/*
 * Copyright (c) 2015, 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.
 */


package org.graalvm.compiler.nodes.graphbuilderconf;

import static java.lang.String.format;
import static org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins.LateClassPlugins.CLOSED_LATE_CLASS_PLUGIN;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import jdk.internal.vm.compiler.collections.EconomicMap;
import jdk.internal.vm.compiler.collections.Equivalence;
import jdk.internal.vm.compiler.collections.MapCursor;
import jdk.internal.vm.compiler.collections.Pair;
import jdk.internal.vm.compiler.collections.UnmodifiableEconomicMap;
import jdk.internal.vm.compiler.collections.UnmodifiableMapCursor;
import org.graalvm.compiler.api.replacements.MethodSubstitution;
import org.graalvm.compiler.api.replacements.MethodSubstitutionRegistry;
import org.graalvm.compiler.bytecode.BytecodeProvider;
import org.graalvm.compiler.core.common.SuppressFBWarnings;
import org.graalvm.compiler.debug.Assertions;
import org.graalvm.compiler.debug.GraalError;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.iterators.NodeIterable;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugin.Receiver;

import jdk.vm.ci.meta.MetaUtil;
import jdk.vm.ci.meta.ResolvedJavaMethod;
import jdk.vm.ci.meta.ResolvedJavaType;
import jdk.vm.ci.meta.Signature;

Manages a set of InvocationPlugins. Most plugins are registered during initialization (i.e., before lookupInvocation(ResolvedJavaMethod) or getBindings is called). These registrations can be made with Registration, register(InvocationPlugin, String, String, Type...), register(InvocationPlugin, Type, String, Type...) or registerOptional(InvocationPlugin, Type, String, Type...). Initialization is not thread-safe and so must only be performed by a single thread. Plugins that are not guaranteed to be made during initialization must use LateRegistration. /**
 * Manages a set of {@link InvocationPlugin}s.
 *
 * Most plugins are registered during initialization (i.e., before
 * {@link #lookupInvocation(ResolvedJavaMethod)} or {@link #getBindings} is called). These
 * registrations can be made with {@link Registration},
 * {@link #register(InvocationPlugin, String, String, Type...)},
 * {@link #register(InvocationPlugin, Type, String, Type...)} or
 * {@link #registerOptional(InvocationPlugin, Type, String, Type...)}. Initialization is not
 * thread-safe and so must only be performed by a single thread.
 *
 * Plugins that are not guaranteed to be made during initialization must use
 * {@link LateRegistration}.
 */
public class InvocationPlugins {

    public static class InvocationPluginReceiver implements InvocationPlugin.Receiver {
        private final GraphBuilderContext parser;
        private ValueNode[] args;
        private ValueNode value;

        public InvocationPluginReceiver(GraphBuilderContext parser) {
            this.parser = parser;
        }

        @Override
        public ValueNode get(boolean performNullCheck) {
            assert args != null : "Cannot get the receiver of a static method";
            if (!performNullCheck) {
                return args[0];
            }
            if (value == null) {
                value = parser.nullCheckedValue(args[0]);
                if (value != args[0]) {
                    args[0] = value;
                }
            }
            return value;
        }

        @Override
        public boolean isConstant() {
            return args[0].isConstant();
        }

        public InvocationPluginReceiver init(ResolvedJavaMethod targetMethod, ValueNode[] newArgs) {
            if (!targetMethod.isStatic()) {
                this.args = newArgs;
                this.value = null;
                return this;
            }
            return null;
        }
    }

    
A symbol for an already resolved method.
/**
     * A symbol for an already resolved method.
     */
    public static class ResolvedJavaSymbol implements Type {
        private final ResolvedJavaType resolved;

        public ResolvedJavaSymbol(ResolvedJavaType type) {
            this.resolved = type;
        }

        public ResolvedJavaType getResolved() {
            return resolved;
        }

        @Override
        public String toString() {
            return resolved.toJavaName();
        }
    }

    
A symbol that is lazily resolved to a Type. /**
     * A symbol that is lazily {@linkplain OptionalLazySymbol#resolve() resolved} to a {@link Type}.
     */
    static class OptionalLazySymbol implements Type {
        private static final Class<?> MASK_NULL = OptionalLazySymbol.class;
        private final String name;
        private Class<?> resolved;

        OptionalLazySymbol(String name) {
            this.name = name;
        }

        @Override
        public String getTypeName() {
            return name;
        }

        
Gets the resolved Class corresponding to this symbol or null if resolution fails. /**
         * Gets the resolved {@link Class} corresponding to this symbol or {@code null} if
         * resolution fails.
         */
        public Class<?> resolve() {
            if (resolved == null) {
                Class<?> resolvedOrNull = resolveClass(name, true);
                resolved = resolvedOrNull == null ? MASK_NULL : resolvedOrNull;
            }
            return resolved == MASK_NULL ? null : resolved;
        }

        @Override
        public String toString() {
            return name;
        }
    }

    
Utility for 
registration of invocation plugins. /**
     * Utility for {@linkplain InvocationPlugins#register(InvocationPlugin, Class, String, Class...)
     * registration} of invocation plugins.
     */
    public static class Registration implements MethodSubstitutionRegistry {

        private final InvocationPlugins plugins;
        private final Type declaringType;
        private final BytecodeProvider methodSubstitutionBytecodeProvider;
        private boolean allowOverwrite;

        @Override
        public Class<?> getReceiverType() {
            return Receiver.class;
        }

        
Creates an object for registering InvocationPlugins for methods declared by a given class. 
Params:
plugins – where to register the plugins
declaringType – the class declaring the methods for which plugins will be registered
           via this object/**
         * Creates an object for registering {@link InvocationPlugin}s for methods declared by a
         * given class.
         *
         * @param plugins where to register the plugins
         * @param declaringType the class declaring the methods for which plugins will be registered
         *            via this object
         */
        public Registration(InvocationPlugins plugins, Type declaringType) {
            this.plugins = plugins;
            this.declaringType = declaringType;
            this.methodSubstitutionBytecodeProvider = null;
        }

        
Creates an object for registering InvocationPlugins for methods declared by a given class. 
Params:
plugins – where to register the plugins
declaringType – the class declaring the methods for which plugins will be registered
           via this object
methodSubstitutionBytecodeProvider – provider used to get the bytecodes to parse for
           method substitutions/**
         * Creates an object for registering {@link InvocationPlugin}s for methods declared by a
         * given class.
         *
         * @param plugins where to register the plugins
         * @param declaringType the class declaring the methods for which plugins will be registered
         *            via this object
         * @param methodSubstitutionBytecodeProvider provider used to get the bytecodes to parse for
         *            method substitutions
         */
        public Registration(InvocationPlugins plugins, Type declaringType, BytecodeProvider methodSubstitutionBytecodeProvider) {
            this.plugins = plugins;
            this.declaringType = declaringType;
            this.methodSubstitutionBytecodeProvider = methodSubstitutionBytecodeProvider;
        }

        
Creates an object for registering InvocationPlugins for methods declared by a given class. 
Params:
plugins – where to register the plugins
declaringClassName – the name of the class class declaring the methods for which
           plugins will be registered via this object
methodSubstitutionBytecodeProvider – provider used to get the bytecodes to parse for
           method substitutions/**
         * Creates an object for registering {@link InvocationPlugin}s for methods declared by a
         * given class.
         *
         * @param plugins where to register the plugins
         * @param declaringClassName the name of the class class declaring the methods for which
         *            plugins will be registered via this object
         * @param methodSubstitutionBytecodeProvider provider used to get the bytecodes to parse for
         *            method substitutions
         */
        public Registration(InvocationPlugins plugins, String declaringClassName, BytecodeProvider methodSubstitutionBytecodeProvider) {
            this.plugins = plugins;
            this.declaringType = new OptionalLazySymbol(declaringClassName);
            this.methodSubstitutionBytecodeProvider = methodSubstitutionBytecodeProvider;
        }

        
Configures this registration to allow or disallow overwriting of invocation plugins.
/**
         * Configures this registration to allow or disallow overwriting of invocation plugins.
         */
        public Registration setAllowOverwrite(boolean allowOverwrite) {
            this.allowOverwrite = allowOverwrite;
            return this;
        }

        
Registers a plugin for a method with no arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with no arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register0(String name, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name);
        }

        
Registers a plugin for a method with 1 argument.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 1 argument.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register1(String name, Type arg, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg);
        }

        
Registers a plugin for a method with 2 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 2 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register2(String name, Type arg1, Type arg2, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2);
        }

        
Registers a plugin for a method with 3 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 3 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register3(String name, Type arg1, Type arg2, Type arg3, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2, arg3);
        }

        
Registers a plugin for a method with 4 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 4 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register4(String name, Type arg1, Type arg2, Type arg3, Type arg4, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2, arg3, arg4);
        }

        
Registers a plugin for a method with 5 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 5 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register5(String name, Type arg1, Type arg2, Type arg3, Type arg4, Type arg5, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2, arg3, arg4, arg5);
        }

        
Registers a plugin for a method with 6 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 6 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register6(String name, Type arg1, Type arg2, Type arg3, Type arg4, Type arg5, Type arg6, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2, arg3, arg4, arg5, arg6);
        }

        
Registers a plugin for a method with 7 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for a method with 7 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void register7(String name, Type arg1, Type arg2, Type arg3, Type arg4, Type arg5, Type arg6, Type arg7, InvocationPlugin plugin) {
            plugins.register(plugin, false, allowOverwrite, declaringType, name, arg1, arg2, arg3, arg4, arg5, arg6, arg7);
        }

        
Registers a plugin for an optional method with no arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for an optional method with no arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void registerOptional0(String name, InvocationPlugin plugin) {
            plugins.register(plugin, true, allowOverwrite, declaringType, name);
        }

        
Registers a plugin for an optional method with 1 argument.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for an optional method with 1 argument.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void registerOptional1(String name, Type arg, InvocationPlugin plugin) {
            plugins.register(plugin, true, allowOverwrite, declaringType, name, arg);
        }

        
Registers a plugin for an optional method with 2 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for an optional method with 2 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void registerOptional2(String name, Type arg1, Type arg2, InvocationPlugin plugin) {
            plugins.register(plugin, true, allowOverwrite, declaringType, name, arg1, arg2);
        }

        
Registers a plugin for an optional method with 3 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for an optional method with 3 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void registerOptional3(String name, Type arg1, Type arg2, Type arg3, InvocationPlugin plugin) {
            plugins.register(plugin, true, allowOverwrite, declaringType, name, arg1, arg2, arg3);
        }

        
Registers a plugin for an optional method with 4 arguments.
Params:
name – the name of the method
plugin – the plugin to be registered/**
         * Registers a plugin for an optional method with 4 arguments.
         *
         * @param name the name of the method
         * @param plugin the plugin to be registered
         */
        public void registerOptional4(String name, Type arg1, Type arg2, Type arg3, Type arg4, InvocationPlugin plugin) {
            plugins.register(plugin, true, allowOverwrite, declaringType, name, arg1, arg2, arg3, arg4);
        }

        
Registers a plugin that implements a method based on the bytecode of a substitute method.
Params:
substituteDeclaringClass – the class declaring the substitute method
name – the name of both the original and substitute method
argumentTypes – the argument types of the method. Element 0 of this array must be the Class value for Receiver iff the method is non-static. Upon returning, element 0 will have been rewritten to declaringClass/**
         * Registers a plugin that implements a method based on the bytecode of a substitute method.
         *
         * @param substituteDeclaringClass the class declaring the substitute method
         * @param name the name of both the original and substitute method
         * @param argumentTypes the argument types of the method. Element 0 of this array must be
         *            the {@link Class} value for {@link InvocationPlugin.Receiver} iff the method
         *            is non-static. Upon returning, element 0 will have been rewritten to
         *            {@code declaringClass}
         */
        @Override
        public void registerMethodSubstitution(Class<?> substituteDeclaringClass, String name, Type... argumentTypes) {
            registerMethodSubstitution(substituteDeclaringClass, name, name, argumentTypes);
        }

        
Registers a plugin that implements a method based on the bytecode of a substitute method.
Params:
substituteDeclaringClass – the class declaring the substitute method
name – the name of both the original method
substituteName – the name of the substitute method
argumentTypes – the argument types of the method. Element 0 of this array must be the Class value for Receiver iff the method is non-static. Upon returning, element 0 will have been rewritten to declaringClass/**
         * Registers a plugin that implements a method based on the bytecode of a substitute method.
         *
         * @param substituteDeclaringClass the class declaring the substitute method
         * @param name the name of both the original method
         * @param substituteName the name of the substitute method
         * @param argumentTypes the argument types of the method. Element 0 of this array must be
         *            the {@link Class} value for {@link InvocationPlugin.Receiver} iff the method
         *            is non-static. Upon returning, element 0 will have been rewritten to
         *            {@code declaringClass}
         */
        @Override
        public void registerMethodSubstitution(Class<?> substituteDeclaringClass, String name, String substituteName, Type... argumentTypes) {
            MethodSubstitutionPlugin plugin = createMethodSubstitution(substituteDeclaringClass, substituteName, argumentTypes);
            plugins.register(plugin, false, allowOverwrite, declaringType, name, argumentTypes);
        }

        public MethodSubstitutionPlugin createMethodSubstitution(Class<?> substituteDeclaringClass, String substituteName, Type... argumentTypes) {
            assert methodSubstitutionBytecodeProvider != null : "Registration used for method substitutions requires a non-null methodSubstitutionBytecodeProvider";
            MethodSubstitutionPlugin plugin = new MethodSubstitutionPlugin(methodSubstitutionBytecodeProvider, substituteDeclaringClass, substituteName, argumentTypes);
            return plugin;
        }

    }

    
Utility for registering plugins after Graal may have been initialized. Registrations made via this class are not finalized until close is called. /**
     * Utility for registering plugins after Graal may have been initialized. Registrations made via
     * this class are not finalized until {@link #close} is called.
     */
    public static class LateRegistration implements AutoCloseable {

        private InvocationPlugins plugins;
        private final List<Binding> bindings = new ArrayList<>();
        private final Type declaringType;

        
Creates an object for registering InvocationPlugins for methods declared by a given class. 
Params:
plugins – where to register the plugins
declaringType – the class declaring the methods for which plugins will be registered
           via this object/**
         * Creates an object for registering {@link InvocationPlugin}s for methods declared by a
         * given class.
         *
         * @param plugins where to register the plugins
         * @param declaringType the class declaring the methods for which plugins will be registered
         *            via this object
         */
        public LateRegistration(InvocationPlugins plugins, Type declaringType) {
            this.plugins = plugins;
            this.declaringType = declaringType;
        }

        
Registers an invocation plugin for a given method. There must be no plugin currently registered for method. 
Params:
argumentTypes – the argument types of the method. Element 0 of this array must be the Class value for Receiver iff the method is non-static. Upon returning, element 0 will have been rewritten to declaringClass/**
         * Registers an invocation plugin for a given method. There must be no plugin currently
         * registered for {@code method}.
         *
         * @param argumentTypes the argument types of the method. Element 0 of this array must be
         *            the {@link Class} value for {@link InvocationPlugin.Receiver} iff the method
         *            is non-static. Upon returning, element 0 will have been rewritten to
         *            {@code declaringClass}
         */
        public void register(InvocationPlugin plugin, String name, Type... argumentTypes) {
            boolean isStatic = argumentTypes.length == 0 || argumentTypes[0] != InvocationPlugin.Receiver.class;
            if (!isStatic) {
                argumentTypes[0] = declaringType;
            }

            assert isStatic || argumentTypes[0] == declaringType;
            Binding binding = new Binding(plugin, isStatic, name, argumentTypes);
            bindings.add(binding);

            assert Checks.check(this.plugins, declaringType, binding);
            assert Checks.checkResolvable(false, declaringType, binding);
        }

        @Override
        public void close() {
            assert plugins != null : String.format("Late registrations of invocation plugins for %s is already closed", declaringType);
            plugins.registerLate(declaringType, bindings);
            plugins = null;
        }
    }

    
Associates an InvocationPlugin with the details of a method it substitutes. /**
     * Associates an {@link InvocationPlugin} with the details of a method it substitutes.
     */
    public static class Binding {
        
The plugin this binding is for.
/**
         * The plugin this binding is for.
         */
        public final InvocationPlugin plugin;

        
Specifies if the associated method is static.
/**
         * Specifies if the associated method is static.
         */
        public final boolean isStatic;

        
The name of the associated method.
/**
         * The name of the associated method.
         */
        public final String name;

        
A partial
method
descriptor for the associated method. The descriptor includes enclosing '(' and ')' characters but omits the return type suffix. /**
         * A partial
         * <a href="http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.3.3">method
         * descriptor</a> for the associated method. The descriptor includes enclosing {@code '('}
         * and {@code ')'} characters but omits the return type suffix.
         */
        public final String argumentsDescriptor;

        
Link in a list of bindings.
/**
         * Link in a list of bindings.
         */
        private Binding next;

        Binding(InvocationPlugin data, boolean isStatic, String name, Type... argumentTypes) {
            this.plugin = data;
            this.isStatic = isStatic;
            this.name = name;
            StringBuilder buf = new StringBuilder();
            buf.append('(');
            for (int i = isStatic ? 0 : 1; i < argumentTypes.length; i++) {
                buf.append(MetaUtil.toInternalName(argumentTypes[i].getTypeName()));
            }
            buf.append(')');
            this.argumentsDescriptor = buf.toString();
            assert !name.equals("<init>") || !isStatic : this;
        }

        Binding(ResolvedJavaMethod resolved, InvocationPlugin data) {
            this.plugin = data;
            this.isStatic = resolved.isStatic();
            this.name = resolved.getName();
            Signature sig = resolved.getSignature();
            String desc = sig.toMethodDescriptor();
            assert desc.indexOf(')') != -1 : desc;
            this.argumentsDescriptor = desc.substring(0, desc.indexOf(')') + 1);
            assert !name.equals("<init>") || !isStatic : this;
        }

        @Override
        public String toString() {
            return name + argumentsDescriptor;
        }
    }

    
Plugin registrations for already resolved methods. If non-null, then registrations is null and no further registrations can be made. /**
     * Plugin registrations for already resolved methods. If non-null, then {@link #registrations}
     * is null and no further registrations can be made.
     */
    private final UnmodifiableEconomicMap<ResolvedJavaMethod, InvocationPlugin> resolvedRegistrations;

    
Map from class names in internal form to the invocation plugin bindings for the class. Tf non-null, then resolvedRegistrations will be null. /**
     * Map from class names in {@linkplain MetaUtil#toInternalName(String) internal} form to the
     * invocation plugin bindings for the class. Tf non-null, then {@link #resolvedRegistrations}
     * will be null.
     */
    private final EconomicMap<String, ClassPlugins> registrations;

    
Deferred registrations as well as the guard for delimiting the initial registration phase. The guard uses double-checked locking which is why this field is volatile. /**
     * Deferred registrations as well as the guard for delimiting the initial registration phase.
     * The guard uses double-checked locking which is why this field is {@code volatile}.
     */
    private volatile List<Runnable> deferredRegistrations = new ArrayList<>();

    
Adds a Runnable for doing registration deferred until the first time get(ResolvedJavaMethod) or closeRegistration() is called on this object. /**
     * Adds a {@link Runnable} for doing registration deferred until the first time
     * {@link #get(ResolvedJavaMethod)} or {@link #closeRegistration()} is called on this object.
     */
    public void defer(Runnable deferrable) {
        assert deferredRegistrations != null : "registration is closed";
        deferredRegistrations.add(deferrable);
    }

    
Support for registering plugins once this object may be accessed by multiple threads.
/**
     * Support for registering plugins once this object may be accessed by multiple threads.
     */
    private volatile LateClassPlugins lateRegistrations;

    
Per-class bindings.
/**
     * Per-class bindings.
     */
    static class ClassPlugins {

        
Maps method names to binding lists.
/**
         * Maps method names to binding lists.
         */
        private final EconomicMap<String, Binding> bindings = EconomicMap.create(Equivalence.DEFAULT);

        
Gets the invocation plugin for a given method.
Returns:
the invocation plugin for method or null/**
         * Gets the invocation plugin for a given method.
         *
         * @return the invocation plugin for {@code method} or {@code null}
         */
        InvocationPlugin get(ResolvedJavaMethod method) {
            assert !method.isBridge();
            Binding binding = bindings.get(method.getName());
            while (binding != null) {
                if (method.isStatic() == binding.isStatic) {
                    if (method.getSignature().toMethodDescriptor().startsWith(binding.argumentsDescriptor)) {
                        return binding.plugin;
                    }
                }
                binding = binding.next;
            }
            return null;
        }

        public void register(Binding binding, boolean allowOverwrite) {
            if (allowOverwrite) {
                if (lookup(binding) != null) {
                    register(binding);
                    return;
                }
            } else {
                assert lookup(binding) == null : "a value is already registered for " + binding;
            }
            register(binding);
        }

        InvocationPlugin lookup(Binding binding) {
            Binding b = bindings.get(binding.name);
            while (b != null) {
                if (b.isStatic == binding.isStatic && b.argumentsDescriptor.equals(binding.argumentsDescriptor)) {
                    return b.plugin;
                }
                b = b.next;
            }
            return null;
        }

        
Registers binding. /**
         * Registers {@code binding}.
         */
        void register(Binding binding) {
            Binding head = bindings.get(binding.name);
            assert binding.next == null;
            binding.next = head;
            bindings.put(binding.name, binding);
        }
    }

    static class LateClassPlugins extends ClassPlugins {
        static final String CLOSED_LATE_CLASS_PLUGIN = "-----";
        private final String className;
        private final LateClassPlugins next;

        LateClassPlugins(LateClassPlugins next, String className) {
            assert next == null || next.className != CLOSED_LATE_CLASS_PLUGIN : "Late registration of invocation plugins is closed";
            this.next = next;
            this.className = className;
        }
    }

    
Registers a binding of a method to an invocation plugin.
Params:
plugin – invocation plugin to be associated with the specified method
isStatic – specifies if the method is static
declaringClass – the class declaring the method
name – the name of the method
argumentTypes – the argument types of the method. Element 0 of this array must be declaringClass iff the method is non-static.
Returns:
an object representing the method/**
     * Registers a binding of a method to an invocation plugin.
     *
     * @param plugin invocation plugin to be associated with the specified method
     * @param isStatic specifies if the method is static
     * @param declaringClass the class declaring the method
     * @param name the name of the method
     * @param argumentTypes the argument types of the method. Element 0 of this array must be
     *            {@code declaringClass} iff the method is non-static.
     * @return an object representing the method
     */
    Binding put(InvocationPlugin plugin, boolean isStatic, boolean allowOverwrite, Type declaringClass, String name, Type... argumentTypes) {
        assert resolvedRegistrations == null : "registration is closed";
        String internalName = MetaUtil.toInternalName(declaringClass.getTypeName());
        assert isStatic || argumentTypes[0] == declaringClass;
        assert deferredRegistrations != null : "initial registration is closed - use " + LateRegistration.class.getName() + " for late registrations";

        ClassPlugins classPlugins = registrations.get(internalName);
        if (classPlugins == null) {
            classPlugins = new ClassPlugins();
            registrations.put(internalName, classPlugins);
        }
        Binding binding = new Binding(plugin, isStatic, name, argumentTypes);
        classPlugins.register(binding, allowOverwrite);
        return binding;
    }

    InvocationPlugin get(ResolvedJavaMethod method) {
        if (resolvedRegistrations != null) {
            return resolvedRegistrations.get(method);
        } else {
            if (!method.isBridge()) {
                ResolvedJavaType declaringClass = method.getDeclaringClass();
                flushDeferrables();
                String internalName = declaringClass.getName();
                ClassPlugins classPlugins = registrations.get(internalName);
                InvocationPlugin res = null;
                if (classPlugins != null) {
                    res = classPlugins.get(method);
                }
                if (res == null) {
                    LateClassPlugins lcp = findLateClassPlugins(internalName);
                    if (lcp != null) {
                        res = lcp.get(method);
                    }
                }
                if (res != null) {
                    // A decorator plugin is trusted since it does not replace
                    // the method it intrinsifies.
                    if (res.isDecorator() || canBeIntrinsified(declaringClass)) {
                        return res;
                    }
                }
                if (testExtensions != null) {
                    // Avoid the synchronization in the common case that there
                    // are no test extensions.
                    synchronized (this) {
                        if (testExtensions != null) {
                            List<Binding> bindings = testExtensions.get(internalName);
                            if (bindings != null) {
                                String name = method.getName();
                                String descriptor = method.getSignature().toMethodDescriptor();
                                for (Binding b : bindings) {
                                    if (b.isStatic == method.isStatic() &&
                                                    b.name.equals(name) &&
                                                    descriptor.startsWith(b.argumentsDescriptor)) {
                                        return b.plugin;
                                    }
                                }
                            }
                        }
                    }
                }
            } else {
                // Supporting plugins for bridge methods would require including
                // the return type in the registered signature. Until needed,
                // this extra complexity is best avoided.
            }
        }
        return null;
    }

    
Determines if methods in a given class can have invocation plugins.
Params:
declaringClass – the class to test/**
     * Determines if methods in a given class can have invocation plugins.
     *
     * @param declaringClass the class to test
     */
    public boolean canBeIntrinsified(ResolvedJavaType declaringClass) {
        return true;
    }

    LateClassPlugins findLateClassPlugins(String internalClassName) {
        for (LateClassPlugins lcp = lateRegistrations; lcp != null; lcp = lcp.next) {
            if (lcp.className.equals(internalClassName)) {
                return lcp;
            }
        }
        return null;
    }

    @SuppressWarnings("serial")
    static class InvocationPlugRegistrationError extends GraalError {
        InvocationPlugRegistrationError(Throwable cause) {
            super(cause);
        }
    }

    private void flushDeferrables() {
        if (deferredRegistrations != null) {
            synchronized (this) {
                if (deferredRegistrations != null) {
                    try {
                        for (Runnable deferrable : deferredRegistrations) {
                            deferrable.run();
                        }
                        deferredRegistrations = null;
                    } catch (InvocationPlugRegistrationError t) {
                        throw t;
                    } catch (Throwable t) {
                        /*
                         * Something went wrong during registration but it's possible we'll end up
                         * coming back into this code. nulling out deferredRegistrations would just
                         * cause other things to break and rerunning them would cause errors about
                         * already registered plugins, so rethrow the original exception during
                         * later invocations.
                         */
                        deferredRegistrations.clear();
                        Runnable rethrow = new Runnable() {
                            @Override
                            public void run() {
                                throw new InvocationPlugRegistrationError(t);
                            }
                        };
                        deferredRegistrations.add(rethrow);
                        rethrow.run();
                    }
                }
            }
        }
    }

    private volatile EconomicMap<String, List<Binding>> testExtensions;

    private static int findBinding(List<Binding> list, Binding key) {
        for (int i = 0; i < list.size(); i++) {
            Binding b = list.get(i);
            if (b.isStatic == key.isStatic && b.name.equals(key.name) && b.argumentsDescriptor.equals(key.argumentsDescriptor)) {
                return i;
            }
        }
        return -1;
    }

    
Extends the plugins in this object with those from other. The added plugins should be removed after the test. This extension mechanism exists only for tests that want to add extra invocation plugins after the compiler has been initialized. 
Params:
ignored – if non-null, the bindings from other already in this object prior to calling this method are added to this list. These bindings are not added to this object./**
     * Extends the plugins in this object with those from {@code other}. The added plugins should be
     * {@linkplain #removeTestPlugins(InvocationPlugins) removed} after the test.
     *
     * This extension mechanism exists only for tests that want to add extra invocation plugins
     * after the compiler has been initialized.
     *
     * @param ignored if non-null, the bindings from {@code other} already in this object prior to
     *            calling this method are added to this list. These bindings are not added to this
     *            object.
     */
    public synchronized void addTestPlugins(InvocationPlugins other, List<Pair<String, Binding>> ignored) {
        assert resolvedRegistrations == null : "registration is closed";
        EconomicMap<String, List<Binding>> otherBindings = other.getBindings(true, false);
        if (otherBindings.isEmpty()) {
            return;
        }
        if (testExtensions == null) {
            testExtensions = EconomicMap.create();
        }
        MapCursor<String, List<Binding>> c = otherBindings.getEntries();
        while (c.advance()) {
            String declaringClass = c.getKey();
            List<Binding> bindings = testExtensions.get(declaringClass);
            if (bindings == null) {
                bindings = new ArrayList<>();
                testExtensions.put(declaringClass, bindings);
            }
            for (Binding b : c.getValue()) {
                int index = findBinding(bindings, b);
                if (index != -1) {
                    if (ignored != null) {
                        ignored.add(Pair.create(declaringClass, b));
                    }
                } else {
                    bindings.add(b);
                }
            }
        }
    }

    
Removes the plugins from other in this object that were added by addTestPlugins. /**
     * Removes the plugins from {@code other} in this object that were added by
     * {@link #addTestPlugins}.
     */
    public synchronized void removeTestPlugins(InvocationPlugins other) {
        assert resolvedRegistrations == null : "registration is closed";
        if (testExtensions != null) {
            MapCursor<String, List<Binding>> c = other.getBindings(false).getEntries();
            while (c.advance()) {
                String declaringClass = c.getKey();
                List<Binding> bindings = testExtensions.get(declaringClass);
                if (bindings != null) {
                    for (Binding b : c.getValue()) {
                        int index = findBinding(bindings, b);
                        if (index != -1) {
                            bindings.remove(index);
                        }
                    }
                    if (bindings.isEmpty()) {
                        testExtensions.removeKey(declaringClass);
                    }
                }
            }
            if (testExtensions.isEmpty()) {
                testExtensions = null;
            }
        }
    }

    synchronized void registerLate(Type declaringType, List<Binding> bindings) {
        String internalName = MetaUtil.toInternalName(declaringType.getTypeName());
        assert findLateClassPlugins(internalName) == null : "Cannot have more than one late registration of invocation plugins for " + internalName;
        LateClassPlugins lateClassPlugins = new LateClassPlugins(lateRegistrations, internalName);
        for (Binding b : bindings) {
            lateClassPlugins.register(b);
        }
        lateRegistrations = lateClassPlugins;
    }

    @SuppressFBWarnings(value = "ES_COMPARING_STRINGS_WITH_EQ", justification = "string literal object identity used as sentinel")
    private synchronized boolean closeLateRegistrations() {
        if (lateRegistrations == null || lateRegistrations.className != CLOSED_LATE_CLASS_PLUGIN) {
            lateRegistrations = new LateClassPlugins(lateRegistrations, CLOSED_LATE_CLASS_PLUGIN);
        }
        return true;
    }

    
Processes deferred registrations and then closes this object for future registration.
/**
     * Processes deferred registrations and then closes this object for future registration.
     */
    public void closeRegistration() {
        assert closeLateRegistrations();
        flushDeferrables();
    }

    public boolean isEmpty() {
        if (resolvedRegistrations != null) {
            return resolvedRegistrations.isEmpty();
        }
        return registrations.size() == 0 && lateRegistrations == null;
    }

    
The plugins searched before searching in this object. /**
     * The plugins {@linkplain #lookupInvocation(ResolvedJavaMethod) searched} before searching in
     * this object.
     */
    protected final InvocationPlugins parent;

    
Creates a set of invocation plugins with no parent.
/**
     * Creates a set of invocation plugins with no parent.
     */
    public InvocationPlugins() {
        this(null);
    }

    
Creates a set of invocation plugins.
Params:
parent – if non-null, this object will be searched first when looking up plugins/**
     * Creates a set of invocation plugins.
     *
     * @param parent if non-null, this object will be searched first when looking up plugins
     */
    public InvocationPlugins(InvocationPlugins parent) {
        InvocationPlugins p = parent;
        this.parent = p;
        this.registrations = EconomicMap.create();
        this.resolvedRegistrations = null;
    }

    
Creates a closed set of invocation plugins for a set of resolved methods. Such an object
cannot have further plugins registered.
/**
     * Creates a closed set of invocation plugins for a set of resolved methods. Such an object
     * cannot have further plugins registered.
     */
    public InvocationPlugins(Map<ResolvedJavaMethod, InvocationPlugin> plugins, InvocationPlugins parent) {
        this.parent = parent;
        this.registrations = null;
        this.deferredRegistrations = null;
        EconomicMap<ResolvedJavaMethod, InvocationPlugin> map = EconomicMap.create(plugins.size());

        for (Map.Entry<ResolvedJavaMethod, InvocationPlugin> entry : plugins.entrySet()) {
            map.put(entry.getKey(), entry.getValue());
        }
        this.resolvedRegistrations = map;
    }

    protected void register(InvocationPlugin plugin, boolean isOptional, boolean allowOverwrite, Type declaringClass, String name, Type... argumentTypes) {
        boolean isStatic = argumentTypes.length == 0 || argumentTypes[0] != InvocationPlugin.Receiver.class;
        if (!isStatic) {
            argumentTypes[0] = declaringClass;
        }
        Binding binding = put(plugin, isStatic, allowOverwrite, declaringClass, name, argumentTypes);
        assert Checks.check(this, declaringClass, binding);
        assert Checks.checkResolvable(isOptional, declaringClass, binding);
    }

    
Registers an invocation plugin for a given method. There must be no plugin currently registered for method. 
Params:
argumentTypes – the argument types of the method. Element 0 of this array must be the Class value for Receiver iff the method is non-static. Upon returning, element 0 will have been rewritten to declaringClass/**
     * Registers an invocation plugin for a given method. There must be no plugin currently
     * registered for {@code method}.
     *
     * @param argumentTypes the argument types of the method. Element 0 of this array must be the
     *            {@link Class} value for {@link InvocationPlugin.Receiver} iff the method is
     *            non-static. Upon returning, element 0 will have been rewritten to
     *            {@code declaringClass}
     */
    public final void register(InvocationPlugin plugin, Type declaringClass, String name, Type... argumentTypes) {
        register(plugin, false, false, declaringClass, name, argumentTypes);
    }

    public final void register(InvocationPlugin plugin, String declaringClass, String name, Type... argumentTypes) {
        register(plugin, false, false, new OptionalLazySymbol(declaringClass), name, argumentTypes);
    }

    
Registers an invocation plugin for a given, optional method. There must be no plugin currently registered for method. 
Params:
argumentTypes – the argument types of the method. Element 0 of this array must be the Class value for Receiver iff the method is non-static. Upon returning, element 0 will have been rewritten to declaringClass/**
     * Registers an invocation plugin for a given, optional method. There must be no plugin
     * currently registered for {@code method}.
     *
     * @param argumentTypes the argument types of the method. Element 0 of this array must be the
     *            {@link Class} value for {@link InvocationPlugin.Receiver} iff the method is
     *            non-static. Upon returning, element 0 will have been rewritten to
     *            {@code declaringClass}
     */
    public final void registerOptional(InvocationPlugin plugin, Type declaringClass, String name, Type... argumentTypes) {
        register(plugin, true, false, declaringClass, name, argumentTypes);
    }

    
Gets the plugin for a given method.
Params:
method – the method to lookup
Returns:
the plugin associated with method or null if none exists/**
     * Gets the plugin for a given method.
     *
     * @param method the method to lookup
     * @return the plugin associated with {@code method} or {@code null} if none exists
     */
    public InvocationPlugin lookupInvocation(ResolvedJavaMethod method) {
        if (parent != null) {
            InvocationPlugin plugin = parent.lookupInvocation(method);
            if (plugin != null) {
                return plugin;
            }
        }
        return get(method);
    }

    
Gets the set of registered invocation plugins.
Returns:
a map from class names in internal form to the invocation plugin bindings for methods in the class/**
     * Gets the set of registered invocation plugins.
     *
     * @return a map from class names in {@linkplain MetaUtil#toInternalName(String) internal} form
     *         to the invocation plugin bindings for methods in the class
     */
    public EconomicMap<String, List<Binding>> getBindings(boolean includeParents) {
        return getBindings(includeParents, true);
    }

    
Gets the set of registered invocation plugins.
Returns:
a map from class names in internal form to the invocation plugin bindings for methods in the class/**
     * Gets the set of registered invocation plugins.
     *
     * @return a map from class names in {@linkplain MetaUtil#toInternalName(String) internal} form
     *         to the invocation plugin bindings for methods in the class
     */
    private EconomicMap<String, List<Binding>> getBindings(boolean includeParents, boolean flushDeferrables) {
        EconomicMap<String, List<Binding>> res = EconomicMap.create(Equivalence.DEFAULT);
        if (parent != null && includeParents) {
            res.putAll(parent.getBindings(true, flushDeferrables));
        }
        if (resolvedRegistrations != null) {
            UnmodifiableMapCursor<ResolvedJavaMethod, InvocationPlugin> cursor = resolvedRegistrations.getEntries();
            while (cursor.advance()) {
                ResolvedJavaMethod method = cursor.getKey();
                InvocationPlugin plugin = cursor.getValue();
                String type = method.getDeclaringClass().getName();
                List<Binding> bindings = res.get(type);
                if (bindings == null) {
                    bindings = new ArrayList<>();
                    res.put(type, bindings);
                }
                bindings.add(new Binding(method, plugin));
            }
        } else {
            if (flushDeferrables) {
                flushDeferrables();
            }
            MapCursor<String, ClassPlugins> classes = registrations.getEntries();
            while (classes.advance()) {
                String type = classes.getKey();
                ClassPlugins cp = classes.getValue();
                collectBindingsTo(res, type, cp);
            }
            for (LateClassPlugins lcp = lateRegistrations; lcp != null; lcp = lcp.next) {
                String type = lcp.className;
                collectBindingsTo(res, type, lcp);
            }
            if (testExtensions != null) {
                // Avoid the synchronization in the common case that there
                // are no test extensions.
                synchronized (this) {
                    if (testExtensions != null) {
                        MapCursor<String, List<Binding>> c = testExtensions.getEntries();
                        while (c.advance()) {
                            String name = c.getKey();
                            List<Binding> bindings = res.get(name);
                            if (bindings == null) {
                                bindings = new ArrayList<>();
                                res.put(name, bindings);
                            }
                            bindings.addAll(c.getValue());
                        }
                    }
                }
            }
        }
        return res;
    }

    private static void collectBindingsTo(EconomicMap<String, List<Binding>> res, String type, ClassPlugins cp) {
        MapCursor<String, Binding> methods = cp.bindings.getEntries();
        while (methods.advance()) {
            List<Binding> bindings = res.get(type);
            if (bindings == null) {
                bindings = new ArrayList<>();
                res.put(type, bindings);
            }
            for (Binding b = methods.getValue(); b != null; b = b.next) {
                bindings.add(b);
            }
        }
    }

    
Gets the invocation plugins searched before searching in this object. /**
     * Gets the invocation plugins {@linkplain #lookupInvocation(ResolvedJavaMethod) searched}
     * before searching in this object.
     */
    public InvocationPlugins getParent() {
        return parent;
    }

    @Override
    public String toString() {
        UnmodifiableMapCursor<String, List<Binding>> entries = getBindings(false, false).getEntries();
        List<String> all = new ArrayList<>();
        while (entries.advance()) {
            String c = MetaUtil.internalNameToJava(entries.getKey(), true, false);
            for (Binding b : entries.getValue()) {
                all.add(c + '.' + b);
            }
        }
        Collections.sort(all);
        StringBuilder buf = new StringBuilder();
        String nl = String.format("%n");
        for (String s : all) {
            if (buf.length() != 0) {
                buf.append(nl);
            }
            buf.append(s);
        }
        if (parent != null) {
            if (buf.length() != 0) {
                buf.append(nl);
            }
            buf.append("// parent").append(nl).append(parent);
        }
        return buf.toString();
    }

    
Code only used in assertions. Putting this in a separate class reduces class load time.
/**
     * Code only used in assertions. Putting this in a separate class reduces class load time.
     */
    private static class Checks {
        private static final int MAX_ARITY = 7;
        
The set of all InvocationPlugin.apply method signatures. /**
         * The set of all {@link InvocationPlugin#apply} method signatures.
         */
        static final Class<?>[][] SIGS;

        static {
            if (!Assertions.assertionsEnabled()) {
                throw new GraalError("%s must only be used in assertions", Checks.class.getName());
            }
            ArrayList<Class<?>[]> sigs = new ArrayList<>(MAX_ARITY);
            for (Method method : InvocationPlugin.class.getDeclaredMethods()) {
                if (!Modifier.isStatic(method.getModifiers()) && method.getName().equals("apply")) {
                    Class<?>[] sig = method.getParameterTypes();
                    assert sig[0] == GraphBuilderContext.class;
                    assert sig[1] == ResolvedJavaMethod.class;
                    assert sig[2] == InvocationPlugin.Receiver.class;
                    assert Arrays.asList(sig).subList(3, sig.length).stream().allMatch(c -> c == ValueNode.class);
                    while (sigs.size() < sig.length - 2) {
                        sigs.add(null);
                    }
                    sigs.set(sig.length - 3, sig);
                }
            }
            assert sigs.indexOf(null) == -1 : format("need to add an apply() method to %s that takes %d %s arguments ", InvocationPlugin.class.getName(), sigs.indexOf(null),
                            ValueNode.class.getSimpleName());
            SIGS = sigs.toArray(new Class<?>[sigs.size()][]);
        }

        static boolean containsBinding(InvocationPlugins p, Type declaringType, Binding key) {
            String internalName = MetaUtil.toInternalName(declaringType.getTypeName());
            ClassPlugins classPlugins = p.registrations.get(internalName);
            return classPlugins != null && classPlugins.lookup(key) != null;
        }

        public static boolean check(InvocationPlugins plugins, Type declaringType, Binding binding) {
            InvocationPlugin plugin = binding.plugin;
            InvocationPlugins p = plugins.parent;
            while (p != null) {
                assert !containsBinding(p, declaringType, binding) : "a plugin is already registered for " + binding;
                p = p.parent;
            }
            if (plugin instanceof ForeignCallPlugin || plugin instanceof GeneratedInvocationPlugin) {
                return true;
            }
            if (plugin instanceof MethodSubstitutionPlugin) {
                MethodSubstitutionPlugin msplugin = (MethodSubstitutionPlugin) plugin;
                Method substitute = msplugin.getJavaSubstitute();
                assert substitute.getAnnotation(MethodSubstitution.class) != null : format("Substitute method must be annotated with @%s: %s", MethodSubstitution.class.getSimpleName(), substitute);
                return true;
            }
            int arguments = parseParameters(binding.argumentsDescriptor).size();
            assert arguments < SIGS.length : format("need to extend %s to support method with %d arguments: %s", InvocationPlugin.class.getSimpleName(), arguments, binding);
            for (Method m : plugin.getClass().getDeclaredMethods()) {
                if (m.getName().equals("apply")) {
                    Class<?>[] parameterTypes = m.getParameterTypes();
                    if (Arrays.equals(SIGS[arguments], parameterTypes)) {
                        return true;
                    }
                }
            }
            throw new AssertionError(format("graph builder plugin for %s not found", binding));
        }

        static boolean checkResolvable(boolean isOptional, Type declaringType, Binding binding) {
            if (declaringType instanceof ResolvedJavaSymbol) {
                return checkResolvable(isOptional, ((ResolvedJavaSymbol) declaringType).getResolved(), binding);
            }
            Class<?> declaringClass = InvocationPlugins.resolveType(declaringType, isOptional);
            if (declaringClass == null) {
                return true;
            }
            if (binding.name.equals("<init>")) {
                if (resolveConstructor(declaringClass, binding) == null && !isOptional) {
                    throw new AssertionError(String.format("Constructor not found: %s%s", declaringClass.getName(), binding.argumentsDescriptor));
                }
            } else {
                if (resolveMethod(declaringClass, binding) == null && !isOptional) {
                    throw new AssertionError(String.format("Method not found: %s.%s%s", declaringClass.getName(), binding.name, binding.argumentsDescriptor));
                }
            }
            return true;
        }

        private static boolean checkResolvable(boolean isOptional, ResolvedJavaType declaringType, Binding binding) {
            if (resolveJavaMethod(declaringType, binding) == null && !isOptional) {
                throw new AssertionError(String.format("Method not found: %s.%s%s", declaringType.toJavaName(), binding.name, binding.argumentsDescriptor));
            }
            return true;
        }
    }

    
Checks a set of nodes added to the graph by an InvocationPlugin. 
Params:
b – the graph builder that applied the plugin
plugin – a plugin that was just applied
newNodes – the nodes added to the graph by plugin
Throws:
AssertionError – if any check fail/**
     * Checks a set of nodes added to the graph by an {@link InvocationPlugin}.
     *
     * @param b the graph builder that applied the plugin
     * @param plugin a plugin that was just applied
     * @param newNodes the nodes added to the graph by {@code plugin}
     * @throws AssertionError if any check fail
     */
    public void checkNewNodes(GraphBuilderContext b, InvocationPlugin plugin, NodeIterable<Node> newNodes) {
        if (parent != null) {
            parent.checkNewNodes(b, plugin, newNodes);
        }
    }

    
Resolves a name to a class.
Params:
className – the name of the class to resolve
optional – if true, resolution failure returns null
Returns:
the resolved class or null if resolution fails and optional is true/**
     * Resolves a name to a class.
     *
     * @param className the name of the class to resolve
     * @param optional if true, resolution failure returns null
     * @return the resolved class or null if resolution fails and {@code optional} is true
     */
    public static Class<?> resolveClass(String className, boolean optional) {
        try {
            // Need to use the system class loader to handle classes
            // loaded by the application class loader which is not
            // delegated to by the JVMCI class loader.
            ClassLoader cl = ClassLoader.getSystemClassLoader();
            return Class.forName(className, false, cl);
        } catch (ClassNotFoundException e) {
            if (optional) {
                return null;
            }
            throw new GraalError("Could not resolve type " + className);
        }
    }

    
Resolves a Type to a Class. 
Params:
type – the type to resolve
optional – if true, resolution failure returns null
Returns:
the resolved class or null if resolution fails and optional is true/**
     * Resolves a {@link Type} to a {@link Class}.
     *
     * @param type the type to resolve
     * @param optional if true, resolution failure returns null
     * @return the resolved class or null if resolution fails and {@code optional} is true
     */
    public static Class<?> resolveType(Type type, boolean optional) {
        if (type instanceof Class) {
            return (Class<?>) type;
        }
        if (type instanceof OptionalLazySymbol) {
            return ((OptionalLazySymbol) type).resolve();
        }
        return resolveClass(type.getTypeName(), optional);
    }

    private static List<String> toInternalTypeNames(Class<?>[] types) {
        String[] res = new String[types.length];
        for (int i = 0; i < types.length; i++) {
            res[i] = MetaUtil.toInternalName(types[i].getTypeName());
        }
        return Arrays.asList(res);
    }

    
Resolves a given binding to a method in a given class. If more than one method with the parameter types matching binding is found and the return types of all the matching methods form an inheritance chain, the one with the most specific type is returned; otherwise NoSuchMethodError is thrown. 
Params:
declaringClass – the class to search for a method matching binding
Returns:
the method (if any) in declaringClass matching binding/**
     * Resolves a given binding to a method in a given class. If more than one method with the
     * parameter types matching {@code binding} is found and the return types of all the matching
     * methods form an inheritance chain, the one with the most specific type is returned; otherwise
     * {@link NoSuchMethodError} is thrown.
     *
     * @param declaringClass the class to search for a method matching {@code binding}
     * @return the method (if any) in {@code declaringClass} matching {@code binding}
     */
    public static Method resolveMethod(Class<?> declaringClass, Binding binding) {
        if (binding.name.equals("<init>")) {
            return null;
        }
        Method[] methods = declaringClass.getDeclaredMethods();
        List<String> parameterTypeNames = parseParameters(binding.argumentsDescriptor);
        Method match = null;
        for (int i = 0; i < methods.length; ++i) {
            Method m = methods[i];
            if (binding.isStatic == Modifier.isStatic(m.getModifiers()) &&
                            m.getName().equals(binding.name) &&
                            parameterTypeNames.equals(toInternalTypeNames(m.getParameterTypes()))) {
                if (match == null) {
                    match = m;
                } else if (match.getReturnType().isAssignableFrom(m.getReturnType())) {
                    // `m` has a more specific return type - choose it
                    // (`match` is most likely a bridge method)
                    match = m;
                } else {
                    if (!m.getReturnType().isAssignableFrom(match.getReturnType())) {
                        throw new NoSuchMethodError(String.format(
                                        "Found 2 methods with same name and parameter types but unrelated return types:%n %s%n %s", match, m));
                    }
                }
            }
        }
        return match;
    }

    
Same as resolveMethod(Class<?>, Binding) and resolveConstructor(Class<?>, Binding) except in terms of ResolvedJavaType and ResolvedJavaMethod. /**
     * Same as {@link #resolveMethod(Class, Binding)} and
     * {@link #resolveConstructor(Class, Binding)} except in terms of {@link ResolvedJavaType} and
     * {@link ResolvedJavaMethod}.
     */
    public static ResolvedJavaMethod resolveJavaMethod(ResolvedJavaType declaringClass, Binding binding) {
        ResolvedJavaMethod[] methods = declaringClass.getDeclaredMethods();
        if (binding.name.equals("<init>")) {
            for (ResolvedJavaMethod m : methods) {
                if (m.getName().equals("<init>") && m.getSignature().toMethodDescriptor().startsWith(binding.argumentsDescriptor)) {
                    return m;
                }
            }
            return null;
        }

        ResolvedJavaMethod match = null;
        for (int i = 0; i < methods.length; ++i) {
            ResolvedJavaMethod m = methods[i];
            if (binding.isStatic == m.isStatic() &&
                            m.getName().equals(binding.name) &&
                            m.getSignature().toMethodDescriptor().startsWith(binding.argumentsDescriptor)) {
                if (match == null) {
                    match = m;
                } else {
                    final ResolvedJavaType matchReturnType = (ResolvedJavaType) match.getSignature().getReturnType(declaringClass);
                    final ResolvedJavaType mReturnType = (ResolvedJavaType) m.getSignature().getReturnType(declaringClass);
                    if (matchReturnType.isAssignableFrom(mReturnType)) {
                        // `m` has a more specific return type - choose it
                        // (`match` is most likely a bridge method)
                        match = m;
                    } else {
                        if (!mReturnType.isAssignableFrom(matchReturnType)) {
                            throw new NoSuchMethodError(String.format(
                                            "Found 2 methods with same name and parameter types but unrelated return types:%n %s%n %s", match, m));
                        }
                    }
                }
            }
        }
        return match;
    }

    
Resolves a given binding to a constructor in a given class.
Params:
declaringClass – the class to search for a constructor matching binding
Returns:
the constructor (if any) in declaringClass matching binding/**
     * Resolves a given binding to a constructor in a given class.
     *
     * @param declaringClass the class to search for a constructor matching {@code binding}
     * @return the constructor (if any) in {@code declaringClass} matching binding
     */
    public static Constructor<?> resolveConstructor(Class<?> declaringClass, Binding binding) {
        if (!binding.name.equals("<init>")) {
            return null;
        }
        Constructor<?>[] constructors = declaringClass.getDeclaredConstructors();
        List<String> parameterTypeNames = parseParameters(binding.argumentsDescriptor);
        for (int i = 0; i < constructors.length; ++i) {
            Constructor<?> c = constructors[i];
            if (parameterTypeNames.equals(toInternalTypeNames(c.getParameterTypes()))) {
                return c;
            }
        }
        return null;
    }

    private static List<String> parseParameters(String argumentsDescriptor) {
        assert argumentsDescriptor.startsWith("(") && argumentsDescriptor.endsWith(")") : argumentsDescriptor;
        List<String> res = new ArrayList<>();
        int cur = 1;
        int end = argumentsDescriptor.length() - 1;
        while (cur != end) {
            char first;
            int start = cur;
            do {
                first = argumentsDescriptor.charAt(cur++);
            } while (first == '[');

            switch (first) {
                case 'L':
                    int endObject = argumentsDescriptor.indexOf(';', cur);
                    if (endObject == -1) {
                        throw new GraalError("Invalid object type at index %d in signature: %s", cur, argumentsDescriptor);
                    }
                    cur = endObject + 1;
                    break;
                case 'V':
                case 'I':
                case 'B':
                case 'C':
                case 'D':
                case 'F':
                case 'J':
                case 'S':
                case 'Z':
                    break;
                default:
                    throw new GraalError("Invalid character at index %d in signature: %s", cur, argumentsDescriptor);
            }
            res.add(argumentsDescriptor.substring(start, cur));
        }
        return res;
    }
}