/*

 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 java.lang.invoke;

import static jdk.internal.org.objectweb.asm.Opcodes.*;

import static java.lang.invoke.LambdaForm.basicTypes;

import static java.lang.invoke.MethodHandleNatives.Constants.REF_invokeStatic;

import static java.lang.invoke.MethodHandleStatics.*;

import java.lang.invoke.LambdaForm.Name;

import java.lang.invoke.LambdaForm.NamedFunction;

import java.lang.invoke.MethodHandles.Lookup;

import java.lang.reflect.Field;

import java.util.Arrays;

import java.util.HashMap;

import sun.invoke.util.ValueConversions;

import sun.invoke.util.Wrapper;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.MethodVisitor;

import jdk.internal.org.objectweb.asm.Type;

/**

 * The flavor of method handle which emulates an invoke instruction

 * on a predetermined argument.  The JVM dispatches to the correct method

 * when the handle is created, not when it is invoked.

 *

 * All bound arguments are encapsulated in dedicated species.

 */

/* non-public */ abstract class BoundMethodHandle extends MethodHandle {

    /* non-public */ BoundMethodHandle(MethodType type, LambdaForm form) {

        super(type, form);

    }

    //

    // BMH API and internals

    //

    static MethodHandle bindSingle(MethodType type, LambdaForm form, char xtype, Object x) {

        // for some type signatures, there exist pre-defined concrete BMH classes

        try {

            switch (xtype) {

            case 'L':

                if (true)  return bindSingle(type, form, x);  // Use known fast path.

                return (BoundMethodHandle) SpeciesData.EMPTY.extendWithType('L').constructor[0].invokeBasic(type, form, x);

            case 'I':

                return (BoundMethodHandle) SpeciesData.EMPTY.extendWithType('I').constructor[0].invokeBasic(type, form, ValueConversions.widenSubword(x));

            case 'J':

                return (BoundMethodHandle) SpeciesData.EMPTY.extendWithType('J').constructor[0].invokeBasic(type, form, (long) x);

            case 'F':

                return (BoundMethodHandle) SpeciesData.EMPTY.extendWithType('F').constructor[0].invokeBasic(type, form, (float) x);

            case 'D':

                return (BoundMethodHandle) SpeciesData.EMPTY.extendWithType('D').constructor[0].invokeBasic(type, form, (double) x);

            default : throw new InternalError("unexpected xtype: " + xtype);

            }

        } catch (Throwable t) {

            throw newInternalError(t);

        }

    }

    static MethodHandle bindSingle(MethodType type, LambdaForm form, Object x) {

            return new Species_L(type, form, x);

    }

    MethodHandle cloneExtend(MethodType type, LambdaForm form, char xtype, Object x) {

        try {

            switch (xtype) {

            case 'L': return cloneExtendL(type, form, x);

            case 'I': return cloneExtendI(type, form, ValueConversions.widenSubword(x));

            case 'J': return cloneExtendJ(type, form, (long) x);

            case 'F': return cloneExtendF(type, form, (float) x);

            case 'D': return cloneExtendD(type, form, (double) x);

            }

        } catch (Throwable t) {

            throw newInternalError(t);

        }

        throw new InternalError("unexpected type: " + xtype);

    }

    @Override

    MethodHandle bindArgument(int pos, char basicType, Object value) {

        MethodType type = type().dropParameterTypes(pos, pos+1);

        LambdaForm form = internalForm().bind(1+pos, speciesData());

        return cloneExtend(type, form, basicType, value);

    }

    @Override

    MethodHandle dropArguments(MethodType srcType, int pos, int drops) {

        LambdaForm form = internalForm().addArguments(pos, srcType.parameterList().subList(pos, pos+drops));

        try {

             return clone(srcType, form);

         } catch (Throwable t) {

             throw newInternalError(t);

         }

    }

    @Override

    MethodHandle permuteArguments(MethodType newType, int[] reorder) {

        try {

             return clone(newType, form.permuteArguments(1, reorder, basicTypes(newType.parameterList())));

         } catch (Throwable t) {

             throw newInternalError(t);

         }

    }

    static final String EXTENSION_TYPES = "LIJFD";

    static final byte INDEX_L = 0, INDEX_I = 1, INDEX_J = 2, INDEX_F = 3, INDEX_D = 4;

    static byte extensionIndex(char type) {

        int i = EXTENSION_TYPES.indexOf(type);

        if (i < 0)  throw new InternalError();

        return (byte) i;

    }

    /**

     * Return the {@link SpeciesData} instance representing this BMH species. All subclasses must provide a

     * static field containing this value, and they must accordingly implement this method.

     */

    protected abstract SpeciesData speciesData();

    @Override

    final Object internalProperties() {

        return "/BMH="+internalValues();

    }

    @Override

    final Object internalValues() {

        Object[] boundValues = new Object[speciesData().fieldCount()];

        for (int i = 0; i < boundValues.length; ++i) {

            boundValues[i] = arg(i);

        }

        return Arrays.asList(boundValues);

    }

    public final Object arg(int i) {

        try {

            switch (speciesData().fieldType(i)) {

            case 'L': return argL(i);

            case 'I': return argI(i);

            case 'F': return argF(i);

            case 'D': return argD(i);

            case 'J': return argJ(i);

            }

        } catch (Throwable ex) {

            throw newInternalError(ex);

        }

        throw new InternalError("unexpected type: " + speciesData().types+"."+i);

    }

    public final Object argL(int i) throws Throwable { return          speciesData().getters[i].invokeBasic(this); }

    public final int    argI(int i) throws Throwable { return (int)    speciesData().getters[i].invokeBasic(this); }

    public final float  argF(int i) throws Throwable { return (float)  speciesData().getters[i].invokeBasic(this); }

    public final double argD(int i) throws Throwable { return (double) speciesData().getters[i].invokeBasic(this); }

    public final long   argJ(int i) throws Throwable { return (long)   speciesData().getters[i].invokeBasic(this); }

    //

    // cloning API

    //

    public abstract BoundMethodHandle clone(MethodType mt, LambdaForm lf) throws Throwable;

    public abstract BoundMethodHandle cloneExtendL(MethodType mt, LambdaForm lf, Object narg) throws Throwable;

    public abstract BoundMethodHandle cloneExtendI(MethodType mt, LambdaForm lf, int    narg) throws Throwable;

    public abstract BoundMethodHandle cloneExtendJ(MethodType mt, LambdaForm lf, long   narg) throws Throwable;

    public abstract BoundMethodHandle cloneExtendF(MethodType mt, LambdaForm lf, float  narg) throws Throwable;

    public abstract BoundMethodHandle cloneExtendD(MethodType mt, LambdaForm lf, double narg) throws Throwable;

    // The following is a grossly irregular hack:

    @Override MethodHandle reinvokerTarget() {

        try {

            return (MethodHandle) argL(0);

        } catch (Throwable ex) {

            throw newInternalError(ex);

        }

    }

    //

    // concrete BMH classes required to close bootstrap loops

    //

    private  // make it private to force users to access the enclosing class first

    static final class Species_L extends BoundMethodHandle {

        final Object argL0;

        public Species_L(MethodType mt, LambdaForm lf, Object argL0) {

            super(mt, lf);

            this.argL0 = argL0;

        }

        // The following is a grossly irregular hack:

        @Override MethodHandle reinvokerTarget() { return (MethodHandle) argL0; }

        @Override

        public SpeciesData speciesData() {

            return SPECIES_DATA;

        }

        public static final SpeciesData SPECIES_DATA = SpeciesData.getForClass("L", Species_L.class);

        @Override

        public final BoundMethodHandle clone(MethodType mt, LambdaForm lf) throws Throwable {

            return new Species_L(mt, lf, argL0);

        }

        @Override

        public final BoundMethodHandle cloneExtendL(MethodType mt, LambdaForm lf, Object narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_L).constructor[0].invokeBasic(mt, lf, argL0, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendI(MethodType mt, LambdaForm lf, int narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_I).constructor[0].invokeBasic(mt, lf, argL0, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendJ(MethodType mt, LambdaForm lf, long narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_J).constructor[0].invokeBasic(mt, lf, argL0, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendF(MethodType mt, LambdaForm lf, float narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_F).constructor[0].invokeBasic(mt, lf, argL0, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendD(MethodType mt, LambdaForm lf, double narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_D).constructor[0].invokeBasic(mt, lf, argL0, narg);

        }

    }

/*

    static final class Species_LL extends BoundMethodHandle {

        final Object argL0;

        final Object argL1;

        public Species_LL(MethodType mt, LambdaForm lf, Object argL0, Object argL1) {

            super(mt, lf);

            this.argL0 = argL0;

            this.argL1 = argL1;

        }

        @Override

        public SpeciesData speciesData() {

            return SPECIES_DATA;

        }

        public static final SpeciesData SPECIES_DATA = SpeciesData.getForClass("LL", Species_LL.class);

        @Override

        public final BoundMethodHandle clone(MethodType mt, LambdaForm lf) throws Throwable {

            return new Species_LL(mt, lf, argL0, argL1);

        }

        @Override

        public final BoundMethodHandle cloneExtendL(MethodType mt, LambdaForm lf, Object narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_L).constructor[0].invokeBasic(mt, lf, argL0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendI(MethodType mt, LambdaForm lf, int narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_I).constructor[0].invokeBasic(mt, lf, argL0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendJ(MethodType mt, LambdaForm lf, long narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_J).constructor[0].invokeBasic(mt, lf, argL0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendF(MethodType mt, LambdaForm lf, float narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_F).constructor[0].invokeBasic(mt, lf, argL0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendD(MethodType mt, LambdaForm lf, double narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_D).constructor[0].invokeBasic(mt, lf, argL0, argL1, narg);

        }

    }

    static final class Species_JL extends BoundMethodHandle {

        final long argJ0;

        final Object argL1;

        public Species_JL(MethodType mt, LambdaForm lf, long argJ0, Object argL1) {

            super(mt, lf);

            this.argJ0 = argJ0;

            this.argL1 = argL1;

        }

        @Override

        public SpeciesData speciesData() {

            return SPECIES_DATA;

        }

        public static final SpeciesData SPECIES_DATA = SpeciesData.getForClass("JL", Species_JL.class);

        @Override public final long   argJ0() { return argJ0; }

        @Override public final Object argL1() { return argL1; }

        @Override

        public final BoundMethodHandle clone(MethodType mt, LambdaForm lf) throws Throwable {

            return new Species_JL(mt, lf, argJ0, argL1);

        }

        @Override

        public final BoundMethodHandle cloneExtendL(MethodType mt, LambdaForm lf, Object narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_L).constructor[0].invokeBasic(mt, lf, argJ0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendI(MethodType mt, LambdaForm lf, int narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_I).constructor[0].invokeBasic(mt, lf, argJ0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendJ(MethodType mt, LambdaForm lf, long narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_J).constructor[0].invokeBasic(mt, lf, argJ0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendF(MethodType mt, LambdaForm lf, float narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_F).constructor[0].invokeBasic(mt, lf, argJ0, argL1, narg);

        }

        @Override

        public final BoundMethodHandle cloneExtendD(MethodType mt, LambdaForm lf, double narg) throws Throwable {

            return (BoundMethodHandle) SPECIES_DATA.extendWithIndex(INDEX_D).constructor[0].invokeBasic(mt, lf, argJ0, argL1, narg);

        }

    }

*/

    //

    // BMH species meta-data

    //

    /**

     * Meta-data wrapper for concrete BMH classes.

     */

    static class SpeciesData {

        final String                             types;

        final Class<? extends BoundMethodHandle> clazz;

        // Bootstrapping requires circular relations MH -> BMH -> SpeciesData -> MH

        // Therefore, we need a non-final link in the chain.  Use array elements.

        final MethodHandle[]                     constructor;

        final MethodHandle[]                     getters;

        final SpeciesData[]                      extensions;

        public int fieldCount() {

            return types.length();

        }

        public char fieldType(int i) {

            return types.charAt(i);

        }

        public String toString() {

            return "SpeciesData["+(isPlaceholder() ? "<placeholder>" : clazz.getSimpleName())+":"+types+"]";

        }

        /**

         * Return a {@link LambdaForm.Name} containing a {@link LambdaForm.NamedFunction} that

         * represents a MH bound to a generic invoker, which in turn forwards to the corresponding

         * getter.

         */

        Name getterName(Name mhName, int i) {

            MethodHandle mh = getters[i];

            assert(mh != null) : this+"."+i;

            return new Name(mh, mhName);

        }

        NamedFunction getterFunction(int i) {

            return new NamedFunction(getters[i]);

        }

        static final SpeciesData EMPTY = new SpeciesData("", BoundMethodHandle.class);

        private SpeciesData(String types, Class<? extends BoundMethodHandle> clazz) {

            this.types = types;

            this.clazz = clazz;

            if (!INIT_DONE) {

                this.constructor = new MethodHandle[1];

                this.getters = new MethodHandle[types.length()];

            } else {

                this.constructor = Factory.makeCtors(clazz, types, null);

                this.getters = Factory.makeGetters(clazz, types, null);

            }

            this.extensions = new SpeciesData[EXTENSION_TYPES.length()];

        }

        private void initForBootstrap() {

            assert(!INIT_DONE);

            if (constructor[0] == null) {

                Factory.makeCtors(clazz, types, this.constructor);

                Factory.makeGetters(clazz, types, this.getters);

            }

        }

        private SpeciesData(String types) {

            // Placeholder only.

            this.types = types;

            this.clazz = null;

            this.constructor = null;

            this.getters = null;

            this.extensions = null;

        }

        private boolean isPlaceholder() { return clazz == null; }

        private static final HashMap<String, SpeciesData> CACHE = new HashMap<>();

        static { CACHE.put("", EMPTY); }  // make bootstrap predictable

        private static final boolean INIT_DONE;  // set after <clinit> finishes...

        SpeciesData extendWithType(char type) {

            int i = extensionIndex(type);

            SpeciesData d = extensions[i];

            if (d != null)  return d;

            extensions[i] = d = get(types+type);

            return d;

        }

        SpeciesData extendWithIndex(byte index) {

            SpeciesData d = extensions[index];

            if (d != null)  return d;

            extensions[index] = d = get(types+EXTENSION_TYPES.charAt(index));

            return d;

        }

        private static SpeciesData get(String types) {

            // Acquire cache lock for query.

            SpeciesData d = lookupCache(types);

            if (!d.isPlaceholder())

                return d;

            synchronized (d) {

                // Use synch. on the placeholder to prevent multiple instantiation of one species.

                // Creating this class forces a recursive call to getForClass.

                if (lookupCache(types).isPlaceholder())

                    Factory.generateConcreteBMHClass(types);

            }

            // Reacquire cache lock.

            d = lookupCache(types);

            // Class loading must have upgraded the cache.

            assert(d != null && !d.isPlaceholder());

            return d;

        }

        static SpeciesData getForClass(String types, Class<? extends BoundMethodHandle> clazz) {

            // clazz is a new class which is initializing its SPECIES_DATA field

            return updateCache(types, new SpeciesData(types, clazz));

        }

        private static synchronized SpeciesData lookupCache(String types) {

            SpeciesData d = CACHE.get(types);

            if (d != null)  return d;

            d = new SpeciesData(types);

            assert(d.isPlaceholder());

            CACHE.put(types, d);

            return d;

        }

        private static synchronized SpeciesData updateCache(String types, SpeciesData d) {

            SpeciesData d2;

            assert((d2 = CACHE.get(types)) == null || d2.isPlaceholder());

            assert(!d.isPlaceholder());

            CACHE.put(types, d);

            return d;

        }

        static {

            // pre-fill the BMH speciesdata cache with BMH's inner classes

            final Class<BoundMethodHandle> rootCls = BoundMethodHandle.class;

            SpeciesData d0 = BoundMethodHandle.SPECIES_DATA;  // trigger class init

            assert(d0 == null || d0 == lookupCache("")) : d0;

            try {

                for (Class<?> c : rootCls.getDeclaredClasses()) {

                    if (rootCls.isAssignableFrom(c)) {

                        final Class<? extends BoundMethodHandle> cbmh = c.asSubclass(BoundMethodHandle.class);

                        SpeciesData d = Factory.speciesDataFromConcreteBMHClass(cbmh);

                        assert(d != null) : cbmh.getName();

                        assert(d.clazz == cbmh);

                        assert(d == lookupCache(d.types));

                    }

                }

            } catch (Throwable e) {

                throw newInternalError(e);

            }

            for (SpeciesData d : CACHE.values()) {

                d.initForBootstrap();

            }

            // Note:  Do not simplify this, because INIT_DONE must not be

            // a compile-time constant during bootstrapping.

            INIT_DONE = Boolean.TRUE;

        }

    }

    static SpeciesData getSpeciesData(String types) {

        return SpeciesData.get(types);

    }

    /**

     * Generation of concrete BMH classes.

     *

     * A concrete BMH species is fit for binding a number of values adhering to a

     * given type pattern. Reference types are erased.

     *

     * BMH species are cached by type pattern.

     *

     * A BMH species has a number of fields with the concrete (possibly erased) types of

     * bound values. Setters are provided as an API in BMH. Getters are exposed as MHs,

     * which can be included as names in lambda forms.

     */

    static class Factory {

        static final String JLO_SIG  = "Ljava/lang/Object;";

        static final String JLS_SIG  = "Ljava/lang/String;";

        static final String JLC_SIG  = "Ljava/lang/Class;";

        static final String MH       = "java/lang/invoke/MethodHandle";

        static final String MH_SIG   = "L"+MH+";";

        static final String BMH      = "java/lang/invoke/BoundMethodHandle";

        static final String BMH_SIG  = "L"+BMH+";";

        static final String SPECIES_DATA     = "java/lang/invoke/BoundMethodHandle$SpeciesData";

        static final String SPECIES_DATA_SIG = "L"+SPECIES_DATA+";";

        static final String SPECIES_PREFIX_NAME = "Species_";

        static final String SPECIES_PREFIX_PATH = BMH + "$" + SPECIES_PREFIX_NAME;

        static final String BMHSPECIES_DATA_EWI_SIG = "(B)" + SPECIES_DATA_SIG;

        static final String BMHSPECIES_DATA_GFC_SIG = "(" + JLS_SIG + JLC_SIG + ")" + SPECIES_DATA_SIG;

        static final String MYSPECIES_DATA_SIG = "()" + SPECIES_DATA_SIG;

        static final String VOID_SIG   = "()V";

        static final String SIG_INCIPIT = "(Ljava/lang/invoke/MethodType;Ljava/lang/invoke/LambdaForm;";

        static final Class<?>[] TYPES = new Class<?>[] { Object.class, int.class, long.class, float.class, double.class };

        static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };

        /**

         * Generate a concrete subclass of BMH for a given combination of bound types.

         *

         * A concrete BMH species adheres to the following schema:

         *

         * <pre>

         * class Species_[[types]] extends BoundMethodHandle {

         *     [[fields]]

         *     final SpeciesData speciesData() { return SpeciesData.get("[[types]]"); }

         * }

         * </pre>

         *

         * The {@code [[types]]} signature is precisely the string that is passed to this

         * method.

         *

         * The {@code [[fields]]} section consists of one field definition per character in

         * the type signature, adhering to the naming schema described in the definition of

         * {@link #makeFieldName}.

         *

         * For example, a concrete BMH species for two reference and one integral bound values

         * would have the following shape:

         *

         * <pre>

         * class BoundMethodHandle { ... private static

         * final class Species_LLI extends BoundMethodHandle {

         *     final Object argL0;

         *     final Object argL1;

         *     final int argI2;

         *     public Species_LLI(MethodType mt, LambdaForm lf, Object argL0, Object argL1, int argI2) {

         *         super(mt, lf);

         *         this.argL0 = argL0;

         *         this.argL1 = argL1;

         *         this.argI2 = argI2;

         *     }

         *     public final SpeciesData speciesData() { return SPECIES_DATA; }

         *     public static final SpeciesData SPECIES_DATA = SpeciesData.getForClass("LLI", Species_LLI.class);

         *     public final BoundMethodHandle clone(MethodType mt, LambdaForm lf) {

         *         return SPECIES_DATA.constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2);

         *     }

         *     public final BoundMethodHandle cloneExtendL(MethodType mt, LambdaForm lf, Object narg) {

         *         return SPECIES_DATA.extendWithIndex(INDEX_L).constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2, narg);

         *     }

         *     public final BoundMethodHandle cloneExtendI(MethodType mt, LambdaForm lf, int narg) {

         *         return SPECIES_DATA.extendWithIndex(INDEX_I).constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2, narg);

         *     }

         *     public final BoundMethodHandle cloneExtendJ(MethodType mt, LambdaForm lf, long narg) {

         *         return SPECIES_DATA.extendWithIndex(INDEX_J).constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2, narg);

         *     }

         *     public final BoundMethodHandle cloneExtendF(MethodType mt, LambdaForm lf, float narg) {

         *         return SPECIES_DATA.extendWithIndex(INDEX_F).constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2, narg);

         *     }

         *     public final BoundMethodHandle cloneExtendD(MethodType mt, LambdaForm lf, double narg) {

         *         return SPECIES_DATA.extendWithIndex(INDEX_D).constructor[0].invokeBasic(mt, lf, argL0, argL1, argI2, narg);

         *     }

         * }

         * </pre>

         *

         * @param types the type signature, wherein reference types are erased to 'L'

         * @return the generated concrete BMH class

         */

        static Class<? extends BoundMethodHandle> generateConcreteBMHClass(String types) {

            final ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);

            final String className  = SPECIES_PREFIX_PATH + types;

            final String sourceFile = SPECIES_PREFIX_NAME + types;

            cw.visit(V1_6, ACC_PUBLIC + ACC_FINAL + ACC_SUPER, className, null, BMH, null);

            cw.visitSource(sourceFile, null);

            // emit static types and SPECIES_DATA fields

            cw.visitField(ACC_PUBLIC + ACC_STATIC, "SPECIES_DATA", SPECIES_DATA_SIG, null, null).visitEnd();

            // emit bound argument fields

            for (int i = 0; i < types.length(); ++i) {

                final char t = types.charAt(i);

                final String fieldName = makeFieldName(types, i);

                final String fieldDesc = t == 'L' ? JLO_SIG : String.valueOf(t);

                cw.visitField(ACC_FINAL, fieldName, fieldDesc, null, null).visitEnd();

            }

            MethodVisitor mv;

            // emit constructor

            mv = cw.visitMethod(ACC_PUBLIC, "<init>", makeSignature(types, true), null, null);

            mv.visitCode();

            mv.visitVarInsn(ALOAD, 0);

            mv.visitVarInsn(ALOAD, 1);

            mv.visitVarInsn(ALOAD, 2);

            mv.visitMethodInsn(INVOKESPECIAL, BMH, "<init>", makeSignature("", true));

            for (int i = 0, j = 0; i < types.length(); ++i, ++j) {

                // i counts the arguments, j counts corresponding argument slots

                char t = types.charAt(i);

                mv.visitVarInsn(ALOAD, 0);

                mv.visitVarInsn(typeLoadOp(t), j + 3); // parameters start at 3

                mv.visitFieldInsn(PUTFIELD, className, makeFieldName(types, i), typeSig(t));

                if (t == 'J' || t == 'D') {

                    ++j; // adjust argument register access

                }

            }

            mv.visitInsn(RETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            // emit implementation of reinvokerTarget()

            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "reinvokerTarget", "()" + MH_SIG, null, null);

            mv.visitCode();

            mv.visitVarInsn(ALOAD, 0);

            mv.visitFieldInsn(GETFIELD, className, "argL0", JLO_SIG);

            mv.visitTypeInsn(CHECKCAST, MH);

            mv.visitInsn(ARETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            // emit implementation of speciesData()

            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "speciesData", MYSPECIES_DATA_SIG, null, null);

            mv.visitCode();

            mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);

            mv.visitInsn(ARETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            // emit clone()

            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "clone", makeSignature("", false), null, E_THROWABLE);

            mv.visitCode();

            // return speciesData().constructor[0].invokeBasic(mt, lf, argL0, ...)

            // obtain constructor

            mv.visitVarInsn(ALOAD, 0);

            mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);

            mv.visitFieldInsn(GETFIELD, SPECIES_DATA, "constructor", "[" + MH_SIG);

            mv.visitInsn(ICONST_0);

            mv.visitInsn(AALOAD);

            // load mt, lf

            mv.visitVarInsn(ALOAD, 1);

            mv.visitVarInsn(ALOAD, 2);

            // put fields on the stack

            emitPushFields(types, className, mv);

            // finally, invoke the constructor and return

            mv.visitMethodInsn(INVOKEVIRTUAL, MH, "invokeBasic", makeSignature(types, false));

            mv.visitInsn(ARETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            // for each type, emit cloneExtendT()

            for (Class<?> c : TYPES) {

                char t = Wrapper.basicTypeChar(c);

                mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "cloneExtend" + t, makeSignature(String.valueOf(t), false), null, E_THROWABLE);

                mv.visitCode();

                // return SPECIES_DATA.extendWithIndex(extensionIndex(t)).constructor[0].invokeBasic(mt, lf, argL0, ..., narg)

                // obtain constructor

                mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);

                int iconstInsn = ICONST_0 + extensionIndex(t);

                assert(iconstInsn <= ICONST_5);

                mv.visitInsn(iconstInsn);

                mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA, "extendWithIndex", BMHSPECIES_DATA_EWI_SIG);

                mv.visitFieldInsn(GETFIELD, SPECIES_DATA, "constructor", "[" + MH_SIG);

                mv.visitInsn(ICONST_0);

                mv.visitInsn(AALOAD);

                // load mt, lf

                mv.visitVarInsn(ALOAD, 1);

                mv.visitVarInsn(ALOAD, 2);

                // put fields on the stack

                emitPushFields(types, className, mv);

                // put narg on stack

                mv.visitVarInsn(typeLoadOp(t), 3);

                // finally, invoke the constructor and return

                mv.visitMethodInsn(INVOKEVIRTUAL, MH, "invokeBasic", makeSignature(types + t, false));

                mv.visitInsn(ARETURN);

                mv.visitMaxs(0, 0);

                mv.visitEnd();

            }

            // emit class initializer

            mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "<clinit>", VOID_SIG, null, null);

            mv.visitCode();

            mv.visitLdcInsn(types);

            mv.visitLdcInsn(Type.getObjectType(className));

            mv.visitMethodInsn(INVOKESTATIC, SPECIES_DATA, "getForClass", BMHSPECIES_DATA_GFC_SIG);

            mv.visitFieldInsn(PUTSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);

            mv.visitInsn(RETURN);

            mv.visitMaxs(0, 0);

            mv.visitEnd();

            cw.visitEnd();

            // load class

            final byte[] classFile = cw.toByteArray();

            InvokerBytecodeGenerator.maybeDump(className, classFile);

            Class<? extends BoundMethodHandle> bmhClass =

                //UNSAFE.defineAnonymousClass(BoundMethodHandle.class, classFile, null).asSubclass(BoundMethodHandle.class);

                UNSAFE.defineClass(className, classFile, 0, classFile.length,

                                   BoundMethodHandle.class.getClassLoader(), null)

                    .asSubclass(BoundMethodHandle.class);

            UNSAFE.ensureClassInitialized(bmhClass);

            return bmhClass;

        }

        private static int typeLoadOp(char t) {

            switch (t) {

            case 'L': return ALOAD;

            case 'I': return ILOAD;

            case 'J': return LLOAD;

            case 'F': return FLOAD;

            case 'D': return DLOAD;

            default : throw new InternalError("unrecognized type " + t);

            }

        }

        private static void emitPushFields(String types, String className, MethodVisitor mv) {

            for (int i = 0; i < types.length(); ++i) {

                char tc = types.charAt(i);

                mv.visitVarInsn(ALOAD, 0);

                mv.visitFieldInsn(GETFIELD, className, makeFieldName(types, i), typeSig(tc));

            }

        }

        static String typeSig(char t) {

            return t == 'L' ? JLO_SIG : String.valueOf(t);

        }

        //

        // Getter MH generation.

        //

        private static MethodHandle makeGetter(Class<?> cbmhClass, String types, int index) {

            String fieldName = makeFieldName(types, index);

            Class<?> fieldType = Wrapper.forBasicType(types.charAt(index)).primitiveType();

            try {

                return LOOKUP.findGetter(cbmhClass, fieldName, fieldType);

            } catch (NoSuchFieldException | IllegalAccessException e) {

                throw newInternalError(e);

            }

        }

        static MethodHandle[] makeGetters(Class<?> cbmhClass, String types, MethodHandle[] mhs) {

            if (mhs == null)  mhs = new MethodHandle[types.length()];

            for (int i = 0; i < mhs.length; ++i) {

                mhs[i] = makeGetter(cbmhClass, types, i);

                assert(mhs[i].internalMemberName().getDeclaringClass() == cbmhClass);

            }

            return mhs;

        }

        static MethodHandle[] makeCtors(Class<? extends BoundMethodHandle> cbmh, String types, MethodHandle mhs[]) {

            if (mhs == null)  mhs = new MethodHandle[1];

            mhs[0] = makeCbmhCtor(cbmh, types);

            return mhs;

        }

        //

        // Auxiliary methods.

        //

        static SpeciesData speciesDataFromConcreteBMHClass(Class<? extends BoundMethodHandle> cbmh) {

            try {

                Field F_SPECIES_DATA = cbmh.getDeclaredField("SPECIES_DATA");

                return (SpeciesData) F_SPECIES_DATA.get(null);

            } catch (ReflectiveOperationException ex) {

                throw newInternalError(ex);

            }

        }

        /**

         * Field names in concrete BMHs adhere to this pattern:

         * arg + type + index

         * where type is a single character (L, I, J, F, D).

         */

        private static String makeFieldName(String types, int index) {

            assert index >= 0 && index < types.length();

            return "arg" + types.charAt(index) + index;

        }

        private static String makeSignature(String types, boolean ctor) {

            StringBuilder buf = new StringBuilder(SIG_INCIPIT);

            for (char c : types.toCharArray()) {

                buf.append(typeSig(c));

            }

            return buf.append(')').append(ctor ? "V" : BMH_SIG).toString();

        }

        static MethodHandle makeCbmhCtor(Class<? extends BoundMethodHandle> cbmh, String types) {

            try {

                return linkConstructor(LOOKUP.findConstructor(cbmh, MethodType.fromMethodDescriptorString(makeSignature(types, true), null)));

            } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | TypeNotPresentException e) {

                throw newInternalError(e);

            }

        }

        /**

         * Wrap a constructor call in a {@link LambdaForm}.

         *

         * If constructors ({@code <init>} methods) are called in LFs, problems might arise if the LFs

         * are turned into bytecode, because the call to the allocator is routed through an MH, and the

         * verifier cannot find a {@code NEW} instruction preceding the {@code INVOKESPECIAL} to

         * {@code <init>}. To avoid this, we add an indirection by invoking {@code <init>} through

         * {@link MethodHandle#linkToSpecial}.

         *

         * The last {@link LambdaForm.Name Name} in the argument's form is expected to be the {@code void}

         * result of the {@code <init>} invocation. This entry is replaced.

         */

        private static MethodHandle linkConstructor(MethodHandle cmh) {

            final LambdaForm lf = cmh.form;

            final int initNameIndex = lf.names.length - 1;

            final Name initName = lf.names[initNameIndex];

            final MemberName ctorMN = initName.function.member;

            final MethodType ctorMT = ctorMN.getInvocationType();

            // obtain function member (call target)

            // linker method type replaces initial parameter (BMH species) with BMH to avoid naming a species (anonymous class!)

            final MethodType linkerMT = ctorMT.changeParameterType(0, BoundMethodHandle.class).appendParameterTypes(MemberName.class);

            MemberName linkerMN = new MemberName(MethodHandle.class, "linkToSpecial", linkerMT, REF_invokeStatic);

            try {

                linkerMN = MemberName.getFactory().resolveOrFail(REF_invokeStatic, linkerMN, null, NoSuchMethodException.class);

                assert(linkerMN.isStatic());

            } catch (ReflectiveOperationException ex) {

                throw newInternalError(ex);

            }

            // extend arguments array

            Object[] newArgs = Arrays.copyOf(initName.arguments, initName.arguments.length + 1);

            newArgs[newArgs.length - 1] = ctorMN;

            // replace function

            final NamedFunction nf = new NamedFunction(linkerMN);

            final Name linkedCtor = new Name(nf, newArgs);

            linkedCtor.initIndex(initNameIndex);

            lf.names[initNameIndex] = linkedCtor;

            return cmh;

        }

    }

    private static final Lookup LOOKUP = Lookup.IMPL_LOOKUP;

    /**

     * All subclasses must provide such a value describing their type signature.

     */

    static final SpeciesData SPECIES_DATA = SpeciesData.EMPTY;

}