1 /*
   2  * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang.invoke;
  27 
  28 import jdk.internal.loader.BootLoader;
  29 import jdk.internal.org.objectweb.asm.ClassWriter;
  30 import jdk.internal.org.objectweb.asm.FieldVisitor;
  31 import jdk.internal.org.objectweb.asm.MethodVisitor;
  32 import jdk.internal.vm.annotation.Stable;
  33 import sun.invoke.util.ValueConversions;
  34 import sun.invoke.util.Wrapper;
  35 
  36 import java.lang.invoke.LambdaForm.NamedFunction;
  37 import java.lang.invoke.MethodHandles.Lookup;
  38 import java.lang.reflect.Field;
  39 import java.util.concurrent.ConcurrentHashMap;
  40 import java.util.concurrent.ConcurrentMap;
  41 import java.util.function.Function;
  42 
  43 import static java.lang.invoke.LambdaForm.BasicType;
  44 import static java.lang.invoke.LambdaForm.BasicType.*;
  45 import static java.lang.invoke.MethodHandleStatics.*;
  46 import static jdk.internal.org.objectweb.asm.Opcodes.*;
  47 
  48 /**
  49  * The flavor of method handle which emulates an invoke instruction
  50  * on a predetermined argument.  The JVM dispatches to the correct method
  51  * when the handle is created, not when it is invoked.
  52  *
  53  * All bound arguments are encapsulated in dedicated species.
  54  */
  55 /*non-public*/ abstract class BoundMethodHandle extends MethodHandle {
  56 
  57     /*non-public*/ BoundMethodHandle(MethodType type, LambdaForm form) {
  58         super(type, form);
  59         assert(speciesData() == speciesData(form));
  60     }
  61 
  62     //
  63     // BMH API and internals
  64     //
  65 
  66     static BoundMethodHandle bindSingle(MethodType type, LambdaForm form, BasicType xtype, Object x) {
  67         // for some type signatures, there exist pre-defined concrete BMH classes
  68         try {
  69             switch (xtype) {
  70             case L_TYPE:
  71                 return bindSingle(type, form, x);  // Use known fast path.
  72             case I_TYPE:
  73                 return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(I_TYPE).constructor().invokeBasic(type, form, ValueConversions.widenSubword(x));
  74             case J_TYPE:
  75                 return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(J_TYPE).constructor().invokeBasic(type, form, (long) x);
  76             case F_TYPE:
  77                 return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(F_TYPE).constructor().invokeBasic(type, form, (float) x);
  78             case D_TYPE:
  79                 return (BoundMethodHandle) SpeciesData.EMPTY.extendWith(D_TYPE).constructor().invokeBasic(type, form, (double) x);
  80             default : throw newInternalError("unexpected xtype: " + xtype);
  81             }
  82         } catch (Throwable t) {
  83             throw uncaughtException(t);
  84         }
  85     }
  86 
  87     /*non-public*/
  88     LambdaFormEditor editor() {
  89         return form.editor();
  90     }
  91 
  92     static BoundMethodHandle bindSingle(MethodType type, LambdaForm form, Object x) {
  93         return Species_L.make(type, form, x);
  94     }
  95 
  96     @Override // there is a default binder in the super class, for 'L' types only
  97     /*non-public*/
  98     BoundMethodHandle bindArgumentL(int pos, Object value) {
  99         return editor().bindArgumentL(this, pos, value);
 100     }
 101     /*non-public*/
 102     BoundMethodHandle bindArgumentI(int pos, int value) {
 103         return editor().bindArgumentI(this, pos, value);
 104     }
 105     /*non-public*/
 106     BoundMethodHandle bindArgumentJ(int pos, long value) {
 107         return editor().bindArgumentJ(this, pos, value);
 108     }
 109     /*non-public*/
 110     BoundMethodHandle bindArgumentF(int pos, float value) {
 111         return editor().bindArgumentF(this, pos, value);
 112     }
 113     /*non-public*/
 114     BoundMethodHandle bindArgumentD(int pos, double value) {
 115         return editor().bindArgumentD(this, pos, value);
 116     }
 117     /*non-public*/
 118     BoundMethodHandle bindArgumentQ(int pos, Object value, MethodHandle unbox) {
 119         return editor().bindArgumentQ(this, pos, value, unbox);
 120     }
 121     @Override
 122     BoundMethodHandle rebind() {
 123         if (!tooComplex()) {
 124             return this;
 125         }
 126         return makeReinvoker(this);
 127     }
 128 
 129     private boolean tooComplex() {
 130         return (fieldCount() > FIELD_COUNT_THRESHOLD ||
 131                 form.expressionCount() > FORM_EXPRESSION_THRESHOLD);
 132     }
 133     private static final int FIELD_COUNT_THRESHOLD = 12;      // largest convenient BMH field count
 134     private static final int FORM_EXPRESSION_THRESHOLD = 24;  // largest convenient BMH expression count
 135 
 136     /**
 137      * A reinvoker MH has this form:
 138      * {@code lambda (bmh, arg*) { thismh = bmh[0]; invokeBasic(thismh, arg*) }}
 139      */
 140     static BoundMethodHandle makeReinvoker(MethodHandle target) {
 141         LambdaForm form = DelegatingMethodHandle.makeReinvokerForm(
 142                 target, MethodTypeForm.LF_REBIND,
 143                 Species_L.SPECIES_DATA, Species_L.SPECIES_DATA.getterFunction(0));
 144         return Species_L.make(target.type(), form, target);
 145     }
 146 
 147     /**
 148      * Return the {@link SpeciesData} instance representing this BMH species. All subclasses must provide a
 149      * static field containing this value, and they must accordingly implement this method.
 150      */
 151     /*non-public*/ abstract SpeciesData speciesData();
 152 
 153     /*non-public*/ static SpeciesData speciesData(LambdaForm form) {
 154         Object c = form.names[0].constraint;
 155         if (c instanceof SpeciesData)
 156             return (SpeciesData) c;
 157         // if there is no BMH constraint, then use the null constraint
 158         return SpeciesData.EMPTY;
 159     }
 160 
 161     /**
 162      * Return the number of fields in this BMH.  Equivalent to speciesData().fieldCount().
 163      */
 164     /*non-public*/ abstract int fieldCount();
 165 
 166     @Override
 167     Object internalProperties() {
 168         return "\n& BMH="+internalValues();
 169     }
 170 
 171     @Override
 172     final String internalValues() {
 173         int count = speciesData().fieldCount();
 174         if (count == 1) {
 175             return "[" + arg(0) + "]";
 176         }
 177         StringBuilder sb = new StringBuilder("[");
 178         for (int i = 0; i < count; ++i) {
 179             sb.append("\n  ").append(i).append(": ( ").append(arg(i)).append(" )");
 180         }
 181         return sb.append("\n]").toString();
 182     }
 183 
 184     /*non-public*/ final Object arg(int i) {
 185         try {
 186             switch (speciesData().fieldType(i)) {
 187             case L_TYPE: return          speciesData().getters[i].invokeBasic(this);
 188             case I_TYPE: return (int)    speciesData().getters[i].invokeBasic(this);
 189             case J_TYPE: return (long)   speciesData().getters[i].invokeBasic(this);
 190             case F_TYPE: return (float)  speciesData().getters[i].invokeBasic(this);
 191             case D_TYPE: return (double) speciesData().getters[i].invokeBasic(this);
 192             }
 193         } catch (Throwable ex) {
 194             throw uncaughtException(ex);
 195         }
 196         throw new InternalError("unexpected type: " + speciesData().typeChars+"."+i);
 197     }
 198 
 199     //
 200     // cloning API
 201     //
 202 
 203     /*non-public*/ abstract BoundMethodHandle copyWith(MethodType mt, LambdaForm lf);
 204     /*non-public*/ abstract BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg);
 205     /*non-public*/ abstract BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int    narg);
 206     /*non-public*/ abstract BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long   narg);
 207     /*non-public*/ abstract BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float  narg);
 208     /*non-public*/ abstract BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg);
 209 
 210     //
 211     // concrete BMH classes required to close bootstrap loops
 212     //
 213 
 214     private  // make it private to force users to access the enclosing class first
 215     static final class Species_L extends BoundMethodHandle {
 216         final Object argL0;
 217         private Species_L(MethodType mt, LambdaForm lf, Object argL0) {
 218             super(mt, lf);
 219             this.argL0 = argL0;
 220         }
 221         @Override
 222         /*non-public*/ SpeciesData speciesData() {
 223             return SPECIES_DATA;
 224         }
 225         @Override
 226         /*non-public*/ int fieldCount() {
 227             return 1;
 228         }
 229         /*non-public*/ static final SpeciesData SPECIES_DATA = new SpeciesData("L", Species_L.class);
 230         /*non-public*/ static BoundMethodHandle make(MethodType mt, LambdaForm lf, Object argL0) {
 231             return new Species_L(mt, lf, argL0);
 232         }
 233         @Override
 234         /*non-public*/ final BoundMethodHandle copyWith(MethodType mt, LambdaForm lf) {
 235             return new Species_L(mt, lf, argL0);
 236         }
 237         @Override
 238         /*non-public*/ final BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg) {
 239             try {
 240                 return (BoundMethodHandle) SPECIES_DATA.extendWith(L_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
 241             } catch (Throwable ex) {
 242                 throw uncaughtException(ex);
 243             }
 244         }
 245         @Override
 246         /*non-public*/ final BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int narg) {
 247             try {
 248                 return (BoundMethodHandle) SPECIES_DATA.extendWith(I_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
 249             } catch (Throwable ex) {
 250                 throw uncaughtException(ex);
 251             }
 252         }
 253         @Override
 254         /*non-public*/ final BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long narg) {
 255             try {
 256                 return (BoundMethodHandle) SPECIES_DATA.extendWith(J_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
 257             } catch (Throwable ex) {
 258                 throw uncaughtException(ex);
 259             }
 260         }
 261         @Override
 262         /*non-public*/ final BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float narg) {
 263             try {
 264                 return (BoundMethodHandle) SPECIES_DATA.extendWith(F_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
 265             } catch (Throwable ex) {
 266                 throw uncaughtException(ex);
 267             }
 268         }
 269         @Override
 270         /*non-public*/ final BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg) {
 271             try {
 272                 return (BoundMethodHandle) SPECIES_DATA.extendWith(D_TYPE).constructor().invokeBasic(mt, lf, argL0, narg);
 273             } catch (Throwable ex) {
 274                 throw uncaughtException(ex);
 275             }
 276         }
 277     }
 278 
 279     //
 280     // BMH species meta-data
 281     //
 282 
 283     /**
 284      * Meta-data wrapper for concrete BMH types.
 285      * Each BMH type corresponds to a given sequence of basic field types (LIJFD).
 286      * The fields are immutable; their values are fully specified at object construction.
 287      * Each BMH type supplies an array of getter functions which may be used in lambda forms.
 288      * A BMH is constructed by cloning a shorter BMH and adding one or more new field values.
 289      * The shortest possible BMH has zero fields; its class is SimpleMethodHandle.
 290      * BMH species are not interrelated by subtyping, even though it would appear that
 291      * a shorter BMH could serve as a supertype of a longer one which extends it.
 292      */
 293     static class SpeciesData {
 294         private final String                             typeChars;
 295         private final BasicType[]                        typeCodes;
 296         private final Class<? extends BoundMethodHandle> clazz;
 297         // Bootstrapping requires circular relations MH -> BMH -> SpeciesData -> MH
 298         // Therefore, we need a non-final link in the chain.  Use array elements.
 299         @Stable private final MethodHandle[]             constructor;
 300         @Stable private final MethodHandle[]             getters;
 301         @Stable private final NamedFunction[]            nominalGetters;
 302         @Stable private final SpeciesData[]              extensions;
 303 
 304         /*non-public*/ int fieldCount() {
 305             return typeCodes.length;
 306         }
 307         /*non-public*/ BasicType fieldType(int i) {
 308             return typeCodes[i];
 309         }
 310         /*non-public*/ char fieldTypeChar(int i) {
 311             return typeChars.charAt(i);
 312         }
 313         String fieldSignature() {
 314             return typeChars;
 315         }
 316         public Class<? extends BoundMethodHandle> fieldHolder() {
 317             return clazz;
 318         }
 319         public String toString() {
 320             return "SpeciesData<"+fieldSignature()+">";
 321         }
 322 
 323         /**
 324          * Return a {@link LambdaForm.Name} containing a {@link LambdaForm.NamedFunction} that
 325          * represents a MH bound to a generic invoker, which in turn forwards to the corresponding
 326          * getter.
 327          */
 328         NamedFunction getterFunction(int i) {
 329             NamedFunction nf = nominalGetters[i];
 330             assert(nf.memberDeclaringClassOrNull() == fieldHolder());
 331             assert(nf.returnType() == fieldType(i));
 332             return nf;
 333         }
 334 
 335         NamedFunction[] getterFunctions() {
 336             return nominalGetters;
 337         }
 338 
 339         MethodHandle[] getterHandles() { return getters; }
 340 
 341         MethodHandle constructor() {
 342             return constructor[0];
 343         }
 344 
 345         static final SpeciesData EMPTY = new SpeciesData("", BoundMethodHandle.class);
 346 
 347         SpeciesData(String types, Class<? extends BoundMethodHandle> clazz) {
 348             this.typeChars = types;
 349             this.typeCodes = basicTypes(types);
 350             this.clazz = clazz;
 351             if (!INIT_DONE) {
 352                 this.constructor = new MethodHandle[1];  // only one ctor
 353                 this.getters = new MethodHandle[types.length()];
 354                 this.nominalGetters = new NamedFunction[types.length()];
 355             } else {
 356                 this.constructor = Factory.makeCtors(clazz, types, null);
 357                 this.getters = Factory.makeGetters(clazz, types, null);
 358                 this.nominalGetters = Factory.makeNominalGetters(types, null, this.getters);
 359             }
 360             this.extensions = new SpeciesData[ARG_TYPE_LIMIT];
 361         }
 362 
 363         private void initForBootstrap() {
 364             assert(!INIT_DONE);
 365             if (constructor() == null) {
 366                 String types = typeChars;
 367                 CACHE.put(types, this);
 368                 Factory.makeCtors(clazz, types, this.constructor);
 369                 Factory.makeGetters(clazz, types, this.getters);
 370                 Factory.makeNominalGetters(types, this.nominalGetters, this.getters);
 371             }
 372         }
 373 
 374         private static final ConcurrentMap<String, SpeciesData> CACHE = new ConcurrentHashMap<>();
 375         private static final boolean INIT_DONE;  // set after <clinit> finishes...
 376 
 377         SpeciesData extendWith(byte type) {
 378             return extendWith(BasicType.basicType(type));
 379         }
 380 
 381         SpeciesData extendWith(BasicType type) {
 382             int ord = type.ordinal();
 383             SpeciesData d = extensions[ord];
 384             if (d != null)  return d;
 385             extensions[ord] = d = get(typeChars+type.basicTypeChar());
 386             return d;
 387         }
 388 
 389         private static SpeciesData get(String types) {
 390             return CACHE.computeIfAbsent(types, new Function<String, SpeciesData>() {
 391                 @Override
 392                 public SpeciesData apply(String types) {
 393                     Class<? extends BoundMethodHandle> bmhcl = Factory.getConcreteBMHClass(types);
 394                     // SpeciesData instantiation may throw VirtualMachineError because of
 395                     // code cache overflow...
 396                     SpeciesData speciesData = new SpeciesData(types, bmhcl);
 397                     // CHM.computeIfAbsent ensures only one SpeciesData will be set
 398                     // successfully on the concrete BMH class if ever
 399                     Factory.setSpeciesDataToConcreteBMHClass(bmhcl, speciesData);
 400                     // the concrete BMH class is published via SpeciesData instance
 401                     // returned here only after it's SPECIES_DATA field is set
 402                     return speciesData;
 403                 }
 404             });
 405         }
 406 
 407         /**
 408          * This is to be called when assertions are enabled. It checks whether SpeciesData for all of the statically
 409          * defined species subclasses of BoundMethodHandle has been added to the SpeciesData cache. See below in the
 410          * static initializer for
 411          */
 412         static boolean speciesDataCachePopulated() {
 413             Class<BoundMethodHandle> rootCls = BoundMethodHandle.class;
 414             for (Class<?> c : rootCls.getDeclaredClasses()) {
 415                 if (rootCls.isAssignableFrom(c)) {
 416                     final Class<? extends BoundMethodHandle> cbmh = c.asSubclass(BoundMethodHandle.class);
 417                     SpeciesData d = Factory.getSpeciesDataFromConcreteBMHClass(cbmh);
 418                     assert(d != null) : cbmh.getName();
 419                     assert(d.clazz == cbmh);
 420                     assert(CACHE.get(d.typeChars) == d);
 421                 }
 422             }
 423             return true;
 424         }
 425 
 426         static {
 427             // Pre-fill the BMH species-data cache with EMPTY and all BMH's inner subclasses.
 428             EMPTY.initForBootstrap();
 429             Species_L.SPECIES_DATA.initForBootstrap();
 430             // check that all static SpeciesData instances have been initialized
 431             assert speciesDataCachePopulated();
 432             // Note:  Do not simplify this, because INIT_DONE must not be
 433             // a compile-time constant during bootstrapping.
 434             INIT_DONE = Boolean.TRUE;
 435         }
 436     }
 437 
 438     static SpeciesData getSpeciesData(String types) {
 439         return SpeciesData.get(types);
 440     }
 441 
 442     /**
 443      * Generation of concrete BMH classes.
 444      *
 445      * A concrete BMH species is fit for binding a number of values adhering to a
 446      * given type pattern. Reference types are erased.
 447      *
 448      * BMH species are cached by type pattern.
 449      *
 450      * A BMH species has a number of fields with the concrete (possibly erased) types of
 451      * bound values. Setters are provided as an API in BMH. Getters are exposed as MHs,
 452      * which can be included as names in lambda forms.
 453      */
 454     static class Factory {
 455 
 456         private static final String JLO_SIG  = "Ljava/lang/Object;";
 457         private static final String MH       = "java/lang/invoke/MethodHandle";
 458         private static final String MH_SIG   = "L"+MH+";";
 459         private static final String BMH      = "java/lang/invoke/BoundMethodHandle";
 460         private static final String BMH_NAME = "java.lang.invoke.BoundMethodHandle";
 461         private static final String BMH_SIG  = "L"+BMH+";";
 462         private static final String SPECIES_DATA     = "java/lang/invoke/BoundMethodHandle$SpeciesData";
 463         private static final String SPECIES_DATA_SIG = "L"+SPECIES_DATA+";";
 464         private static final String STABLE_SIG       = "Ljdk/internal/vm/annotation/Stable;";
 465 
 466         private static final String SPECIES_PREFIX_NAME = "Species_";
 467         private static final String SPECIES_PREFIX_PATH = BMH + "$" + SPECIES_PREFIX_NAME;
 468         private static final String SPECIES_CLASS_PREFIX = BMH_NAME + "$" + SPECIES_PREFIX_NAME;
 469 
 470         private static final String BMHSPECIES_DATA_EWI_SIG = "(B)" + SPECIES_DATA_SIG;
 471         private static final String MYSPECIES_DATA_SIG = "()" + SPECIES_DATA_SIG;
 472         private static final String INT_SIG    = "()I";
 473 
 474         private static final String SIG_INCIPIT = "(Ljava/lang/invoke/MethodType;Ljava/lang/invoke/LambdaForm;";
 475 
 476         private static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };
 477 
 478         private static final ConcurrentMap<String, Class<? extends BoundMethodHandle>> CLASS_CACHE = new ConcurrentHashMap<>();
 479 
 480         /**
 481          * Get a concrete subclass of BMH for a given combination of bound types.
 482          *
 483          * @param types the type signature, wherein reference types are erased to 'L'
 484          * @return the concrete BMH class
 485          */
 486         static Class<? extends BoundMethodHandle> getConcreteBMHClass(String types) {
 487             // CHM.computeIfAbsent ensures generateConcreteBMHClass is called
 488             // only once per key.
 489             return CLASS_CACHE.computeIfAbsent(
 490                 types, new Function<String, Class<? extends BoundMethodHandle>>() {
 491                     @Override
 492                     public Class<? extends BoundMethodHandle> apply(String types) {
 493                         String shortTypes = LambdaForm.shortenSignature(types);
 494                         String className = SPECIES_CLASS_PREFIX + shortTypes;
 495                         Class<?> c = BootLoader.loadClassOrNull(className);
 496                         if (TRACE_RESOLVE) {
 497                             System.out.println("[BMH_RESOLVE] " + shortTypes +
 498                                     (c != null ? " (success)" : " (fail)") );
 499                         }
 500                         if (c != null) {
 501                             return c.asSubclass(BoundMethodHandle.class);
 502                         } else {
 503                             // Not pregenerated, generate the class
 504                             return generateConcreteBMHClass(shortTypes, types);
 505                         }
 506                     }
 507                 });
 508         }
 509 
 510         /**
 511          * Generate a concrete subclass of BMH for a given combination of bound types.
 512          *
 513          * A concrete BMH species adheres to the following schema:
 514          *
 515          * <pre>
 516          * class Species_[[types]] extends BoundMethodHandle {
 517          *     [[fields]]
 518          *     final SpeciesData speciesData() { return SpeciesData.get("[[types]]"); }
 519          * }
 520          * </pre>
 521          *
 522          * The {@code [[types]]} signature is precisely the string that is passed to this
 523          * method.
 524          *
 525          * The {@code [[fields]]} section consists of one field definition per character in
 526          * the type signature, adhering to the naming schema described in the definition of
 527          * {@link #makeFieldName}.
 528          *
 529          * For example, a concrete BMH species for two reference and one integral bound values
 530          * would have the following shape:
 531          *
 532          * <pre>
 533          * class BoundMethodHandle { ... private static
 534          * final class Species_LLI extends BoundMethodHandle {
 535          *     final Object argL0;
 536          *     final Object argL1;
 537          *     final int argI2;
 538          *     private Species_LLI(MethodType mt, LambdaForm lf, Object argL0, Object argL1, int argI2) {
 539          *         super(mt, lf);
 540          *         this.argL0 = argL0;
 541          *         this.argL1 = argL1;
 542          *         this.argI2 = argI2;
 543          *     }
 544          *     final SpeciesData speciesData() { return SPECIES_DATA; }
 545          *     final int fieldCount() { return 3; }
 546          *     @Stable static SpeciesData SPECIES_DATA; // injected afterwards
 547          *     static BoundMethodHandle make(MethodType mt, LambdaForm lf, Object argL0, Object argL1, int argI2) {
 548          *         return new Species_LLI(mt, lf, argL0, argL1, argI2);
 549          *     }
 550          *     final BoundMethodHandle copyWith(MethodType mt, LambdaForm lf) {
 551          *         return new Species_LLI(mt, lf, argL0, argL1, argI2);
 552          *     }
 553          *     final BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg) {
 554          *         return SPECIES_DATA.extendWith(L_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
 555          *     }
 556          *     final BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int narg) {
 557          *         return SPECIES_DATA.extendWith(I_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
 558          *     }
 559          *     final BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long narg) {
 560          *         return SPECIES_DATA.extendWith(J_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
 561          *     }
 562          *     final BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float narg) {
 563          *         return SPECIES_DATA.extendWith(F_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
 564          *     }
 565          *     public final BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg) {
 566          *         return SPECIES_DATA.extendWith(D_TYPE).constructor().invokeBasic(mt, lf, argL0, argL1, argI2, narg);
 567          *     }
 568          * }
 569          * </pre>
 570          *
 571          * @param types the type signature, wherein reference types are erased to 'L'
 572          * @return the generated concrete BMH class
 573          */
 574         static Class<? extends BoundMethodHandle> generateConcreteBMHClass(String shortTypes,
 575                 String types) {
 576             final String className  = speciesInternalClassName(shortTypes);
 577             byte[] classFile = generateConcreteBMHClassBytes(shortTypes, types, className);
 578 
 579             // load class
 580             InvokerBytecodeGenerator.maybeDump(className, classFile);
 581             Class<? extends BoundMethodHandle> bmhClass =
 582                 UNSAFE.defineClass(className, classFile, 0, classFile.length,
 583                                    BoundMethodHandle.class.getClassLoader(), null)
 584                     .asSubclass(BoundMethodHandle.class);
 585 
 586             return bmhClass;
 587         }
 588 
 589         static String speciesInternalClassName(String shortTypes) {
 590             return SPECIES_PREFIX_PATH + shortTypes;
 591         }
 592 
 593         static byte[] generateConcreteBMHClassBytes(final String shortTypes,
 594                 final String types, final String className) {
 595             final String sourceFile = SPECIES_PREFIX_NAME + shortTypes;
 596 
 597             final ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
 598             final int NOT_ACC_PUBLIC = 0;  // not ACC_PUBLIC
 599             cw.visit(V1_6, NOT_ACC_PUBLIC + ACC_FINAL + ACC_SUPER, className, null, BMH, null);
 600             cw.visitSource(sourceFile, null);
 601 
 602             // emit static types and SPECIES_DATA fields
 603             FieldVisitor fw = cw.visitField(NOT_ACC_PUBLIC + ACC_STATIC, "SPECIES_DATA", SPECIES_DATA_SIG, null, null);
 604             fw.visitAnnotation(STABLE_SIG, true);
 605             fw.visitEnd();
 606 
 607             // emit bound argument fields
 608             for (int i = 0; i < types.length(); ++i) {
 609                 final char t = types.charAt(i);
 610                 final String fieldName = makeFieldName(types, i);
 611                 final String fieldDesc = t == 'L' ? JLO_SIG : String.valueOf(t);
 612                 cw.visitField(ACC_FINAL, fieldName, fieldDesc, null, null).visitEnd();
 613             }
 614 
 615             MethodVisitor mv;
 616 
 617             // emit constructor
 618             mv = cw.visitMethod(ACC_PRIVATE, "<init>", makeSignature(types, true), null, null);
 619             mv.visitCode();
 620             mv.visitVarInsn(ALOAD, 0); // this
 621             mv.visitVarInsn(ALOAD, 1); // type
 622             mv.visitVarInsn(ALOAD, 2); // form
 623 
 624             mv.visitMethodInsn(INVOKESPECIAL, BMH, "<init>", makeSignature("", true), false);
 625 
 626             for (int i = 0, j = 0; i < types.length(); ++i, ++j) {
 627                 // i counts the arguments, j counts corresponding argument slots
 628                 char t = types.charAt(i);
 629                 mv.visitVarInsn(ALOAD, 0);
 630                 mv.visitVarInsn(typeLoadOp(t), j + 3); // parameters start at 3
 631                 mv.visitFieldInsn(PUTFIELD, className, makeFieldName(types, i), typeSig(t));
 632                 if (t == 'J' || t == 'D') {
 633                     ++j; // adjust argument register access
 634                 }
 635             }
 636 
 637             mv.visitInsn(RETURN);
 638             mv.visitMaxs(0, 0);
 639             mv.visitEnd();
 640 
 641             // emit implementation of speciesData()
 642             mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "speciesData", MYSPECIES_DATA_SIG, null, null);
 643             mv.visitCode();
 644             mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);
 645             mv.visitInsn(ARETURN);
 646             mv.visitMaxs(0, 0);
 647             mv.visitEnd();
 648 
 649             // emit implementation of fieldCount()
 650             mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "fieldCount", INT_SIG, null, null);
 651             mv.visitCode();
 652             int fc = types.length();
 653             if (fc <= (ICONST_5 - ICONST_0)) {
 654                 mv.visitInsn(ICONST_0 + fc);
 655             } else {
 656                 mv.visitIntInsn(SIPUSH, fc);
 657             }
 658             mv.visitInsn(IRETURN);
 659             mv.visitMaxs(0, 0);
 660             mv.visitEnd();
 661             // emit make()  ...factory method wrapping constructor
 662             mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_STATIC, "make", makeSignature(types, false), null, null);
 663             mv.visitCode();
 664             // make instance
 665             mv.visitTypeInsn(NEW, className);
 666             mv.visitInsn(DUP);
 667             // load mt, lf
 668             mv.visitVarInsn(ALOAD, 0);  // type
 669             mv.visitVarInsn(ALOAD, 1);  // form
 670             // load factory method arguments
 671             for (int i = 0, j = 0; i < types.length(); ++i, ++j) {
 672                 // i counts the arguments, j counts corresponding argument slots
 673                 char t = types.charAt(i);
 674                 mv.visitVarInsn(typeLoadOp(t), j + 2); // parameters start at 3
 675                 if (t == 'J' || t == 'D') {
 676                     ++j; // adjust argument register access
 677                 }
 678             }
 679 
 680             // finally, invoke the constructor and return
 681             mv.visitMethodInsn(INVOKESPECIAL, className, "<init>", makeSignature(types, true), false);
 682             mv.visitInsn(ARETURN);
 683             mv.visitMaxs(0, 0);
 684             mv.visitEnd();
 685 
 686             // emit copyWith()
 687             mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "copyWith", makeSignature("", false), null, null);
 688             mv.visitCode();
 689             // make instance
 690             mv.visitTypeInsn(NEW, className);
 691             mv.visitInsn(DUP);
 692             // load mt, lf
 693             mv.visitVarInsn(ALOAD, 1);
 694             mv.visitVarInsn(ALOAD, 2);
 695             // put fields on the stack
 696             emitPushFields(types, className, mv);
 697             // finally, invoke the constructor and return
 698             mv.visitMethodInsn(INVOKESPECIAL, className, "<init>", makeSignature(types, true), false);
 699             mv.visitInsn(ARETURN);
 700             mv.visitMaxs(0, 0);
 701             mv.visitEnd();
 702 
 703             // for each type, emit copyWithExtendT()
 704             for (BasicType type : BasicType.ARG_TYPES) {
 705                 if (type == Q_TYPE) continue;
 706                 int ord = type.ordinal();
 707                 char btChar = type.basicTypeChar();
 708                 mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_FINAL, "copyWithExtend" + btChar, makeSignature(String.valueOf(btChar), false), null, E_THROWABLE);
 709                 mv.visitCode();
 710                 // return SPECIES_DATA.extendWith(t).constructor().invokeBasic(mt, lf, argL0, ..., narg)
 711                 // obtain constructor
 712                 mv.visitFieldInsn(GETSTATIC, className, "SPECIES_DATA", SPECIES_DATA_SIG);
 713                 int iconstInsn = ICONST_0 + ord;
 714                 assert(iconstInsn <= ICONST_5);
 715                 mv.visitInsn(iconstInsn);
 716                 mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA, "extendWith", BMHSPECIES_DATA_EWI_SIG, false);
 717                 mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA, "constructor", "()" + MH_SIG, false);
 718                 // load mt, lf
 719                 mv.visitVarInsn(ALOAD, 1);
 720                 mv.visitVarInsn(ALOAD, 2);
 721                 // put fields on the stack
 722                 emitPushFields(types, className, mv);
 723                 // put narg on stack
 724                 mv.visitVarInsn(typeLoadOp(btChar), 3);
 725                 // finally, invoke the constructor and return
 726                 mv.visitMethodInsn(INVOKEVIRTUAL, MH, "invokeBasic", makeSignature(types + btChar, false), false);
 727                 mv.visitInsn(ARETURN);
 728                 mv.visitMaxs(0, 0);
 729                 mv.visitEnd();
 730             }
 731 
 732             cw.visitEnd();
 733 
 734             return cw.toByteArray();
 735         }
 736 
 737         private static int typeLoadOp(char t) {
 738             switch (t) {
 739             case 'L': return ALOAD;
 740             case 'I': return ILOAD;
 741             case 'J': return LLOAD;
 742             case 'F': return FLOAD;
 743             case 'D': return DLOAD;
 744             default : throw newInternalError("unrecognized type " + t);
 745             }
 746         }
 747 
 748         private static void emitPushFields(String types, String className, MethodVisitor mv) {
 749             for (int i = 0; i < types.length(); ++i) {
 750                 char tc = types.charAt(i);
 751                 mv.visitVarInsn(ALOAD, 0);
 752                 mv.visitFieldInsn(GETFIELD, className, makeFieldName(types, i), typeSig(tc));
 753             }
 754         }
 755 
 756         static String typeSig(char t) {
 757             return t == 'L' ? JLO_SIG : String.valueOf(t);
 758         }
 759 
 760         //
 761         // Getter MH generation.
 762         //
 763 
 764         private static MethodHandle makeGetter(Class<?> cbmhClass, String types, int index) {
 765             String fieldName = makeFieldName(types, index);
 766             Class<?> fieldType = Wrapper.forBasicType(types.charAt(index)).primitiveType();
 767             try {
 768                 return LOOKUP.findGetter(cbmhClass, fieldName, fieldType);
 769             } catch (NoSuchFieldException | IllegalAccessException e) {
 770                 throw newInternalError(e);
 771             }
 772         }
 773 
 774         static MethodHandle[] makeGetters(Class<?> cbmhClass, String types, MethodHandle[] mhs) {
 775             if (mhs == null)  mhs = new MethodHandle[types.length()];
 776             for (int i = 0; i < mhs.length; ++i) {
 777                 mhs[i] = makeGetter(cbmhClass, types, i);
 778                 assert(mhs[i].internalMemberName().getDeclaringClass() == cbmhClass);
 779             }
 780             return mhs;
 781         }
 782 
 783         static MethodHandle[] makeCtors(Class<? extends BoundMethodHandle> cbmh, String types, MethodHandle mhs[]) {
 784             if (mhs == null)  mhs = new MethodHandle[1];
 785             if (types.equals(""))  return mhs;  // hack for empty BMH species
 786             mhs[0] = makeCbmhCtor(cbmh, types);
 787             return mhs;
 788         }
 789 
 790         static NamedFunction[] makeNominalGetters(String types, NamedFunction[] nfs, MethodHandle[] getters) {
 791             if (nfs == null)  nfs = new NamedFunction[types.length()];
 792             for (int i = 0; i < nfs.length; ++i) {
 793                 nfs[i] = new NamedFunction(getters[i]);
 794             }
 795             return nfs;
 796         }
 797 
 798         //
 799         // Auxiliary methods.
 800         //
 801 
 802         static SpeciesData getSpeciesDataFromConcreteBMHClass(Class<? extends BoundMethodHandle> cbmh) {
 803             try {
 804                 Field F_SPECIES_DATA = cbmh.getDeclaredField("SPECIES_DATA");
 805                 return (SpeciesData) F_SPECIES_DATA.get(null);
 806             } catch (ReflectiveOperationException ex) {
 807                 throw newInternalError(ex);
 808             }
 809         }
 810 
 811         static void setSpeciesDataToConcreteBMHClass(Class<? extends BoundMethodHandle> cbmh, SpeciesData speciesData) {
 812             try {
 813                 Field F_SPECIES_DATA = cbmh.getDeclaredField("SPECIES_DATA");
 814                 // ## FIXME: annotation parser can't create proxy classes until module system is fully initialzed
 815                 // assert F_SPECIES_DATA.getDeclaredAnnotation(Stable.class) != null;
 816                 F_SPECIES_DATA.set(null, speciesData);
 817             } catch (ReflectiveOperationException ex) {
 818                 throw newInternalError(ex);
 819             }
 820         }
 821 
 822         /**
 823          * Field names in concrete BMHs adhere to this pattern:
 824          * arg + type + index
 825          * where type is a single character (L, I, J, F, D).
 826          */
 827         private static String makeFieldName(String types, int index) {
 828             assert index >= 0 && index < types.length();
 829             return "arg" + types.charAt(index) + index;
 830         }
 831 
 832         private static String makeSignature(String types, boolean ctor) {
 833             StringBuilder buf = new StringBuilder(SIG_INCIPIT);
 834             int len = types.length();
 835             for (int i = 0; i < len; i++) {
 836                 buf.append(typeSig(types.charAt(i)));
 837             }
 838             return buf.append(')').append(ctor ? "V" : BMH_SIG).toString();
 839         }
 840 
 841         private static MethodType makeConstructorType(String types) {
 842             int length = types.length();
 843             Class<?> ptypes[] = new Class<?>[length + 2];
 844             ptypes[0] = MethodType.class;
 845             ptypes[1] = LambdaForm.class;
 846             for (int i = 0; i < length; i++) {
 847                 ptypes[i + 2] = BasicType.basicType(types.charAt(i)).basicTypeClass();
 848             }
 849             return MethodType.makeImpl(BoundMethodHandle.class, ptypes, true);
 850         }
 851 
 852         static MethodHandle makeCbmhCtor(Class<? extends BoundMethodHandle> cbmh, String types) {
 853             try {
 854                 return LOOKUP.findStatic(cbmh, "make", makeConstructorType(types));
 855             } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | TypeNotPresentException e) {
 856                 throw newInternalError(e);
 857             }
 858         }
 859     }
 860 
 861     static final Lookup LOOKUP = Lookup.IMPL_LOOKUP;
 862 
 863     /**
 864      * All subclasses must provide such a value describing their type signature.
 865      */
 866     static final SpeciesData SPECIES_DATA = SpeciesData.EMPTY;
 867 
 868     private static final SpeciesData[] SPECIES_DATA_CACHE = new SpeciesData[6];
 869     private static SpeciesData checkCache(int size, String types) {
 870         int idx = size - 1;
 871         SpeciesData data = SPECIES_DATA_CACHE[idx];
 872         if (data != null)  return data;
 873         SPECIES_DATA_CACHE[idx] = data = getSpeciesData(types);
 874         return data;
 875     }
 876     static SpeciesData speciesData_L()      { return checkCache(1, "L"); }
 877     static SpeciesData speciesData_LL()     { return checkCache(2, "LL"); }
 878     static SpeciesData speciesData_LLL()    { return checkCache(3, "LLL"); }
 879     static SpeciesData speciesData_LLLL()   { return checkCache(4, "LLLL"); }
 880     static SpeciesData speciesData_LLLLL()  { return checkCache(5, "LLLLL"); }
 881 }