rev 12327 : 8062543: Replace uses of MethodHandleImpl.castReference with Class.cast

   1 /*
   2  * Copyright (c) 2008, 2013, 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 java.security.AccessController;
  29 import java.security.PrivilegedAction;
  30 import java.util.ArrayList;
  31 import java.util.Arrays;
  32 import java.util.Collections;
  33 import java.util.function.Function;
  34 
  35 import sun.invoke.empty.Empty;
  36 import sun.invoke.util.ValueConversions;
  37 import sun.invoke.util.VerifyType;
  38 import sun.invoke.util.Wrapper;
  39 import sun.reflect.CallerSensitive;
  40 import sun.reflect.Reflection;
  41 import static java.lang.invoke.LambdaForm.*;
  42 import static java.lang.invoke.MethodHandleStatics.*;
  43 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
  44 
  45 /**
  46  * Trusted implementation code for MethodHandle.
  47  * @author jrose
  48  */
  49 /*non-public*/ abstract class MethodHandleImpl {
  50     // Do not adjust this except for special platforms:
  51     private static final int MAX_ARITY;
  52     static {
  53         final Object[] values = { 255 };
  54         AccessController.doPrivileged(new PrivilegedAction<>() {
  55             @Override
  56             public Void run() {
  57                 values[0] = Integer.getInteger(MethodHandleImpl.class.getName()+".MAX_ARITY", 255);
  58                 return null;
  59             }
  60         });
  61         MAX_ARITY = (Integer) values[0];
  62     }
  63 
  64     /// Factory methods to create method handles:
  65 
  66     static void initStatics() {
  67         // Trigger selected static initializations.
  68         MemberName.Factory.INSTANCE.getClass();
  69     }
  70 
  71     static MethodHandle makeArrayElementAccessor(Class<?> arrayClass, boolean isSetter) {
  72         if (arrayClass == Object[].class)
  73             return (isSetter ? ArrayAccessor.OBJECT_ARRAY_SETTER : ArrayAccessor.OBJECT_ARRAY_GETTER);
  74         if (!arrayClass.isArray())
  75             throw newIllegalArgumentException("not an array: "+arrayClass);
  76         MethodHandle[] cache = ArrayAccessor.TYPED_ACCESSORS.get(arrayClass);
  77         int cacheIndex = (isSetter ? ArrayAccessor.SETTER_INDEX : ArrayAccessor.GETTER_INDEX);
  78         MethodHandle mh = cache[cacheIndex];
  79         if (mh != null)  return mh;
  80         mh = ArrayAccessor.getAccessor(arrayClass, isSetter);
  81         MethodType correctType = ArrayAccessor.correctType(arrayClass, isSetter);
  82         if (mh.type() != correctType) {
  83             assert(mh.type().parameterType(0) == Object[].class);
  84             assert((isSetter ? mh.type().parameterType(2) : mh.type().returnType()) == Object.class);
  85             assert(isSetter || correctType.parameterType(0).getComponentType() == correctType.returnType());
  86             // safe to view non-strictly, because element type follows from array type
  87             mh = mh.viewAsType(correctType, false);
  88         }
  89         mh = makeIntrinsic(mh, (isSetter ? Intrinsic.ARRAY_STORE : Intrinsic.ARRAY_LOAD));
  90         // Atomically update accessor cache.
  91         synchronized(cache) {
  92             if (cache[cacheIndex] == null) {
  93                 cache[cacheIndex] = mh;
  94             } else {
  95                 // Throw away newly constructed accessor and use cached version.
  96                 mh = cache[cacheIndex];
  97             }
  98         }
  99         return mh;
 100     }
 101 
 102     static final class ArrayAccessor {
 103         /// Support for array element access
 104         static final int GETTER_INDEX = 0, SETTER_INDEX = 1, INDEX_LIMIT = 2;
 105         static final ClassValue<MethodHandle[]> TYPED_ACCESSORS
 106                 = new ClassValue<MethodHandle[]>() {
 107                     @Override
 108                     protected MethodHandle[] computeValue(Class<?> type) {
 109                         return new MethodHandle[INDEX_LIMIT];
 110                     }
 111                 };
 112         static final MethodHandle OBJECT_ARRAY_GETTER, OBJECT_ARRAY_SETTER;
 113         static {
 114             MethodHandle[] cache = TYPED_ACCESSORS.get(Object[].class);
 115             cache[GETTER_INDEX] = OBJECT_ARRAY_GETTER = makeIntrinsic(getAccessor(Object[].class, false), Intrinsic.ARRAY_LOAD);
 116             cache[SETTER_INDEX] = OBJECT_ARRAY_SETTER = makeIntrinsic(getAccessor(Object[].class, true),  Intrinsic.ARRAY_STORE);
 117 
 118             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_GETTER.internalMemberName()));
 119             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_SETTER.internalMemberName()));
 120         }
 121 
 122         static int     getElementI(int[]     a, int i)            { return              a[i]; }
 123         static long    getElementJ(long[]    a, int i)            { return              a[i]; }
 124         static float   getElementF(float[]   a, int i)            { return              a[i]; }
 125         static double  getElementD(double[]  a, int i)            { return              a[i]; }
 126         static boolean getElementZ(boolean[] a, int i)            { return              a[i]; }
 127         static byte    getElementB(byte[]    a, int i)            { return              a[i]; }
 128         static short   getElementS(short[]   a, int i)            { return              a[i]; }
 129         static char    getElementC(char[]    a, int i)            { return              a[i]; }
 130         static Object  getElementL(Object[]  a, int i)            { return              a[i]; }
 131 
 132         static void    setElementI(int[]     a, int i, int     x) {              a[i] = x; }
 133         static void    setElementJ(long[]    a, int i, long    x) {              a[i] = x; }
 134         static void    setElementF(float[]   a, int i, float   x) {              a[i] = x; }
 135         static void    setElementD(double[]  a, int i, double  x) {              a[i] = x; }
 136         static void    setElementZ(boolean[] a, int i, boolean x) {              a[i] = x; }
 137         static void    setElementB(byte[]    a, int i, byte    x) {              a[i] = x; }
 138         static void    setElementS(short[]   a, int i, short   x) {              a[i] = x; }
 139         static void    setElementC(char[]    a, int i, char    x) {              a[i] = x; }
 140         static void    setElementL(Object[]  a, int i, Object  x) {              a[i] = x; }
 141 
 142         static String name(Class<?> arrayClass, boolean isSetter) {
 143             Class<?> elemClass = arrayClass.getComponentType();
 144             if (elemClass == null)  throw newIllegalArgumentException("not an array", arrayClass);
 145             return (!isSetter ? "getElement" : "setElement") + Wrapper.basicTypeChar(elemClass);
 146         }
 147         static MethodType type(Class<?> arrayClass, boolean isSetter) {
 148             Class<?> elemClass = arrayClass.getComponentType();
 149             Class<?> arrayArgClass = arrayClass;
 150             if (!elemClass.isPrimitive()) {
 151                 arrayArgClass = Object[].class;
 152                 elemClass = Object.class;
 153             }
 154             return !isSetter ?
 155                     MethodType.methodType(elemClass,  arrayArgClass, int.class) :
 156                     MethodType.methodType(void.class, arrayArgClass, int.class, elemClass);
 157         }
 158         static MethodType correctType(Class<?> arrayClass, boolean isSetter) {
 159             Class<?> elemClass = arrayClass.getComponentType();
 160             return !isSetter ?
 161                     MethodType.methodType(elemClass,  arrayClass, int.class) :
 162                     MethodType.methodType(void.class, arrayClass, int.class, elemClass);
 163         }
 164         static MethodHandle getAccessor(Class<?> arrayClass, boolean isSetter) {
 165             String     name = name(arrayClass, isSetter);
 166             MethodType type = type(arrayClass, isSetter);
 167             try {
 168                 return IMPL_LOOKUP.findStatic(ArrayAccessor.class, name, type);
 169             } catch (ReflectiveOperationException ex) {
 170                 throw uncaughtException(ex);
 171             }
 172         }
 173     }
 174 
 175     /**
 176      * Create a JVM-level adapter method handle to conform the given method
 177      * handle to the similar newType, using only pairwise argument conversions.
 178      * For each argument, convert incoming argument to the exact type needed.
 179      * The argument conversions allowed are casting, boxing and unboxing,
 180      * integral widening or narrowing, and floating point widening or narrowing.
 181      * @param srcType required call type
 182      * @param target original method handle
 183      * @param strict if true, only asType conversions are allowed; if false, explicitCastArguments conversions allowed
 184      * @param monobox if true, unboxing conversions are assumed to be exactly typed (Integer to int only, not long or double)
 185      * @return an adapter to the original handle with the desired new type,
 186      *          or the original target if the types are already identical
 187      *          or null if the adaptation cannot be made
 188      */
 189     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 190                                             boolean strict, boolean monobox) {
 191         MethodType dstType = target.type();
 192         if (srcType == dstType)
 193             return target;
 194         return makePairwiseConvertByEditor(target, srcType, strict, monobox);
 195     }
 196 
 197     private static int countNonNull(Object[] array) {
 198         int count = 0;
 199         for (Object x : array) {
 200             if (x != null)  ++count;
 201         }
 202         return count;
 203     }
 204 
 205     static MethodHandle makePairwiseConvertByEditor(MethodHandle target, MethodType srcType,
 206                                                     boolean strict, boolean monobox) {
 207         Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
 208         int convCount = countNonNull(convSpecs);
 209         if (convCount == 0)
 210             return target.viewAsType(srcType, strict);
 211         MethodType basicSrcType = srcType.basicType();
 212         MethodType midType = target.type().basicType();
 213         BoundMethodHandle mh = target.rebind();
 214         // FIXME: Reduce number of bindings when there is more than one Class conversion.
 215         // FIXME: Reduce number of bindings when there are repeated conversions.
 216         for (int i = 0; i < convSpecs.length-1; i++) {
 217             Object convSpec = convSpecs[i];
 218             if (convSpec == null)  continue;
 219             MethodHandle fn;
 220             if (convSpec instanceof Class) {
 221                 fn = Lazy.MH_castReference.bindTo(convSpec);
 222             } else {
 223                 fn = (MethodHandle) convSpec;
 224             }
 225             Class<?> newType = basicSrcType.parameterType(i);
 226             if (--convCount == 0)
 227                 midType = srcType;
 228             else
 229                 midType = midType.changeParameterType(i, newType);
 230             LambdaForm form2 = mh.editor().filterArgumentForm(1+i, BasicType.basicType(newType));
 231             mh = mh.copyWithExtendL(midType, form2, fn);
 232             mh = mh.rebind();
 233         }
 234         Object convSpec = convSpecs[convSpecs.length-1];
 235         if (convSpec != null) {
 236             MethodHandle fn;
 237             if (convSpec instanceof Class) {
 238                 if (convSpec == void.class)
 239                     fn = null;
 240                 else
 241                     fn = Lazy.MH_castReference.bindTo(convSpec);
 242             } else {
 243                 fn = (MethodHandle) convSpec;
 244             }
 245             Class<?> newType = basicSrcType.returnType();
 246             assert(--convCount == 0);
 247             midType = srcType;
 248             if (fn != null) {
 249                 mh = mh.rebind();  // rebind if too complex
 250                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), false);
 251                 mh = mh.copyWithExtendL(midType, form2, fn);
 252             } else {
 253                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), true);
 254                 mh = mh.copyWith(midType, form2);
 255             }
 256         }
 257         assert(convCount == 0);
 258         assert(mh.type().equals(srcType));
 259         return mh;
 260     }
 261 
 262     static MethodHandle makePairwiseConvertIndirect(MethodHandle target, MethodType srcType,
 263                                                     boolean strict, boolean monobox) {
 264         assert(target.type().parameterCount() == srcType.parameterCount());
 265         // Calculate extra arguments (temporaries) required in the names array.
 266         Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
 267         final int INARG_COUNT = srcType.parameterCount();
 268         int convCount = countNonNull(convSpecs);
 269         boolean retConv = (convSpecs[INARG_COUNT] != null);
 270         boolean retVoid = srcType.returnType() == void.class;
 271         if (retConv && retVoid) {
 272             convCount -= 1;
 273             retConv = false;
 274         }
 275 
 276         final int IN_MH         = 0;
 277         final int INARG_BASE    = 1;
 278         final int INARG_LIMIT   = INARG_BASE + INARG_COUNT;
 279         final int NAME_LIMIT    = INARG_LIMIT + convCount + 1;
 280         final int RETURN_CONV   = (!retConv ? -1         : NAME_LIMIT - 1);
 281         final int OUT_CALL      = (!retConv ? NAME_LIMIT : RETURN_CONV) - 1;
 282         final int RESULT        = (retVoid ? -1 : NAME_LIMIT - 1);
 283 
 284         // Now build a LambdaForm.
 285         MethodType lambdaType = srcType.basicType().invokerType();
 286         Name[] names = arguments(NAME_LIMIT - INARG_LIMIT, lambdaType);
 287 
 288         // Collect the arguments to the outgoing call, maybe with conversions:
 289         final int OUTARG_BASE = 0;  // target MH is Name.function, name Name.arguments[0]
 290         Object[] outArgs = new Object[OUTARG_BASE + INARG_COUNT];
 291 
 292         int nameCursor = INARG_LIMIT;
 293         for (int i = 0; i < INARG_COUNT; i++) {
 294             Object convSpec = convSpecs[i];
 295             if (convSpec == null) {
 296                 // do nothing: difference is trivial
 297                 outArgs[OUTARG_BASE + i] = names[INARG_BASE + i];
 298                 continue;
 299             }
 300 
 301             Name conv;
 302             if (convSpec instanceof Class) {
 303                 Class<?> convClass = (Class<?>) convSpec;
 304                 conv = new Name(Lazy.MH_castReference, convClass, names[INARG_BASE + i]);
 305             } else {
 306                 MethodHandle fn = (MethodHandle) convSpec;
 307                 conv = new Name(fn, names[INARG_BASE + i]);
 308             }
 309             assert(names[nameCursor] == null);
 310             names[nameCursor++] = conv;
 311             assert(outArgs[OUTARG_BASE + i] == null);
 312             outArgs[OUTARG_BASE + i] = conv;
 313         }
 314 
 315         // Build argument array for the call.
 316         assert(nameCursor == OUT_CALL);
 317         names[OUT_CALL] = new Name(target, outArgs);
 318 
 319         Object convSpec = convSpecs[INARG_COUNT];
 320         if (!retConv) {
 321             assert(OUT_CALL == names.length-1);
 322         } else {
 323             Name conv;
 324             if (convSpec == void.class) {
 325                 conv = new Name(LambdaForm.constantZero(BasicType.basicType(srcType.returnType())));
 326             } else if (convSpec instanceof Class) {
 327                 Class<?> convClass = (Class<?>) convSpec;
 328                 conv = new Name(Lazy.MH_castReference, convClass, names[OUT_CALL]);
 329             } else {
 330                 MethodHandle fn = (MethodHandle) convSpec;
 331                 if (fn.type().parameterCount() == 0)
 332                     conv = new Name(fn);  // don't pass retval to void conversion
 333                 else
 334                     conv = new Name(fn, names[OUT_CALL]);
 335             }
 336             assert(names[RETURN_CONV] == null);
 337             names[RETURN_CONV] = conv;
 338             assert(RETURN_CONV == names.length-1);
 339         }
 340 
 341         LambdaForm form = new LambdaForm("convert", lambdaType.parameterCount(), names, RESULT);
 342         return SimpleMethodHandle.make(srcType, form);
 343     }
 344 
 345     /**
 346      * Identity function, with reference cast.
 347      * @param t an arbitrary reference type
 348      * @param x an arbitrary reference value
 349      * @return the same value x
 350      */
 351     @ForceInline
 352     @SuppressWarnings("unchecked")
 353     static <T,U> T castReference(Class<? extends T> t, U x) {
 354         // inlined Class.cast because we can't ForceInline it
 355         if (x != null && !t.isInstance(x))
 356             throw newClassCastException(t, x);
 357         return (T) x;
 358     }
 359 
 360     private static ClassCastException newClassCastException(Class<?> t, Object obj) {
 361         return new ClassCastException("Cannot cast " + obj.getClass().getName() + " to " + t.getName());
 362     }
 363 
 364     static Object[] computeValueConversions(MethodType srcType, MethodType dstType,
 365                                             boolean strict, boolean monobox) {
 366         final int INARG_COUNT = srcType.parameterCount();
 367         Object[] convSpecs = new Object[INARG_COUNT+1];
 368         for (int i = 0; i <= INARG_COUNT; i++) {
 369             boolean isRet = (i == INARG_COUNT);
 370             Class<?> src = isRet ? dstType.returnType() : srcType.parameterType(i);
 371             Class<?> dst = isRet ? srcType.returnType() : dstType.parameterType(i);
 372             if (!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)) {
 373                 convSpecs[i] = valueConversion(src, dst, strict, monobox);
 374             }
 375         }
 376         return convSpecs;
 377     }
 378     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 379                                             boolean strict) {
 380         return makePairwiseConvert(target, srcType, strict, /*monobox=*/ false);
 381     }
 382 
 383     /**
 384      * Find a conversion function from the given source to the given destination.
 385      * This conversion function will be used as a LF NamedFunction.
 386      * Return a Class object if a simple cast is needed.
 387      * Return void.class if void is involved.
 388      */
 389     static Object valueConversion(Class<?> src, Class<?> dst, boolean strict, boolean monobox) {
 390         assert(!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict));  // caller responsibility
 391         if (dst == void.class)
 392             return dst;
 393         MethodHandle fn;
 394         if (src.isPrimitive()) {
 395             if (src == void.class) {
 396                 return void.class;  // caller must recognize this specially
 397             } else if (dst.isPrimitive()) {
 398                 // Examples: int->byte, byte->int, boolean->int (!strict)
 399                 fn = ValueConversions.convertPrimitive(src, dst);
 400             } else {
 401                 // Examples: int->Integer, boolean->Object, float->Number
 402                 Wrapper wsrc = Wrapper.forPrimitiveType(src);
 403                 fn = ValueConversions.boxExact(wsrc);
 404                 assert(fn.type().parameterType(0) == wsrc.primitiveType());
 405                 assert(fn.type().returnType() == wsrc.wrapperType());
 406                 if (!VerifyType.isNullConversion(wsrc.wrapperType(), dst, strict)) {
 407                     // Corner case, such as int->Long, which will probably fail.
 408                     MethodType mt = MethodType.methodType(dst, src);
 409                     if (strict)
 410                         fn = fn.asType(mt);
 411                     else
 412                         fn = MethodHandleImpl.makePairwiseConvert(fn, mt, /*strict=*/ false);
 413                 }
 414             }
 415         } else if (dst.isPrimitive()) {
 416             Wrapper wdst = Wrapper.forPrimitiveType(dst);
 417             if (monobox || src == wdst.wrapperType()) {
 418                 // Use a strongly-typed unboxer, if possible.
 419                 fn = ValueConversions.unboxExact(wdst, strict);
 420             } else {
 421                 // Examples:  Object->int, Number->int, Comparable->int, Byte->int
 422                 // must include additional conversions
 423                 // src must be examined at runtime, to detect Byte, Character, etc.
 424                 fn = (strict
 425                         ? ValueConversions.unboxWiden(wdst)
 426                         : ValueConversions.unboxCast(wdst));
 427             }
 428         } else {
 429             // Simple reference conversion.
 430             // Note:  Do not check for a class hierarchy relation
 431             // between src and dst.  In all cases a 'null' argument
 432             // will pass the cast conversion.
 433             return dst;
 434         }
 435         assert(fn.type().parameterCount() <= 1) : "pc"+Arrays.asList(src.getSimpleName(), dst.getSimpleName(), fn);
 436         return fn;
 437     }
 438 
 439     static MethodHandle makeVarargsCollector(MethodHandle target, Class<?> arrayType) {
 440         MethodType type = target.type();
 441         int last = type.parameterCount() - 1;
 442         if (type.parameterType(last) != arrayType)
 443             target = target.asType(type.changeParameterType(last, arrayType));
 444         target = target.asFixedArity();  // make sure this attribute is turned off
 445         return new AsVarargsCollector(target, arrayType);
 446     }
 447 
 448     private static final class AsVarargsCollector extends DelegatingMethodHandle {
 449         private final MethodHandle target;
 450         private final Class<?> arrayType;
 451         private @Stable MethodHandle asCollectorCache;
 452 
 453         AsVarargsCollector(MethodHandle target, Class<?> arrayType) {
 454             this(target.type(), target, arrayType);
 455         }
 456         AsVarargsCollector(MethodType type, MethodHandle target, Class<?> arrayType) {
 457             super(type, target);
 458             this.target = target;
 459             this.arrayType = arrayType;
 460             this.asCollectorCache = target.asCollector(arrayType, 0);
 461         }
 462 
 463         @Override
 464         public boolean isVarargsCollector() {
 465             return true;
 466         }
 467 
 468         @Override
 469         protected MethodHandle getTarget() {
 470             return target;
 471         }
 472 
 473         @Override
 474         public MethodHandle asFixedArity() {
 475             return target;
 476         }
 477 
 478         @Override
 479         MethodHandle setVarargs(MemberName member) {
 480             if (member.isVarargs())  return this;
 481             return asFixedArity();
 482         }
 483 
 484         @Override
 485         public MethodHandle asTypeUncached(MethodType newType) {
 486             MethodType type = this.type();
 487             int collectArg = type.parameterCount() - 1;
 488             int newArity = newType.parameterCount();
 489             if (newArity == collectArg+1 &&
 490                 type.parameterType(collectArg).isAssignableFrom(newType.parameterType(collectArg))) {
 491                 // if arity and trailing parameter are compatible, do normal thing
 492                 return asTypeCache = asFixedArity().asType(newType);
 493             }
 494             // check cache
 495             MethodHandle acc = asCollectorCache;
 496             if (acc != null && acc.type().parameterCount() == newArity)
 497                 return asTypeCache = acc.asType(newType);
 498             // build and cache a collector
 499             int arrayLength = newArity - collectArg;
 500             MethodHandle collector;
 501             try {
 502                 collector = asFixedArity().asCollector(arrayType, arrayLength);
 503                 assert(collector.type().parameterCount() == newArity) : "newArity="+newArity+" but collector="+collector;
 504             } catch (IllegalArgumentException ex) {
 505                 throw new WrongMethodTypeException("cannot build collector", ex);
 506             }
 507             asCollectorCache = collector;
 508             return asTypeCache = collector.asType(newType);
 509         }
 510 
 511         @Override
 512         boolean viewAsTypeChecks(MethodType newType, boolean strict) {
 513             super.viewAsTypeChecks(newType, true);
 514             if (strict) return true;
 515             // extra assertion for non-strict checks:
 516             assert (type().lastParameterType().getComponentType()
 517                     .isAssignableFrom(
 518                             newType.lastParameterType().getComponentType()))
 519                     : Arrays.asList(this, newType);
 520             return true;
 521         }
 522     }
 523 
 524     /** Factory method:  Spread selected argument. */
 525     static MethodHandle makeSpreadArguments(MethodHandle target,
 526                                             Class<?> spreadArgType, int spreadArgPos, int spreadArgCount) {
 527         MethodType targetType = target.type();
 528 
 529         for (int i = 0; i < spreadArgCount; i++) {
 530             Class<?> arg = VerifyType.spreadArgElementType(spreadArgType, i);
 531             if (arg == null)  arg = Object.class;
 532             targetType = targetType.changeParameterType(spreadArgPos + i, arg);
 533         }
 534         target = target.asType(targetType);
 535 
 536         MethodType srcType = targetType
 537                 .replaceParameterTypes(spreadArgPos, spreadArgPos + spreadArgCount, spreadArgType);
 538         // Now build a LambdaForm.
 539         MethodType lambdaType = srcType.invokerType();
 540         Name[] names = arguments(spreadArgCount + 2, lambdaType);
 541         int nameCursor = lambdaType.parameterCount();
 542         int[] indexes = new int[targetType.parameterCount()];
 543 
 544         for (int i = 0, argIndex = 1; i < targetType.parameterCount() + 1; i++, argIndex++) {
 545             Class<?> src = lambdaType.parameterType(i);
 546             if (i == spreadArgPos) {
 547                 // Spread the array.
 548                 MethodHandle aload = MethodHandles.arrayElementGetter(spreadArgType);
 549                 Name array = names[argIndex];
 550                 names[nameCursor++] = new Name(Lazy.NF_checkSpreadArgument, array, spreadArgCount);
 551                 for (int j = 0; j < spreadArgCount; i++, j++) {
 552                     indexes[i] = nameCursor;
 553                     names[nameCursor++] = new Name(aload, array, j);
 554                 }
 555             } else if (i < indexes.length) {
 556                 indexes[i] = argIndex;
 557             }
 558         }
 559         assert(nameCursor == names.length-1);  // leave room for the final call
 560 
 561         // Build argument array for the call.
 562         Name[] targetArgs = new Name[targetType.parameterCount()];
 563         for (int i = 0; i < targetType.parameterCount(); i++) {
 564             int idx = indexes[i];
 565             targetArgs[i] = names[idx];
 566         }
 567         names[names.length - 1] = new Name(target, (Object[]) targetArgs);
 568 
 569         LambdaForm form = new LambdaForm("spread", lambdaType.parameterCount(), names);
 570         return SimpleMethodHandle.make(srcType, form);
 571     }
 572 
 573     static void checkSpreadArgument(Object av, int n) {
 574         if (av == null) {
 575             if (n == 0)  return;
 576         } else if (av instanceof Object[]) {
 577             int len = ((Object[])av).length;
 578             if (len == n)  return;
 579         } else {
 580             int len = java.lang.reflect.Array.getLength(av);
 581             if (len == n)  return;
 582         }
 583         // fall through to error:
 584         throw newIllegalArgumentException("array is not of length "+n);
 585     }
 586 
 587     /**
 588      * Pre-initialized NamedFunctions for bootstrapping purposes.
 589      * Factored in an inner class to delay initialization until first usage.
 590      */
 591     static class Lazy {
 592         private static final Class<?> MHI = MethodHandleImpl.class;

 593 
 594         private static final MethodHandle[] ARRAYS;
 595         private static final MethodHandle[] FILL_ARRAYS;
 596 
 597         static final NamedFunction NF_checkSpreadArgument;
 598         static final NamedFunction NF_guardWithCatch;
 599         static final NamedFunction NF_throwException;
 600         static final NamedFunction NF_profileBoolean;
 601 
 602         static final MethodHandle MH_castReference;
 603         static final MethodHandle MH_selectAlternative;
 604         static final MethodHandle MH_copyAsPrimitiveArray;
 605         static final MethodHandle MH_fillNewTypedArray;
 606         static final MethodHandle MH_fillNewArray;
 607         static final MethodHandle MH_arrayIdentity;
 608 
 609         static {
 610             ARRAYS      = makeArrays();
 611             FILL_ARRAYS = makeFillArrays();
 612 
 613             try {
 614                 NF_checkSpreadArgument = new NamedFunction(MHI.getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
 615                 NF_guardWithCatch      = new NamedFunction(MHI.getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
 616                                                                                  MethodHandle.class, Object[].class));
 617                 NF_throwException      = new NamedFunction(MHI.getDeclaredMethod("throwException", Throwable.class));
 618                 NF_profileBoolean      = new NamedFunction(MHI.getDeclaredMethod("profileBoolean", boolean.class, int[].class));
 619 
 620                 NF_checkSpreadArgument.resolve();
 621                 NF_guardWithCatch.resolve();
 622                 NF_throwException.resolve();
 623                 NF_profileBoolean.resolve();
 624 
 625                 MH_castReference        = IMPL_LOOKUP.findStatic(MHI, "castReference",
 626                                             MethodType.methodType(Object.class, Class.class, Object.class));
 627                 MH_copyAsPrimitiveArray = IMPL_LOOKUP.findStatic(MHI, "copyAsPrimitiveArray",
 628                                             MethodType.methodType(Object.class, Wrapper.class, Object[].class));
 629                 MH_arrayIdentity        = IMPL_LOOKUP.findStatic(MHI, "identity",
 630                                             MethodType.methodType(Object[].class, Object[].class));
 631                 MH_fillNewArray         = IMPL_LOOKUP.findStatic(MHI, "fillNewArray",
 632                                             MethodType.methodType(Object[].class, Integer.class, Object[].class));
 633                 MH_fillNewTypedArray    = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
 634                                             MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
 635 
 636                 MH_selectAlternative    = makeIntrinsic(
 637                         IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
 638                                 MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class)),
 639                         Intrinsic.SELECT_ALTERNATIVE);
 640             } catch (ReflectiveOperationException ex) {
 641                 throw newInternalError(ex);
 642             }
 643         }
 644     }
 645 
 646     /** Factory method:  Collect or filter selected argument(s). */
 647     static MethodHandle makeCollectArguments(MethodHandle target,
 648                 MethodHandle collector, int collectArgPos, boolean retainOriginalArgs) {
 649         MethodType targetType = target.type();          // (a..., c, [b...])=>r
 650         MethodType collectorType = collector.type();    // (b...)=>c
 651         int collectArgCount = collectorType.parameterCount();
 652         Class<?> collectValType = collectorType.returnType();
 653         int collectValCount = (collectValType == void.class ? 0 : 1);
 654         MethodType srcType = targetType                 // (a..., [b...])=>r
 655                 .dropParameterTypes(collectArgPos, collectArgPos+collectValCount);
 656         if (!retainOriginalArgs) {                      // (a..., b...)=>r
 657             srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterList());
 658         }
 659         // in  arglist: [0: ...keep1 | cpos: collect...  | cpos+cacount: keep2... ]
 660         // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
 661         // out(retain): [0: ...keep1 | cpos: cV? coll... | cpos+cvc+cac: keep2... ]
 662 
 663         // Now build a LambdaForm.
 664         MethodType lambdaType = srcType.invokerType();
 665         Name[] names = arguments(2, lambdaType);
 666         final int collectNamePos = names.length - 2;
 667         final int targetNamePos  = names.length - 1;
 668 
 669         Name[] collectorArgs = Arrays.copyOfRange(names, 1 + collectArgPos, 1 + collectArgPos + collectArgCount);
 670         names[collectNamePos] = new Name(collector, (Object[]) collectorArgs);
 671 
 672         // Build argument array for the target.
 673         // Incoming LF args to copy are: [ (mh) headArgs collectArgs tailArgs ].
 674         // Output argument array is [ headArgs (collectVal)? (collectArgs)? tailArgs ].
 675         Name[] targetArgs = new Name[targetType.parameterCount()];
 676         int inputArgPos  = 1;  // incoming LF args to copy to target
 677         int targetArgPos = 0;  // fill pointer for targetArgs
 678         int chunk = collectArgPos;  // |headArgs|
 679         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 680         inputArgPos  += chunk;
 681         targetArgPos += chunk;
 682         if (collectValType != void.class) {
 683             targetArgs[targetArgPos++] = names[collectNamePos];
 684         }
 685         chunk = collectArgCount;
 686         if (retainOriginalArgs) {
 687             System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 688             targetArgPos += chunk;   // optionally pass on the collected chunk
 689         }
 690         inputArgPos += chunk;
 691         chunk = targetArgs.length - targetArgPos;  // all the rest
 692         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 693         assert(inputArgPos + chunk == collectNamePos);  // use of rest of input args also
 694         names[targetNamePos] = new Name(target, (Object[]) targetArgs);
 695 
 696         LambdaForm form = new LambdaForm("collect", lambdaType.parameterCount(), names);
 697         return SimpleMethodHandle.make(srcType, form);
 698     }
 699 
 700     @LambdaForm.Hidden
 701     static
 702     MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback) {
 703         if (testResult) {
 704             return target;
 705         } else {
 706             return fallback;
 707         }
 708     }
 709 
 710     // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
 711     @LambdaForm.Hidden
 712     static
 713     boolean profileBoolean(boolean result, int[] counters) {
 714         // Profile is int[2] where [0] and [1] correspond to false and true occurrences respectively.
 715         int idx = result ? 1 : 0;
 716         try {
 717             counters[idx] = Math.addExact(counters[idx], 1);
 718         } catch (ArithmeticException e) {
 719             // Avoid continuous overflow by halving the problematic count.
 720             counters[idx] = counters[idx] / 2;
 721         }
 722         return result;
 723     }
 724 
 725     // Intrinsified by C2. Returns true if obj is a compile-time constant.
 726     @LambdaForm.Hidden
 727     static
 728     boolean isCompileConstant(Object obj) {
 729         return false;
 730     }
 731 
 732     static
 733     MethodHandle makeGuardWithTest(MethodHandle test,
 734                                    MethodHandle target,
 735                                    MethodHandle fallback) {
 736         MethodType type = target.type();
 737         assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
 738         MethodType basicType = type.basicType();
 739         LambdaForm form = makeGuardWithTestForm(basicType);
 740         BoundMethodHandle mh;
 741         try {
 742             if (PROFILE_GWT) {
 743                 int[] counts = new int[2];
 744                 mh = (BoundMethodHandle)
 745                         BoundMethodHandle.speciesData_LLLL().constructor().invokeBasic(type, form,
 746                                 (Object) test, (Object) profile(target), (Object) profile(fallback), counts);
 747             } else {
 748                 mh = (BoundMethodHandle)
 749                         BoundMethodHandle.speciesData_LLL().constructor().invokeBasic(type, form,
 750                                 (Object) test, (Object) profile(target), (Object) profile(fallback));
 751             }
 752         } catch (Throwable ex) {
 753             throw uncaughtException(ex);
 754         }
 755         assert(mh.type() == type);
 756         return mh;
 757     }
 758 
 759 
 760     static
 761     MethodHandle profile(MethodHandle target) {
 762         if (DONT_INLINE_THRESHOLD >= 0) {
 763             return makeBlockInliningWrapper(target);
 764         } else {
 765             return target;
 766         }
 767     }
 768 
 769     /**
 770      * Block inlining during JIT-compilation of a target method handle if it hasn't been invoked enough times.
 771      * Corresponding LambdaForm has @DontInline when compiled into bytecode.
 772      */
 773     static
 774     MethodHandle makeBlockInliningWrapper(MethodHandle target) {
 775         LambdaForm lform;
 776         if (DONT_INLINE_THRESHOLD > 0) {
 777             lform = PRODUCE_BLOCK_INLINING_FORM.apply(target);
 778         } else {
 779             lform = PRODUCE_REINVOKER_FORM.apply(target);
 780         }
 781         return new CountingWrapper(target, lform,
 782                 PRODUCE_BLOCK_INLINING_FORM, PRODUCE_REINVOKER_FORM,
 783                                    DONT_INLINE_THRESHOLD);
 784     }
 785 
 786     /** Constructs reinvoker lambda form which block inlining during JIT-compilation for a particular method handle */
 787     private static final Function<MethodHandle, LambdaForm> PRODUCE_BLOCK_INLINING_FORM = new Function<MethodHandle, LambdaForm>() {
 788         @Override
 789         public LambdaForm apply(MethodHandle target) {
 790             return DelegatingMethodHandle.makeReinvokerForm(target,
 791                                MethodTypeForm.LF_DELEGATE_BLOCK_INLINING, CountingWrapper.class, "reinvoker.dontInline", false,
 792                                DelegatingMethodHandle.NF_getTarget, CountingWrapper.NF_maybeStopCounting);
 793         }
 794     };
 795 
 796     /** Constructs simple reinvoker lambda form for a particular method handle */
 797     private static final Function<MethodHandle, LambdaForm> PRODUCE_REINVOKER_FORM = new Function<MethodHandle, LambdaForm>() {
 798         @Override
 799         public LambdaForm apply(MethodHandle target) {
 800             return DelegatingMethodHandle.makeReinvokerForm(target,
 801                     MethodTypeForm.LF_DELEGATE, DelegatingMethodHandle.class, DelegatingMethodHandle.NF_getTarget);
 802         }
 803     };
 804 
 805     /**
 806      * Counting method handle. It has 2 states: counting and non-counting.
 807      * It is in counting state for the first n invocations and then transitions to non-counting state.
 808      * Behavior in counting and non-counting states is determined by lambda forms produced by
 809      * countingFormProducer & nonCountingFormProducer respectively.
 810      */
 811     static class CountingWrapper extends DelegatingMethodHandle {
 812         private final MethodHandle target;
 813         private int count;
 814         private Function<MethodHandle, LambdaForm> countingFormProducer;
 815         private Function<MethodHandle, LambdaForm> nonCountingFormProducer;
 816         private volatile boolean isCounting;
 817 
 818         private CountingWrapper(MethodHandle target, LambdaForm lform,
 819                                 Function<MethodHandle, LambdaForm> countingFromProducer,
 820                                 Function<MethodHandle, LambdaForm> nonCountingFormProducer,
 821                                 int count) {
 822             super(target.type(), lform);
 823             this.target = target;
 824             this.count = count;
 825             this.countingFormProducer = countingFromProducer;
 826             this.nonCountingFormProducer = nonCountingFormProducer;
 827             this.isCounting = (count > 0);
 828         }
 829 
 830         @Hidden
 831         @Override
 832         protected MethodHandle getTarget() {
 833             return target;
 834         }
 835 
 836         @Override
 837         public MethodHandle asTypeUncached(MethodType newType) {
 838             MethodHandle newTarget = target.asType(newType);
 839             MethodHandle wrapper;
 840             if (isCounting) {
 841                 LambdaForm lform;
 842                 lform = countingFormProducer.apply(newTarget);
 843                 wrapper = new CountingWrapper(newTarget, lform, countingFormProducer, nonCountingFormProducer, DONT_INLINE_THRESHOLD);
 844             } else {
 845                 wrapper = newTarget; // no need for a counting wrapper anymore
 846             }
 847             return (asTypeCache = wrapper);
 848         }
 849 
 850         boolean countDown() {
 851             int c = count;
 852             if (c <= 1) {
 853                 // Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
 854                 if (isCounting) {
 855                     isCounting = false;
 856                     return true;
 857                 } else {
 858                     return false;
 859                 }
 860             } else {
 861                 count = c - 1;
 862                 return false;
 863             }
 864         }
 865 
 866         @Hidden
 867         static void maybeStopCounting(Object o1) {
 868              CountingWrapper wrapper = (CountingWrapper) o1;
 869              if (wrapper.countDown()) {
 870                  // Reached invocation threshold. Replace counting behavior with a non-counting one.
 871                  LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
 872                  lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
 873                  wrapper.updateForm(lform);
 874              }
 875         }
 876 
 877         static final NamedFunction NF_maybeStopCounting;
 878         static {
 879             Class<?> THIS_CLASS = CountingWrapper.class;
 880             try {
 881                 NF_maybeStopCounting = new NamedFunction(THIS_CLASS.getDeclaredMethod("maybeStopCounting", Object.class));
 882             } catch (ReflectiveOperationException ex) {
 883                 throw newInternalError(ex);
 884             }
 885         }
 886     }
 887 
 888     static
 889     LambdaForm makeGuardWithTestForm(MethodType basicType) {
 890         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWT);
 891         if (lform != null)  return lform;
 892         final int THIS_MH      = 0;  // the BMH_LLL
 893         final int ARG_BASE     = 1;  // start of incoming arguments
 894         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 895         int nameCursor = ARG_LIMIT;
 896         final int GET_TEST     = nameCursor++;
 897         final int GET_TARGET   = nameCursor++;
 898         final int GET_FALLBACK = nameCursor++;
 899         final int GET_COUNTERS = PROFILE_GWT ? nameCursor++ : -1;
 900         final int CALL_TEST    = nameCursor++;
 901         final int PROFILE      = (GET_COUNTERS != -1) ? nameCursor++ : -1;
 902         final int TEST         = nameCursor-1; // previous statement: either PROFILE or CALL_TEST
 903         final int SELECT_ALT   = nameCursor++;
 904         final int CALL_TARGET  = nameCursor++;
 905         assert(CALL_TARGET == SELECT_ALT+1);  // must be true to trigger IBG.emitSelectAlternative
 906 
 907         MethodType lambdaType = basicType.invokerType();
 908         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 909 
 910         BoundMethodHandle.SpeciesData data =
 911                 (GET_COUNTERS != -1) ? BoundMethodHandle.speciesData_LLLL()
 912                                      : BoundMethodHandle.speciesData_LLL();
 913         names[THIS_MH] = names[THIS_MH].withConstraint(data);
 914         names[GET_TEST]     = new Name(data.getterFunction(0), names[THIS_MH]);
 915         names[GET_TARGET]   = new Name(data.getterFunction(1), names[THIS_MH]);
 916         names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
 917         if (GET_COUNTERS != -1) {
 918             names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
 919         }
 920         Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
 921 
 922         // call test
 923         MethodType testType = basicType.changeReturnType(boolean.class).basicType();
 924         invokeArgs[0] = names[GET_TEST];
 925         names[CALL_TEST] = new Name(testType, invokeArgs);
 926 
 927         // profile branch
 928         if (PROFILE != -1) {
 929             names[PROFILE] = new Name(Lazy.NF_profileBoolean, names[CALL_TEST], names[GET_COUNTERS]);
 930         }
 931         // call selectAlternative
 932         names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[TEST], names[GET_TARGET], names[GET_FALLBACK]);
 933 
 934         // call target or fallback
 935         invokeArgs[0] = names[SELECT_ALT];
 936         names[CALL_TARGET] = new Name(basicType, invokeArgs);
 937 
 938         lform = new LambdaForm("guard", lambdaType.parameterCount(), names, /*forceInline=*/true);
 939 
 940         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
 941     }
 942 
 943     /**
 944      * The LambdaForm shape for catchException combinator is the following:
 945      * <blockquote><pre>{@code
 946      *  guardWithCatch=Lambda(a0:L,a1:L,a2:L)=>{
 947      *    t3:L=BoundMethodHandle$Species_LLLLL.argL0(a0:L);
 948      *    t4:L=BoundMethodHandle$Species_LLLLL.argL1(a0:L);
 949      *    t5:L=BoundMethodHandle$Species_LLLLL.argL2(a0:L);
 950      *    t6:L=BoundMethodHandle$Species_LLLLL.argL3(a0:L);
 951      *    t7:L=BoundMethodHandle$Species_LLLLL.argL4(a0:L);
 952      *    t8:L=MethodHandle.invokeBasic(t6:L,a1:L,a2:L);
 953      *    t9:L=MethodHandleImpl.guardWithCatch(t3:L,t4:L,t5:L,t8:L);
 954      *   t10:I=MethodHandle.invokeBasic(t7:L,t9:L);t10:I}
 955      * }</pre></blockquote>
 956      *
 957      * argL0 and argL2 are target and catcher method handles. argL1 is exception class.
 958      * argL3 and argL4 are auxiliary method handles: argL3 boxes arguments and wraps them into Object[]
 959      * (ValueConversions.array()) and argL4 unboxes result if necessary (ValueConversions.unbox()).
 960      *
 961      * Having t8 and t10 passed outside and not hardcoded into a lambda form allows to share lambda forms
 962      * among catchException combinators with the same basic type.
 963      */
 964     private static LambdaForm makeGuardWithCatchForm(MethodType basicType) {
 965         MethodType lambdaType = basicType.invokerType();
 966 
 967         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWC);
 968         if (lform != null) {
 969             return lform;
 970         }
 971         final int THIS_MH      = 0;  // the BMH_LLLLL
 972         final int ARG_BASE     = 1;  // start of incoming arguments
 973         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 974 
 975         int nameCursor = ARG_LIMIT;
 976         final int GET_TARGET       = nameCursor++;
 977         final int GET_CLASS        = nameCursor++;
 978         final int GET_CATCHER      = nameCursor++;
 979         final int GET_COLLECT_ARGS = nameCursor++;
 980         final int GET_UNBOX_RESULT = nameCursor++;
 981         final int BOXED_ARGS       = nameCursor++;
 982         final int TRY_CATCH        = nameCursor++;
 983         final int UNBOX_RESULT     = nameCursor++;
 984 
 985         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 986 
 987         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
 988         names[THIS_MH]          = names[THIS_MH].withConstraint(data);
 989         names[GET_TARGET]       = new Name(data.getterFunction(0), names[THIS_MH]);
 990         names[GET_CLASS]        = new Name(data.getterFunction(1), names[THIS_MH]);
 991         names[GET_CATCHER]      = new Name(data.getterFunction(2), names[THIS_MH]);
 992         names[GET_COLLECT_ARGS] = new Name(data.getterFunction(3), names[THIS_MH]);
 993         names[GET_UNBOX_RESULT] = new Name(data.getterFunction(4), names[THIS_MH]);
 994 
 995         // FIXME: rework argument boxing/result unboxing logic for LF interpretation
 996 
 997         // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
 998         MethodType collectArgsType = basicType.changeReturnType(Object.class);
 999         MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
1000         Object[] args = new Object[invokeBasic.type().parameterCount()];
1001         args[0] = names[GET_COLLECT_ARGS];
1002         System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT-ARG_BASE);
1003         names[BOXED_ARGS] = new Name(makeIntrinsic(invokeBasic, Intrinsic.GUARD_WITH_CATCH), args);
1004 
1005         // t_{i+1}:L=MethodHandleImpl.guardWithCatch(target:L,exType:L,catcher:L,t_{i}:L);
1006         Object[] gwcArgs = new Object[] {names[GET_TARGET], names[GET_CLASS], names[GET_CATCHER], names[BOXED_ARGS]};
1007         names[TRY_CATCH] = new Name(Lazy.NF_guardWithCatch, gwcArgs);
1008 
1009         // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
1010         MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
1011         Object[] unboxArgs  = new Object[] {names[GET_UNBOX_RESULT], names[TRY_CATCH]};
1012         names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
1013 
1014         lform = new LambdaForm("guardWithCatch", lambdaType.parameterCount(), names);
1015 
1016         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWC, lform);
1017     }
1018 
1019     static
1020     MethodHandle makeGuardWithCatch(MethodHandle target,
1021                                     Class<? extends Throwable> exType,
1022                                     MethodHandle catcher) {
1023         MethodType type = target.type();
1024         LambdaForm form = makeGuardWithCatchForm(type.basicType());
1025 
1026         // Prepare auxiliary method handles used during LambdaForm interpretation.
1027         // Box arguments and wrap them into Object[]: ValueConversions.array().
1028         MethodType varargsType = type.changeReturnType(Object[].class);
1029         MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
1030         // Result unboxing: ValueConversions.unbox() OR ValueConversions.identity() OR ValueConversions.ignore().
1031         MethodHandle unboxResult;
1032         Class<?> rtype = type.returnType();
1033         if (rtype.isPrimitive()) {
1034             if (rtype == void.class) {
1035                 unboxResult = ValueConversions.ignore();
1036             } else {
1037                 Wrapper w = Wrapper.forPrimitiveType(type.returnType());
1038                 unboxResult = ValueConversions.unboxExact(w);
1039             }
1040         } else {
1041             unboxResult = MethodHandles.identity(Object.class);
1042         }
1043 
1044         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
1045         BoundMethodHandle mh;
1046         try {
1047             mh = (BoundMethodHandle)
1048                     data.constructor().invokeBasic(type, form, (Object) target, (Object) exType, (Object) catcher,
1049                                                    (Object) collectArgs, (Object) unboxResult);
1050         } catch (Throwable ex) {
1051             throw uncaughtException(ex);
1052         }
1053         assert(mh.type() == type);
1054         return mh;
1055     }
1056 
1057     /**
1058      * Intrinsified during LambdaForm compilation
1059      * (see {@link InvokerBytecodeGenerator#emitGuardWithCatch emitGuardWithCatch}).
1060      */
1061     @LambdaForm.Hidden
1062     static Object guardWithCatch(MethodHandle target, Class<? extends Throwable> exType, MethodHandle catcher,
1063                                  Object... av) throws Throwable {
1064         // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case.
1065         try {
1066             return target.asFixedArity().invokeWithArguments(av);
1067         } catch (Throwable t) {
1068             if (!exType.isInstance(t)) throw t;
1069             return catcher.asFixedArity().invokeWithArguments(prepend(t, av));
1070         }
1071     }
1072 
1073     /** Prepend an element {@code elem} to an {@code array}. */
1074     @LambdaForm.Hidden
1075     private static Object[] prepend(Object elem, Object[] array) {
1076         Object[] newArray = new Object[array.length+1];
1077         newArray[0] = elem;
1078         System.arraycopy(array, 0, newArray, 1, array.length);
1079         return newArray;
1080     }
1081 
1082     static
1083     MethodHandle throwException(MethodType type) {
1084         assert(Throwable.class.isAssignableFrom(type.parameterType(0)));
1085         int arity = type.parameterCount();
1086         if (arity > 1) {
1087             MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
1088             mh = MethodHandles.dropArguments(mh, 1, type.parameterList().subList(1, arity));
1089             return mh;
1090         }
1091         return makePairwiseConvert(Lazy.NF_throwException.resolvedHandle(), type, false, true);
1092     }
1093 
1094     static <T extends Throwable> Empty throwException(T t) throws T { throw t; }
1095 
1096     static MethodHandle[] FAKE_METHOD_HANDLE_INVOKE = new MethodHandle[2];
1097     static MethodHandle fakeMethodHandleInvoke(MemberName method) {
1098         int idx;
1099         assert(method.isMethodHandleInvoke());
1100         switch (method.getName()) {
1101         case "invoke":       idx = 0; break;
1102         case "invokeExact":  idx = 1; break;
1103         default:             throw new InternalError(method.getName());
1104         }
1105         MethodHandle mh = FAKE_METHOD_HANDLE_INVOKE[idx];
1106         if (mh != null)  return mh;
1107         MethodType type = MethodType.methodType(Object.class, UnsupportedOperationException.class,
1108                                                 MethodHandle.class, Object[].class);
1109         mh = throwException(type);
1110         mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke MethodHandle"));
1111         if (!method.getInvocationType().equals(mh.type()))
1112             throw new InternalError(method.toString());
1113         mh = mh.withInternalMemberName(method, false);
1114         mh = mh.asVarargsCollector(Object[].class);
1115         assert(method.isVarargs());
1116         FAKE_METHOD_HANDLE_INVOKE[idx] = mh;
1117         return mh;
1118     }
1119 
1120     /**
1121      * Create an alias for the method handle which, when called,
1122      * appears to be called from the same class loader and protection domain
1123      * as hostClass.
1124      * This is an expensive no-op unless the method which is called
1125      * is sensitive to its caller.  A small number of system methods
1126      * are in this category, including Class.forName and Method.invoke.
1127      */
1128     static
1129     MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1130         return BindCaller.bindCaller(mh, hostClass);
1131     }
1132 
1133     // Put the whole mess into its own nested class.
1134     // That way we can lazily load the code and set up the constants.
1135     private static class BindCaller {
1136         static
1137         MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1138             // Do not use this function to inject calls into system classes.
1139             if (hostClass == null
1140                 ||    (hostClass.isArray() ||
1141                        hostClass.isPrimitive() ||
1142                        hostClass.getName().startsWith("java.") ||
1143                        hostClass.getName().startsWith("sun."))) {
1144                 throw new InternalError();  // does not happen, and should not anyway
1145             }
1146             // For simplicity, convert mh to a varargs-like method.
1147             MethodHandle vamh = prepareForInvoker(mh);
1148             // Cache the result of makeInjectedInvoker once per argument class.
1149             MethodHandle bccInvoker = CV_makeInjectedInvoker.get(hostClass);
1150             return restoreToType(bccInvoker.bindTo(vamh), mh, hostClass);
1151         }
1152 
1153         private static MethodHandle makeInjectedInvoker(Class<?> hostClass) {
1154             Class<?> bcc = UNSAFE.defineAnonymousClass(hostClass, T_BYTES, null);
1155             if (hostClass.getClassLoader() != bcc.getClassLoader())
1156                 throw new InternalError(hostClass.getName()+" (CL)");
1157             try {
1158                 if (hostClass.getProtectionDomain() != bcc.getProtectionDomain())
1159                     throw new InternalError(hostClass.getName()+" (PD)");
1160             } catch (SecurityException ex) {
1161                 // Self-check was blocked by security manager.  This is OK.
1162                 // In fact the whole try body could be turned into an assertion.
1163             }
1164             try {
1165                 MethodHandle init = IMPL_LOOKUP.findStatic(bcc, "init", MethodType.methodType(void.class));
1166                 init.invokeExact();  // force initialization of the class
1167             } catch (Throwable ex) {
1168                 throw uncaughtException(ex);
1169             }
1170             MethodHandle bccInvoker;
1171             try {
1172                 MethodType invokerMT = MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1173                 bccInvoker = IMPL_LOOKUP.findStatic(bcc, "invoke_V", invokerMT);
1174             } catch (ReflectiveOperationException ex) {
1175                 throw uncaughtException(ex);
1176             }
1177             // Test the invoker, to ensure that it really injects into the right place.
1178             try {
1179                 MethodHandle vamh = prepareForInvoker(MH_checkCallerClass);
1180                 Object ok = bccInvoker.invokeExact(vamh, new Object[]{hostClass, bcc});
1181             } catch (Throwable ex) {
1182                 throw new InternalError(ex);
1183             }
1184             return bccInvoker;
1185         }
1186         private static ClassValue<MethodHandle> CV_makeInjectedInvoker = new ClassValue<MethodHandle>() {
1187             @Override protected MethodHandle computeValue(Class<?> hostClass) {
1188                 return makeInjectedInvoker(hostClass);
1189             }
1190         };
1191 
1192         // Adapt mh so that it can be called directly from an injected invoker:
1193         private static MethodHandle prepareForInvoker(MethodHandle mh) {
1194             mh = mh.asFixedArity();
1195             MethodType mt = mh.type();
1196             int arity = mt.parameterCount();
1197             MethodHandle vamh = mh.asType(mt.generic());
1198             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1199             vamh = vamh.asSpreader(Object[].class, arity);
1200             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1201             return vamh;
1202         }
1203 
1204         // Undo the adapter effect of prepareForInvoker:
1205         private static MethodHandle restoreToType(MethodHandle vamh,
1206                                                   MethodHandle original,
1207                                                   Class<?> hostClass) {
1208             MethodType type = original.type();
1209             MethodHandle mh = vamh.asCollector(Object[].class, type.parameterCount());
1210             MemberName member = original.internalMemberName();
1211             mh = mh.asType(type);
1212             mh = new WrappedMember(mh, type, member, original.isInvokeSpecial(), hostClass);
1213             return mh;
1214         }
1215 
1216         private static final MethodHandle MH_checkCallerClass;
1217         static {
1218             final Class<?> THIS_CLASS = BindCaller.class;
1219             assert(checkCallerClass(THIS_CLASS, THIS_CLASS));
1220             try {
1221                 MH_checkCallerClass = IMPL_LOOKUP
1222                     .findStatic(THIS_CLASS, "checkCallerClass",
1223                                 MethodType.methodType(boolean.class, Class.class, Class.class));
1224                 assert((boolean) MH_checkCallerClass.invokeExact(THIS_CLASS, THIS_CLASS));
1225             } catch (Throwable ex) {
1226                 throw new InternalError(ex);
1227             }
1228         }
1229 
1230         @CallerSensitive
1231         private static boolean checkCallerClass(Class<?> expected, Class<?> expected2) {
1232             // This method is called via MH_checkCallerClass and so it's
1233             // correct to ask for the immediate caller here.
1234             Class<?> actual = Reflection.getCallerClass();
1235             if (actual != expected && actual != expected2)
1236                 throw new InternalError("found "+actual.getName()+", expected "+expected.getName()
1237                                         +(expected == expected2 ? "" : ", or else "+expected2.getName()));
1238             return true;
1239         }
1240 
1241         private static final byte[] T_BYTES;
1242         static {
1243             final Object[] values = {null};
1244             AccessController.doPrivileged(new PrivilegedAction<>() {
1245                     public Void run() {
1246                         try {
1247                             Class<T> tClass = T.class;
1248                             String tName = tClass.getName();
1249                             String tResource = tName.substring(tName.lastIndexOf('.')+1)+".class";
1250                             java.net.URLConnection uconn = tClass.getResource(tResource).openConnection();
1251                             int len = uconn.getContentLength();
1252                             byte[] bytes = new byte[len];
1253                             try (java.io.InputStream str = uconn.getInputStream()) {
1254                                 int nr = str.read(bytes);
1255                                 if (nr != len)  throw new java.io.IOException(tResource);
1256                             }
1257                             values[0] = bytes;
1258                         } catch (java.io.IOException ex) {
1259                             throw new InternalError(ex);
1260                         }
1261                         return null;
1262                     }
1263                 });
1264             T_BYTES = (byte[]) values[0];
1265         }
1266 
1267         // The following class is used as a template for Unsafe.defineAnonymousClass:
1268         private static class T {
1269             static void init() { }  // side effect: initializes this class
1270             static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
1271                 return vamh.invokeExact(args);
1272             }
1273         }
1274     }
1275 
1276 
1277     /** This subclass allows a wrapped method handle to be re-associated with an arbitrary member name. */
1278     private static final class WrappedMember extends DelegatingMethodHandle {
1279         private final MethodHandle target;
1280         private final MemberName member;
1281         private final Class<?> callerClass;
1282         private final boolean isInvokeSpecial;
1283 
1284         private WrappedMember(MethodHandle target, MethodType type,
1285                               MemberName member, boolean isInvokeSpecial,
1286                               Class<?> callerClass) {
1287             super(type, target);
1288             this.target = target;
1289             this.member = member;
1290             this.callerClass = callerClass;
1291             this.isInvokeSpecial = isInvokeSpecial;
1292         }
1293 
1294         @Override
1295         MemberName internalMemberName() {
1296             return member;
1297         }
1298         @Override
1299         Class<?> internalCallerClass() {
1300             return callerClass;
1301         }
1302         @Override
1303         boolean isInvokeSpecial() {
1304             return isInvokeSpecial;
1305         }
1306         @Override
1307         protected MethodHandle getTarget() {
1308             return target;
1309         }
1310         @Override
1311         public MethodHandle asTypeUncached(MethodType newType) {
1312             // This MH is an alias for target, except for the MemberName
1313             // Drop the MemberName if there is any conversion.
1314             return asTypeCache = target.asType(newType);
1315         }
1316     }
1317 
1318     static MethodHandle makeWrappedMember(MethodHandle target, MemberName member, boolean isInvokeSpecial) {
1319         if (member.equals(target.internalMemberName()) && isInvokeSpecial == target.isInvokeSpecial())
1320             return target;
1321         return new WrappedMember(target, target.type(), member, isInvokeSpecial, null);
1322     }
1323 
1324     /** Intrinsic IDs */
1325     /*non-public*/
1326     enum Intrinsic {
1327         SELECT_ALTERNATIVE,
1328         GUARD_WITH_CATCH,
1329         NEW_ARRAY,
1330         ARRAY_LOAD,
1331         ARRAY_STORE,
1332         IDENTITY,
1333         ZERO,
1334         NONE // no intrinsic associated
1335     }
1336 
1337     /** Mark arbitrary method handle as intrinsic.
1338      * InvokerBytecodeGenerator uses this info to produce more efficient bytecode shape. */
1339     private static final class IntrinsicMethodHandle extends DelegatingMethodHandle {
1340         private final MethodHandle target;
1341         private final Intrinsic intrinsicName;
1342 
1343         IntrinsicMethodHandle(MethodHandle target, Intrinsic intrinsicName) {
1344             super(target.type(), target);
1345             this.target = target;
1346             this.intrinsicName = intrinsicName;
1347         }
1348 
1349         @Override
1350         protected MethodHandle getTarget() {
1351             return target;
1352         }
1353 
1354         @Override
1355         Intrinsic intrinsicName() {
1356             return intrinsicName;
1357         }
1358 
1359         @Override
1360         public MethodHandle asTypeUncached(MethodType newType) {
1361             // This MH is an alias for target, except for the intrinsic name
1362             // Drop the name if there is any conversion.
1363             return asTypeCache = target.asType(newType);
1364         }
1365 
1366         @Override
1367         String internalProperties() {
1368             return super.internalProperties() +
1369                     "\n& Intrinsic="+intrinsicName;
1370         }
1371 
1372         @Override
1373         public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
1374             if (intrinsicName == Intrinsic.IDENTITY) {
1375                 MethodType resultType = type().asCollectorType(arrayType, arrayLength);
1376                 MethodHandle newArray = MethodHandleImpl.varargsArray(arrayType, arrayLength);
1377                 return newArray.asType(resultType);
1378             }
1379             return super.asCollector(arrayType, arrayLength);
1380         }
1381     }
1382 
1383     static MethodHandle makeIntrinsic(MethodHandle target, Intrinsic intrinsicName) {
1384         if (intrinsicName == target.intrinsicName())
1385             return target;
1386         return new IntrinsicMethodHandle(target, intrinsicName);
1387     }
1388 
1389     static MethodHandle makeIntrinsic(MethodType type, LambdaForm form, Intrinsic intrinsicName) {
1390         return new IntrinsicMethodHandle(SimpleMethodHandle.make(type, form), intrinsicName);
1391     }
1392 
1393     /// Collection of multiple arguments.
1394 
1395     private static MethodHandle findCollector(String name, int nargs, Class<?> rtype, Class<?>... ptypes) {
1396         MethodType type = MethodType.genericMethodType(nargs)
1397                 .changeReturnType(rtype)
1398                 .insertParameterTypes(0, ptypes);
1399         try {
1400             return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, name, type);
1401         } catch (ReflectiveOperationException ex) {
1402             return null;
1403         }
1404     }
1405 
1406     private static final Object[] NO_ARGS_ARRAY = {};
1407     private static Object[] makeArray(Object... args) { return args; }
1408     private static Object[] array() { return NO_ARGS_ARRAY; }
1409     private static Object[] array(Object a0)
1410                 { return makeArray(a0); }
1411     private static Object[] array(Object a0, Object a1)
1412                 { return makeArray(a0, a1); }
1413     private static Object[] array(Object a0, Object a1, Object a2)
1414                 { return makeArray(a0, a1, a2); }
1415     private static Object[] array(Object a0, Object a1, Object a2, Object a3)
1416                 { return makeArray(a0, a1, a2, a3); }
1417     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1418                                   Object a4)
1419                 { return makeArray(a0, a1, a2, a3, a4); }
1420     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1421                                   Object a4, Object a5)
1422                 { return makeArray(a0, a1, a2, a3, a4, a5); }
1423     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1424                                   Object a4, Object a5, Object a6)
1425                 { return makeArray(a0, a1, a2, a3, a4, a5, a6); }
1426     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1427                                   Object a4, Object a5, Object a6, Object a7)
1428                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7); }
1429     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1430                                   Object a4, Object a5, Object a6, Object a7,
1431                                   Object a8)
1432                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8); }
1433     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1434                                   Object a4, Object a5, Object a6, Object a7,
1435                                   Object a8, Object a9)
1436                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); }
1437 
1438     private static final int ARRAYS_COUNT = 11;
1439 
1440     private static MethodHandle[] makeArrays() {
1441         MethodHandle[] mhs = new MethodHandle[MAX_ARITY + 1];
1442         for (int i = 0; i < ARRAYS_COUNT; i++) {
1443             MethodHandle mh = findCollector("array", i, Object[].class);
1444             mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1445             mhs[i] = mh;
1446         }
1447         assert(assertArrayMethodCount(mhs));
1448         return mhs;
1449     }
1450 
1451     private static boolean assertArrayMethodCount(MethodHandle[] mhs) {
1452         assert(findCollector("array", ARRAYS_COUNT, Object[].class) == null);
1453         for (int i = 0; i < ARRAYS_COUNT; i++) {
1454             assert(mhs[i] != null);
1455         }
1456         return true;
1457     }
1458 
1459     // filling versions of the above:
1460     // using Integer len instead of int len and no varargs to avoid bootstrapping problems
1461     private static Object[] fillNewArray(Integer len, Object[] /*not ...*/ args) {
1462         Object[] a = new Object[len];
1463         fillWithArguments(a, 0, args);
1464         return a;
1465     }
1466     private static Object[] fillNewTypedArray(Object[] example, Integer len, Object[] /*not ...*/ args) {
1467         Object[] a = Arrays.copyOf(example, len);
1468         assert(a.getClass() != Object[].class);
1469         fillWithArguments(a, 0, args);
1470         return a;
1471     }
1472     private static void fillWithArguments(Object[] a, int pos, Object... args) {
1473         System.arraycopy(args, 0, a, pos, args.length);
1474     }
1475     // using Integer pos instead of int pos to avoid bootstrapping problems
1476     private static Object[] fillArray(Integer pos, Object[] a, Object a0)
1477                 { fillWithArguments(a, pos, a0); return a; }
1478     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1)
1479                 { fillWithArguments(a, pos, a0, a1); return a; }
1480     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2)
1481                 { fillWithArguments(a, pos, a0, a1, a2); return a; }
1482     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3)
1483                 { fillWithArguments(a, pos, a0, a1, a2, a3); return a; }
1484     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1485                                   Object a4)
1486                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4); return a; }
1487     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1488                                   Object a4, Object a5)
1489                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5); return a; }
1490     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1491                                   Object a4, Object a5, Object a6)
1492                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6); return a; }
1493     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1494                                   Object a4, Object a5, Object a6, Object a7)
1495                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7); return a; }
1496     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1497                                   Object a4, Object a5, Object a6, Object a7,
1498                                   Object a8)
1499                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8); return a; }
1500     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1501                                   Object a4, Object a5, Object a6, Object a7,
1502                                   Object a8, Object a9)
1503                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); return a; }
1504 
1505     private static final int FILL_ARRAYS_COUNT = 11; // current number of fillArray methods
1506 
1507     private static MethodHandle[] makeFillArrays() {
1508         MethodHandle[] mhs = new MethodHandle[FILL_ARRAYS_COUNT];
1509         mhs[0] = null;  // there is no empty fill; at least a0 is required
1510         for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1511             MethodHandle mh = findCollector("fillArray", i, Object[].class, Integer.class, Object[].class);
1512             mhs[i] = mh;
1513         }
1514         assert(assertFillArrayMethodCount(mhs));
1515         return mhs;
1516     }
1517 
1518     private static boolean assertFillArrayMethodCount(MethodHandle[] mhs) {
1519         assert(findCollector("fillArray", FILL_ARRAYS_COUNT, Object[].class, Integer.class, Object[].class) == null);
1520         for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1521             assert(mhs[i] != null);
1522         }
1523         return true;
1524     }
1525 
1526     private static Object copyAsPrimitiveArray(Wrapper w, Object... boxes) {
1527         Object a = w.makeArray(boxes.length);
1528         w.copyArrayUnboxing(boxes, 0, a, 0, boxes.length);
1529         return a;
1530     }
1531 
1532     /** Return a method handle that takes the indicated number of Object
1533      *  arguments and returns an Object array of them, as if for varargs.
1534      */
1535     static MethodHandle varargsArray(int nargs) {
1536         MethodHandle mh = Lazy.ARRAYS[nargs];
1537         if (mh != null)  return mh;
1538         mh = buildVarargsArray(Lazy.MH_fillNewArray, Lazy.MH_arrayIdentity, nargs);
1539         assert(assertCorrectArity(mh, nargs));
1540         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1541         return Lazy.ARRAYS[nargs] = mh;
1542     }
1543 
1544     private static boolean assertCorrectArity(MethodHandle mh, int arity) {
1545         assert(mh.type().parameterCount() == arity) : "arity != "+arity+": "+mh;
1546         return true;
1547     }
1548 
1549     // Array identity function (used as Lazy.MH_arrayIdentity).
1550     static <T> T[] identity(T[] x) {
1551         return x;
1552     }
1553 
1554     private static MethodHandle buildVarargsArray(MethodHandle newArray, MethodHandle finisher, int nargs) {
1555         // Build up the result mh as a sequence of fills like this:
1556         //   finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
1557         // The various fill(_,10*I,___*[J]) are reusable.
1558         int leftLen = Math.min(nargs, LEFT_ARGS);  // absorb some arguments immediately
1559         int rightLen = nargs - leftLen;
1560         MethodHandle leftCollector = newArray.bindTo(nargs);
1561         leftCollector = leftCollector.asCollector(Object[].class, leftLen);
1562         MethodHandle mh = finisher;
1563         if (rightLen > 0) {
1564             MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
1565             if (mh == Lazy.MH_arrayIdentity)
1566                 mh = rightFiller;
1567             else
1568                 mh = MethodHandles.collectArguments(mh, 0, rightFiller);
1569         }
1570         if (mh == Lazy.MH_arrayIdentity)
1571             mh = leftCollector;
1572         else
1573             mh = MethodHandles.collectArguments(mh, 0, leftCollector);
1574         return mh;
1575     }
1576 
1577     private static final int LEFT_ARGS = FILL_ARRAYS_COUNT - 1;
1578     private static final MethodHandle[] FILL_ARRAY_TO_RIGHT = new MethodHandle[MAX_ARITY+1];
1579     /** fill_array_to_right(N).invoke(a, argL..arg[N-1])
1580      *  fills a[L]..a[N-1] with corresponding arguments,
1581      *  and then returns a.  The value L is a global constant (LEFT_ARGS).
1582      */
1583     private static MethodHandle fillToRight(int nargs) {
1584         MethodHandle filler = FILL_ARRAY_TO_RIGHT[nargs];
1585         if (filler != null)  return filler;
1586         filler = buildFiller(nargs);
1587         assert(assertCorrectArity(filler, nargs - LEFT_ARGS + 1));
1588         return FILL_ARRAY_TO_RIGHT[nargs] = filler;
1589     }
1590     private static MethodHandle buildFiller(int nargs) {
1591         if (nargs <= LEFT_ARGS)
1592             return Lazy.MH_arrayIdentity;  // no args to fill; return the array unchanged
1593         // we need room for both mh and a in mh.invoke(a, arg*[nargs])
1594         final int CHUNK = LEFT_ARGS;
1595         int rightLen = nargs % CHUNK;
1596         int midLen = nargs - rightLen;
1597         if (rightLen == 0) {
1598             midLen = nargs - (rightLen = CHUNK);
1599             if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
1600                 // build some precursors from left to right
1601                 for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK)
1602                     if (j > LEFT_ARGS)  fillToRight(j);
1603             }
1604         }
1605         if (midLen < LEFT_ARGS) rightLen = nargs - (midLen = LEFT_ARGS);
1606         assert(rightLen > 0);
1607         MethodHandle midFill = fillToRight(midLen);  // recursive fill
1608         MethodHandle rightFill = Lazy.FILL_ARRAYS[rightLen].bindTo(midLen);  // [midLen..nargs-1]
1609         assert(midFill.type().parameterCount()   == 1 + midLen - LEFT_ARGS);
1610         assert(rightFill.type().parameterCount() == 1 + rightLen);
1611 
1612         // Combine the two fills:
1613         //   right(mid(a, x10..x19), x20..x23)
1614         // The final product will look like this:
1615         //   right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
1616         if (midLen == LEFT_ARGS)
1617             return rightFill;
1618         else
1619             return MethodHandles.collectArguments(rightFill, 0, midFill);
1620     }
1621 
1622     // Type-polymorphic version of varargs maker.
1623     private static final ClassValue<MethodHandle[]> TYPED_COLLECTORS
1624         = new ClassValue<MethodHandle[]>() {
1625             @Override
1626             protected MethodHandle[] computeValue(Class<?> type) {
1627                 return new MethodHandle[256];
1628             }
1629     };
1630 
1631     static final int MAX_JVM_ARITY = 255;  // limit imposed by the JVM
1632 
1633     /** Return a method handle that takes the indicated number of
1634      *  typed arguments and returns an array of them.
1635      *  The type argument is the array type.
1636      */
1637     static MethodHandle varargsArray(Class<?> arrayType, int nargs) {
1638         Class<?> elemType = arrayType.getComponentType();
1639         if (elemType == null)  throw new IllegalArgumentException("not an array: "+arrayType);
1640         // FIXME: Need more special casing and caching here.
1641         if (nargs >= MAX_JVM_ARITY/2 - 1) {
1642             int slots = nargs;
1643             final int MAX_ARRAY_SLOTS = MAX_JVM_ARITY - 1;  // 1 for receiver MH
1644             if (slots <= MAX_ARRAY_SLOTS && elemType.isPrimitive())
1645                 slots *= Wrapper.forPrimitiveType(elemType).stackSlots();
1646             if (slots > MAX_ARRAY_SLOTS)
1647                 throw new IllegalArgumentException("too many arguments: "+arrayType.getSimpleName()+", length "+nargs);
1648         }
1649         if (elemType == Object.class)
1650             return varargsArray(nargs);
1651         // other cases:  primitive arrays, subtypes of Object[]
1652         MethodHandle cache[] = TYPED_COLLECTORS.get(elemType);
1653         MethodHandle mh = nargs < cache.length ? cache[nargs] : null;
1654         if (mh != null)  return mh;
1655         if (nargs == 0) {
1656             Object example = java.lang.reflect.Array.newInstance(arrayType.getComponentType(), 0);
1657             mh = MethodHandles.constant(arrayType, example);
1658         } else if (elemType.isPrimitive()) {
1659             MethodHandle builder = Lazy.MH_fillNewArray;
1660             MethodHandle producer = buildArrayProducer(arrayType);
1661             mh = buildVarargsArray(builder, producer, nargs);
1662         } else {
1663             Class<? extends Object[]> objArrayType = arrayType.asSubclass(Object[].class);
1664             Object[] example = Arrays.copyOf(NO_ARGS_ARRAY, 0, objArrayType);
1665             MethodHandle builder = Lazy.MH_fillNewTypedArray.bindTo(example);
1666             MethodHandle producer = Lazy.MH_arrayIdentity; // must be weakly typed
1667             mh = buildVarargsArray(builder, producer, nargs);
1668         }
1669         mh = mh.asType(MethodType.methodType(arrayType, Collections.<Class<?>>nCopies(nargs, elemType)));
1670         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1671         assert(assertCorrectArity(mh, nargs));
1672         if (nargs < cache.length)
1673             cache[nargs] = mh;
1674         return mh;
1675     }
1676 
1677     private static MethodHandle buildArrayProducer(Class<?> arrayType) {
1678         Class<?> elemType = arrayType.getComponentType();
1679         assert(elemType.isPrimitive());
1680         return Lazy.MH_copyAsPrimitiveArray.bindTo(Wrapper.forPrimitiveType(elemType));
1681     }
1682 
1683     /*non-public*/ static void assertSame(Object mh1, Object mh2) {
1684         if (mh1 != mh2) {
1685             String msg = String.format("mh1 != mh2: mh1 = %s (form: %s); mh2 = %s (form: %s)",
1686                     mh1, ((MethodHandle)mh1).form,
1687                     mh2, ((MethodHandle)mh2).form);
1688             throw newInternalError(msg);
1689         }
1690     }
1691 }
--- EOF ---