Mercurial > hg > graal-compiler
diff src/share/vm/classfile/defaultMethods.cpp @ 6934:4735d2c84362
7200776: Implement default methods in interfaces
Summary: Add generic type analysis and default method selection algorithms
Reviewed-by: coleenp, acorn
author | kamg |
---|---|
date | Thu, 11 Oct 2012 12:25:42 -0400 |
parents | |
children | b2dbd323c668 |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/classfile/defaultMethods.cpp Thu Oct 11 12:25:42 2012 -0400 @@ -0,0 +1,1387 @@ +/* + * Copyright (c) 2012, 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/genericSignatures.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(); + } + } +}; + +class ContextMark : public PseudoScopeMark { + private: + generic::Context::Mark _mark; + public: + ContextMark(const generic::Context::Mark& cm) : _mark(cm) {} + virtual void destroy() { _mark.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 +// language-level method. Because of erasure, these methods may have different +// signatures. 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 +// language-equivalent method defined in an interface. +class MethodFamily : public ResourceObj { + private: + + generic::MethodDescriptor* _descriptor; // language-level description + 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); + assert(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(generic::MethodDescriptor* canonical_desc) + : _descriptor(canonical_desc), _selected_target(NULL), + _exception_message(NULL) {} + + generic::MethodDescriptor* descriptor() const { return _descriptor; } + + bool descriptor_matches(generic::MethodDescriptor* md, generic::Context* ctx) { + return descriptor()->covariant_match(md, ctx); + } + + 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_on(outputStream* str) const { + print_on(str, 0); + } + + void print_on(outputStream* str, int indent) const { + streamIndentor si(str, indent * 2); + + generic::Context ctx(NULL); // empty, as _descriptor already canonicalized + TempNewSymbol family = descriptor()->reify_signature(&ctx, Thread::current()); + str->indent().print_cr("Logical Method %s:", family->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 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: + MethodFamily* _method; + QualifiedState _qualification_state; + + void set_qualification_state(QualifiedState state) { + _qualification_state = state; + } + + public: + StatefulMethodFamily(generic::MethodDescriptor* md, generic::Context* ctx) { + _method = new MethodFamily(md->canonicalize(ctx)); + _qualification_state = QUALIFIED; + } + + void set_target_if_empty(Method* m) { _method->set_target_if_empty(m); } + + MethodFamily* get_method_family() { return _method; } + + bool descriptor_matches(generic::MethodDescriptor* md, generic::Context* ctx) { + return _method->descriptor_matches(md, ctx); + } + + 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->record_qualified_method(mo); + } else { + _method->record_disqualified_method(mo); + } + // Everything found "above"??? this method in the hierarchy walk is set to + // disqualified + set_qualification_state(DISQUALIFIED); + return mark; +} + +class StatefulMethodFamilies : public ResourceObj { + private: + GrowableArray<StatefulMethodFamily*> _methods; + + public: + StatefulMethodFamily* find_matching( + generic::MethodDescriptor* md, generic::Context* ctx) { + for (int i = 0; i < _methods.length(); ++i) { + StatefulMethodFamily* existing = _methods.at(i); + if (existing->descriptor_matches(md, ctx)) { + return existing; + } + } + return NULL; + } + + StatefulMethodFamily* find_matching_or_create( + generic::MethodDescriptor* md, generic::Context* ctx) { + StatefulMethodFamily* method = find_matching(md, ctx); + if (method == NULL) { + method = new StatefulMethodFamily(md, ctx); + _methods.append(method); + } + return method; + } + + void extract_families_into(GrowableArray<MethodFamily*>* array) { + for (int i = 0; i < _methods.length(); ++i) { + array->append(_methods.at(i)->get_method_family()); + } + } +}; + +// 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 type hierarchy looking for all methods with a specific +// method name. The result of this is a set of method families each of +// which is populated with a set of methods that implement the same +// language-level signature. +class FindMethodsByName : public HierarchyVisitor<FindMethodsByName> { + private: + // Context data + Thread* THREAD; + generic::DescriptorCache* _cache; + Symbol* _method_name; + generic::Context* _ctx; + StatefulMethodFamilies _families; + + public: + + FindMethodsByName(generic::DescriptorCache* cache, Symbol* name, + generic::Context* ctx, Thread* thread) : + _cache(cache), _method_name(name), _ctx(ctx), THREAD(thread) {} + + void get_discovered_families(GrowableArray<MethodFamily*>* methods) { + _families.extract_families_into(methods); + } + + void* new_node_data(InstanceKlass* cls) { return new PseudoScope(); } + void free_node_data(void* node_data) { + PseudoScope::cast(node_data)->destroy(); + } + + bool visit() { + PseudoScope* scope = PseudoScope::cast(current_data()); + InstanceKlass* klass = current_class(); + InstanceKlass* sub = current_depth() > 0 ? class_at_depth(1) : NULL; + + ContextMark* cm = new ContextMark(_ctx->mark()); + scope->add_mark(cm); // will restore context when scope is freed + + _ctx->apply_type_arguments(sub, klass, THREAD); + + int start, end = 0; + start = klass->find_method_by_name(_method_name, &end); + if (start != -1) { + for (int i = start; i < end; ++i) { + Method* m = klass->methods()->at(i); + // This gets the method's parameter list with its generic type + // parameters resolved + generic::MethodDescriptor* md = _cache->descriptor_for(m, THREAD); + + // Find all methods on this hierarchy that match this method + // (name, signature). This class collects other families of this + // method name. + StatefulMethodFamily* family = + _families.find_matching_or_create(md, _ctx); + + if (klass->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; + } +}; + +#ifndef PRODUCT +static void print_families( + GrowableArray<MethodFamily*>* methods, Symbol* match) { + streamIndentor si(tty, 4); + if (methods->length() == 0) { + tty->indent(); + tty->print_cr("No Logical Method found"); + } + for (int i = 0; i < methods->length(); ++i) { + tty->indent(); + MethodFamily* lm = methods->at(i); + if (lm->contains_signature(match)) { + tty->print_cr("<Matching>"); + } else { + tty->print_cr("<Non-Matching>"); + } + lm->print_on(tty, 1); + } +} +#endif // ndef PRODUCT + +static void merge_in_new_methods(InstanceKlass* klass, + GrowableArray<Method*>* new_methods, TRAPS); +static void create_overpasses( + GrowableArray<EmptyVtableSlot*>* slots, InstanceKlass* klass, 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, using generic signature +// information to partition any methods that match the name into method families +// where each family contains methods whose signatures are equivalent at the +// language level (i.e., their reified parameters match and return values are +// covariant). Check those sets to see if they contain a signature that matches +// the slot we're looking at (if we're lucky, there might be other empty slots +// that we can fill using the same analysis). +// +// 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. If +// the method set we're using contains methods (qualified or not) with a +// different runtime signature than the method we're creating, then we have to +// create bridges with those signatures too. +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); + + generic::DescriptorCache cache; + + // 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 + if (slot->is_bound()) { +#ifndef PRODUCT + if (TraceDefaultMethods) { + streamIndentor si(tty, 4); + tty->indent().print_cr("Already bound to logical method:"); + slot->get_binding()->print_on(tty, 1); + } +#endif // ndef PRODUCT + continue; // covered by previous processing + } + + generic::Context ctx(&cache); + FindMethodsByName visitor(&cache, slot->name(), &ctx, CHECK); + visitor.run(klass); + + GrowableArray<MethodFamily*> discovered_families; + visitor.get_discovered_families(&discovered_families); + +#ifndef PRODUCT + if (TraceDefaultMethods) { + print_families(&discovered_families, slot->signature()); + } +#endif // ndef PRODUCT + + // Find and populate any other slots that match the discovered families + for (int j = i; j < empty_slots->length(); ++j) { + EmptyVtableSlot* open_slot = empty_slots->at(j); + + if (slot->name() == open_slot->name()) { + for (int k = 0; k < discovered_families.length(); ++k) { + MethodFamily* lm = discovered_families.at(k); + + if (lm->contains_signature(open_slot->signature())) { + lm->determine_target(klass, CHECK); + open_slot->bind_family(lm); + } + } + } + } + } + +#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 +} + + +/** + * Generic analysis was used upon interface '_target' and found a unique + * default method candidate with generic signature '_method_desc'. 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 covariantly 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> { + private: + generic::DescriptorCache* _cache; + Thread* THREAD; + + InstanceKlass* _target; + + Symbol* _method_name; + InstanceKlass* _method_holder; + generic::MethodDescriptor* _method_desc; + bool _found_shadow; + + bool path_has_shadow() { + generic::Context ctx(_cache); + + for (int i = current_depth() - 1; i > 0; --i) { + InstanceKlass* ik = class_at_depth(i); + InstanceKlass* sub = class_at_depth(i + 1); + ctx.apply_type_arguments(sub, ik, THREAD); + + if (ik->is_interface()) { + int end; + int start = ik->find_method_by_name(_method_name, &end); + if (start != -1) { + for (int j = start; j < end; ++j) { + Method* mo = ik->methods()->at(j); + generic::MethodDescriptor* md = _cache->descriptor_for(mo, THREAD); + if (_method_desc->covariant_match(md, &ctx)) { + return true; + } + } + } + } + } + return false; + } + + public: + + ShadowChecker(generic::DescriptorCache* cache, Thread* thread, + Symbol* name, InstanceKlass* holder, generic::MethodDescriptor* desc, + InstanceKlass* target) + : _cache(cache), THREAD(thread), _method_name(name), _method_holder(holder), + _method_desc(desc), _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; + } + + bool found_shadow() { return _found_shadow; } +}; + +// 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. +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* direction = InstanceKlass::cast(super); + + // Keep entire hierarchy alive for the duration of the computation + KeepAliveRegistrar keepAlive(THREAD); + KeepAliveVisitor loadKeepAlive(&keepAlive); + loadKeepAlive.run(current_class); + +#ifndef PRODUCT + if (TraceDefaultMethods) { + tty->print_cr("Finding super default method %s.%s%s from %s", + direction->name()->as_C_string(), + method_name->as_C_string(), sig->as_C_string(), + current_class->name()->as_C_string()); + } +#endif // ndef PRODUCT + + if (!direction->is_interface()) { + // We should not be here + return NULL; + } + + generic::DescriptorCache cache; + generic::Context ctx(&cache); + + // Prime the initial generic context for current -> direction + ctx.apply_type_arguments(current_class, direction, CHECK_NULL); + + FindMethodsByName visitor(&cache, method_name, &ctx, CHECK_NULL); + visitor.run(direction); + + GrowableArray<MethodFamily*> families; + visitor.get_discovered_families(&families); + +#ifndef PRODUCT + if (TraceDefaultMethods) { + print_families(&families, sig); + } +#endif // ndef PRODUCT + + MethodFamily* selected_family = NULL; + + for (int i = 0; i < families.length(); ++i) { + MethodFamily* lm = families.at(i); + if (lm->contains_signature(sig)) { + lm->determine_target(current_class, CHECK_NULL); + selected_family = lm; + } + } + + if (selected_family->has_target()) { + Method* target = selected_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 + ShadowChecker checker(&cache, THREAD, target->name(), + holder, selected_family->descriptor(), direction); + 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) { + tty->print(" Returning "); + print_method(tty, target, true); + tty->print_cr(""); + } +#endif // ndef PRODUCT + return target; + } + } else { + assert(selected_family->throws_exception(), "must have target or throw"); + THROW_MSG_(vmSymbols::java_lang_AbstractMethodError(), + selected_family->get_exception_message()->as_C_string(), NULL); + } +} + + +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(in.type() == out.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 = static_cast<address>(bytecodes->adr_at(0)); + int code_length = bytecodes->length(); + + Method* m = Method::allocate(cp->pool_holder()->class_loader_data(), + code_length, flags, 0, 0, 0, 0, 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)); + m->set_generic_signature_index(0); +#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<AnnotationArray*>* original_annots[NUM_ARRAYS]; + + Array<Method*>* original_methods = klass->methods(); + Annotations* annots = klass->annotations(); + original_annots[ANNOTATIONS] = annots->methods_annotations(); + original_annots[PARAMETERS] = annots->methods_parameter_annotations(); + original_annots[DEFAULTS] = annots->methods_default_annotations(); + + 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<AnnotationArray*>* merged_annots[NUM_ARRAYS]; + + Array<Method*>* merged_methods = MetadataFactory::new_array<Method*>( + klass->class_loader_data(), new_size, NULL, CHECK); + for (int i = 0; i < NUM_ARRAYS; ++i) { + if (original_annots[i] != NULL) { + merged_annots[i] = MetadataFactory::new_array<AnnotationArray*>( + klass->class_loader_data(), new_size, CHECK); + } else { + merged_annots[i] = NULL; + } + } + 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); + for (int j = 0; j < NUM_ARRAYS; ++j) { + if (merged_annots[j] != NULL) { + merged_annots[j]->at_put(i, original_annots[j]->at(orig_idx)); + original_annots[j]->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); + annots->set_methods_annotations(merged_annots[ANNOTATIONS]); + annots->set_methods_parameter_annotations(merged_annots[PARAMETERS]); + annots->set_methods_default_annotations(merged_annots[DEFAULTS]); + + ClassLoaderData* cld = klass->class_loader_data(); + MetadataFactory::free_array(cld, original_methods); + for (int i = 0; i < NUM_ARRAYS; ++i) { + MetadataFactory::free_array(cld, original_annots[i]); + } + if (original_ordering->length() > 0) { + klass->set_method_ordering(merged_ordering); + MetadataFactory::free_array(cld, original_ordering); + } +} +