determine_target(klass, CHECK);
     slot->bind_family(family);
   }
 }
 static void merge_in_new_methods(InstanceKlass* klass,
     GrowableArray<Method*>* new_methods, TRAPS);
 // This is the guts of the default methods implementation.  This is called just
 // after the classfile has been parsed if some ancestor has default methods.
 //
 // First if finds any name/signature slots that need any implementation (either
 // because they are miranda or a superclass's implementation is an overpass
 // itself).  For each slot, iterate over the hierarchy, to see if they contain a
 // signature that matches the slot we are looking at.
 //
 // For each slot filled, we generate an overpass method that either calls the
 // unique default method candidate using invokespecial, or throws an exception
 // (in the case of no default method candidates, or more than one valid
 // candidate).  These methods are then added to the class's method list.
 // The JVM does not create bridges nor handle generic signatures here.
 void DefaultMethods::generate_default_methods(
     InstanceKlass* klass, GrowableArray<Method*>* mirandas, TRAPS) {
   // This resource mark is the bound for all memory allocation that takes
   // place during default method processing.  After this goes out of scope,
   // all (Resource) objects' memory will be reclaimed.  Be careful if adding an
   // embedded resource mark under here as that memory can't be used outside
   // whatever scope it's in.
   ResourceMark rm(THREAD);
   // Keep entire hierarchy alive for the duration of the computation
   KeepAliveRegistrar keepAlive(THREAD);
   KeepAliveVisitor loadKeepAlive(&keepAlive);
   loadKeepAlive.run(klass);
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     ResourceMark rm;  // be careful with these!
     tty->print_cr("Class %s requires default method processing",
         klass->name()->as_klass_external_name());
     PrintHierarchy printer;
     printer.run(klass);
   }
 #endif // ndef PRODUCT
   GrowableArray<EmptyVtableSlot*>* empty_slots =
       find_empty_vtable_slots(klass, mirandas, CHECK);
   for (int i = 0; i < empty_slots->length(); ++i) {
     EmptyVtableSlot* slot = empty_slots->at(i);
 #ifndef PRODUCT
     if (TraceDefaultMethods) {
       streamIndentor si(tty, 2);
       tty->indent().print("Looking for default methods for slot ");
       slot->print_on(tty);
       tty->print_cr("");
     }
 #endif // ndef PRODUCT
     generate_erased_defaults(klass, empty_slots, slot, CHECK);
  }
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     tty->print_cr("Creating overpasses...");
   }
 #endif // ndef PRODUCT
   create_overpasses(empty_slots, klass, CHECK);
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     tty->print_cr("Default method processing complete");
   }
 #endif // ndef PRODUCT
 }
 /**
  * Interface inheritance rules were used to find a unique default method
  * candidate for the resolved class. This
  * method is only viable if it would also be in the set of default method
  * candidates if we ran a full analysis on the current class.
  *
  * The only reason that the method would not be in the set of candidates for
  * the current class is if that there's another matching method
  * which is "more specific" than the found method -- i.e., one could find a
  * path in the interface hierarchy in which the matching method appears
  * before we get to '_target'.
  *
  * In order to determine this, we examine all of the implemented
  * interfaces.  If we find path that leads to the '_target' interface, then
  * we examine that path to see if there are any methods that would shadow
  * the selected method along that path.
  */
 class ShadowChecker : public HierarchyVisitor<ShadowChecker> {
  protected:
   Thread* THREAD;
   InstanceKlass* _target;
   Symbol* _method_name;
   InstanceKlass* _method_holder;
   bool _found_shadow;
  public:
   ShadowChecker(Thread* thread, Symbol* name, InstanceKlass* holder,
                 InstanceKlass* target)
                 : THREAD(thread), _method_name(name), _method_holder(holder),
                 _target(target), _found_shadow(false) {}
   void* new_node_data(InstanceKlass* cls) { return NULL; }
   void free_node_data(void* data) { return; }
   bool visit() {
     InstanceKlass* ik = current_class();
     if (ik == _target && current_depth() == 1) {
       return false; // This was the specified super -- no need to search it
     }
     if (ik == _method_holder || ik == _target) {
       // We found a path that should be examined to see if it shadows _method
       if (path_has_shadow()) {
         _found_shadow = true;
         cancel_iteration();
       }
       return false; // no need to continue up hierarchy
     }
     return true;
   }
   virtual bool path_has_shadow() = 0;
   bool found_shadow() { return _found_shadow; }
 };
 // Used for Invokespecial.
 // Invokespecial is allowed to invoke a concrete interface method
 // and can be used to disambuiguate among qualified candidates,
 // which are methods in immediate superinterfaces,
 // but may not be used to invoke a candidate that would be shadowed
 // from the perspective of the caller.
 // Invokespecial is also used in the overpass generation today
 // We re-run the shadowchecker because we can't distinguish this case,
 // but it should return the same answer, since the overpass target
 // is now the invokespecial caller.
 class ErasedShadowChecker : public ShadowChecker {
  private:
   bool path_has_shadow() {
     for (int i = current_depth() - 1; i > 0; --i) {
       InstanceKlass* ik = class_at_depth(i);
       if (ik->is_interface()) {
         int end;
         int start = ik->find_method_by_name(_method_name, &end);
         if (start != -1) {
           return true;
         }
       }
     }
     return false;
   }
  public:
   ErasedShadowChecker(Thread* thread, Symbol* name, InstanceKlass* holder,
                 InstanceKlass* target)
     : ShadowChecker(thread, name, holder, target) {}
 };
 // Find the unique qualified candidate from the perspective of the super_class
 // which is the resolved_klass, which must be an immediate superinterface
 // of klass
 Method* find_erased_super_default(InstanceKlass* current_class, InstanceKlass* super_class, Symbol* method_name, Symbol* sig, TRAPS) {
   FindMethodsByErasedSig visitor(method_name, sig);
   visitor.run(super_class);      // find candidates from resolved_klass
   MethodFamily* family;
   visitor.get_discovered_family(&family);
   if (family != NULL) {
     family->determine_target(current_class, CHECK_NULL);  // get target from current_class
   }
   if (family->has_target()) {
     Method* target = family->get_selected_target();
     InstanceKlass* holder = InstanceKlass::cast(target->method_holder());
     // Verify that the identified method is valid from the context of
     // the current class, which is the caller class for invokespecial
     // link resolution, i.e. ensure there it is not shadowed.
     // You can use invokespecial to disambiguate interface methods, but
     // you can not use it to skip over an interface method that would shadow it.
     ErasedShadowChecker checker(THREAD, target->name(), holder, super_class);
     checker.run(current_class);
     if (checker.found_shadow()) {
 #ifndef PRODUCT
       if (TraceDefaultMethods) {
         tty->print_cr("    Only candidate found was shadowed.");
       }
 #endif // ndef PRODUCT
       THROW_MSG_(vmSymbols::java_lang_AbstractMethodError(),
                  "Accessible default method not found", NULL);
     } else {
 #ifndef PRODUCT
       if (TraceDefaultMethods) {
         family->print_sig_on(tty, target->signature(), 1);
       }
 #endif // ndef PRODUCT
       return target;
     }
   } else {
     assert(family->throws_exception(), "must have target or throw");
     THROW_MSG_(vmSymbols::java_lang_AbstractMethodError(),
                family->get_exception_message()->as_C_string(), NULL);
   }
 }
 // This is called during linktime when we find an invokespecial call that
 // refers to a direct superinterface.  It indicates that we should find the
 // default method in the hierarchy of that superinterface, and if that method
 // would have been a candidate from the point of view of 'this' class, then we
 // return that method.
 // This logic assumes that the super is a direct superclass of the caller
 Method* DefaultMethods::find_super_default(
     Klass* cls, Klass* super, Symbol* method_name, Symbol* sig, TRAPS) {
   ResourceMark rm(THREAD);
   assert(cls != NULL && super != NULL, "Need real classes");
   InstanceKlass* current_class = InstanceKlass::cast(cls);
   InstanceKlass* super_class = InstanceKlass::cast(super);
   // Keep entire hierarchy alive for the duration of the computation
   KeepAliveRegistrar keepAlive(THREAD);
   KeepAliveVisitor loadKeepAlive(&keepAlive);
   loadKeepAlive.run(current_class);   // get hierarchy from current class
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     tty->print_cr("Finding super default method %s.%s%s from %s",
       super_class->name()->as_C_string(),
       method_name->as_C_string(), sig->as_C_string(),
       current_class->name()->as_C_string());
   }
 #endif // ndef PRODUCT
   assert(super_class->is_interface(), "only call for default methods");
   Method* target = NULL;
   target = find_erased_super_default(current_class, super_class,
                                      method_name, sig, CHECK_NULL);
 #ifndef PRODUCT
   if (target != NULL) {
     if (TraceDefaultMethods) {
       tty->print("    Returning ");
       print_method(tty, target, true);
       tty->print_cr("");
     }
   }
 #endif // ndef PRODUCT
   return target;
 }
 #ifndef PRODUCT
 // Return true is broad type is a covariant return of narrow type
 static bool covariant_return_type(BasicType narrow, BasicType broad) {
   if (narrow == broad) {
     return true;
   }
   if (broad == T_OBJECT) {
     return true;
   }
   return false;
 }
 #endif // ndef PRODUCT
 static int assemble_redirect(
     BytecodeConstantPool* cp, BytecodeBuffer* buffer,
     Symbol* incoming, Method* target, TRAPS) {
   BytecodeAssembler assem(buffer, cp);
   SignatureStream in(incoming, true);
   SignatureStream out(target->signature(), true);
   u2 parameter_count = 0;
   assem.aload(parameter_count++); // load 'this'
   while (!in.at_return_type()) {
     assert(!out.at_return_type(), "Parameter counts do not match");
     BasicType bt = in.type();
     assert(out.type() == bt, "Parameter types are not compatible");
     assem.load(bt, parameter_count);
     if (in.is_object() && in.as_symbol(THREAD) != out.as_symbol(THREAD)) {
       assem.checkcast(out.as_symbol(THREAD));
     } else if (bt == T_LONG || bt == T_DOUBLE) {
       ++parameter_count; // longs and doubles use two slots
     }
     ++parameter_count;
     in.next();
     out.next();
   }
   assert(out.at_return_type(), "Parameter counts do not match");
   assert(covariant_return_type(out.type(), in.type()), "Return types are not compatible");
   if (parameter_count == 1 && (in.type() == T_LONG || in.type() == T_DOUBLE)) {
     ++parameter_count; // need room for return value
   }
   if (target->method_holder()->is_interface()) {
     assem.invokespecial(target);
   } else {
     assem.invokevirtual(target);
   }
   if (in.is_object() && in.as_symbol(THREAD) != out.as_symbol(THREAD)) {
     assem.checkcast(in.as_symbol(THREAD));
   }
   assem._return(in.type());
   return parameter_count;
 }
 static int assemble_abstract_method_error(
     BytecodeConstantPool* cp, BytecodeBuffer* buffer, Symbol* message, TRAPS) {
   Symbol* errorName = vmSymbols::java_lang_AbstractMethodError();
   Symbol* init = vmSymbols::object_initializer_name();
   Symbol* sig = vmSymbols::string_void_signature();
   BytecodeAssembler assem(buffer, cp);
   assem._new(errorName);
   assem.dup();
   assem.load_string(message);
   assem.invokespecial(errorName, init, sig);
   assem.athrow();
   return 3; // max stack size: [ exception, exception, string ]
 }
 static Method* new_method(
     BytecodeConstantPool* cp, BytecodeBuffer* bytecodes, Symbol* name,
     Symbol* sig, AccessFlags flags, int max_stack, int params,
     ConstMethod::MethodType mt, TRAPS) {
   address code_start = 0;
   int code_length = 0;
   InlineTableSizes sizes;
   if (bytecodes != NULL && bytecodes->length() > 0) {
     code_start = static_cast<address>(bytecodes->adr_at(0));
     code_length = bytecodes->length();
   }
   Method* m = Method::allocate(cp->pool_holder()->class_loader_data(),
                                code_length, flags, &sizes,
                                mt, CHECK_NULL);
   m->set_constants(NULL); // This will get filled in later
   m->set_name_index(cp->utf8(name));
   m->set_signature_index(cp->utf8(sig));
 #ifdef CC_INTERP
   ResultTypeFinder rtf(sig);
   m->set_result_index(rtf.type());
 #endif
   m->set_size_of_parameters(params);
   m->set_max_stack(max_stack);
   m->set_max_locals(params);
   m->constMethod()->set_stackmap_data(NULL);
   m->set_code(code_start);
   m->set_force_inline(true);
   return m;
 }
 static void switchover_constant_pool(BytecodeConstantPool* bpool,
     InstanceKlass* klass, GrowableArray<Method*>* new_methods, TRAPS) {
   if (new_methods->length() > 0) {
     ConstantPool* cp = bpool->create_constant_pool(CHECK);
     if (cp != klass->constants()) {
       klass->class_loader_data()->add_to_deallocate_list(klass->constants());
       klass->set_constants(cp);
       cp->set_pool_holder(klass);
       for (int i = 0; i < new_methods->length(); ++i) {
         new_methods->at(i)->set_constants(cp);
       }
       for (int i = 0; i < klass->methods()->length(); ++i) {
         Method* mo = klass->methods()->at(i);
         mo->set_constants(cp);
       }
     }
   }
 }
 // A "bridge" is a method created by javac to bridge the gap between
 // an implementation and a generically-compatible, but different, signature.
 // Bridges have actual bytecode implementation in classfiles.
 // An "overpass", on the other hand, performs the same function as a bridge
 // but does not occur in a classfile; the VM creates overpass itself,
 // when it needs a path to get from a call site to an default method, and
 // a bridge doesn't exist.
 static void create_overpasses(
     GrowableArray<EmptyVtableSlot*>* slots,
     InstanceKlass* klass, TRAPS) {
   GrowableArray<Method*> overpasses;
   BytecodeConstantPool bpool(klass->constants());
   for (int i = 0; i < slots->length(); ++i) {
     EmptyVtableSlot* slot = slots->at(i);
     if (slot->is_bound()) {
       MethodFamily* method = slot->get_binding();
       int max_stack = 0;
       BytecodeBuffer buffer;
 #ifndef PRODUCT
       if (TraceDefaultMethods) {
         tty->print("for slot: ");
         slot->print_on(tty);
         tty->print_cr("");
         if (method->has_target()) {
           method->print_selected(tty, 1);
         } else {
           method->print_exception(tty, 1);
         }
       }
 #endif // ndef PRODUCT
       if (method->has_target()) {
         Method* selected = method->get_selected_target();
         max_stack = assemble_redirect(
             &bpool, &buffer, slot->signature(), selected, CHECK);
       } else if (method->throws_exception()) {
         max_stack = assemble_abstract_method_error(
             &bpool, &buffer, method->get_exception_message(), CHECK);
       }
       AccessFlags flags = accessFlags_from(
           JVM_ACC_PUBLIC | JVM_ACC_SYNTHETIC | JVM_ACC_BRIDGE);
       Method* m = new_method(&bpool, &buffer, slot->name(), slot->signature(),
           flags, max_stack, slot->size_of_parameters(),
           ConstMethod::OVERPASS, CHECK);
       if (m != NULL) {
         overpasses.push(m);
       }
     }
   }
 #ifndef PRODUCT
   if (TraceDefaultMethods) {
     tty->print_cr("Created %d overpass methods", overpasses.length());
   }
 #endif // ndef PRODUCT
   switchover_constant_pool(&bpool, klass, &overpasses, CHECK);
   merge_in_new_methods(klass, &overpasses, CHECK);
 }
 static void sort_methods(GrowableArray<Method*>* methods) {
   // Note that this must sort using the same key as is used for sorting
   // methods in InstanceKlass.
   bool sorted = true;
   for (int i = methods->length() - 1; i > 0; --i) {
     for (int j = 0; j < i; ++j) {
       Method* m1 = methods->at(j);
       Method* m2 = methods->at(j + 1);
       if ((uintptr_t)m1->name() > (uintptr_t)m2->name()) {
         methods->at_put(j, m2);
         methods->at_put(j + 1, m1);
         sorted = false;
       }
     }
     if (sorted) break;
     sorted = true;
   }
 #ifdef ASSERT
   uintptr_t prev = 0;
   for (int i = 0; i < methods->length(); ++i) {
     Method* mh = methods->at(i);
     uintptr_t nv = (uintptr_t)mh->name();
     assert(nv >= prev, "Incorrect overpass method ordering");
     prev = nv;
   }
 #endif
 }
 static void merge_in_new_methods(InstanceKlass* klass,
     GrowableArray<Method*>* new_methods, TRAPS) {
   enum { ANNOTATIONS, PARAMETERS, DEFAULTS, NUM_ARRAYS };
   Array<Method*>* original_methods = klass->methods();
   Array<int>* original_ordering = klass->method_ordering();
   Array<int>* merged_ordering = Universe::the_empty_int_array();
   int new_size = klass->methods()->length() + new_methods->length();
   Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>(
       klass->class_loader_data(), new_size, NULL, CHECK);
   if (original_ordering != NULL && original_ordering->length() > 0) {
     merged_ordering = MetadataFactory::new_array<int>(
         klass->class_loader_data(), new_size, CHECK);
   }
   int method_order_index = klass->methods()->length();
   sort_methods(new_methods);
   // Perform grand merge of existing methods and new methods
   int orig_idx = 0;
   int new_idx = 0;
   for (int i = 0; i < new_size; ++i) {
     Method* orig_method = NULL;
     Method* new_method = NULL;
     if (orig_idx < original_methods->length()) {
       orig_method = original_methods->at(orig_idx);
     }
     if (new_idx < new_methods->length()) {
       new_method = new_methods->at(new_idx);
     }
     if (orig_method != NULL &&
         (new_method == NULL || orig_method->name() < new_method->name())) {
       merged_methods->at_put(i, orig_method);
       original_methods->at_put(orig_idx, NULL);
       if (merged_ordering->length() > 0) {
         merged_ordering->at_put(i, original_ordering->at(orig_idx));
       }
       ++orig_idx;
     } else {
       merged_methods->at_put(i, new_method);
       if (merged_ordering->length() > 0) {
         merged_ordering->at_put(i, method_order_index++);
       }
       ++new_idx;
     }
     // update idnum for new location
     merged_methods->at(i)->set_method_idnum(i);
   }
   // Verify correct order
 #ifdef ASSERT
   uintptr_t prev = 0;
   for (int i = 0; i < merged_methods->length(); ++i) {
     Method* mo = merged_methods->at(i);
     uintptr_t nv = (uintptr_t)mo->name();
     assert(nv >= prev, "Incorrect method ordering");
     prev = nv;
   }
 #endif
   // Replace klass methods with new merged lists
   klass->set_methods(merged_methods);
   klass->set_initial_method_idnum(new_size);
   ClassLoaderData* cld = klass->class_loader_data();
   MetadataFactory::free_array(cld, original_methods);
   if (original_ordering->length() > 0) {
     klass->set_method_ordering(merged_ordering);
     MetadataFactory::free_array(cld, original_ordering);
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/defaultMethods.cpp@91b93f523ec6 (annotated)

src/share/vm/classfile/defaultMethods.cpp