diff -r e0041b182e31 -r a2008587c13f src/java.base/share/classes/java/lang/invoke/ClassSpecializer.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/lang/invoke/ClassSpecializer.java	Thu Nov 16 00:58:50 2017 +0100
@@ -0,0 +1,1030 @@
+/*
+ * Copyright (c) 2017, 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 jdk.internal.loader.BootLoader;
+import jdk.internal.org.objectweb.asm.ClassWriter;
+import jdk.internal.org.objectweb.asm.FieldVisitor;
+import jdk.internal.org.objectweb.asm.MethodVisitor;
+import jdk.internal.vm.annotation.Stable;
+import sun.invoke.util.BytecodeName;
+
+import java.lang.reflect.*;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.security.ProtectionDomain;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.function.Function;
+
+import static java.lang.invoke.LambdaForm.*;
+import static java.lang.invoke.MethodHandleNatives.Constants.REF_getStatic;
+import static java.lang.invoke.MethodHandleNatives.Constants.REF_putStatic;
+import static java.lang.invoke.MethodHandleStatics.*;
+import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
+import static jdk.internal.org.objectweb.asm.Opcodes.*;
+
+/**
+ * Class specialization code.
+ * @param <T> top class under which species classes are created.
+ * @param <K> key which identifies individual specializations.
+ * @param <S> species data type.
+ */
+/*non-public*/
+abstract class ClassSpecializer<T,K,S extends ClassSpecializer<T,K,S>.SpeciesData> {
+    private final Class<T> topClass;
+    private final Class<K> keyType;
+    private final Class<S> metaType;
+    private final MemberName sdAccessor;
+    private final String sdFieldName;
+    private final List<MemberName> transformMethods;
+    private final MethodType baseConstructorType;
+    private final S topSpecies;
+    private final ConcurrentMap<K, S> cache = new ConcurrentHashMap<>();
+    private final Factory factory;
+    private @Stable boolean topClassIsSuper;
+
+    /** Return the top type mirror, for type {@code T} */
+    public final Class<T> topClass() { return topClass; }
+
+    /** Return the key type mirror, for type {@code K} */
+    public final Class<K> keyType() { return keyType; }
+
+    /** Return the species metadata type mirror, for type {@code S} */
+    public final Class<S> metaType() { return metaType; }
+
+    /** Report the leading arguments (if any) required by every species factory.
+     * Every species factory adds its own field types as additional arguments,
+     * but these arguments always come first, in every factory method.
+     */
+    protected MethodType baseConstructorType() { return baseConstructorType; }
+
+    /** Return the trivial species for the null sequence of arguments. */
+    protected final S topSpecies() { return topSpecies; }
+
+    /** Return the list of transform methods originally given at creation of this specializer. */
+    protected final List<MemberName> transformMethods() { return transformMethods; }
+
+    /** Return the factory object used to build and load concrete species code. */
+    protected final Factory factory() { return factory; }
+
+    /**
+     * Constructor for this class specializer.
+     * @param topClass type mirror for T
+     * @param keyType type mirror for K
+     * @param metaType type mirror for S
+     * @param baseConstructorType principal constructor type
+     * @param sdAccessor the method used to get the speciesData
+     * @param sdFieldName the name of the species data field, inject the speciesData object
+     * @param transformMethods optional list of transformMethods
+     */
+    protected ClassSpecializer(Class<T> topClass,
+                               Class<K> keyType,
+                               Class<S> metaType,
+                               MethodType baseConstructorType,
+                               MemberName sdAccessor,
+                               String sdFieldName,
+                               List<MemberName> transformMethods) {
+        this.topClass = topClass;
+        this.keyType = keyType;
+        this.metaType = metaType;
+        this.sdAccessor = sdAccessor;
+        // FIXME: use List.copyOf once 8177290 is in
+        this.transformMethods = List.of(transformMethods.toArray(new MemberName[transformMethods.size()]));
+        this.sdFieldName = sdFieldName;
+        this.baseConstructorType = baseConstructorType.changeReturnType(void.class);
+        this.factory = makeFactory();
+        K tsk = topSpeciesKey();
+        S topSpecies = null;
+        if (tsk != null && topSpecies == null) {
+            // if there is a key, build the top species if needed:
+            topSpecies = findSpecies(tsk);
+        }
+        this.topSpecies = topSpecies;
+    }
+
+    // Utilities for subclass constructors:
+    protected static <T> Constructor<T> reflectConstructor(Class<T> defc, Class<?>... ptypes) {
+        try {
+            return defc.getDeclaredConstructor(ptypes);
+        } catch (NoSuchMethodException ex) {
+            throw newIAE(defc.getName()+"("+MethodType.methodType(void.class, ptypes)+")", ex);
+        }
+    }
+
+    protected static Field reflectField(Class<?> defc, String name) {
+        try {
+            return defc.getDeclaredField(name);
+        } catch (NoSuchFieldException ex) {
+            throw newIAE(defc.getName()+"."+name, ex);
+        }
+    }
+
+    private static RuntimeException newIAE(String message, Throwable cause) {
+        return new IllegalArgumentException(message, cause);
+    }
+
+    public final S findSpecies(K key) {
+        S speciesData = cache.computeIfAbsent(key, new Function<>() {
+            @Override
+            public S apply(K key1) {
+                return factory.loadSpecies(newSpeciesData(key1));
+            }
+        });
+        // Note:  Species instantiation may throw VirtualMachineError because of
+        // code cache overflow.  If this happens the species bytecode may be
+        // loaded but not linked to its species metadata (with MH's etc).
+        // That will cause a throw out of CHM.computeIfAbsent,
+        // which will shut down the caller thread.
+        //
+        // In a latter attempt to get the same species, the already-loaded
+        // class will be present in the system dictionary, causing an
+        // error when the species generator tries to reload it.
+        // We try to detect this case and link the pre-existing code.
+        //
+        // Although it would be better to start fresh by loading a new
+        // copy, we have to salvage the previously loaded but broken code.
+        // (As an alternative, we might spin a new class with a new name,
+        // or use the anonymous class mechanism.)
+        //
+        // In the end, as long as everybody goes through the same CHM,
+        // CHM.computeIfAbsent will ensure only one SpeciesData will be set
+        // successfully on a concrete class if ever.
+        // The concrete class is published via SpeciesData instance
+        // returned here only after the class and species data are linked together.
+        assert(speciesData != null);
+        return speciesData;
+    }
+
+    /**
+     * Meta-data wrapper for concrete subtypes of the top class.
+     * Each concrete subtype corresponds to a given sequence of basic field types (LIJFD).
+     * The fields are immutable; their values are fully specified at object construction.
+     * Each species supplies an array of getter functions which may be used in lambda forms.
+     * A concrete value is always constructed from the full tuple of its field values,
+     * accompanied by the required constructor parameters.
+     * There *may* also be transforms which cloning a species instance and
+     * either replace a constructor parameter or add one or more new field values.
+     * The shortest possible species has zero fields.
+     * Subtypes are not interrelated among themselves by subtyping, even though
+     * it would appear that a shorter species could serve as a supertype of a
+     * longer one which extends it.
+     */
+    public abstract class SpeciesData {
+        // Bootstrapping requires circular relations Class -> SpeciesData -> Class
+        // Therefore, we need non-final links in the chain.  Use @Stable fields.
+        private final K key;
+        private final List<Class<?>> fieldTypes;
+        @Stable private Class<? extends T> speciesCode;
+        @Stable private List<MethodHandle> factories;
+        @Stable private List<MethodHandle> getters;
+        @Stable private List<LambdaForm.NamedFunction> nominalGetters;
+        @Stable private final MethodHandle[] transformHelpers = new MethodHandle[transformMethods.size()];
+
+        protected SpeciesData(K key) {
+            this.key = keyType.cast(Objects.requireNonNull(key));
+            List<Class<?>> types = deriveFieldTypes(key);
+            // TODO: List.copyOf
+            int arity = types.size();
+            this.fieldTypes = List.of(types.toArray(new Class<?>[arity]));
+        }
+
+        public final K key() {
+            return key;
+        }
+
+        protected final List<Class<?>> fieldTypes() {
+            return fieldTypes;
+        }
+
+        protected final int fieldCount() {
+            return fieldTypes.size();
+        }
+
+        protected ClassSpecializer<T,K,S> outer() {
+            return ClassSpecializer.this;
+        }
+
+        protected final boolean isResolved() {
+            return speciesCode != null && factories != null && !factories.isEmpty();
+        }
+
+        @Override public String toString() {
+            return metaType.getSimpleName() + "[" + key.toString() + " => " + (isResolved() ? speciesCode.getSimpleName() : "UNRESOLVED") + "]";
+        }
+
+        @Override
+        public int hashCode() {
+            return key.hashCode();
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (!(obj instanceof ClassSpecializer.SpeciesData)) {
+                return false;
+            }
+            @SuppressWarnings("rawtypes")
+            ClassSpecializer.SpeciesData that = (ClassSpecializer.SpeciesData) obj;
+            return this.outer() == that.outer() && this.key.equals(that.key);
+        }
+
+        /** Throws NPE if this species is not yet resolved. */
+        protected final Class<? extends T> speciesCode() {
+            return Objects.requireNonNull(speciesCode);
+        }
+
+        /**
+         * Return a {@link MethodHandle} which can get the indexed field of this species.
+         * The return type is the type of the species field it accesses.
+         * The argument type is the {@code fieldHolder} class of this species.
+         */
+        protected MethodHandle getter(int i) {
+            return getters.get(i);
+        }
+
+        /**
+         * 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.
+         */
+        protected LambdaForm.NamedFunction getterFunction(int i) {
+            LambdaForm.NamedFunction nf = nominalGetters.get(i);
+            assert(nf.memberDeclaringClassOrNull() == speciesCode());
+            assert(nf.returnType() == BasicType.basicType(fieldTypes.get(i)));
+            return nf;
+        }
+
+        protected List<LambdaForm.NamedFunction> getterFunctions() {
+            return nominalGetters;
+        }
+
+        protected List<MethodHandle> getters() {
+            return getters;
+        }
+
+        protected MethodHandle factory() {
+            return factories.get(0);
+        }
+
+        protected MethodHandle transformHelper(int whichtm) {
+            MethodHandle mh = transformHelpers[whichtm];
+            if (mh != null)  return mh;
+            mh = deriveTransformHelper(transformMethods().get(whichtm), whichtm);
+            // Do a little type checking before we start using the MH.
+            // (It will be called with invokeBasic, so this is our only chance.)
+            final MethodType mt = transformHelperType(whichtm);
+            mh = mh.asType(mt);
+            return transformHelpers[whichtm] = mh;
+        }
+
+        private final MethodType transformHelperType(int whichtm) {
+            MemberName tm = transformMethods().get(whichtm);
+            ArrayList<Class<?>> args = new ArrayList<>();
+            ArrayList<Class<?>> fields = new ArrayList<>();
+            Collections.addAll(args, tm.getParameterTypes());
+            fields.addAll(fieldTypes());
+            List<Class<?>> helperArgs = deriveTransformHelperArguments(tm, whichtm, args, fields);
+            return MethodType.methodType(tm.getReturnType(), helperArgs);
+        }
+
+        // Hooks for subclasses:
+
+        /**
+         * Given a key, derive the list of field types, which all instances of this
+         * species must store.
+         */
+        protected abstract List<Class<?>> deriveFieldTypes(K key);
+
+        /**
+         * Given the index of a method in the transforms list, supply a factory
+         * method that takes the arguments of the transform, plus the local fields,
+         * and produce a value of the required type.
+         * You can override this to return null or throw if there are no transforms.
+         * This method exists so that the transforms can be "grown" lazily.
+         * This is necessary if the transform *adds* a field to an instance,
+         * which sometimtes requires the creation, on the fly, of an extended species.
+         * This method is only called once for any particular parameter.
+         * The species caches the result in a private array.
+         *
+         * @param transform the transform being implemented
+         * @param whichtm the index of that transform in the original list of transforms
+         * @return the method handle which creates a new result from a mix of transform
+         * arguments and field values
+         */
+        protected abstract MethodHandle deriveTransformHelper(MemberName transform, int whichtm);
+
+        /**
+         * During code generation, this method is called once per transform to determine
+         * what is the mix of arguments to hand to the transform-helper.  The bytecode
+         * which marshals these arguments is open-coded in the species-specific transform.
+         * The two lists are of opaque objects, which you shouldn't do anything with besides
+         * reordering them into the output list.  (They are both mutable, to make editing
+         * easier.)  The imputed types of the args correspond to the transform's parameter
+         * list, while the imputed types of the fields correspond to the species field types.
+         * After code generation, this method may be called occasionally by error-checking code.
+         *
+         * @param transform the transform being implemented
+         * @param whichtm the index of that transform in the original list of transforms
+         * @param args a list of opaque objects representing the incoming transform arguments
+         * @param fields a list of opaque objects representing the field values of the receiver
+         * @param <X> the common element type of the various lists
+         * @return a new list
+         */
+        protected abstract <X> List<X> deriveTransformHelperArguments(MemberName transform, int whichtm,
+                                                                      List<X> args, List<X> fields);
+
+        /** Given a key, generate the name of the class which implements the species for that key.
+         * This algorithm must be stable.
+         *
+         * @return class name, which by default is {@code outer().topClass().getName() + "$Species_" + deriveTypeString(key)}
+         */
+        protected String deriveClassName() {
+            return outer().topClass().getName() + "$Species_" + deriveTypeString();
+        }
+
+        /**
+         * Default implementation collects basic type characters,
+         * plus possibly type names, if some types don't correspond
+         * to basic types.
+         *
+         * @return a string suitable for use in a class name
+         */
+        protected String deriveTypeString() {
+            List<Class<?>> types = fieldTypes();
+            StringBuilder buf = new StringBuilder();
+            StringBuilder end = new StringBuilder();
+            for (Class<?> type : types) {
+                BasicType basicType = BasicType.basicType(type);
+                if (basicType.basicTypeClass() == type) {
+                    buf.append(basicType.basicTypeChar());
+                } else {
+                    buf.append('V');
+                    end.append(classSig(type));
+                }
+            }
+            String typeString;
+            if (end.length() > 0) {
+                typeString = BytecodeName.toBytecodeName(buf.append("_").append(end).toString());
+            } else {
+                typeString = buf.toString();
+            }
+            return LambdaForm.shortenSignature(typeString);
+        }
+
+        /**
+         * Report what immediate super-class to use for the concrete class of this species.
+         * Normally this is {@code topClass}, but if that is an interface, the factory must override.
+         * The super-class must provide a constructor which takes the {@code baseConstructorType} arguments, if any.
+         * This hook also allows the code generator to use more than one canned supertype for species.
+         *
+         * @return the super-class of the class to be generated
+         */
+        protected Class<? extends T> deriveSuperClass() {
+            final Class<T> topc = topClass();
+            if (!topClassIsSuper) {
+                try {
+                    final Constructor<T> con = reflectConstructor(topc, baseConstructorType().parameterArray());
+                    if (!topc.isInterface() && !Modifier.isPrivate(con.getModifiers())) {
+                        topClassIsSuper = true;
+                    }
+                } catch (Exception|InternalError ex) {
+                    // fall through...
+                }
+                if (!topClassIsSuper) {
+                    throw newInternalError("must override if the top class cannot serve as a super class");
+                }
+            }
+            return topc;
+        }
+    }
+
+    protected abstract S newSpeciesData(K key);
+
+    protected K topSpeciesKey() {
+        return null;  // null means don't report a top species
+    }
+
+    /**
+     * Code generation support for instances.
+     * Subclasses can modify the behavior.
+     */
+    public class Factory {
+        /**
+         * Get a concrete subclass of the top class for a given combination of bound types.
+         *
+         * @param speciesData the species requiring the class, not yet linked
+         * @return a linked version of the same species
+         */
+        S loadSpecies(S speciesData) {
+            String className = speciesData.deriveClassName();
+            assert(className.indexOf('/') < 0) : className;
+            Class<?> salvage = null;
+            try {
+                salvage = BootLoader.loadClassOrNull(className);
+                if (TRACE_RESOLVE && salvage != null) {
+                    // Used by jlink species pregeneration plugin, see
+                    // jdk.tools.jlink.internal.plugins.GenerateJLIClassesPlugin
+                    System.out.println("[SPECIES_RESOLVE] " + className + " (salvaged)");
+                }
+            } catch (Error ex) {
+                if (TRACE_RESOLVE) {
+                    System.out.println("[SPECIES_FRESOLVE] " + className + " (Error) " + ex.getMessage());
+                }
+            }
+            final Class<? extends T> speciesCode;
+            if (salvage != null) {
+                speciesCode = salvage.asSubclass(topClass());
+                factory.linkSpeciesDataToCode(speciesData, speciesCode);
+                factory.linkCodeToSpeciesData(speciesCode, speciesData, true);
+            } else {
+                // Not pregenerated, generate the class
+                try {
+                    speciesCode = generateConcreteSpeciesCode(className, speciesData);
+                    if (TRACE_RESOLVE) {
+                        // Used by jlink species pregeneration plugin, see
+                        // jdk.tools.jlink.internal.plugins.GenerateJLIClassesPlugin
+                        System.out.println("[SPECIES_RESOLVE] " + className + " (generated)");
+                    }
+                    // This operation causes a lot of churn:
+                    linkSpeciesDataToCode(speciesData, speciesCode);
+                    // This operation commits the relation, but causes little churn:
+                    linkCodeToSpeciesData(speciesCode, speciesData, false);
+                } catch (Error ex) {
+                    if (TRACE_RESOLVE) {
+                        System.out.println("[SPECIES_RESOLVE] " + className + " (Error #2)" );
+                    }
+                    // We can get here if there is a race condition loading a class.
+                    // Or maybe we are out of resources.  Back out of the CHM.get and retry.
+                    throw ex;
+                }
+            }
+
+            if (!speciesData.isResolved()) {
+                throw newInternalError("bad species class linkage for " + className + ": " + speciesData);
+            }
+            assert(speciesData == factory.loadSpeciesDataFromCode(speciesCode));
+            return speciesData;
+        }
+
+        /**
+         * Generate a concrete subclass of the top class for a given combination of bound types.
+         *
+         * A concrete species subclass roughly matches the following schema:
+         *
+         * <pre>
+         * class Species_[[types]] extends [[T]] {
+         *     final [[S]] speciesData() { return ... }
+         *     static [[T]] make([[fields]]) { return ... }
+         *     [[fields]]
+         *     final [[T]] transform([[args]]) { return ... }
+         * }
+         * </pre>
+         *
+         * The {@code [[types]]} signature is precisely the key for the species.
+         *
+         * 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 #chooseFieldName}.
+         *
+         * For example, a concrete species for two references and one integral bound value
+         * has a shape like the following:
+         *
+         * <pre>
+         * class TopClass { ... private static
+         * final class Species_LLI extends TopClass {
+         *     final Object argL0;
+         *     final Object argL1;
+         *     final int argI2;
+         *     private Species_LLI(CT ctarg, ..., Object argL0, Object argL1, int argI2) {
+         *         super(ctarg, ...);
+         *         this.argL0 = argL0;
+         *         this.argL1 = argL1;
+         *         this.argI2 = argI2;
+         *     }
+         *     final SpeciesData speciesData() { return BMH_SPECIES; }
+         *     &#64;Stable static SpeciesData BMH_SPECIES; // injected afterwards
+         *     static TopClass make(CT ctarg, ..., Object argL0, Object argL1, int argI2) {
+         *         return new Species_LLI(ctarg, ..., argL0, argL1, argI2);
+         *     }
+         *     final TopClass copyWith(CT ctarg, ...) {
+         *         return new Species_LLI(ctarg, ..., argL0, argL1, argI2);
+         *     }
+         *     // two transforms, for the sake of illustration:
+         *     final TopClass copyWithExtendL(CT ctarg, ..., Object narg) {
+         *         return BMH_SPECIES.transform(L_TYPE).invokeBasic(ctarg, ..., argL0, argL1, argI2, narg);
+         *     }
+         *     final TopClass copyWithExtendI(CT ctarg, ..., int narg) {
+         *         return BMH_SPECIES.transform(I_TYPE).invokeBasic(ctarg, ..., argL0, argL1, argI2, narg);
+         *     }
+         * }
+         * </pre>
+         *
+         * @param className of the species
+         * @param speciesData what species we are generating
+         * @return the generated concrete TopClass class
+         */
+        Class<? extends T> generateConcreteSpeciesCode(String className, ClassSpecializer<T,K,S>.SpeciesData speciesData) {
+            byte[] classFile = generateConcreteSpeciesCodeFile(className, speciesData);
+
+            // load class
+            InvokerBytecodeGenerator.maybeDump(classBCName(className), classFile);
+            Class<?> speciesCode;
+
+            ClassLoader cl = topClass().getClassLoader();
+            ProtectionDomain pd = null;
+            if (cl != null) {
+                pd = AccessController.doPrivileged(
+                        new PrivilegedAction<>() {
+                            @Override
+                            public ProtectionDomain run() {
+                                return topClass().getProtectionDomain();
+                            }
+                        });
+            }
+            try {
+                speciesCode = UNSAFE.defineClass(className, classFile, 0, classFile.length, cl, pd);
+            } catch (Exception ex) {
+                throw newInternalError(ex);
+            }
+
+            return speciesCode.asSubclass(topClass());
+        }
+
+        // These are named like constants because there is only one per specialization scheme:
+        private final String SPECIES_DATA = classBCName(metaType);
+        private final String SPECIES_DATA_SIG = classSig(SPECIES_DATA);
+        private final String SPECIES_DATA_NAME = sdAccessor.getName();
+        private final int SPECIES_DATA_MODS = sdAccessor.getModifiers();
+        private final List<String> TRANSFORM_NAMES;  // derived from transformMethods
+        private final List<MethodType> TRANSFORM_TYPES;
+        private final List<Integer> TRANSFORM_MODS;
+        {
+            // Tear apart transformMethods to get the names, types, and modifiers.
+            List<String> tns = new ArrayList<>();
+            List<MethodType> tts = new ArrayList<>();
+            List<Integer> tms = new ArrayList<>();
+            for (int i = 0; i < transformMethods.size(); i++) {
+                MemberName tm = transformMethods.get(i);
+                tns.add(tm.getName());
+                final MethodType tt = tm.getMethodType();
+                tts.add(tt);
+                tms.add(tm.getModifiers());
+            }
+            TRANSFORM_NAMES = List.of(tns.toArray(new String[0]));
+            TRANSFORM_TYPES = List.of(tts.toArray(new MethodType[0]));
+            TRANSFORM_MODS = List.of(tms.toArray(new Integer[0]));
+        }
+        private static final int ACC_PPP = ACC_PUBLIC | ACC_PRIVATE | ACC_PROTECTED;
+
+        /*non-public*/ byte[] generateConcreteSpeciesCodeFile(String className0, ClassSpecializer<T,K,S>.SpeciesData speciesData) {
+            final String className = classBCName(className0);
+            final String superClassName = classBCName(speciesData.deriveSuperClass());
+
+            final ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
+            final int NOT_ACC_PUBLIC = 0;  // not ACC_PUBLIC
+            cw.visit(V1_6, NOT_ACC_PUBLIC + ACC_FINAL + ACC_SUPER, className, null, superClassName, null);
+
+            final String sourceFile = className.substring(className.lastIndexOf('.')+1);
+            cw.visitSource(sourceFile, null);
+
+            // emit static types and BMH_SPECIES fields
+            FieldVisitor fw = cw.visitField(NOT_ACC_PUBLIC + ACC_STATIC, sdFieldName, SPECIES_DATA_SIG, null, null);
+            fw.visitAnnotation(STABLE_SIG, true);
+            fw.visitEnd();
+
+            // handy holder for dealing with groups of typed values (ctor arguments and fields)
+            class Var {
+                final int index;
+                final String name;
+                final Class<?> type;
+                final String desc;
+                final BasicType basicType;
+                final int slotIndex;
+                Var(int index, int slotIndex) {
+                    this.index = index;
+                    this.slotIndex = slotIndex;
+                    name = null; type = null; desc = null;
+                    basicType = BasicType.V_TYPE;
+                }
+                Var(String name, Class<?> type, Var prev) {
+                    int slotIndex = prev.nextSlotIndex();
+                    int index = prev.nextIndex();
+                    if (name == null)  name = "x";
+                    if (name.endsWith("#"))
+                        name = name.substring(0, name.length()-1) + index;
+                    assert(!type.equals(void.class));
+                    String desc = classSig(type);
+                    BasicType basicType = BasicType.basicType(type);
+                    this.index = index;
+                    this.name = name;
+                    this.type = type;
+                    this.desc = desc;
+                    this.basicType = basicType;
+                    this.slotIndex = slotIndex;
+                }
+                Var lastOf(List<Var> vars) {
+                    int n = vars.size();
+                    return (n == 0 ? this : vars.get(n-1));
+                }
+                <X> List<Var> fromTypes(List<X> types) {
+                    Var prev = this;
+                    ArrayList<Var> result = new ArrayList<>(types.size());
+                    int i = 0;
+                    for (X x : types) {
+                        String vn = name;
+                        Class<?> vt;
+                        if (x instanceof Class) {
+                            vt = (Class<?>) x;
+                            // make the names friendlier if debugging
+                            assert((vn = vn + "_" + (i++)) != null);
+                        } else {
+                            @SuppressWarnings("unchecked")
+                            Var v = (Var) x;
+                            vn = v.name;
+                            vt = v.type;
+                        }
+                        prev = new Var(vn, vt, prev);
+                        result.add(prev);
+                    }
+                    return result;
+                }
+
+                int slotSize() { return basicType.basicTypeSlots(); }
+                int nextIndex() { return index + (slotSize() == 0 ? 0 : 1); }
+                int nextSlotIndex() { return slotIndex >= 0 ? slotIndex + slotSize() : slotIndex; }
+                boolean isInHeap() { return slotIndex < 0; }
+                void emitVarInstruction(int asmop, MethodVisitor mv) {
+                    if (asmop == ALOAD)
+                        asmop = typeLoadOp(basicType.basicTypeChar());
+                    else
+                        throw new AssertionError("bad op="+asmop+" for desc="+desc);
+                    mv.visitVarInsn(asmop, slotIndex);
+                }
+                public void emitFieldInsn(int asmop, MethodVisitor mv) {
+                    mv.visitFieldInsn(asmop, className, name, desc);
+                }
+            }
+
+            final Var NO_THIS = new Var(0, 0),
+                    AFTER_THIS = new Var(0, 1),
+                    IN_HEAP = new Var(0, -1);
+
+            // figure out the field types
+            final List<Class<?>> fieldTypes = speciesData.fieldTypes();
+            final List<Var> fields = new ArrayList<>(fieldTypes.size());
+            {
+                Var nextF = IN_HEAP;
+                for (Class<?> ft : fieldTypes) {
+                    String fn = chooseFieldName(ft, nextF.nextIndex());
+                    nextF = new Var(fn, ft, nextF);
+                    fields.add(nextF);
+                }
+            }
+
+            // emit bound argument fields
+            for (Var field : fields) {
+                cw.visitField(ACC_FINAL, field.name, field.desc, null, null).visitEnd();
+            }
+
+            MethodVisitor mv;
+
+            // emit implementation of speciesData()
+            mv = cw.visitMethod((SPECIES_DATA_MODS & ACC_PPP) + ACC_FINAL,
+                    SPECIES_DATA_NAME, "()" + SPECIES_DATA_SIG, null, null);
+            mv.visitCode();
+            mv.visitFieldInsn(GETSTATIC, className, sdFieldName, SPECIES_DATA_SIG);
+            mv.visitInsn(ARETURN);
+            mv.visitMaxs(0, 0);
+            mv.visitEnd();
+
+            // figure out the constructor arguments
+            MethodType superCtorType = ClassSpecializer.this.baseConstructorType();
+            MethodType thisCtorType = superCtorType.appendParameterTypes(fieldTypes);
+
+            // emit constructor
+            {
+                mv = cw.visitMethod(ACC_PRIVATE,
+                        "<init>", methodSig(thisCtorType), null, null);
+                mv.visitCode();
+                mv.visitVarInsn(ALOAD, 0); // this
+
+                final List<Var> ctorArgs = AFTER_THIS.fromTypes(superCtorType.parameterList());
+                for (Var ca : ctorArgs) {
+                    ca.emitVarInstruction(ALOAD, mv);
+                }
+
+                // super(ca...)
+                mv.visitMethodInsn(INVOKESPECIAL, superClassName,
+                        "<init>", methodSig(superCtorType), false);
+
+                // store down fields
+                Var lastFV = AFTER_THIS.lastOf(ctorArgs);
+                for (Var f : fields) {
+                    // this.argL1 = argL1
+                    mv.visitVarInsn(ALOAD, 0);  // this
+                    lastFV = new Var(f.name, f.type, lastFV);
+                    lastFV.emitVarInstruction(ALOAD, mv);
+                    f.emitFieldInsn(PUTFIELD, mv);
+                }
+
+                mv.visitInsn(RETURN);
+                mv.visitMaxs(0, 0);
+                mv.visitEnd();
+            }
+
+            // emit make()  ...factory method wrapping constructor
+            {
+                MethodType ftryType = thisCtorType.changeReturnType(topClass());
+                mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_STATIC,
+                        "make", methodSig(ftryType), null, null);
+                mv.visitCode();
+                // make instance
+                mv.visitTypeInsn(NEW, className);
+                mv.visitInsn(DUP);
+                // load factory method arguments:  ctarg... and arg...
+                for (Var v : NO_THIS.fromTypes(ftryType.parameterList())) {
+                    v.emitVarInstruction(ALOAD, mv);
+                }
+
+                // finally, invoke the constructor and return
+                mv.visitMethodInsn(INVOKESPECIAL, className,
+                        "<init>", methodSig(thisCtorType), false);
+                mv.visitInsn(ARETURN);
+                mv.visitMaxs(0, 0);
+                mv.visitEnd();
+            }
+
+            // For each transform, emit the customized override of the transform method.
+            // This method mixes together some incoming arguments (from the transform's
+            // static type signature) with the field types themselves, and passes
+            // the resulting mish-mosh of values to a method handle produced by
+            // the species itself.  (Typically this method handle is the factory
+            // method of this species or a related one.)
+            for (int whichtm = 0; whichtm < TRANSFORM_NAMES.size(); whichtm++) {
+                final String     TNAME = TRANSFORM_NAMES.get(whichtm);
+                final MethodType TTYPE = TRANSFORM_TYPES.get(whichtm);
+                final int        TMODS = TRANSFORM_MODS.get(whichtm);
+                mv = cw.visitMethod((TMODS & ACC_PPP) | ACC_FINAL,
+                        TNAME, TTYPE.toMethodDescriptorString(), null, E_THROWABLE);
+                mv.visitCode();
+                // return a call to the corresponding "transform helper", something like this:
+                //   MY_SPECIES.transformHelper(whichtm).invokeBasic(ctarg, ..., argL0, ..., xarg)
+                mv.visitFieldInsn(GETSTATIC, className,
+                        sdFieldName, SPECIES_DATA_SIG);
+                emitIntConstant(whichtm, mv);
+                mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA,
+                        "transformHelper", "(I)" + MH_SIG, false);
+
+                List<Var> targs = AFTER_THIS.fromTypes(TTYPE.parameterList());
+                List<Var> tfields = new ArrayList<>(fields);
+                // mix them up and load them for the transform helper:
+                List<Var> helperArgs = speciesData.deriveTransformHelperArguments(transformMethods.get(whichtm), whichtm, targs, tfields);
+                List<Class<?>> helperTypes = new ArrayList<>(helperArgs.size());
+                for (Var ha : helperArgs) {
+                    helperTypes.add(ha.basicType.basicTypeClass());
+                    if (ha.isInHeap()) {
+                        assert(tfields.contains(ha));
+                        mv.visitVarInsn(ALOAD, 0);
+                        ha.emitFieldInsn(GETFIELD, mv);
+                    } else {
+                        assert(targs.contains(ha));
+                        ha.emitVarInstruction(ALOAD, mv);
+                    }
+                }
+
+                // jump into the helper (which is probably a factory method)
+                final Class<?> rtype = TTYPE.returnType();
+                final BasicType rbt = BasicType.basicType(rtype);
+                MethodType invokeBasicType = MethodType.methodType(rbt.basicTypeClass(), helperTypes);
+                mv.visitMethodInsn(INVOKEVIRTUAL, MH,
+                        "invokeBasic", methodSig(invokeBasicType), false);
+                if (rbt == BasicType.L_TYPE) {
+                    mv.visitTypeInsn(CHECKCAST, classBCName(rtype));
+                    mv.visitInsn(ARETURN);
+                } else {
+                    throw newInternalError("NYI: transform of type "+rtype);
+                }
+                mv.visitMaxs(0, 0);
+                mv.visitEnd();
+            }
+
+            cw.visitEnd();
+
+            return cw.toByteArray();
+        }
+
+        private 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 newInternalError("unrecognized type " + t);
+            }
+        }
+
+        private void emitIntConstant(int con, MethodVisitor mv) {
+            if (ICONST_M1 - ICONST_0 <= con && con <= ICONST_5 - ICONST_0)
+                mv.visitInsn(ICONST_0 + con);
+            else if (con == (byte) con)
+                mv.visitIntInsn(BIPUSH, con);
+            else if (con == (short) con)
+                mv.visitIntInsn(SIPUSH, con);
+            else {
+                mv.visitLdcInsn(con);
+            }
+
+        }
+
+        //
+        // Getter MH generation.
+        //
+
+        private MethodHandle findGetter(Class<?> speciesCode, List<Class<?>> types, int index) {
+            Class<?> fieldType = types.get(index);
+            String fieldName = chooseFieldName(fieldType, index);
+            try {
+                return IMPL_LOOKUP.findGetter(speciesCode, fieldName, fieldType);
+            } catch (NoSuchFieldException | IllegalAccessException e) {
+                throw newInternalError(e);
+            }
+        }
+
+        private List<MethodHandle> findGetters(Class<?> speciesCode, List<Class<?>> types) {
+            MethodHandle[] mhs = new MethodHandle[types.size()];
+            for (int i = 0; i < mhs.length; ++i) {
+                mhs[i] = findGetter(speciesCode, types, i);
+                assert(mhs[i].internalMemberName().getDeclaringClass() == speciesCode);
+            }
+            return List.of(mhs);
+        }
+
+        private List<MethodHandle> findFactories(Class<? extends T> speciesCode, List<Class<?>> types) {
+            MethodHandle[] mhs = new MethodHandle[1];
+            mhs[0] = findFactory(speciesCode, types);
+            return List.of(mhs);
+        }
+
+        List<LambdaForm.NamedFunction> makeNominalGetters(List<Class<?>> types, List<MethodHandle> getters) {
+            LambdaForm.NamedFunction[] nfs = new LambdaForm.NamedFunction[types.size()];
+            for (int i = 0; i < nfs.length; ++i) {
+                nfs[i] = new LambdaForm.NamedFunction(getters.get(i));
+            }
+            return List.of(nfs);
+        }
+
+        //
+        // Auxiliary methods.
+        //
+
+        protected void linkSpeciesDataToCode(ClassSpecializer<T,K,S>.SpeciesData speciesData, Class<? extends T> speciesCode) {
+            speciesData.speciesCode = speciesCode.asSubclass(topClass);
+            final List<Class<?>> types = speciesData.fieldTypes;
+            speciesData.factories = this.findFactories(speciesCode, types);
+            speciesData.getters = this.findGetters(speciesCode, types);
+            speciesData.nominalGetters = this.makeNominalGetters(types, speciesData.getters);
+        }
+
+        private Field reflectSDField(Class<? extends T> speciesCode) {
+            final Field field = reflectField(speciesCode, sdFieldName);
+            assert(field.getType() == metaType);
+            assert(Modifier.isStatic(field.getModifiers()));
+            return field;
+        }
+
+        private S readSpeciesDataFromCode(Class<? extends T> speciesCode) {
+            try {
+                MemberName sdField = IMPL_LOOKUP.resolveOrFail(REF_getStatic, speciesCode, sdFieldName, metaType);
+                Object base = MethodHandleNatives.staticFieldBase(sdField);
+                long offset = MethodHandleNatives.staticFieldOffset(sdField);
+                UNSAFE.loadFence();
+                return metaType.cast(UNSAFE.getObject(base, offset));
+            } catch (Error err) {
+                throw err;
+            } catch (Exception ex) {
+                throw newInternalError("Failed to load speciesData from speciesCode: " + speciesCode.getName(), ex);
+            } catch (Throwable t) {
+                throw uncaughtException(t);
+            }
+        }
+
+        protected S loadSpeciesDataFromCode(Class<? extends T> speciesCode) {
+            if (speciesCode == topClass()) {
+                return topSpecies;
+            }
+            S result = readSpeciesDataFromCode(speciesCode);
+            if (result.outer() != ClassSpecializer.this) {
+                throw newInternalError("wrong class");
+            }
+            return result;
+        }
+
+        protected void linkCodeToSpeciesData(Class<? extends T> speciesCode, ClassSpecializer<T,K,S>.SpeciesData speciesData, boolean salvage) {
+            try {
+                assert(readSpeciesDataFromCode(speciesCode) == null ||
+                    (salvage && readSpeciesDataFromCode(speciesCode).equals(speciesData)));
+
+                MemberName sdField = IMPL_LOOKUP.resolveOrFail(REF_putStatic, speciesCode, sdFieldName, metaType);
+                Object base = MethodHandleNatives.staticFieldBase(sdField);
+                long offset = MethodHandleNatives.staticFieldOffset(sdField);
+                UNSAFE.storeFence();
+                UNSAFE.putObject(base, offset, speciesData);
+                UNSAFE.storeFence();
+            } catch (Error err) {
+                throw err;
+            } catch (Exception ex) {
+                throw newInternalError("Failed to link speciesData to speciesCode: " + speciesCode.getName(), ex);
+            } catch (Throwable t) {
+                throw uncaughtException(t);
+            }
+        }
+
+        /**
+         * Field names in concrete species classes adhere to this pattern:
+         * type + index, where type is a single character (L, I, J, F, D).
+         * The factory subclass can customize this.
+         * The name is purely cosmetic, since it applies to a private field.
+         */
+        protected String chooseFieldName(Class<?> type, int index) {
+            BasicType bt = BasicType.basicType(type);
+            return "" + bt.basicTypeChar() + index;
+        }
+
+        MethodHandle findFactory(Class<? extends T> speciesCode, List<Class<?>> types) {
+            final MethodType type = baseConstructorType().changeReturnType(topClass()).appendParameterTypes(types);
+            try {
+                return IMPL_LOOKUP.findStatic(speciesCode, "make", type);
+            } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | TypeNotPresentException e) {
+                throw newInternalError(e);
+            }
+        }
+    }
+
+    /** Hook that virtualizes the Factory class, allowing subclasses to extend it. */
+    protected Factory makeFactory() {
+        return new Factory();
+    }
+
+
+    // Other misc helpers:
+    private static final String MH = "java/lang/invoke/MethodHandle";
+    private static final String MH_SIG = "L" + MH + ";";
+    private static final String STABLE = "jdk/internal/vm/annotation/Stable";
+    private static final String STABLE_SIG = "L" + STABLE + ";";
+    private static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };
+    static {
+        assert(MH_SIG.equals(classSig(MethodHandle.class)));
+        assert(MH.equals(classBCName(MethodHandle.class)));
+    }
+
+    static String methodSig(MethodType mt) {
+        return mt.toMethodDescriptorString();
+    }
+    static String classSig(Class<?> cls) {
+        if (cls.isPrimitive() || cls.isArray())
+            return MethodType.methodType(cls).toMethodDescriptorString().substring(2);
+        return classSig(classBCName(cls));
+    }
+    static String classSig(String bcName) {
+        assert(bcName.indexOf('.') < 0);
+        assert(!bcName.endsWith(";"));
+        assert(!bcName.startsWith("["));
+        return "L" + bcName + ";";
+    }
+    static String classBCName(Class<?> cls) {
+        return classBCName(className(cls));
+    }
+    static String classBCName(String str) {
+        assert(str.indexOf('/') < 0) : str;
+        return str.replace('.', '/');
+    }
+    static String className(Class<?> cls) {
+        assert(!cls.isArray() && !cls.isPrimitive());
+        return cls.getName();
+    }
+}