rev 13050 : 8142334: Improve lazy initialization of java.lang.invoke
Reviewed-by: psandoz, vlivanov, mhaupt

   1 /*
   2  * Copyright (c) 2008, 2015, 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 jdk.internal.HotSpotIntrinsicCandidate;
  40 import sun.reflect.CallerSensitive;
  41 import sun.reflect.Reflection;
  42 import static java.lang.invoke.LambdaForm.*;
  43 import static java.lang.invoke.MethodHandleStatics.*;
  44 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
  45 
  46 /**
  47  * Trusted implementation code for MethodHandle.
  48  * @author jrose
  49  */
  50 /*non-public*/ abstract class MethodHandleImpl {
  51     // Do not adjust this except for special platforms:
  52     private static final int MAX_ARITY;
  53     static {
  54         final Object[] values = { 255 };
  55         AccessController.doPrivileged(new PrivilegedAction<>() {
  56             @Override
  57             public Void run() {
  58                 values[0] = Integer.getInteger(MethodHandleImpl.class.getName()+".MAX_ARITY", 255);
  59                 return null;
  60             }
  61         });
  62         MAX_ARITY = (Integer) values[0];
  63     }
  64 
  65     /// Factory methods to create method handles:
  66 
  67     static void initStatics() {
  68         // Trigger selected static initializations.
  69         MemberName.Factory.INSTANCE.getClass();
  70     }
  71 
  72     static MethodHandle makeArrayElementAccessor(Class<?> arrayClass, boolean isSetter) {
  73         if (arrayClass == Object[].class)
  74             return (isSetter ? ArrayAccessor.OBJECT_ARRAY_SETTER : ArrayAccessor.OBJECT_ARRAY_GETTER);
  75         if (!arrayClass.isArray())
  76             throw newIllegalArgumentException("not an array: "+arrayClass);
  77         MethodHandle[] cache = ArrayAccessor.TYPED_ACCESSORS.get(arrayClass);
  78         int cacheIndex = (isSetter ? ArrayAccessor.SETTER_INDEX : ArrayAccessor.GETTER_INDEX);
  79         MethodHandle mh = cache[cacheIndex];
  80         if (mh != null)  return mh;
  81         mh = ArrayAccessor.getAccessor(arrayClass, isSetter);
  82         MethodType correctType = ArrayAccessor.correctType(arrayClass, isSetter);
  83         if (mh.type() != correctType) {
  84             assert(mh.type().parameterType(0) == Object[].class);
  85             assert((isSetter ? mh.type().parameterType(2) : mh.type().returnType()) == Object.class);
  86             assert(isSetter || correctType.parameterType(0).getComponentType() == correctType.returnType());
  87             // safe to view non-strictly, because element type follows from array type
  88             mh = mh.viewAsType(correctType, false);
  89         }
  90         mh = makeIntrinsic(mh, (isSetter ? Intrinsic.ARRAY_STORE : Intrinsic.ARRAY_LOAD));
  91         // Atomically update accessor cache.
  92         synchronized(cache) {
  93             if (cache[cacheIndex] == null) {
  94                 cache[cacheIndex] = mh;
  95             } else {
  96                 // Throw away newly constructed accessor and use cached version.
  97                 mh = cache[cacheIndex];
  98             }
  99         }
 100         return mh;
 101     }
 102 
 103     static final class ArrayAccessor {
 104         /// Support for array element access
 105         static final int GETTER_INDEX = 0, SETTER_INDEX = 1, INDEX_LIMIT = 2;
 106         static final ClassValue<MethodHandle[]> TYPED_ACCESSORS
 107                 = new ClassValue<MethodHandle[]>() {
 108                     @Override
 109                     protected MethodHandle[] computeValue(Class<?> type) {
 110                         return new MethodHandle[INDEX_LIMIT];
 111                     }
 112                 };
 113         static final MethodHandle OBJECT_ARRAY_GETTER, OBJECT_ARRAY_SETTER;
 114         static {
 115             MethodHandle[] cache = TYPED_ACCESSORS.get(Object[].class);
 116             cache[GETTER_INDEX] = OBJECT_ARRAY_GETTER = makeIntrinsic(getAccessor(Object[].class, false), Intrinsic.ARRAY_LOAD);
 117             cache[SETTER_INDEX] = OBJECT_ARRAY_SETTER = makeIntrinsic(getAccessor(Object[].class, true),  Intrinsic.ARRAY_STORE);
 118 
 119             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_GETTER.internalMemberName()));
 120             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_SETTER.internalMemberName()));
 121         }
 122 
 123         static int     getElementI(int[]     a, int i)            { return              a[i]; }
 124         static long    getElementJ(long[]    a, int i)            { return              a[i]; }
 125         static float   getElementF(float[]   a, int i)            { return              a[i]; }
 126         static double  getElementD(double[]  a, int i)            { return              a[i]; }
 127         static boolean getElementZ(boolean[] a, int i)            { return              a[i]; }
 128         static byte    getElementB(byte[]    a, int i)            { return              a[i]; }
 129         static short   getElementS(short[]   a, int i)            { return              a[i]; }
 130         static char    getElementC(char[]    a, int i)            { return              a[i]; }
 131         static Object  getElementL(Object[]  a, int i)            { return              a[i]; }
 132 
 133         static void    setElementI(int[]     a, int i, int     x) {              a[i] = x; }
 134         static void    setElementJ(long[]    a, int i, long    x) {              a[i] = x; }
 135         static void    setElementF(float[]   a, int i, float   x) {              a[i] = x; }
 136         static void    setElementD(double[]  a, int i, double  x) {              a[i] = x; }
 137         static void    setElementZ(boolean[] a, int i, boolean x) {              a[i] = x; }
 138         static void    setElementB(byte[]    a, int i, byte    x) {              a[i] = x; }
 139         static void    setElementS(short[]   a, int i, short   x) {              a[i] = x; }
 140         static void    setElementC(char[]    a, int i, char    x) {              a[i] = x; }
 141         static void    setElementL(Object[]  a, int i, Object  x) {              a[i] = x; }
 142 
 143         static String name(Class<?> arrayClass, boolean isSetter) {
 144             Class<?> elemClass = arrayClass.getComponentType();
 145             if (elemClass == null)  throw newIllegalArgumentException("not an array", arrayClass);
 146             return (!isSetter ? "getElement" : "setElement") + Wrapper.basicTypeChar(elemClass);
 147         }
 148         static MethodType type(Class<?> arrayClass, boolean isSetter) {
 149             Class<?> elemClass = arrayClass.getComponentType();
 150             Class<?> arrayArgClass = arrayClass;
 151             if (!elemClass.isPrimitive()) {
 152                 arrayArgClass = Object[].class;
 153                 elemClass = Object.class;
 154             }
 155             return !isSetter ?
 156                     MethodType.methodType(elemClass,  arrayArgClass, int.class) :
 157                     MethodType.methodType(void.class, arrayArgClass, int.class, elemClass);
 158         }
 159         static MethodType correctType(Class<?> arrayClass, boolean isSetter) {
 160             Class<?> elemClass = arrayClass.getComponentType();
 161             return !isSetter ?
 162                     MethodType.methodType(elemClass,  arrayClass, int.class) :
 163                     MethodType.methodType(void.class, arrayClass, int.class, elemClass);
 164         }
 165         static MethodHandle getAccessor(Class<?> arrayClass, boolean isSetter) {
 166             String     name = name(arrayClass, isSetter);
 167             MethodType type = type(arrayClass, isSetter);
 168             try {
 169                 return IMPL_LOOKUP.findStatic(ArrayAccessor.class, name, type);
 170             } catch (ReflectiveOperationException ex) {
 171                 throw uncaughtException(ex);
 172             }
 173         }
 174     }
 175 
 176     /**
 177      * Create a JVM-level adapter method handle to conform the given method
 178      * handle to the similar newType, using only pairwise argument conversions.
 179      * For each argument, convert incoming argument to the exact type needed.
 180      * The argument conversions allowed are casting, boxing and unboxing,
 181      * integral widening or narrowing, and floating point widening or narrowing.
 182      * @param srcType required call type
 183      * @param target original method handle
 184      * @param strict if true, only asType conversions are allowed; if false, explicitCastArguments conversions allowed
 185      * @param monobox if true, unboxing conversions are assumed to be exactly typed (Integer to int only, not long or double)
 186      * @return an adapter to the original handle with the desired new type,
 187      *          or the original target if the types are already identical
 188      *          or null if the adaptation cannot be made
 189      */
 190     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 191                                             boolean strict, boolean monobox) {
 192         MethodType dstType = target.type();
 193         if (srcType == dstType)
 194             return target;
 195         return makePairwiseConvertByEditor(target, srcType, strict, monobox);
 196     }
 197 
 198     private static int countNonNull(Object[] array) {
 199         int count = 0;
 200         for (Object x : array) {
 201             if (x != null)  ++count;
 202         }
 203         return count;
 204     }
 205 
 206     static MethodHandle makePairwiseConvertByEditor(MethodHandle target, MethodType srcType,
 207                                                     boolean strict, boolean monobox) {
 208         Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
 209         int convCount = countNonNull(convSpecs);
 210         if (convCount == 0)
 211             return target.viewAsType(srcType, strict);
 212         MethodType basicSrcType = srcType.basicType();
 213         MethodType midType = target.type().basicType();
 214         BoundMethodHandle mh = target.rebind();
 215         // FIXME: Reduce number of bindings when there is more than one Class conversion.
 216         // FIXME: Reduce number of bindings when there are repeated conversions.
 217         for (int i = 0; i < convSpecs.length-1; i++) {
 218             Object convSpec = convSpecs[i];
 219             if (convSpec == null)  continue;
 220             MethodHandle fn;
 221             if (convSpec instanceof Class) {
 222                 fn = Lazy.MH_cast.bindTo(convSpec);
 223             } else {
 224                 fn = (MethodHandle) convSpec;
 225             }
 226             Class<?> newType = basicSrcType.parameterType(i);
 227             if (--convCount == 0)
 228                 midType = srcType;
 229             else
 230                 midType = midType.changeParameterType(i, newType);
 231             LambdaForm form2 = mh.editor().filterArgumentForm(1+i, BasicType.basicType(newType));
 232             mh = mh.copyWithExtendL(midType, form2, fn);
 233             mh = mh.rebind();
 234         }
 235         Object convSpec = convSpecs[convSpecs.length-1];
 236         if (convSpec != null) {
 237             MethodHandle fn;
 238             if (convSpec instanceof Class) {
 239                 if (convSpec == void.class)
 240                     fn = null;
 241                 else
 242                     fn = Lazy.MH_cast.bindTo(convSpec);
 243             } else {
 244                 fn = (MethodHandle) convSpec;
 245             }
 246             Class<?> newType = basicSrcType.returnType();
 247             assert(--convCount == 0);
 248             midType = srcType;
 249             if (fn != null) {
 250                 mh = mh.rebind();  // rebind if too complex
 251                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), false);
 252                 mh = mh.copyWithExtendL(midType, form2, fn);
 253             } else {
 254                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), true);
 255                 mh = mh.copyWith(midType, form2);
 256             }
 257         }
 258         assert(convCount == 0);
 259         assert(mh.type().equals(srcType));
 260         return mh;
 261     }
 262 
 263     static MethodHandle makePairwiseConvertIndirect(MethodHandle target, MethodType srcType,
 264                                                     boolean strict, boolean monobox) {
 265         assert(target.type().parameterCount() == srcType.parameterCount());
 266         // Calculate extra arguments (temporaries) required in the names array.
 267         Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
 268         final int INARG_COUNT = srcType.parameterCount();
 269         int convCount = countNonNull(convSpecs);
 270         boolean retConv = (convSpecs[INARG_COUNT] != null);
 271         boolean retVoid = srcType.returnType() == void.class;
 272         if (retConv && retVoid) {
 273             convCount -= 1;
 274             retConv = false;
 275         }
 276 
 277         final int IN_MH         = 0;
 278         final int INARG_BASE    = 1;
 279         final int INARG_LIMIT   = INARG_BASE + INARG_COUNT;
 280         final int NAME_LIMIT    = INARG_LIMIT + convCount + 1;
 281         final int RETURN_CONV   = (!retConv ? -1         : NAME_LIMIT - 1);
 282         final int OUT_CALL      = (!retConv ? NAME_LIMIT : RETURN_CONV) - 1;
 283         final int RESULT        = (retVoid ? -1 : NAME_LIMIT - 1);
 284 
 285         // Now build a LambdaForm.
 286         MethodType lambdaType = srcType.basicType().invokerType();
 287         Name[] names = arguments(NAME_LIMIT - INARG_LIMIT, lambdaType);
 288 
 289         // Collect the arguments to the outgoing call, maybe with conversions:
 290         final int OUTARG_BASE = 0;  // target MH is Name.function, name Name.arguments[0]
 291         Object[] outArgs = new Object[OUTARG_BASE + INARG_COUNT];
 292 
 293         int nameCursor = INARG_LIMIT;
 294         for (int i = 0; i < INARG_COUNT; i++) {
 295             Object convSpec = convSpecs[i];
 296             if (convSpec == null) {
 297                 // do nothing: difference is trivial
 298                 outArgs[OUTARG_BASE + i] = names[INARG_BASE + i];
 299                 continue;
 300             }
 301 
 302             Name conv;
 303             if (convSpec instanceof Class) {
 304                 Class<?> convClass = (Class<?>) convSpec;
 305                 conv = new Name(Lazy.MH_cast, convClass, names[INARG_BASE + i]);
 306             } else {
 307                 MethodHandle fn = (MethodHandle) convSpec;
 308                 conv = new Name(fn, names[INARG_BASE + i]);
 309             }
 310             assert(names[nameCursor] == null);
 311             names[nameCursor++] = conv;
 312             assert(outArgs[OUTARG_BASE + i] == null);
 313             outArgs[OUTARG_BASE + i] = conv;
 314         }
 315 
 316         // Build argument array for the call.
 317         assert(nameCursor == OUT_CALL);
 318         names[OUT_CALL] = new Name(target, outArgs);
 319 
 320         Object convSpec = convSpecs[INARG_COUNT];
 321         if (!retConv) {
 322             assert(OUT_CALL == names.length-1);
 323         } else {
 324             Name conv;
 325             if (convSpec == void.class) {
 326                 conv = new Name(LambdaForm.constantZero(BasicType.basicType(srcType.returnType())));
 327             } else if (convSpec instanceof Class) {
 328                 Class<?> convClass = (Class<?>) convSpec;
 329                 conv = new Name(Lazy.MH_cast, convClass, names[OUT_CALL]);
 330             } else {
 331                 MethodHandle fn = (MethodHandle) convSpec;
 332                 if (fn.type().parameterCount() == 0)
 333                     conv = new Name(fn);  // don't pass retval to void conversion
 334                 else
 335                     conv = new Name(fn, names[OUT_CALL]);
 336             }
 337             assert(names[RETURN_CONV] == null);
 338             names[RETURN_CONV] = conv;
 339             assert(RETURN_CONV == names.length-1);
 340         }
 341 
 342         LambdaForm form = new LambdaForm("convert", lambdaType.parameterCount(), names, RESULT);
 343         return SimpleMethodHandle.make(srcType, form);
 344     }
 345 
 346     static Object[] computeValueConversions(MethodType srcType, MethodType dstType,
 347                                             boolean strict, boolean monobox) {
 348         final int INARG_COUNT = srcType.parameterCount();
 349         Object[] convSpecs = new Object[INARG_COUNT+1];
 350         for (int i = 0; i <= INARG_COUNT; i++) {
 351             boolean isRet = (i == INARG_COUNT);
 352             Class<?> src = isRet ? dstType.returnType() : srcType.parameterType(i);
 353             Class<?> dst = isRet ? srcType.returnType() : dstType.parameterType(i);
 354             if (!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)) {
 355                 convSpecs[i] = valueConversion(src, dst, strict, monobox);
 356             }
 357         }
 358         return convSpecs;
 359     }
 360     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 361                                             boolean strict) {
 362         return makePairwiseConvert(target, srcType, strict, /*monobox=*/ false);
 363     }
 364 
 365     /**
 366      * Find a conversion function from the given source to the given destination.
 367      * This conversion function will be used as a LF NamedFunction.
 368      * Return a Class object if a simple cast is needed.
 369      * Return void.class if void is involved.
 370      */
 371     static Object valueConversion(Class<?> src, Class<?> dst, boolean strict, boolean monobox) {
 372         assert(!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict));  // caller responsibility
 373         if (dst == void.class)
 374             return dst;
 375         MethodHandle fn;
 376         if (src.isPrimitive()) {
 377             if (src == void.class) {
 378                 return void.class;  // caller must recognize this specially
 379             } else if (dst.isPrimitive()) {
 380                 // Examples: int->byte, byte->int, boolean->int (!strict)
 381                 fn = ValueConversions.convertPrimitive(src, dst);
 382             } else {
 383                 // Examples: int->Integer, boolean->Object, float->Number
 384                 Wrapper wsrc = Wrapper.forPrimitiveType(src);
 385                 fn = ValueConversions.boxExact(wsrc);
 386                 assert(fn.type().parameterType(0) == wsrc.primitiveType());
 387                 assert(fn.type().returnType() == wsrc.wrapperType());
 388                 if (!VerifyType.isNullConversion(wsrc.wrapperType(), dst, strict)) {
 389                     // Corner case, such as int->Long, which will probably fail.
 390                     MethodType mt = MethodType.methodType(dst, src);
 391                     if (strict)
 392                         fn = fn.asType(mt);
 393                     else
 394                         fn = MethodHandleImpl.makePairwiseConvert(fn, mt, /*strict=*/ false);
 395                 }
 396             }
 397         } else if (dst.isPrimitive()) {
 398             Wrapper wdst = Wrapper.forPrimitiveType(dst);
 399             if (monobox || src == wdst.wrapperType()) {
 400                 // Use a strongly-typed unboxer, if possible.
 401                 fn = ValueConversions.unboxExact(wdst, strict);
 402             } else {
 403                 // Examples:  Object->int, Number->int, Comparable->int, Byte->int
 404                 // must include additional conversions
 405                 // src must be examined at runtime, to detect Byte, Character, etc.
 406                 fn = (strict
 407                         ? ValueConversions.unboxWiden(wdst)
 408                         : ValueConversions.unboxCast(wdst));
 409             }
 410         } else {
 411             // Simple reference conversion.
 412             // Note:  Do not check for a class hierarchy relation
 413             // between src and dst.  In all cases a 'null' argument
 414             // will pass the cast conversion.
 415             return dst;
 416         }
 417         assert(fn.type().parameterCount() <= 1) : "pc"+Arrays.asList(src.getSimpleName(), dst.getSimpleName(), fn);
 418         return fn;
 419     }
 420 
 421     static MethodHandle makeVarargsCollector(MethodHandle target, Class<?> arrayType) {
 422         MethodType type = target.type();
 423         int last = type.parameterCount() - 1;
 424         if (type.parameterType(last) != arrayType)
 425             target = target.asType(type.changeParameterType(last, arrayType));
 426         target = target.asFixedArity();  // make sure this attribute is turned off
 427         return new AsVarargsCollector(target, arrayType);
 428     }
 429 
 430     private static final class AsVarargsCollector extends DelegatingMethodHandle {
 431         private final MethodHandle target;
 432         private final Class<?> arrayType;
 433         private @Stable MethodHandle asCollectorCache;
 434 
 435         AsVarargsCollector(MethodHandle target, Class<?> arrayType) {
 436             this(target.type(), target, arrayType);
 437         }
 438         AsVarargsCollector(MethodType type, MethodHandle target, Class<?> arrayType) {
 439             super(type, target);
 440             this.target = target;
 441             this.arrayType = arrayType;
 442             this.asCollectorCache = target.asCollector(arrayType, 0);
 443         }
 444 
 445         @Override
 446         public boolean isVarargsCollector() {
 447             return true;
 448         }
 449 
 450         @Override
 451         protected MethodHandle getTarget() {
 452             return target;
 453         }
 454 
 455         @Override
 456         public MethodHandle asFixedArity() {
 457             return target;
 458         }
 459 
 460         @Override
 461         MethodHandle setVarargs(MemberName member) {
 462             if (member.isVarargs())  return this;
 463             return asFixedArity();
 464         }
 465 
 466         @Override
 467         public MethodHandle asTypeUncached(MethodType newType) {
 468             MethodType type = this.type();
 469             int collectArg = type.parameterCount() - 1;
 470             int newArity = newType.parameterCount();
 471             if (newArity == collectArg+1 &&
 472                 type.parameterType(collectArg).isAssignableFrom(newType.parameterType(collectArg))) {
 473                 // if arity and trailing parameter are compatible, do normal thing
 474                 return asTypeCache = asFixedArity().asType(newType);
 475             }
 476             // check cache
 477             MethodHandle acc = asCollectorCache;
 478             if (acc != null && acc.type().parameterCount() == newArity)
 479                 return asTypeCache = acc.asType(newType);
 480             // build and cache a collector
 481             int arrayLength = newArity - collectArg;
 482             MethodHandle collector;
 483             try {
 484                 collector = asFixedArity().asCollector(arrayType, arrayLength);
 485                 assert(collector.type().parameterCount() == newArity) : "newArity="+newArity+" but collector="+collector;
 486             } catch (IllegalArgumentException ex) {
 487                 throw new WrongMethodTypeException("cannot build collector", ex);
 488             }
 489             asCollectorCache = collector;
 490             return asTypeCache = collector.asType(newType);
 491         }
 492 
 493         @Override
 494         boolean viewAsTypeChecks(MethodType newType, boolean strict) {
 495             super.viewAsTypeChecks(newType, true);
 496             if (strict) return true;
 497             // extra assertion for non-strict checks:
 498             assert (type().lastParameterType().getComponentType()
 499                     .isAssignableFrom(
 500                             newType.lastParameterType().getComponentType()))
 501                     : Arrays.asList(this, newType);
 502             return true;
 503         }
 504     }
 505 
 506     /** Factory method:  Spread selected argument. */
 507     static MethodHandle makeSpreadArguments(MethodHandle target,
 508                                             Class<?> spreadArgType, int spreadArgPos, int spreadArgCount) {
 509         MethodType targetType = target.type();
 510 
 511         for (int i = 0; i < spreadArgCount; i++) {
 512             Class<?> arg = VerifyType.spreadArgElementType(spreadArgType, i);
 513             if (arg == null)  arg = Object.class;
 514             targetType = targetType.changeParameterType(spreadArgPos + i, arg);
 515         }
 516         target = target.asType(targetType);
 517 
 518         MethodType srcType = targetType
 519                 .replaceParameterTypes(spreadArgPos, spreadArgPos + spreadArgCount, spreadArgType);
 520         // Now build a LambdaForm.
 521         MethodType lambdaType = srcType.invokerType();
 522         Name[] names = arguments(spreadArgCount + 2, lambdaType);
 523         int nameCursor = lambdaType.parameterCount();
 524         int[] indexes = new int[targetType.parameterCount()];
 525 
 526         for (int i = 0, argIndex = 1; i < targetType.parameterCount() + 1; i++, argIndex++) {
 527             Class<?> src = lambdaType.parameterType(i);
 528             if (i == spreadArgPos) {
 529                 // Spread the array.
 530                 MethodHandle aload = MethodHandles.arrayElementGetter(spreadArgType);
 531                 Name array = names[argIndex];
 532                 names[nameCursor++] = new Name(Lazy.NF_checkSpreadArgument, array, spreadArgCount);
 533                 for (int j = 0; j < spreadArgCount; i++, j++) {
 534                     indexes[i] = nameCursor;
 535                     names[nameCursor++] = new Name(aload, array, j);
 536                 }
 537             } else if (i < indexes.length) {
 538                 indexes[i] = argIndex;
 539             }
 540         }
 541         assert(nameCursor == names.length-1);  // leave room for the final call
 542 
 543         // Build argument array for the call.
 544         Name[] targetArgs = new Name[targetType.parameterCount()];
 545         for (int i = 0; i < targetType.parameterCount(); i++) {
 546             int idx = indexes[i];
 547             targetArgs[i] = names[idx];
 548         }
 549         names[names.length - 1] = new Name(target, (Object[]) targetArgs);
 550 
 551         LambdaForm form = new LambdaForm("spread", lambdaType.parameterCount(), names);
 552         return SimpleMethodHandle.make(srcType, form);
 553     }
 554 
 555     static void checkSpreadArgument(Object av, int n) {
 556         if (av == null) {
 557             if (n == 0)  return;
 558         } else if (av instanceof Object[]) {
 559             int len = ((Object[])av).length;
 560             if (len == n)  return;
 561         } else {
 562             int len = java.lang.reflect.Array.getLength(av);
 563             if (len == n)  return;
 564         }
 565         // fall through to error:
 566         throw newIllegalArgumentException("array is not of length "+n);
 567     }
 568 
 569     /**
 570      * Pre-initialized NamedFunctions for bootstrapping purposes.
 571      * Factored in an inner class to delay initialization until first usage.
 572      */
 573     static class Lazy {
 574         private static final Class<?> MHI = MethodHandleImpl.class;
 575         private static final Class<?> CLS = Class.class;
 576 
 577         private static final MethodHandle[] ARRAYS;
 578         private static final MethodHandle[] FILL_ARRAYS;
 579 
 580         static final NamedFunction NF_checkSpreadArgument;
 581         static final NamedFunction NF_guardWithCatch;
 582         static final NamedFunction NF_throwException;
 583         static final NamedFunction NF_profileBoolean;
 584 
 585         static final MethodHandle MH_cast;
 586         static final MethodHandle MH_selectAlternative;
 587         static final MethodHandle MH_copyAsPrimitiveArray;
 588         static final MethodHandle MH_fillNewTypedArray;
 589         static final MethodHandle MH_fillNewArray;
 590         static final MethodHandle MH_arrayIdentity;
 591 
 592         static {
 593             ARRAYS      = makeArrays();
 594             FILL_ARRAYS = makeFillArrays();
 595 
 596             try {
 597                 NF_checkSpreadArgument = new NamedFunction(MHI.getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
 598                 NF_guardWithCatch      = new NamedFunction(MHI.getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
 599                                                                                  MethodHandle.class, Object[].class));
 600                 NF_throwException      = new NamedFunction(MHI.getDeclaredMethod("throwException", Throwable.class));
 601                 NF_profileBoolean      = new NamedFunction(MHI.getDeclaredMethod("profileBoolean", boolean.class, int[].class));
 602 
 603                 NF_checkSpreadArgument.resolve();
 604                 NF_guardWithCatch.resolve();
 605                 NF_throwException.resolve();
 606                 NF_profileBoolean.resolve();
 607 
 608                 MH_cast                 = IMPL_LOOKUP.findVirtual(CLS, "cast",
 609                                             MethodType.methodType(Object.class, Object.class));
 610                 MH_copyAsPrimitiveArray = IMPL_LOOKUP.findStatic(MHI, "copyAsPrimitiveArray",
 611                                             MethodType.methodType(Object.class, Wrapper.class, Object[].class));
 612                 MH_arrayIdentity        = IMPL_LOOKUP.findStatic(MHI, "identity",
 613                                             MethodType.methodType(Object[].class, Object[].class));
 614                 MH_fillNewArray         = IMPL_LOOKUP.findStatic(MHI, "fillNewArray",
 615                                             MethodType.methodType(Object[].class, Integer.class, Object[].class));
 616                 MH_fillNewTypedArray    = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
 617                                             MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
 618 
 619                 MH_selectAlternative    = makeIntrinsic(
 620                         IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
 621                                 MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class)),
 622                         Intrinsic.SELECT_ALTERNATIVE);
 623             } catch (ReflectiveOperationException ex) {
 624                 throw newInternalError(ex);
 625             }
 626         }
 627     }
 628 
 629     /** Factory method:  Collect or filter selected argument(s). */
 630     static MethodHandle makeCollectArguments(MethodHandle target,
 631                 MethodHandle collector, int collectArgPos, boolean retainOriginalArgs) {
 632         MethodType targetType = target.type();          // (a..., c, [b...])=>r
 633         MethodType collectorType = collector.type();    // (b...)=>c
 634         int collectArgCount = collectorType.parameterCount();
 635         Class<?> collectValType = collectorType.returnType();
 636         int collectValCount = (collectValType == void.class ? 0 : 1);
 637         MethodType srcType = targetType                 // (a..., [b...])=>r
 638                 .dropParameterTypes(collectArgPos, collectArgPos+collectValCount);
 639         if (!retainOriginalArgs) {                      // (a..., b...)=>r
 640             srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterList());
 641         }
 642         // in  arglist: [0: ...keep1 | cpos: collect...  | cpos+cacount: keep2... ]
 643         // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
 644         // out(retain): [0: ...keep1 | cpos: cV? coll... | cpos+cvc+cac: keep2... ]
 645 
 646         // Now build a LambdaForm.
 647         MethodType lambdaType = srcType.invokerType();
 648         Name[] names = arguments(2, lambdaType);
 649         final int collectNamePos = names.length - 2;
 650         final int targetNamePos  = names.length - 1;
 651 
 652         Name[] collectorArgs = Arrays.copyOfRange(names, 1 + collectArgPos, 1 + collectArgPos + collectArgCount);
 653         names[collectNamePos] = new Name(collector, (Object[]) collectorArgs);
 654 
 655         // Build argument array for the target.
 656         // Incoming LF args to copy are: [ (mh) headArgs collectArgs tailArgs ].
 657         // Output argument array is [ headArgs (collectVal)? (collectArgs)? tailArgs ].
 658         Name[] targetArgs = new Name[targetType.parameterCount()];
 659         int inputArgPos  = 1;  // incoming LF args to copy to target
 660         int targetArgPos = 0;  // fill pointer for targetArgs
 661         int chunk = collectArgPos;  // |headArgs|
 662         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 663         inputArgPos  += chunk;
 664         targetArgPos += chunk;
 665         if (collectValType != void.class) {
 666             targetArgs[targetArgPos++] = names[collectNamePos];
 667         }
 668         chunk = collectArgCount;
 669         if (retainOriginalArgs) {
 670             System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 671             targetArgPos += chunk;   // optionally pass on the collected chunk
 672         }
 673         inputArgPos += chunk;
 674         chunk = targetArgs.length - targetArgPos;  // all the rest
 675         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 676         assert(inputArgPos + chunk == collectNamePos);  // use of rest of input args also
 677         names[targetNamePos] = new Name(target, (Object[]) targetArgs);
 678 
 679         LambdaForm form = new LambdaForm("collect", lambdaType.parameterCount(), names);
 680         return SimpleMethodHandle.make(srcType, form);
 681     }
 682 
 683     @LambdaForm.Hidden
 684     static
 685     MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback) {
 686         if (testResult) {
 687             return target;
 688         } else {
 689             return fallback;
 690         }
 691     }
 692 
 693     // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
 694     @LambdaForm.Hidden
 695     @jdk.internal.HotSpotIntrinsicCandidate
 696     static
 697     boolean profileBoolean(boolean result, int[] counters) {
 698         // Profile is int[2] where [0] and [1] correspond to false and true occurrences respectively.
 699         int idx = result ? 1 : 0;
 700         try {
 701             counters[idx] = Math.addExact(counters[idx], 1);
 702         } catch (ArithmeticException e) {
 703             // Avoid continuous overflow by halving the problematic count.
 704             counters[idx] = counters[idx] / 2;
 705         }
 706         return result;
 707     }
 708 
 709     // Intrinsified by C2. Returns true if obj is a compile-time constant.
 710     @LambdaForm.Hidden
 711     @jdk.internal.HotSpotIntrinsicCandidate
 712     static
 713     boolean isCompileConstant(Object obj) {
 714         return false;
 715     }
 716 
 717     static
 718     MethodHandle makeGuardWithTest(MethodHandle test,
 719                                    MethodHandle target,
 720                                    MethodHandle fallback) {
 721         MethodType type = target.type();
 722         assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
 723         MethodType basicType = type.basicType();
 724         LambdaForm form = makeGuardWithTestForm(basicType);
 725         BoundMethodHandle mh;
 726         try {
 727             if (PROFILE_GWT) {
 728                 int[] counts = new int[2];
 729                 mh = (BoundMethodHandle)
 730                         BoundMethodHandle.speciesData_LLLL().constructor().invokeBasic(type, form,
 731                                 (Object) test, (Object) profile(target), (Object) profile(fallback), counts);
 732             } else {
 733                 mh = (BoundMethodHandle)
 734                         BoundMethodHandle.speciesData_LLL().constructor().invokeBasic(type, form,
 735                                 (Object) test, (Object) profile(target), (Object) profile(fallback));
 736             }
 737         } catch (Throwable ex) {
 738             throw uncaughtException(ex);
 739         }
 740         assert(mh.type() == type);
 741         return mh;
 742     }
 743 
 744 
 745     static
 746     MethodHandle profile(MethodHandle target) {
 747         if (DONT_INLINE_THRESHOLD >= 0) {
 748             return makeBlockInliningWrapper(target);
 749         } else {
 750             return target;
 751         }
 752     }
 753 
 754     /**
 755      * Block inlining during JIT-compilation of a target method handle if it hasn't been invoked enough times.
 756      * Corresponding LambdaForm has @DontInline when compiled into bytecode.
 757      */
 758     static
 759     MethodHandle makeBlockInliningWrapper(MethodHandle target) {
 760         LambdaForm lform;
 761         if (DONT_INLINE_THRESHOLD > 0) {
 762             lform = PRODUCE_BLOCK_INLINING_FORM.apply(target);
 763         } else {
 764             lform = PRODUCE_REINVOKER_FORM.apply(target);
 765         }
 766         return new CountingWrapper(target, lform,
 767                 PRODUCE_BLOCK_INLINING_FORM, PRODUCE_REINVOKER_FORM,
 768                                    DONT_INLINE_THRESHOLD);
 769     }
 770 
 771     /** Constructs reinvoker lambda form which block inlining during JIT-compilation for a particular method handle */
 772     private static final Function<MethodHandle, LambdaForm> PRODUCE_BLOCK_INLINING_FORM = new Function<MethodHandle, LambdaForm>() {
 773         @Override
 774         public LambdaForm apply(MethodHandle target) {
 775             return DelegatingMethodHandle.makeReinvokerForm(target,
 776                                MethodTypeForm.LF_DELEGATE_BLOCK_INLINING, CountingWrapper.class, "reinvoker.dontInline", false,
 777                                DelegatingMethodHandle.NF_getTarget, CountingWrapper.NF_maybeStopCounting);
 778         }
 779     };
 780 
 781     /** Constructs simple reinvoker lambda form for a particular method handle */
 782     private static final Function<MethodHandle, LambdaForm> PRODUCE_REINVOKER_FORM = new Function<MethodHandle, LambdaForm>() {
 783         @Override
 784         public LambdaForm apply(MethodHandle target) {
 785             return DelegatingMethodHandle.makeReinvokerForm(target,
 786                     MethodTypeForm.LF_DELEGATE, DelegatingMethodHandle.class, DelegatingMethodHandle.NF_getTarget);
 787         }
 788     };
 789 
 790     /**
 791      * Counting method handle. It has 2 states: counting and non-counting.
 792      * It is in counting state for the first n invocations and then transitions to non-counting state.
 793      * Behavior in counting and non-counting states is determined by lambda forms produced by
 794      * countingFormProducer & nonCountingFormProducer respectively.
 795      */
 796     static class CountingWrapper extends DelegatingMethodHandle {
 797         private final MethodHandle target;
 798         private int count;
 799         private Function<MethodHandle, LambdaForm> countingFormProducer;
 800         private Function<MethodHandle, LambdaForm> nonCountingFormProducer;
 801         private volatile boolean isCounting;
 802 
 803         private CountingWrapper(MethodHandle target, LambdaForm lform,
 804                                 Function<MethodHandle, LambdaForm> countingFromProducer,
 805                                 Function<MethodHandle, LambdaForm> nonCountingFormProducer,
 806                                 int count) {
 807             super(target.type(), lform);
 808             this.target = target;
 809             this.count = count;
 810             this.countingFormProducer = countingFromProducer;
 811             this.nonCountingFormProducer = nonCountingFormProducer;
 812             this.isCounting = (count > 0);
 813         }
 814 
 815         @Hidden
 816         @Override
 817         protected MethodHandle getTarget() {
 818             return target;
 819         }
 820 
 821         @Override
 822         public MethodHandle asTypeUncached(MethodType newType) {
 823             MethodHandle newTarget = target.asType(newType);
 824             MethodHandle wrapper;
 825             if (isCounting) {
 826                 LambdaForm lform;
 827                 lform = countingFormProducer.apply(newTarget);
 828                 wrapper = new CountingWrapper(newTarget, lform, countingFormProducer, nonCountingFormProducer, DONT_INLINE_THRESHOLD);
 829             } else {
 830                 wrapper = newTarget; // no need for a counting wrapper anymore
 831             }
 832             return (asTypeCache = wrapper);
 833         }
 834 
 835         boolean countDown() {
 836             int c = count;
 837             if (c <= 1) {
 838                 // Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
 839                 if (isCounting) {
 840                     isCounting = false;
 841                     return true;
 842                 } else {
 843                     return false;
 844                 }
 845             } else {
 846                 count = c - 1;
 847                 return false;
 848             }
 849         }
 850 
 851         @Hidden
 852         static void maybeStopCounting(Object o1) {
 853              CountingWrapper wrapper = (CountingWrapper) o1;
 854              if (wrapper.countDown()) {
 855                  // Reached invocation threshold. Replace counting behavior with a non-counting one.
 856                  LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
 857                  lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
 858                  wrapper.updateForm(lform);
 859              }
 860         }
 861 
 862         static final NamedFunction NF_maybeStopCounting;
 863         static {
 864             Class<?> THIS_CLASS = CountingWrapper.class;
 865             try {
 866                 NF_maybeStopCounting = new NamedFunction(THIS_CLASS.getDeclaredMethod("maybeStopCounting", Object.class));
 867             } catch (ReflectiveOperationException ex) {
 868                 throw newInternalError(ex);
 869             }
 870         }
 871     }
 872 
 873     static
 874     LambdaForm makeGuardWithTestForm(MethodType basicType) {
 875         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWT);
 876         if (lform != null)  return lform;
 877         final int THIS_MH      = 0;  // the BMH_LLL
 878         final int ARG_BASE     = 1;  // start of incoming arguments
 879         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 880         int nameCursor = ARG_LIMIT;
 881         final int GET_TEST     = nameCursor++;
 882         final int GET_TARGET   = nameCursor++;
 883         final int GET_FALLBACK = nameCursor++;
 884         final int GET_COUNTERS = PROFILE_GWT ? nameCursor++ : -1;
 885         final int CALL_TEST    = nameCursor++;
 886         final int PROFILE      = (GET_COUNTERS != -1) ? nameCursor++ : -1;
 887         final int TEST         = nameCursor-1; // previous statement: either PROFILE or CALL_TEST
 888         final int SELECT_ALT   = nameCursor++;
 889         final int CALL_TARGET  = nameCursor++;
 890         assert(CALL_TARGET == SELECT_ALT+1);  // must be true to trigger IBG.emitSelectAlternative
 891 
 892         MethodType lambdaType = basicType.invokerType();
 893         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 894 
 895         BoundMethodHandle.SpeciesData data =
 896                 (GET_COUNTERS != -1) ? BoundMethodHandle.speciesData_LLLL()
 897                                      : BoundMethodHandle.speciesData_LLL();
 898         names[THIS_MH] = names[THIS_MH].withConstraint(data);
 899         names[GET_TEST]     = new Name(data.getterFunction(0), names[THIS_MH]);
 900         names[GET_TARGET]   = new Name(data.getterFunction(1), names[THIS_MH]);
 901         names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
 902         if (GET_COUNTERS != -1) {
 903             names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
 904         }
 905         Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
 906 
 907         // call test
 908         MethodType testType = basicType.changeReturnType(boolean.class).basicType();
 909         invokeArgs[0] = names[GET_TEST];
 910         names[CALL_TEST] = new Name(testType, invokeArgs);
 911 
 912         // profile branch
 913         if (PROFILE != -1) {
 914             names[PROFILE] = new Name(Lazy.NF_profileBoolean, names[CALL_TEST], names[GET_COUNTERS]);
 915         }
 916         // call selectAlternative
 917         names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[TEST], names[GET_TARGET], names[GET_FALLBACK]);
 918 
 919         // call target or fallback
 920         invokeArgs[0] = names[SELECT_ALT];
 921         names[CALL_TARGET] = new Name(basicType, invokeArgs);
 922 
 923         lform = new LambdaForm("guard", lambdaType.parameterCount(), names, /*forceInline=*/true);
 924 
 925         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
 926     }
 927 
 928     /**
 929      * The LambdaForm shape for catchException combinator is the following:
 930      * <blockquote><pre>{@code
 931      *  guardWithCatch=Lambda(a0:L,a1:L,a2:L)=>{
 932      *    t3:L=BoundMethodHandle$Species_LLLLL.argL0(a0:L);
 933      *    t4:L=BoundMethodHandle$Species_LLLLL.argL1(a0:L);
 934      *    t5:L=BoundMethodHandle$Species_LLLLL.argL2(a0:L);
 935      *    t6:L=BoundMethodHandle$Species_LLLLL.argL3(a0:L);
 936      *    t7:L=BoundMethodHandle$Species_LLLLL.argL4(a0:L);
 937      *    t8:L=MethodHandle.invokeBasic(t6:L,a1:L,a2:L);
 938      *    t9:L=MethodHandleImpl.guardWithCatch(t3:L,t4:L,t5:L,t8:L);
 939      *   t10:I=MethodHandle.invokeBasic(t7:L,t9:L);t10:I}
 940      * }</pre></blockquote>
 941      *
 942      * argL0 and argL2 are target and catcher method handles. argL1 is exception class.
 943      * argL3 and argL4 are auxiliary method handles: argL3 boxes arguments and wraps them into Object[]
 944      * (ValueConversions.array()) and argL4 unboxes result if necessary (ValueConversions.unbox()).
 945      *
 946      * Having t8 and t10 passed outside and not hardcoded into a lambda form allows to share lambda forms
 947      * among catchException combinators with the same basic type.
 948      */
 949     private static LambdaForm makeGuardWithCatchForm(MethodType basicType) {
 950         MethodType lambdaType = basicType.invokerType();
 951 
 952         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWC);
 953         if (lform != null) {
 954             return lform;
 955         }
 956         final int THIS_MH      = 0;  // the BMH_LLLLL
 957         final int ARG_BASE     = 1;  // start of incoming arguments
 958         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 959 
 960         int nameCursor = ARG_LIMIT;
 961         final int GET_TARGET       = nameCursor++;
 962         final int GET_CLASS        = nameCursor++;
 963         final int GET_CATCHER      = nameCursor++;
 964         final int GET_COLLECT_ARGS = nameCursor++;
 965         final int GET_UNBOX_RESULT = nameCursor++;
 966         final int BOXED_ARGS       = nameCursor++;
 967         final int TRY_CATCH        = nameCursor++;
 968         final int UNBOX_RESULT     = nameCursor++;
 969 
 970         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 971 
 972         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
 973         names[THIS_MH]          = names[THIS_MH].withConstraint(data);
 974         names[GET_TARGET]       = new Name(data.getterFunction(0), names[THIS_MH]);
 975         names[GET_CLASS]        = new Name(data.getterFunction(1), names[THIS_MH]);
 976         names[GET_CATCHER]      = new Name(data.getterFunction(2), names[THIS_MH]);
 977         names[GET_COLLECT_ARGS] = new Name(data.getterFunction(3), names[THIS_MH]);
 978         names[GET_UNBOX_RESULT] = new Name(data.getterFunction(4), names[THIS_MH]);
 979 
 980         // FIXME: rework argument boxing/result unboxing logic for LF interpretation
 981 
 982         // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
 983         MethodType collectArgsType = basicType.changeReturnType(Object.class);
 984         MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
 985         Object[] args = new Object[invokeBasic.type().parameterCount()];
 986         args[0] = names[GET_COLLECT_ARGS];
 987         System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT-ARG_BASE);
 988         names[BOXED_ARGS] = new Name(makeIntrinsic(invokeBasic, Intrinsic.GUARD_WITH_CATCH), args);
 989 
 990         // t_{i+1}:L=MethodHandleImpl.guardWithCatch(target:L,exType:L,catcher:L,t_{i}:L);
 991         Object[] gwcArgs = new Object[] {names[GET_TARGET], names[GET_CLASS], names[GET_CATCHER], names[BOXED_ARGS]};
 992         names[TRY_CATCH] = new Name(Lazy.NF_guardWithCatch, gwcArgs);
 993 
 994         // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
 995         MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
 996         Object[] unboxArgs  = new Object[] {names[GET_UNBOX_RESULT], names[TRY_CATCH]};
 997         names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
 998 
 999         lform = new LambdaForm("guardWithCatch", lambdaType.parameterCount(), names);
1000 
1001         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWC, lform);
1002     }
1003 
1004     static
1005     MethodHandle makeGuardWithCatch(MethodHandle target,
1006                                     Class<? extends Throwable> exType,
1007                                     MethodHandle catcher) {
1008         MethodType type = target.type();
1009         LambdaForm form = makeGuardWithCatchForm(type.basicType());
1010 
1011         // Prepare auxiliary method handles used during LambdaForm interpretation.
1012         // Box arguments and wrap them into Object[]: ValueConversions.array().
1013         MethodType varargsType = type.changeReturnType(Object[].class);
1014         MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
1015         // Result unboxing: ValueConversions.unbox() OR ValueConversions.identity() OR ValueConversions.ignore().
1016         MethodHandle unboxResult;
1017         Class<?> rtype = type.returnType();
1018         if (rtype.isPrimitive()) {
1019             if (rtype == void.class) {
1020                 unboxResult = ValueConversions.ignore();
1021             } else {
1022                 Wrapper w = Wrapper.forPrimitiveType(type.returnType());
1023                 unboxResult = ValueConversions.unboxExact(w);
1024             }
1025         } else {
1026             unboxResult = MethodHandles.identity(Object.class);
1027         }
1028 
1029         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
1030         BoundMethodHandle mh;
1031         try {
1032             mh = (BoundMethodHandle)
1033                     data.constructor().invokeBasic(type, form, (Object) target, (Object) exType, (Object) catcher,
1034                                                    (Object) collectArgs, (Object) unboxResult);
1035         } catch (Throwable ex) {
1036             throw uncaughtException(ex);
1037         }
1038         assert(mh.type() == type);
1039         return mh;
1040     }
1041 
1042     /**
1043      * Intrinsified during LambdaForm compilation
1044      * (see {@link InvokerBytecodeGenerator#emitGuardWithCatch emitGuardWithCatch}).
1045      */
1046     @LambdaForm.Hidden
1047     static Object guardWithCatch(MethodHandle target, Class<? extends Throwable> exType, MethodHandle catcher,
1048                                  Object... av) throws Throwable {
1049         // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case.
1050         try {
1051             return target.asFixedArity().invokeWithArguments(av);
1052         } catch (Throwable t) {
1053             if (!exType.isInstance(t)) throw t;
1054             return catcher.asFixedArity().invokeWithArguments(prepend(t, av));
1055         }
1056     }
1057 
1058     /** Prepend an element {@code elem} to an {@code array}. */
1059     @LambdaForm.Hidden
1060     private static Object[] prepend(Object elem, Object[] array) {
1061         Object[] newArray = new Object[array.length+1];
1062         newArray[0] = elem;
1063         System.arraycopy(array, 0, newArray, 1, array.length);
1064         return newArray;
1065     }
1066 
1067     static
1068     MethodHandle throwException(MethodType type) {
1069         assert(Throwable.class.isAssignableFrom(type.parameterType(0)));
1070         int arity = type.parameterCount();
1071         if (arity > 1) {
1072             MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
1073             mh = MethodHandles.dropArguments(mh, 1, type.parameterList().subList(1, arity));
1074             return mh;
1075         }
1076         return makePairwiseConvert(Lazy.NF_throwException.resolvedHandle(), type, false, true);
1077     }
1078 
1079     static <T extends Throwable> Empty throwException(T t) throws T { throw t; }
1080 
1081     static MethodHandle[] FAKE_METHOD_HANDLE_INVOKE = new MethodHandle[2];
1082     static MethodHandle fakeMethodHandleInvoke(MemberName method) {
1083         int idx;
1084         assert(method.isMethodHandleInvoke());
1085         switch (method.getName()) {
1086         case "invoke":       idx = 0; break;
1087         case "invokeExact":  idx = 1; break;
1088         default:             throw new InternalError(method.getName());
1089         }
1090         MethodHandle mh = FAKE_METHOD_HANDLE_INVOKE[idx];
1091         if (mh != null)  return mh;
1092         MethodType type = MethodType.methodType(Object.class, UnsupportedOperationException.class,
1093                                                 MethodHandle.class, Object[].class);
1094         mh = throwException(type);
1095         mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke MethodHandle"));
1096         if (!method.getInvocationType().equals(mh.type()))
1097             throw new InternalError(method.toString());
1098         mh = mh.withInternalMemberName(method, false);
1099         mh = mh.asVarargsCollector(Object[].class);
1100         assert(method.isVarargs());
1101         FAKE_METHOD_HANDLE_INVOKE[idx] = mh;
1102         return mh;
1103     }
1104 
1105     /**
1106      * Create an alias for the method handle which, when called,
1107      * appears to be called from the same class loader and protection domain
1108      * as hostClass.
1109      * This is an expensive no-op unless the method which is called
1110      * is sensitive to its caller.  A small number of system methods
1111      * are in this category, including Class.forName and Method.invoke.
1112      */
1113     static
1114     MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1115         return BindCaller.bindCaller(mh, hostClass);
1116     }
1117 
1118     // Put the whole mess into its own nested class.
1119     // That way we can lazily load the code and set up the constants.
1120     private static class BindCaller {
1121         static
1122         MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1123             // Do not use this function to inject calls into system classes.
1124             if (hostClass == null
1125                 ||    (hostClass.isArray() ||
1126                        hostClass.isPrimitive() ||
1127                        hostClass.getName().startsWith("java.") ||
1128                        hostClass.getName().startsWith("sun."))) {
1129                 throw new InternalError();  // does not happen, and should not anyway
1130             }
1131             // For simplicity, convert mh to a varargs-like method.
1132             MethodHandle vamh = prepareForInvoker(mh);
1133             // Cache the result of makeInjectedInvoker once per argument class.
1134             MethodHandle bccInvoker = CV_makeInjectedInvoker.get(hostClass);
1135             return restoreToType(bccInvoker.bindTo(vamh), mh, hostClass);
1136         }
1137 
1138         private static MethodHandle makeInjectedInvoker(Class<?> hostClass) {
1139             Class<?> bcc = UNSAFE.defineAnonymousClass(hostClass, T_BYTES, null);
1140             if (hostClass.getClassLoader() != bcc.getClassLoader())
1141                 throw new InternalError(hostClass.getName()+" (CL)");
1142             try {
1143                 if (hostClass.getProtectionDomain() != bcc.getProtectionDomain())
1144                     throw new InternalError(hostClass.getName()+" (PD)");
1145             } catch (SecurityException ex) {
1146                 // Self-check was blocked by security manager.  This is OK.
1147                 // In fact the whole try body could be turned into an assertion.
1148             }
1149             try {
1150                 MethodHandle init = IMPL_LOOKUP.findStatic(bcc, "init", MethodType.methodType(void.class));
1151                 init.invokeExact();  // force initialization of the class
1152             } catch (Throwable ex) {
1153                 throw uncaughtException(ex);
1154             }
1155             MethodHandle bccInvoker;
1156             try {
1157                 MethodType invokerMT = MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1158                 bccInvoker = IMPL_LOOKUP.findStatic(bcc, "invoke_V", invokerMT);
1159             } catch (ReflectiveOperationException ex) {
1160                 throw uncaughtException(ex);
1161             }
1162             // Test the invoker, to ensure that it really injects into the right place.
1163             try {
1164                 MethodHandle vamh = prepareForInvoker(MH_checkCallerClass);
1165                 Object ok = bccInvoker.invokeExact(vamh, new Object[]{hostClass, bcc});
1166             } catch (Throwable ex) {
1167                 throw new InternalError(ex);
1168             }
1169             return bccInvoker;
1170         }
1171         private static ClassValue<MethodHandle> CV_makeInjectedInvoker = new ClassValue<MethodHandle>() {
1172             @Override protected MethodHandle computeValue(Class<?> hostClass) {
1173                 return makeInjectedInvoker(hostClass);
1174             }
1175         };
1176 
1177         // Adapt mh so that it can be called directly from an injected invoker:
1178         private static MethodHandle prepareForInvoker(MethodHandle mh) {
1179             mh = mh.asFixedArity();
1180             MethodType mt = mh.type();
1181             int arity = mt.parameterCount();
1182             MethodHandle vamh = mh.asType(mt.generic());
1183             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1184             vamh = vamh.asSpreader(Object[].class, arity);
1185             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1186             return vamh;
1187         }
1188 
1189         // Undo the adapter effect of prepareForInvoker:
1190         private static MethodHandle restoreToType(MethodHandle vamh,
1191                                                   MethodHandle original,
1192                                                   Class<?> hostClass) {
1193             MethodType type = original.type();
1194             MethodHandle mh = vamh.asCollector(Object[].class, type.parameterCount());
1195             MemberName member = original.internalMemberName();
1196             mh = mh.asType(type);
1197             mh = new WrappedMember(mh, type, member, original.isInvokeSpecial(), hostClass);
1198             return mh;
1199         }
1200 
1201         private static final MethodHandle MH_checkCallerClass;
1202         static {
1203             final Class<?> THIS_CLASS = BindCaller.class;
1204             assert(checkCallerClass(THIS_CLASS, THIS_CLASS));
1205             try {
1206                 MH_checkCallerClass = IMPL_LOOKUP
1207                     .findStatic(THIS_CLASS, "checkCallerClass",
1208                                 MethodType.methodType(boolean.class, Class.class, Class.class));
1209                 assert((boolean) MH_checkCallerClass.invokeExact(THIS_CLASS, THIS_CLASS));
1210             } catch (Throwable ex) {
1211                 throw new InternalError(ex);
1212             }
1213         }
1214 
1215         @CallerSensitive
1216         private static boolean checkCallerClass(Class<?> expected, Class<?> expected2) {
1217             // This method is called via MH_checkCallerClass and so it's
1218             // correct to ask for the immediate caller here.
1219             Class<?> actual = Reflection.getCallerClass();
1220             if (actual != expected && actual != expected2)
1221                 throw new InternalError("found "+actual.getName()+", expected "+expected.getName()
1222                                         +(expected == expected2 ? "" : ", or else "+expected2.getName()));
1223             return true;
1224         }
1225 
1226         private static final byte[] T_BYTES;
1227         static {
1228             final Object[] values = {null};
1229             AccessController.doPrivileged(new PrivilegedAction<>() {
1230                     public Void run() {
1231                         try {
1232                             Class<T> tClass = T.class;
1233                             String tName = tClass.getName();
1234                             String tResource = tName.substring(tName.lastIndexOf('.')+1)+".class";
1235                             java.net.URLConnection uconn = tClass.getResource(tResource).openConnection();
1236                             int len = uconn.getContentLength();
1237                             byte[] bytes = new byte[len];
1238                             try (java.io.InputStream str = uconn.getInputStream()) {
1239                                 int nr = str.read(bytes);
1240                                 if (nr != len)  throw new java.io.IOException(tResource);
1241                             }
1242                             values[0] = bytes;
1243                         } catch (java.io.IOException ex) {
1244                             throw new InternalError(ex);
1245                         }
1246                         return null;
1247                     }
1248                 });
1249             T_BYTES = (byte[]) values[0];
1250         }
1251 
1252         // The following class is used as a template for Unsafe.defineAnonymousClass:
1253         private static class T {
1254             static void init() { }  // side effect: initializes this class
1255             static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
1256                 return vamh.invokeExact(args);
1257             }
1258         }
1259     }
1260 
1261 
1262     /** This subclass allows a wrapped method handle to be re-associated with an arbitrary member name. */
1263     private static final class WrappedMember extends DelegatingMethodHandle {
1264         private final MethodHandle target;
1265         private final MemberName member;
1266         private final Class<?> callerClass;
1267         private final boolean isInvokeSpecial;
1268 
1269         private WrappedMember(MethodHandle target, MethodType type,
1270                               MemberName member, boolean isInvokeSpecial,
1271                               Class<?> callerClass) {
1272             super(type, target);
1273             this.target = target;
1274             this.member = member;
1275             this.callerClass = callerClass;
1276             this.isInvokeSpecial = isInvokeSpecial;
1277         }
1278 
1279         @Override
1280         MemberName internalMemberName() {
1281             return member;
1282         }
1283         @Override
1284         Class<?> internalCallerClass() {
1285             return callerClass;
1286         }
1287         @Override
1288         boolean isInvokeSpecial() {
1289             return isInvokeSpecial;
1290         }
1291         @Override
1292         protected MethodHandle getTarget() {
1293             return target;
1294         }
1295         @Override
1296         public MethodHandle asTypeUncached(MethodType newType) {
1297             // This MH is an alias for target, except for the MemberName
1298             // Drop the MemberName if there is any conversion.
1299             return asTypeCache = target.asType(newType);
1300         }
1301     }
1302 
1303     static MethodHandle makeWrappedMember(MethodHandle target, MemberName member, boolean isInvokeSpecial) {
1304         if (member.equals(target.internalMemberName()) && isInvokeSpecial == target.isInvokeSpecial())
1305             return target;
1306         return new WrappedMember(target, target.type(), member, isInvokeSpecial, null);
1307     }
1308 
1309     /** Intrinsic IDs */
1310     /*non-public*/
1311     enum Intrinsic {
1312         SELECT_ALTERNATIVE,
1313         GUARD_WITH_CATCH,
1314         NEW_ARRAY,
1315         ARRAY_LOAD,
1316         ARRAY_STORE,
1317         IDENTITY,
1318         ZERO,
1319         NONE // no intrinsic associated
1320     }
1321 
1322     /** Mark arbitrary method handle as intrinsic.
1323      * InvokerBytecodeGenerator uses this info to produce more efficient bytecode shape. */
1324     private static final class IntrinsicMethodHandle extends DelegatingMethodHandle {
1325         private final MethodHandle target;
1326         private final Intrinsic intrinsicName;
1327 
1328         IntrinsicMethodHandle(MethodHandle target, Intrinsic intrinsicName) {
1329             super(target.type(), target);
1330             this.target = target;
1331             this.intrinsicName = intrinsicName;
1332         }
1333 
1334         @Override
1335         protected MethodHandle getTarget() {
1336             return target;
1337         }
1338 
1339         @Override
1340         Intrinsic intrinsicName() {
1341             return intrinsicName;
1342         }
1343 
1344         @Override
1345         public MethodHandle asTypeUncached(MethodType newType) {
1346             // This MH is an alias for target, except for the intrinsic name
1347             // Drop the name if there is any conversion.
1348             return asTypeCache = target.asType(newType);
1349         }
1350 
1351         @Override
1352         String internalProperties() {
1353             return super.internalProperties() +
1354                     "\n& Intrinsic="+intrinsicName;
1355         }
1356 
1357         @Override
1358         public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
1359             if (intrinsicName == Intrinsic.IDENTITY) {
1360                 MethodType resultType = type().asCollectorType(arrayType, arrayLength);
1361                 MethodHandle newArray = MethodHandleImpl.varargsArray(arrayType, arrayLength);
1362                 return newArray.asType(resultType);
1363             }
1364             return super.asCollector(arrayType, arrayLength);
1365         }
1366     }
1367 
1368     static MethodHandle makeIntrinsic(MethodHandle target, Intrinsic intrinsicName) {
1369         if (intrinsicName == target.intrinsicName())
1370             return target;
1371         return new IntrinsicMethodHandle(target, intrinsicName);
1372     }
1373 
1374     static MethodHandle makeIntrinsic(MethodType type, LambdaForm form, Intrinsic intrinsicName) {
1375         return new IntrinsicMethodHandle(SimpleMethodHandle.make(type, form), intrinsicName);
1376     }
1377 
1378     /// Collection of multiple arguments.
1379 
1380     private static MethodHandle findCollector(String name, int nargs, Class<?> rtype, Class<?>... ptypes) {
1381         MethodType type = MethodType.genericMethodType(nargs)
1382                 .changeReturnType(rtype)
1383                 .insertParameterTypes(0, ptypes);
1384         try {
1385             return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, name, type);
1386         } catch (ReflectiveOperationException ex) {
1387             return null;
1388         }
1389     }
1390 
1391     private static final Object[] NO_ARGS_ARRAY = {};
1392     private static Object[] makeArray(Object... args) { return args; }
1393     private static Object[] array() { return NO_ARGS_ARRAY; }
1394     private static Object[] array(Object a0)
1395                 { return makeArray(a0); }
1396     private static Object[] array(Object a0, Object a1)
1397                 { return makeArray(a0, a1); }
1398     private static Object[] array(Object a0, Object a1, Object a2)
1399                 { return makeArray(a0, a1, a2); }
1400     private static Object[] array(Object a0, Object a1, Object a2, Object a3)
1401                 { return makeArray(a0, a1, a2, a3); }
1402     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1403                                   Object a4)
1404                 { return makeArray(a0, a1, a2, a3, a4); }
1405     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1406                                   Object a4, Object a5)
1407                 { return makeArray(a0, a1, a2, a3, a4, a5); }
1408     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1409                                   Object a4, Object a5, Object a6)
1410                 { return makeArray(a0, a1, a2, a3, a4, a5, a6); }
1411     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1412                                   Object a4, Object a5, Object a6, Object a7)
1413                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7); }
1414     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1415                                   Object a4, Object a5, Object a6, Object a7,
1416                                   Object a8)
1417                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8); }
1418     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1419                                   Object a4, Object a5, Object a6, Object a7,
1420                                   Object a8, Object a9)
1421                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); }
1422 
1423     private static final int ARRAYS_COUNT = 11;
1424 
1425     private static MethodHandle[] makeArrays() {
1426         MethodHandle[] mhs = new MethodHandle[MAX_ARITY + 1];
1427         for (int i = 0; i < ARRAYS_COUNT; i++) {
1428             MethodHandle mh = findCollector("array", i, Object[].class);
1429             mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1430             mhs[i] = mh;
1431         }
1432         assert(assertArrayMethodCount(mhs));
1433         return mhs;
1434     }
1435 
1436     private static boolean assertArrayMethodCount(MethodHandle[] mhs) {
1437         assert(findCollector("array", ARRAYS_COUNT, Object[].class) == null);
1438         for (int i = 0; i < ARRAYS_COUNT; i++) {
1439             assert(mhs[i] != null);
1440         }
1441         return true;
1442     }
1443 
1444     // filling versions of the above:
1445     // using Integer len instead of int len and no varargs to avoid bootstrapping problems
1446     private static Object[] fillNewArray(Integer len, Object[] /*not ...*/ args) {
1447         Object[] a = new Object[len];
1448         fillWithArguments(a, 0, args);
1449         return a;
1450     }
1451     private static Object[] fillNewTypedArray(Object[] example, Integer len, Object[] /*not ...*/ args) {
1452         Object[] a = Arrays.copyOf(example, len);
1453         assert(a.getClass() != Object[].class);
1454         fillWithArguments(a, 0, args);
1455         return a;
1456     }
1457     private static void fillWithArguments(Object[] a, int pos, Object... args) {
1458         System.arraycopy(args, 0, a, pos, args.length);
1459     }
1460     // using Integer pos instead of int pos to avoid bootstrapping problems
1461     private static Object[] fillArray(Integer pos, Object[] a, Object a0)
1462                 { fillWithArguments(a, pos, a0); return a; }
1463     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1)
1464                 { fillWithArguments(a, pos, a0, a1); return a; }
1465     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2)
1466                 { fillWithArguments(a, pos, a0, a1, a2); return a; }
1467     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3)
1468                 { fillWithArguments(a, pos, a0, a1, a2, a3); return a; }
1469     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1470                                   Object a4)
1471                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4); return a; }
1472     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1473                                   Object a4, Object a5)
1474                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5); return a; }
1475     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1476                                   Object a4, Object a5, Object a6)
1477                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6); return a; }
1478     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1479                                   Object a4, Object a5, Object a6, Object a7)
1480                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7); return a; }
1481     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1482                                   Object a4, Object a5, Object a6, Object a7,
1483                                   Object a8)
1484                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8); return a; }
1485     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1486                                   Object a4, Object a5, Object a6, Object a7,
1487                                   Object a8, Object a9)
1488                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); return a; }
1489 
1490     private static final int FILL_ARRAYS_COUNT = 11; // current number of fillArray methods

1491 
1492     private static MethodHandle[] makeFillArrays() {
1493         MethodHandle[] mhs = new MethodHandle[FILL_ARRAYS_COUNT];
1494         mhs[0] = null;  // there is no empty fill; at least a0 is required
1495         for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1496             MethodHandle mh = findCollector("fillArray", i, Object[].class, Integer.class, Object[].class);
1497             mhs[i] = mh;
1498         }
1499         assert(assertFillArrayMethodCount(mhs));
1500         return mhs;
1501     }
1502 
1503     private static boolean assertFillArrayMethodCount(MethodHandle[] mhs) {
1504         assert(findCollector("fillArray", FILL_ARRAYS_COUNT, Object[].class, Integer.class, Object[].class) == null);
1505         for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1506             assert(mhs[i] != null);
1507         }
1508         return true;


1509     }
1510 
1511     private static Object copyAsPrimitiveArray(Wrapper w, Object... boxes) {
1512         Object a = w.makeArray(boxes.length);
1513         w.copyArrayUnboxing(boxes, 0, a, 0, boxes.length);
1514         return a;
1515     }
1516 
1517     /** Return a method handle that takes the indicated number of Object
1518      *  arguments and returns an Object array of them, as if for varargs.
1519      */
1520     static MethodHandle varargsArray(int nargs) {
1521         MethodHandle mh = Lazy.ARRAYS[nargs];
1522         if (mh != null)  return mh;
1523         mh = buildVarargsArray(Lazy.MH_fillNewArray, Lazy.MH_arrayIdentity, nargs);







1524         assert(assertCorrectArity(mh, nargs));
1525         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1526         return Lazy.ARRAYS[nargs] = mh;
1527     }
1528 
1529     private static boolean assertCorrectArity(MethodHandle mh, int arity) {
1530         assert(mh.type().parameterCount() == arity) : "arity != "+arity+": "+mh;
1531         return true;
1532     }
1533 
1534     // Array identity function (used as Lazy.MH_arrayIdentity).
1535     static <T> T[] identity(T[] x) {
1536         return x;
1537     }
1538 
1539     private static MethodHandle buildVarargsArray(MethodHandle newArray, MethodHandle finisher, int nargs) {
1540         // Build up the result mh as a sequence of fills like this:
1541         //   finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
1542         // The various fill(_,10*I,___*[J]) are reusable.
1543         int leftLen = Math.min(nargs, LEFT_ARGS);  // absorb some arguments immediately
1544         int rightLen = nargs - leftLen;
1545         MethodHandle leftCollector = newArray.bindTo(nargs);
1546         leftCollector = leftCollector.asCollector(Object[].class, leftLen);
1547         MethodHandle mh = finisher;
1548         if (rightLen > 0) {
1549             MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
1550             if (mh == Lazy.MH_arrayIdentity)
1551                 mh = rightFiller;
1552             else
1553                 mh = MethodHandles.collectArguments(mh, 0, rightFiller);
1554         }
1555         if (mh == Lazy.MH_arrayIdentity)
1556             mh = leftCollector;
1557         else
1558             mh = MethodHandles.collectArguments(mh, 0, leftCollector);
1559         return mh;
1560     }
1561 
1562     private static final int LEFT_ARGS = FILL_ARRAYS_COUNT - 1;
1563     private static final MethodHandle[] FILL_ARRAY_TO_RIGHT = new MethodHandle[MAX_ARITY+1];
1564     /** fill_array_to_right(N).invoke(a, argL..arg[N-1])
1565      *  fills a[L]..a[N-1] with corresponding arguments,
1566      *  and then returns a.  The value L is a global constant (LEFT_ARGS).
1567      */
1568     private static MethodHandle fillToRight(int nargs) {
1569         MethodHandle filler = FILL_ARRAY_TO_RIGHT[nargs];
1570         if (filler != null)  return filler;
1571         filler = buildFiller(nargs);
1572         assert(assertCorrectArity(filler, nargs - LEFT_ARGS + 1));
1573         return FILL_ARRAY_TO_RIGHT[nargs] = filler;
1574     }
1575     private static MethodHandle buildFiller(int nargs) {
1576         if (nargs <= LEFT_ARGS)
1577             return Lazy.MH_arrayIdentity;  // no args to fill; return the array unchanged
1578         // we need room for both mh and a in mh.invoke(a, arg*[nargs])
1579         final int CHUNK = LEFT_ARGS;
1580         int rightLen = nargs % CHUNK;
1581         int midLen = nargs - rightLen;
1582         if (rightLen == 0) {
1583             midLen = nargs - (rightLen = CHUNK);
1584             if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
1585                 // build some precursors from left to right
1586                 for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK)
1587                     if (j > LEFT_ARGS)  fillToRight(j);
1588             }
1589         }
1590         if (midLen < LEFT_ARGS) rightLen = nargs - (midLen = LEFT_ARGS);
1591         assert(rightLen > 0);
1592         MethodHandle midFill = fillToRight(midLen);  // recursive fill
1593         MethodHandle rightFill = Lazy.FILL_ARRAYS[rightLen].bindTo(midLen);  // [midLen..nargs-1]
1594         assert(midFill.type().parameterCount()   == 1 + midLen - LEFT_ARGS);
1595         assert(rightFill.type().parameterCount() == 1 + rightLen);
1596 
1597         // Combine the two fills:
1598         //   right(mid(a, x10..x19), x20..x23)
1599         // The final product will look like this:
1600         //   right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
1601         if (midLen == LEFT_ARGS)
1602             return rightFill;
1603         else
1604             return MethodHandles.collectArguments(rightFill, 0, midFill);
1605     }
1606 
1607     // Type-polymorphic version of varargs maker.
1608     private static final ClassValue<MethodHandle[]> TYPED_COLLECTORS
1609         = new ClassValue<MethodHandle[]>() {
1610             @Override
1611             protected MethodHandle[] computeValue(Class<?> type) {
1612                 return new MethodHandle[256];
1613             }
1614     };
1615 
1616     static final int MAX_JVM_ARITY = 255;  // limit imposed by the JVM
1617 
1618     /** Return a method handle that takes the indicated number of
1619      *  typed arguments and returns an array of them.
1620      *  The type argument is the array type.
1621      */
1622     static MethodHandle varargsArray(Class<?> arrayType, int nargs) {
1623         Class<?> elemType = arrayType.getComponentType();
1624         if (elemType == null)  throw new IllegalArgumentException("not an array: "+arrayType);
1625         // FIXME: Need more special casing and caching here.
1626         if (nargs >= MAX_JVM_ARITY/2 - 1) {
1627             int slots = nargs;
1628             final int MAX_ARRAY_SLOTS = MAX_JVM_ARITY - 1;  // 1 for receiver MH
1629             if (slots <= MAX_ARRAY_SLOTS && elemType.isPrimitive())
1630                 slots *= Wrapper.forPrimitiveType(elemType).stackSlots();
1631             if (slots > MAX_ARRAY_SLOTS)
1632                 throw new IllegalArgumentException("too many arguments: "+arrayType.getSimpleName()+", length "+nargs);
1633         }
1634         if (elemType == Object.class)
1635             return varargsArray(nargs);
1636         // other cases:  primitive arrays, subtypes of Object[]
1637         MethodHandle cache[] = TYPED_COLLECTORS.get(elemType);
1638         MethodHandle mh = nargs < cache.length ? cache[nargs] : null;
1639         if (mh != null)  return mh;
1640         if (nargs == 0) {
1641             Object example = java.lang.reflect.Array.newInstance(arrayType.getComponentType(), 0);
1642             mh = MethodHandles.constant(arrayType, example);
1643         } else if (elemType.isPrimitive()) {
1644             MethodHandle builder = Lazy.MH_fillNewArray;
1645             MethodHandle producer = buildArrayProducer(arrayType);
1646             mh = buildVarargsArray(builder, producer, nargs);
1647         } else {
1648             Class<? extends Object[]> objArrayType = arrayType.asSubclass(Object[].class);
1649             Object[] example = Arrays.copyOf(NO_ARGS_ARRAY, 0, objArrayType);
1650             MethodHandle builder = Lazy.MH_fillNewTypedArray.bindTo(example);
1651             MethodHandle producer = Lazy.MH_arrayIdentity; // must be weakly typed
1652             mh = buildVarargsArray(builder, producer, nargs);
1653         }
1654         mh = mh.asType(MethodType.methodType(arrayType, Collections.<Class<?>>nCopies(nargs, elemType)));
1655         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1656         assert(assertCorrectArity(mh, nargs));
1657         if (nargs < cache.length)
1658             cache[nargs] = mh;
1659         return mh;
1660     }
1661 
1662     private static MethodHandle buildArrayProducer(Class<?> arrayType) {
1663         Class<?> elemType = arrayType.getComponentType();
1664         assert(elemType.isPrimitive());
1665         return Lazy.MH_copyAsPrimitiveArray.bindTo(Wrapper.forPrimitiveType(elemType));
1666     }
1667 
1668     /*non-public*/ static void assertSame(Object mh1, Object mh2) {
1669         if (mh1 != mh2) {
1670             String msg = String.format("mh1 != mh2: mh1 = %s (form: %s); mh2 = %s (form: %s)",
1671                     mh1, ((MethodHandle)mh1).form,
1672                     mh2, ((MethodHandle)mh2).form);
1673             throw newInternalError(msg);
1674         }






















































































































1675     }
1676 }
--- EOF ---