src/java.base/share/classes/java/lang/invoke/BoundMethodHandle.java

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rev 17771 : 8184777: species logic for BoundMethodHandle doesn't scale, needs refactor

@@ -23,29 +23,22 @@
  * 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.ValueConversions;
-import sun.invoke.util.Wrapper;
 
-import java.lang.invoke.LambdaForm.NamedFunction;
-import java.lang.invoke.MethodHandles.Lookup;
-import java.lang.reflect.Field;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-import java.util.function.Function;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
 
 import static java.lang.invoke.LambdaForm.BasicType;
 import static java.lang.invoke.LambdaForm.BasicType.*;
-import static java.lang.invoke.MethodHandleStatics.*;
-import static jdk.internal.org.objectweb.asm.Opcodes.*;
+import static java.lang.invoke.MethodHandleStatics.newInternalError;
+import static java.lang.invoke.MethodHandleStatics.uncaughtException;
 
 /**
  * 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.

@@ -54,11 +47,11 @@
  */
 /*non-public*/ abstract class BoundMethodHandle extends MethodHandle {
 
     /*non-public*/ BoundMethodHandle(MethodType type, LambdaForm form) {
         super(type, form);
-        assert(speciesData() == speciesData(form));
+        assert(speciesData() == formSpeciesData(form));
     }
 
     //
     // BMH API and internals
     //

@@ -68,17 +61,17 @@
         try {
             switch (xtype) {
             case L_TYPE:
                 return bindSingle(type, form, x);  // Use known fast path.
             case I_TYPE:
-                return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(I_TYPE).constructor().invokeBasic(type, form, ValueConversions.widenSubword(x));
+                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(I_TYPE_NUM).factory().invokeBasic(type, form, ValueConversions.widenSubword(x));
             case J_TYPE:
-                return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(J_TYPE).constructor().invokeBasic(type, form, (long) x);
+                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(J_TYPE_NUM).factory().invokeBasic(type, form, (long) x);
             case F_TYPE:
-                return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(F_TYPE).constructor().invokeBasic(type, form, (float) x);
+                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(F_TYPE_NUM).factory().invokeBasic(type, form, (float) x);
             case D_TYPE:
-                return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(D_TYPE).constructor().invokeBasic(type, form, (double) x);
+                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(D_TYPE_NUM).factory().invokeBasic(type, form, (double) x);
             default : throw newInternalError("unexpected xtype: " + xtype);
             }
         } catch (Throwable t) {
             throw uncaughtException(t);
         }

@@ -96,10 +89,11 @@
     @Override // there is a default binder in the super class, for 'L' types only
     /*non-public*/
     BoundMethodHandle bindArgumentL(int pos, Object value) {
         return editor().bindArgumentL(this, pos, value);
     }
+
     /*non-public*/
     BoundMethodHandle bindArgumentI(int pos, int value) {
         return editor().bindArgumentI(this, pos, value);
     }
     /*non-public*/

@@ -112,11 +106,10 @@
     }
     /*non-public*/
     BoundMethodHandle bindArgumentD(int pos, double value) {
         return editor().bindArgumentD(this, pos, value);
     }
-
     @Override
     BoundMethodHandle rebind() {
         if (!tooComplex()) {
             return this;
         }

@@ -135,41 +128,42 @@
      * {@code lambda (bmh, arg*) { thismh = bmh[0]; invokeBasic(thismh, arg*) }}
      */
     static BoundMethodHandle makeReinvoker(MethodHandle target) {
         LambdaForm form = DelegatingMethodHandle.makeReinvokerForm(
                 target, MethodTypeForm.LF_REBIND,
-                Species_L.SPECIES_DATA, Species_L.SPECIES_DATA.getterFunction(0));
+                Species_L.BMH_SPECIES, Species_L.BMH_SPECIES.getterFunction(0));
         return Species_L.make(target.type(), form, target);
     }
 
     /**
-     * Return the {@link SpeciesData} instance representing this BMH species. All subclasses must provide a
+     * Return the {@link BMHSpecies} instance representing this BMH species. All subclasses must provide a
      * static field containing this value, and they must accordingly implement this method.
      */
-    /*non-public*/ abstract SpeciesData speciesData();
+    /*non-public*/ abstract BMHSpecies speciesData();
 
-    /*non-public*/ static SpeciesData speciesData(LambdaForm form) {
+    /*non-public*/ static BMHSpecies formSpeciesData(LambdaForm form) {
         Object c = form.names[0].constraint;
-        if (c instanceof SpeciesData)
-            return (SpeciesData) c;
+        if (c instanceof BMHSpecies) {
+            return (BMHSpecies) c;
+        }
         // if there is no BMH constraint, then use the null constraint
-        return SpeciesData.EMPTY;
+        return SPECIALIZER.topSpecies();
     }
 
     /**
      * Return the number of fields in this BMH.  Equivalent to speciesData().fieldCount().
      */
-    /*non-public*/ abstract int fieldCount();
+    /*non-public*/ final int fieldCount() { return speciesData().fieldCount(); }
 
     @Override
     Object internalProperties() {
         return "\n& BMH="+internalValues();
     }
 
     @Override
     final String internalValues() {
-        int count = speciesData().fieldCount();
+        int count = fieldCount();
         if (count == 1) {
             return "[" + arg(0) + "]";
         }
         StringBuilder sb = new StringBuilder("[");
         for (int i = 0; i < count; ++i) {

@@ -178,21 +172,21 @@
         return sb.append("\n]").toString();
     }
 
     /*non-public*/ final Object arg(int i) {
         try {
-            switch (speciesData().fieldType(i)) {
-            case L_TYPE: return          speciesData().getters[i].invokeBasic(this);
-            case I_TYPE: return (int)    speciesData().getters[i].invokeBasic(this);
-            case J_TYPE: return (long)   speciesData().getters[i].invokeBasic(this);
-            case F_TYPE: return (float)  speciesData().getters[i].invokeBasic(this);
-            case D_TYPE: return (double) speciesData().getters[i].invokeBasic(this);
+            switch (BasicType.basicType(speciesData().fieldTypes().get(i))) {
+            case L_TYPE: return          speciesData().getter(i).invokeBasic(this);
+            case I_TYPE: return (int)    speciesData().getter(i).invokeBasic(this);
+            case J_TYPE: return (long)   speciesData().getter(i).invokeBasic(this);
+            case F_TYPE: return (float)  speciesData().getter(i).invokeBasic(this);
+            case D_TYPE: return (double) speciesData().getter(i).invokeBasic(this);
             }
         } catch (Throwable ex) {
             throw uncaughtException(ex);
         }
-        throw new InternalError("unexpected type: " + speciesData().typeChars+"."+i);
+        throw new InternalError("unexpected type: " + speciesData().key()+"."+i);
     }
 
     //
     // cloning API
     //

@@ -214,228 +208,199 @@
         private Species_L(MethodType mt, LambdaForm lf, Object argL0) {
             super(mt, lf);
             this.argL0 = argL0;
         }
         @Override
-        /*non-public*/ SpeciesData speciesData() {
-            return SPECIES_DATA;
-        }
-        @Override
-        /*non-public*/ int fieldCount() {
-            return 1;
+        /*non-public*/ BMHSpecies speciesData() {
+            return BMH_SPECIES;
         }
-        /*non-public*/ static final SpeciesData SPECIES_DATA = new SpeciesData("L", Species_L.class);
+        /*non-public*/ static @Stable
+        BMHSpecies BMH_SPECIES;
         /*non-public*/ static BoundMethodHandle make(MethodType mt, LambdaForm lf, Object argL0) {
             return new Species_L(mt, lf, argL0);
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWith(MethodType mt, LambdaForm lf) {
             return new Species_L(mt, lf, argL0);
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg) {
             try {
-                return (BoundMethodHandle) SPECIES_DATA.extendWith(L_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
+                return (BoundMethodHandle) BMH_SPECIES.extendWith(L_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
             } catch (Throwable ex) {
                 throw uncaughtException(ex);
             }
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int narg) {
             try {
-                return (BoundMethodHandle) SPECIES_DATA.extendWith(I_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
+                return (BoundMethodHandle) BMH_SPECIES.extendWith(I_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
             } catch (Throwable ex) {
                 throw uncaughtException(ex);
             }
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long narg) {
             try {
-                return (BoundMethodHandle) SPECIES_DATA.extendWith(J_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
+                return (BoundMethodHandle) BMH_SPECIES.extendWith(J_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
             } catch (Throwable ex) {
                 throw uncaughtException(ex);
             }
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float narg) {
             try {
-                return (BoundMethodHandle) SPECIES_DATA.extendWith(F_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
+                return (BoundMethodHandle) BMH_SPECIES.extendWith(F_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
             } catch (Throwable ex) {
                 throw uncaughtException(ex);
             }
         }
         @Override
         /*non-public*/ final BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg) {
             try {
-                return (BoundMethodHandle) SPECIES_DATA.extendWith(D_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
+                return (BoundMethodHandle) BMH_SPECIES.extendWith(D_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
             } catch (Throwable ex) {
                 throw uncaughtException(ex);
             }
         }
     }
 
     //
     // BMH species meta-data
     //
 
-    /**
-     * Meta-data wrapper for concrete BMH types.
-     * Each BMH type corresponds to a given sequence of basic field types (LIJFD).
-     * The fields are immutable; their values are fully specified at object construction.
-     * Each BMH type supplies an array of getter functions which may be used in lambda forms.
-     * A BMH is constructed by cloning a shorter BMH and adding one or more new field values.
-     * The shortest possible BMH has zero fields; its class is SimpleMethodHandle.
-     * BMH species are not interrelated by subtyping, even though it would appear that
-     * a shorter BMH could serve as a supertype of a longer one which extends it.
-     */
-    static class SpeciesData {
-        private final String                             typeChars;
-        private final BasicType[]                        typeCodes;
-        private 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.
-        @Stable private final MethodHandle[]             constructor;
-        @Stable private final MethodHandle[]             getters;
-        @Stable private final NamedFunction[]            nominalGetters;
-        @Stable private final SpeciesData[]              extensions;
-
-        /*non-public*/ int fieldCount() {
-            return typeCodes.length;
-        }
-        /*non-public*/ BasicType fieldType(int i) {
-            return typeCodes[i];
-        }
-        /*non-public*/ char fieldTypeChar(int i) {
-            return typeChars.charAt(i);
-        }
-        String fieldSignature() {
-            return typeChars;
+    /*non-public*/
+    static final class BMHSpecies extends ClassSpecializer<BoundMethodHandle, String, BMHSpecies>.SpeciesData<BoundMethodHandle, String> {
+        // This array is filled in lazily, as new species come into being over time.
+        @Stable final private BMHSpecies[] extensions = new BMHSpecies[ARG_TYPE_LIMIT];
+
+        public BMHSpecies(Specializer outer, String key) {
+            outer.super(key);
         }
-        public Class<? extends BoundMethodHandle> fieldHolder() {
-            return clazz;
+
+        @Override
+        protected List<Class<?>> deriveFieldTypes(String key) {
+            ArrayList<Class<?>> types = new ArrayList<>(key.length());
+            for (int i = 0; i < key.length(); i++) {
+                types.add(basicType(key.charAt(i)).basicTypeClass());
         }
-        public String toString() {
-            return "SpeciesData<"+fieldSignature()+">";
+            return 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.
-         */
-        NamedFunction getterFunction(int i) {
-            NamedFunction nf = nominalGetters[i];
-            assert(nf.memberDeclaringClassOrNull() == fieldHolder());
-            assert(nf.returnType() == fieldType(i));
-            return nf;
+        @Override
+        protected String deriveTypeString() {
+            // (If/when we have to add nominal types, just inherit the more complex default.)
+            return key();
         }
 
-        NamedFunction[] getterFunctions() {
-            return nominalGetters;
+        @Override
+        protected MethodHandle deriveTransformHelper(Method transform, int whichtm) {
+            if (whichtm == Specializer.TN_COPY_NO_EXTEND)
+                return factory();
+            else if (whichtm < ARG_TYPE_LIMIT)
+                return extendWith((byte)whichtm).factory();
+            else
+                throw newInternalError("bad transform");
         }
 
-        MethodHandle[] getterHandles() { return getters; }
-
-        MethodHandle constructor() {
-            return constructor[0];
+        @Override
+        protected <X> List<X> deriveTransformHelperArguments(Method transform, int whichtm, List<X> args, List<X> fields) {
+            assert(verifyTHAargs(transform, whichtm, args, fields));
+            // The rule is really simple:  Keep the first two arguments
+            // the same, then put in the fields, then put any other argument.
+            args.addAll(2, fields);
+            return args;
         }
-
-        static final SpeciesData EMPTY = new SpeciesData("", BoundMethodHandle.class);
-
-        SpeciesData(String types, Class<? extends BoundMethodHandle> clazz) {
-            this.typeChars = types;
-            this.typeCodes = basicTypes(types);
-            this.clazz = clazz;
-            if (!INIT_DONE) {
-                this.constructor = new MethodHandle[1];  // only one ctor
-                this.getters = new MethodHandle[types.length()];
-                this.nominalGetters = new NamedFunction[types.length()];
+        private boolean verifyTHAargs(Method transform, int whichtm, List<?> args, List<?> fields) {
+            assert(transform == Specializer.BMH_TRANSFORMS.get(whichtm));
+            assert(args.size() == transform.getParameterCount());
+            assert(fields.size() == this.fieldCount());
+            final int MH_AND_LF = 2;
+            if (whichtm == Specializer.TN_COPY_NO_EXTEND) {
+                assert(transform.getParameterCount() == MH_AND_LF);
+            } else if (whichtm < ARG_TYPE_LIMIT) {
+                assert(transform.getParameterCount() == MH_AND_LF+1);
+                final BasicType type = basicType((byte) whichtm);
+                assert(transform.getParameterTypes()[MH_AND_LF] == type.basicTypeClass());
             } else {
-                this.constructor = Factory.makeCtors(clazz, types, null);
-                this.getters = Factory.makeGetters(clazz, types, null);
-                this.nominalGetters = Factory.makeNominalGetters(types, null, this.getters);
+                return false;
             }
-            this.extensions = new SpeciesData[ARG_TYPE_LIMIT];
+            return true;
         }
+        //private boolean verfiyTHA();
 
-        private void initForBootstrap() {
-            assert(!INIT_DONE);
-            if (constructor() == null) {
-                String types = typeChars;
-                CACHE.put(types, this);
-                Factory.makeCtors(clazz, types, this.constructor);
-                Factory.makeGetters(clazz, types, this.getters);
-                Factory.makeNominalGetters(types, this.nominalGetters, this.getters);
+        /*non-public*/ BMHSpecies extendWith(byte typeNum) {
+            BMHSpecies sd = extensions[typeNum];
+            if (sd != null)  return sd;
+            sd = SPECIALIZER.findSpecies(key() + BasicType.basicType(typeNum).basicTypeChar());
+            extensions[typeNum] = sd;
+            return sd;
             }
         }
 
-        private static final ConcurrentMap<String, SpeciesData> CACHE = new ConcurrentHashMap<>();
-        private static final boolean INIT_DONE;  // set after <clinit> finishes...
+    /*non-public*/
+    static final Specializer SPECIALIZER = new Specializer();
 
-        SpeciesData extendWith(byte type) {
-            return extendWith(BasicType.basicType(type));
+    /*non-public*/
+    static final class Specializer extends ClassSpecializer<BoundMethodHandle, String, BMHSpecies> {
+        private Specializer() {
+            super(  // Reified type parameters:
+                    BoundMethodHandle.class, String.class, BMHSpecies.class,
+                    // Principal constructor type:
+                    MethodType.methodType(void.class, MethodType.class, LambdaForm.class),
+                    // Required linkage between class and species:
+                    reflectMethod(BoundMethodHandle.class, "speciesData"),
+                    "BMH_SPECIES",
+                    BMH_TRANSFORMS);
         }
 
-        SpeciesData extendWith(BasicType type) {
-            int ord = type.ordinal();
-            SpeciesData d = extensions[ord];
-            if (d != null)  return d;
-            extensions[ord] = d = get(typeChars+type.basicTypeChar());
-            return d;
+        @Override
+        protected String topSpeciesKey() {
+            return "";
         }
 
-        private static SpeciesData get(String types) {
-            return CACHE.computeIfAbsent(types, new Function<String, SpeciesData>() {
                 @Override
-                public SpeciesData apply(String types) {
-                    Class<? extends BoundMethodHandle> bmhcl = Factory.getConcreteBMHClass(types);
-                    // SpeciesData instantiation may throw VirtualMachineError because of
-                    // code cache overflow...
-                    SpeciesData speciesData = new SpeciesData(types, bmhcl);
-                    // CHM.computeIfAbsent ensures only one SpeciesData will be set
-                    // successfully on the concrete BMH class if ever
-                    Factory.setSpeciesDataToConcreteBMHClass(bmhcl, speciesData);
-                    // the concrete BMH class is published via SpeciesData instance
-                    // returned here only after it's SPECIES_DATA field is set
-                    return speciesData;
-                }
-            });
+        protected String addFieldTypeToKey(String key, Class<?> type) {
+            BasicType bt = basicType(type);
+            if (type != bt.basicTypeClass())  throw newInternalError("must be basic-type");
+            Objects.requireNonNull(key);
+            return key + bt.basicTypeChar();
         }
 
-        /**
-         * This is to be called when assertions are enabled. It checks whether SpeciesData for all of the statically
-         * defined species subclasses of BoundMethodHandle has been added to the SpeciesData cache. See below in the
-         * static initializer for
-         */
-        static boolean speciesDataCachePopulated() {
-            Class<BoundMethodHandle> rootCls = BoundMethodHandle.class;
-            for (Class<?> c : rootCls.getDeclaredClasses()) {
-                if (rootCls.isAssignableFrom(c)) {
-                    final Class<? extends BoundMethodHandle> cbmh = c.asSubclass(BoundMethodHandle.class);
-                    SpeciesData d = Factory.getSpeciesDataFromConcreteBMHClass(cbmh);
-                    assert(d != null) : cbmh.getName();
-                    assert(d.clazz == cbmh);
-                    assert(CACHE.get(d.typeChars) == d);
-                }
-            }
-            return true;
+        @Override
+        protected List<Class<? extends BoundMethodHandle>> predeclaredSpeciesCode() {
+            List<Class<? extends BoundMethodHandle>> result = new ArrayList<>();
+            // pick up all nested classes (Species_L):
+            result.addAll(super.predeclaredSpeciesCode());
+            // pick up the special nullary version:
+            result.add(SimpleMethodHandle.class);
+            return result;
         }
 
-        static {
-            // Pre-fill the BMH species-data cache with EMPTY and all BMH's inner subclasses.
-            EMPTY.initForBootstrap();
-            Species_L.SPECIES_DATA.initForBootstrap();
-            // check that all static SpeciesData instances have been initialized
-            assert speciesDataCachePopulated();
-            // Note:  Do not simplify this, because INIT_DONE must not be
-            // a compile-time constant during bootstrapping.
-            INIT_DONE = Boolean.TRUE;
-        }
+        @Override
+        protected BMHSpecies newSpeciesData(String key) {
+            return new BMHSpecies(this, key);
     }
 
-    static SpeciesData getSpeciesData(String types) {
-        return SpeciesData.get(types);
+        static final List<Method> BMH_TRANSFORMS;
+        static final int TN_COPY_NO_EXTEND = V_TYPE_NUM;
+        static {
+            ArrayList<Method> result = new ArrayList<>();
+            final Class<BoundMethodHandle> BMH = BoundMethodHandle.class;
+            Class<?>[] params = { MethodType.class, LambdaForm.class, null };
+            // for each basic type T, note the transform BMH::copyWithExtendT(MT, LF, T)
+            for (BasicType type : BasicType.ARG_TYPES) {
+                final String tname = "copyWithExtend" + type.basicTypeChar();
+                params[params.length-1] = type.basicTypeClass();
+                result.add(ClassSpecializer.reflectMethod(BMH, tname, params));
+            }
+            // at the end add BMH::copyWith(MT, LF)
+            assert(result.size() == TN_COPY_NO_EXTEND);
+            result.add(ClassSpecializer.reflectMethod(BMH, "copyWith", params[0], params[1]));
+            // as it happens, there is one transform per BasicType including V_TYPE
+            assert(result.size() == TYPE_LIMIT);
+            BMH_TRANSFORMS = List.of(result.toArray(new Method[result.size()]));
     }
 
     /**
      * Generation of concrete BMH classes.
      *

@@ -446,432 +411,41 @@
      *
      * 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 {
-
-        private static final String JLO_SIG  = "Ljava/lang/Object;";
-        private static final String MH       = "java/lang/invoke/MethodHandle";
-        private static final String MH_SIG   = "L"+MH+";";
-        private static final String BMH      = "java/lang/invoke/BoundMethodHandle";
-        private static final String BMH_NAME = "java.lang.invoke.BoundMethodHandle";
-        private static final String BMH_SIG  = "L"+BMH+";";
-        private static final String SPECIES_DATA     = "java/lang/invoke/BoundMethodHandle$SpeciesData";
-        private static final String SPECIES_DATA_SIG = "L"+SPECIES_DATA+";";
-        private static final String STABLE_SIG       = "Ljdk/internal/vm/annotation/Stable;";
-
-        private static final String SPECIES_PREFIX_NAME = "Species_";
-        private static final String SPECIES_PREFIX_PATH = BMH + "$" + SPECIES_PREFIX_NAME;
-        private static final String SPECIES_CLASS_PREFIX = BMH_NAME + "$" + SPECIES_PREFIX_NAME;
-
-        private static final String BMHSPECIES_DATA_EWI_SIG = "(B)" + SPECIES_DATA_SIG;
-        private static final String MYSPECIES_DATA_SIG = "()" + SPECIES_DATA_SIG;
-        private static final String INT_SIG    = "()I";
-
-        private static final String SIG_INCIPIT = "(Ljava/lang/invoke/MethodType;Ljava/lang/invoke/LambdaForm;";
-
-        private static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };
-
-        private static final ConcurrentMap<String, Class<? extends BoundMethodHandle>> CLASS_CACHE = new ConcurrentHashMap<>();
-
-        /**
-         * Get a concrete subclass of BMH for a given combination of bound types.
-         *
-         * @param types the type signature, wherein reference types are erased to 'L'
-         * @return the concrete BMH class
-         */
-        static Class<? extends BoundMethodHandle> getConcreteBMHClass(String types) {
-            // CHM.computeIfAbsent ensures generateConcreteBMHClass is called
-            // only once per key.
-            return CLASS_CACHE.computeIfAbsent(
-                types, new Function<String, Class<? extends BoundMethodHandle>>() {
-                    @Override
-                    public Class<? extends BoundMethodHandle> apply(String types) {
-                        String shortTypes = LambdaForm.shortenSignature(types);
-                        String className = SPECIES_CLASS_PREFIX + shortTypes;
-                        Class<?> c = BootLoader.loadClassOrNull(className);
-                        if (TRACE_RESOLVE) {
-                            System.out.println("[BMH_RESOLVE] " + shortTypes +
-                                    (c != null ? " (success)" : " (fail)") );
-                        }
-                        if (c != null) {
-                            return c.asSubclass(BoundMethodHandle.class);
-                        } else {
-                            // Not pregenerated, generate the class
-                            return generateConcreteBMHClass(shortTypes, types);
-                        }
-                    }
-                });
-        }
-
-        /**
-         * 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;
-         *     private Species_LLI(MethodType mt, LambdaForm lf, Object argL0, Object argL1, int argI2) {
-         *         super(mt, lf);
-         *         this.argL0 = argL0;
-         *         this.argL1 = argL1;
-         *         this.argI2 = argI2;
-         *     }
-         *     final SpeciesData speciesData() { return SPECIES_DATA; }
-         *     final int fieldCount() { return 3; }
-         *     &#64;Stable static SpeciesData SPECIES_DATA; // injected afterwards
-         *     static BoundMethodHandle make(MethodType mt, LambdaForm lf, Object argL0, Object argL1, int argI2) {
-         *         return new Species_LLI(mt, lf, argL0, argL1, argI2);
-         *     }
-         *     final BoundMethodHandle copyWith(MethodType mt, LambdaForm lf) {
-         *         return new Species_LLI(mt, lf, argL0, argL1, argI2);
-         *     }
-         *     final BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg) {
-         *         return SPECIES_DATA.extendWith(L_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
-         *     }
-         *     final BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int narg) {
-         *         return SPECIES_DATA.extendWith(I_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
-         *     }
-         *     final BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long narg) {
-         *         return SPECIES_DATA.extendWith(J_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
-         *     }
-         *     final BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float narg) {
-         *         return SPECIES_DATA.extendWith(F_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
-         *     }
-         *     public final BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg) {
-         *         return SPECIES_DATA.extendWith(D_TYPE).constructor().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 shortTypes,
-                String types) {
-            final String className  = speciesInternalClassName(shortTypes);
-            byte[] classFile = generateConcreteBMHClassBytes(shortTypes, types, className);
-
-            // load class
-            InvokerBytecodeGenerator.maybeDump(className, classFile);
-            Class<? extends BoundMethodHandle> bmhClass =
-                UNSAFE.defineClass(className, classFile, 0, classFile.length,
-                                   BoundMethodHandle.class.getClassLoader(), null)
-                    .asSubclass(BoundMethodHandle.class);
-
-            return bmhClass;
-        }
-
-        static String speciesInternalClassName(String shortTypes) {
-            return SPECIES_PREFIX_PATH + shortTypes;
-        }
-
-        static byte[] generateConcreteBMHClassBytes(final String shortTypes,
-                final String types, final String className) {
-            final String sourceFile = SPECIES_PREFIX_NAME + shortTypes;
-
-            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, BMH, null);
-            cw.visitSource(sourceFile, null);
-
-            // emit static types and SPECIES_DATA fields
-            FieldVisitor fw = cw.visitField(NOT_ACC_PUBLIC + ACC_STATIC, "SPECIES_DATA", SPECIES_DATA_SIG, null, null);
-            fw.visitAnnotation(STABLE_SIG, true);
-            fw.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_PRIVATE, "<init>", makeSignature(types, true), null, null);
-            mv.visitCode();
-            mv.visitVarInsn(ALOAD, 0); // this
-            mv.visitVarInsn(ALOAD, 1); // type
-            mv.visitVarInsn(ALOAD, 2); // form
-
-            mv.visitMethodInsn(INVOKESPECIAL, BMH, "<init>", makeSignature("", true), false);
-
-            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 speciesData()
-            mv = cw.visitMethod(NOT_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 implementation of fieldCount()
-            mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "fieldCount", INT_SIG, null, null);
-            mv.visitCode();
-            int fc = types.length();
-            if (fc <= (ICONST_5 - ICONST_0)) {
-                mv.visitInsn(ICONST_0 + fc);
-            } else {
-                mv.visitIntInsn(SIPUSH, fc);
-            }
-            mv.visitInsn(IRETURN);
-            mv.visitMaxs(0, 0);
-            mv.visitEnd();
-            // emit make()  ...factory method wrapping constructor
-            mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_STATIC, "make", makeSignature(types, false), null, null);
-            mv.visitCode();
-            // make instance
-            mv.visitTypeInsn(NEW, className);
-            mv.visitInsn(DUP);
-            // load mt, lf
-            mv.visitVarInsn(ALOAD, 0);  // type
-            mv.visitVarInsn(ALOAD, 1);  // form
-            // load factory method arguments
-            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(typeLoadOp(t), j + 2); // parameters start at 3
-                if (t == 'J' || t == 'D') {
-                    ++j; // adjust argument register access
-                }
-            }
-
-            // finally, invoke the constructor and return
-            mv.visitMethodInsn(INVOKESPECIAL, className, "<init>", makeSignature(types, true), false);
-            mv.visitInsn(ARETURN);
-            mv.visitMaxs(0, 0);
-            mv.visitEnd();
-
-            // emit copyWith()
-            mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "copyWith", makeSignature("", false), null, null);
-            mv.visitCode();
-            // make instance
-            mv.visitTypeInsn(NEW, className);
-            mv.visitInsn(DUP);
-            // 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(INVOKESPECIAL, className, "<init>", makeSignature(types, true), false);
-            mv.visitInsn(ARETURN);
-            mv.visitMaxs(0, 0);
-            mv.visitEnd();
-
-            // for each type, emit copyWithExtendT()
-            for (BasicType type : BasicType.ARG_TYPES) {
-                int ord = type.ordinal();
-                char btChar = type.basicTypeChar();
-                mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "copyWithExtend" + btChar, makeSignature(String.valueOf(btChar), false), null, E_THROWABLE);
-                mv.visitCode();
-                // return SPECIES_DATA.extendWith(t).constructor().invokeBasic(mt, lf, argL0, ..., narg)
-                // obtain constructor
-                mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);
-                int iconstInsn = ICONST_0 + ord;
-                assert(iconstInsn <= ICONST_5);
-                mv.visitInsn(iconstInsn);
-                mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA, "extendWith", BMHSPECIES_DATA_EWI_SIG, false);
-                mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA, "constructor", "()" + MH_SIG, false);
-                // 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(btChar), 3);
-                // finally, invoke the constructor and return
-                mv.visitMethodInsn(INVOKEVIRTUAL, MH, "invokeBasic", makeSignature(types + btChar, false), false);
-                mv.visitInsn(ARETURN);
-                mv.visitMaxs(0, 0);
-                mv.visitEnd();
-            }
-
-            cw.visitEnd();
-
-            return cw.toByteArray();
-        }
-
-        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 newInternalError("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];
-            if (types.equals(""))  return mhs;  // hack for empty BMH species
-            mhs[0] = makeCbmhCtor(cbmh, types);
-            return mhs;
-        }
-
-        static NamedFunction[] makeNominalGetters(String types, NamedFunction[] nfs, MethodHandle[] getters) {
-            if (nfs == null)  nfs = new NamedFunction[types.length()];
-            for (int i = 0; i < nfs.length; ++i) {
-                nfs[i] = new NamedFunction(getters[i]);
-            }
-            return nfs;
-        }
-
-        //
-        // Auxiliary methods.
-        //
-
-        static SpeciesData getSpeciesDataFromConcreteBMHClass(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);
-            }
-        }
-
-        static void setSpeciesDataToConcreteBMHClass(Class<? extends BoundMethodHandle> cbmh, SpeciesData speciesData) {
-            try {
-                Field F_SPECIES_DATA = cbmh.getDeclaredField("SPECIES_DATA");
-                // ## FIXME: annotation parser can't create proxy classes until module system is fully initialzed
-                // assert F_SPECIES_DATA.getDeclaredAnnotation(Stable.class) != null;
-                F_SPECIES_DATA.set(null, speciesData);
-            } 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);
-            int len = types.length();
-            for (int i = 0; i < len; i++) {
-                buf.append(typeSig(types.charAt(i)));
-            }
-            return buf.append(')').append(ctor ? "V" : BMH_SIG).toString();
+        class Factory extends ClassSpecializer<BoundMethodHandle, String, BMHSpecies>.Factory {
+            @Override
+            protected String chooseFieldName(Class<?> type, int index) {
+                return "arg" + super.chooseFieldName(type, index);
         }
 
-        private static MethodType makeConstructorType(String types) {
-            int length = types.length();
-            Class<?> ptypes[] = new Class<?>[length + 2];
-            ptypes[0] = MethodType.class;
-            ptypes[1] = LambdaForm.class;
-            for (int i = 0; i < length; i++) {
-                ptypes[i + 2] = BasicType.basicType(types.charAt(i)).basicTypeClass();
+            @Override protected String loadSpeciesKeyFromPredefinedClass(Class<? extends BoundMethodHandle> speciesClass) {
+                if (speciesClass == SimpleMethodHandle.class)  return "";
+                assert(speciesClass.getEnclosingClass() == BoundMethodHandle.class);
+                String name = speciesClass.getSimpleName();
+                assert(name.startsWith("Species_"));
+                final String key = name.substring(name.indexOf('_') + 1);
+                return key;
             }
-            return MethodType.makeImpl(BoundMethodHandle.class, ptypes, true);
         }
 
-        static MethodHandle makeCbmhCtor(Class<? extends BoundMethodHandle> cbmh, String types) {
-            try {
-                return LOOKUP.findStatic(cbmh, "make", makeConstructorType(types));
-            } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | TypeNotPresentException e) {
-                throw newInternalError(e);
-            }
+        @Override
+        protected Factory makeFactory() {
+            return new Factory();
         }
     }
 
-    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;
-
-    private static final SpeciesData[] SPECIES_DATA_CACHE = new SpeciesData[6];
-    private static SpeciesData checkCache(int size, String types) {
+    private static final BMHSpecies[] SPECIES_DATA_CACHE = new BMHSpecies[6];
+    private static BMHSpecies checkCache(int size, String types) {
         int idx = size - 1;
-        SpeciesData data = SPECIES_DATA_CACHE[idx];
+        BMHSpecies data = SPECIES_DATA_CACHE[idx];
         if (data != null)  return data;
-        SPECIES_DATA_CACHE[idx] = data = getSpeciesData(types);
+        SPECIES_DATA_CACHE[idx] = data = SPECIALIZER.findSpecies(types);
         return data;
     }
-    static SpeciesData speciesData_L()      { return checkCache(1, "L"); }
-    static SpeciesData speciesData_LL()     { return checkCache(2, "LL"); }
-    static SpeciesData speciesData_LLL()    { return checkCache(3, "LLL"); }
-    static SpeciesData speciesData_LLLL()   { return checkCache(4, "LLLL"); }
-    static SpeciesData speciesData_LLLLL()  { return checkCache(5, "LLLLL"); }
+    static BMHSpecies speciesData_L()      { return checkCache(1, "L"); }
+    static BMHSpecies speciesData_LL()     { return checkCache(2, "LL"); }
+    static BMHSpecies speciesData_LLL()    { return checkCache(3, "LLL"); }
+    static BMHSpecies speciesData_LLLL()   { return checkCache(4, "LLLL"); }
+    static BMHSpecies speciesData_LLLLL()  { return checkCache(5, "LLLLL"); }
 }