1 /*
   2  * Copyright (c) 2008, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang.invoke;
  27 
  28 import jdk.internal.access.JavaLangInvokeAccess;
  29 import jdk.internal.access.SharedSecrets;
  30 import jdk.internal.org.objectweb.asm.AnnotationVisitor;
  31 import jdk.internal.org.objectweb.asm.ClassWriter;
  32 import jdk.internal.org.objectweb.asm.MethodVisitor;
  33 import jdk.internal.reflect.CallerSensitive;
  34 import jdk.internal.reflect.Reflection;
  35 import jdk.internal.vm.annotation.ForceInline;
  36 import jdk.internal.vm.annotation.Hidden;
  37 import jdk.internal.vm.annotation.Stable;
  38 import sun.invoke.empty.Empty;
  39 import sun.invoke.util.ValueConversions;
  40 import sun.invoke.util.VerifyType;
  41 import sun.invoke.util.Wrapper;
  42 
  43 import java.lang.reflect.Array;

  44 import java.util.Arrays;
  45 import java.util.Collections;
  46 import java.util.HashMap;
  47 import java.util.Iterator;
  48 import java.util.List;
  49 import java.util.Map;
  50 import java.util.function.Function;
  51 import java.util.stream.Stream;
  52 
  53 import static java.lang.invoke.LambdaForm.*;
  54 import static java.lang.invoke.MethodHandleStatics.*;
  55 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
  56 import static jdk.internal.org.objectweb.asm.Opcodes.*;
  57 
  58 /**
  59  * Trusted implementation code for MethodHandle.
  60  * @author jrose
  61  */
  62 /*non-public*/
  63 abstract class MethodHandleImpl {
  64 
  65     /// Factory methods to create method handles:
  66 
  67     static MethodHandle makeArrayElementAccessor(Class<?> arrayClass, ArrayAccess access) {
  68         if (arrayClass == Object[].class) {
  69             return ArrayAccess.objectAccessor(access);
  70         }
  71         if (!arrayClass.isArray())
  72             throw newIllegalArgumentException("not an array: "+arrayClass);
  73         MethodHandle[] cache = ArrayAccessor.TYPED_ACCESSORS.get(arrayClass);
  74         int cacheIndex = ArrayAccess.cacheIndex(access);
  75         MethodHandle mh = cache[cacheIndex];
  76         if (mh != null)  return mh;
  77         mh = ArrayAccessor.getAccessor(arrayClass, access);
  78         MethodType correctType = ArrayAccessor.correctType(arrayClass, access);
  79         if (mh.type() != correctType) {
  80             assert(mh.type().parameterType(0) == Object[].class);
  81             /* if access == SET */ assert(access != ArrayAccess.SET || mh.type().parameterType(2) == Object.class);
  82             /* if access == GET */ assert(access != ArrayAccess.GET ||
  83                     (mh.type().returnType() == Object.class &&
  84                      correctType.parameterType(0).getComponentType() == correctType.returnType()));
  85             // safe to view non-strictly, because element type follows from array type
  86             mh = mh.viewAsType(correctType, false);
  87         }
  88         mh = makeIntrinsic(mh, ArrayAccess.intrinsic(access));
  89         // Atomically update accessor cache.
  90         synchronized(cache) {
  91             if (cache[cacheIndex] == null) {
  92                 cache[cacheIndex] = mh;
  93             } else {
  94                 // Throw away newly constructed accessor and use cached version.
  95                 mh = cache[cacheIndex];
  96             }
  97         }
  98         return mh;
  99     }
 100 
 101     enum ArrayAccess {
 102         GET, SET, LENGTH;
 103 
 104         // As ArrayAccess and ArrayAccessor have a circular dependency, the ArrayAccess properties cannot be stored in
 105         // final fields.
 106 
 107         static String opName(ArrayAccess a) {
 108             switch (a) {
 109                 case GET: return "getElement";
 110                 case SET: return "setElement";
 111                 case LENGTH: return "length";
 112             }
 113             throw unmatchedArrayAccess(a);
 114         }
 115 
 116         static MethodHandle objectAccessor(ArrayAccess a) {
 117             switch (a) {
 118                 case GET: return ArrayAccessor.OBJECT_ARRAY_GETTER;
 119                 case SET: return ArrayAccessor.OBJECT_ARRAY_SETTER;
 120                 case LENGTH: return ArrayAccessor.OBJECT_ARRAY_LENGTH;
 121             }
 122             throw unmatchedArrayAccess(a);
 123         }
 124 
 125         static int cacheIndex(ArrayAccess a) {
 126             switch (a) {
 127                 case GET: return ArrayAccessor.GETTER_INDEX;
 128                 case SET: return ArrayAccessor.SETTER_INDEX;
 129                 case LENGTH: return ArrayAccessor.LENGTH_INDEX;
 130             }
 131             throw unmatchedArrayAccess(a);
 132         }
 133 
 134         static Intrinsic intrinsic(ArrayAccess a) {
 135             switch (a) {
 136                 case GET: return Intrinsic.ARRAY_LOAD;
 137                 case SET: return Intrinsic.ARRAY_STORE;
 138                 case LENGTH: return Intrinsic.ARRAY_LENGTH;
 139             }
 140             throw unmatchedArrayAccess(a);
 141         }
 142     }
 143 
 144     static InternalError unmatchedArrayAccess(ArrayAccess a) {
 145         return newInternalError("should not reach here (unmatched ArrayAccess: " + a + ")");
 146     }
 147 
 148     static final class ArrayAccessor {
 149         /// Support for array element and length access
 150         static final int GETTER_INDEX = 0, SETTER_INDEX = 1, LENGTH_INDEX = 2, INDEX_LIMIT = 3;
 151         static final ClassValue<MethodHandle[]> TYPED_ACCESSORS
 152                 = new ClassValue<MethodHandle[]>() {
 153                     @Override
 154                     protected MethodHandle[] computeValue(Class<?> type) {
 155                         return new MethodHandle[INDEX_LIMIT];
 156                     }
 157                 };
 158         static final MethodHandle OBJECT_ARRAY_GETTER, OBJECT_ARRAY_SETTER, OBJECT_ARRAY_LENGTH;
 159         static {
 160             MethodHandle[] cache = TYPED_ACCESSORS.get(Object[].class);
 161             cache[GETTER_INDEX] = OBJECT_ARRAY_GETTER = makeIntrinsic(getAccessor(Object[].class, ArrayAccess.GET),    Intrinsic.ARRAY_LOAD);
 162             cache[SETTER_INDEX] = OBJECT_ARRAY_SETTER = makeIntrinsic(getAccessor(Object[].class, ArrayAccess.SET),    Intrinsic.ARRAY_STORE);
 163             cache[LENGTH_INDEX] = OBJECT_ARRAY_LENGTH = makeIntrinsic(getAccessor(Object[].class, ArrayAccess.LENGTH), Intrinsic.ARRAY_LENGTH);
 164 
 165             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_GETTER.internalMemberName()));
 166             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_SETTER.internalMemberName()));
 167             assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_LENGTH.internalMemberName()));
 168         }
 169 
 170         static int     getElementI(int[]     a, int i)            { return              a[i]; }
 171         static long    getElementJ(long[]    a, int i)            { return              a[i]; }
 172         static float   getElementF(float[]   a, int i)            { return              a[i]; }
 173         static double  getElementD(double[]  a, int i)            { return              a[i]; }
 174         static boolean getElementZ(boolean[] a, int i)            { return              a[i]; }
 175         static byte    getElementB(byte[]    a, int i)            { return              a[i]; }
 176         static short   getElementS(short[]   a, int i)            { return              a[i]; }
 177         static char    getElementC(char[]    a, int i)            { return              a[i]; }
 178         static Object  getElementL(Object[]  a, int i)            { return              a[i]; }
 179 
 180         static void    setElementI(int[]     a, int i, int     x) {              a[i] = x; }
 181         static void    setElementJ(long[]    a, int i, long    x) {              a[i] = x; }
 182         static void    setElementF(float[]   a, int i, float   x) {              a[i] = x; }
 183         static void    setElementD(double[]  a, int i, double  x) {              a[i] = x; }
 184         static void    setElementZ(boolean[] a, int i, boolean x) {              a[i] = x; }
 185         static void    setElementB(byte[]    a, int i, byte    x) {              a[i] = x; }
 186         static void    setElementS(short[]   a, int i, short   x) {              a[i] = x; }
 187         static void    setElementC(char[]    a, int i, char    x) {              a[i] = x; }
 188         static void    setElementL(Object[]  a, int i, Object  x) {              a[i] = x; }
 189 
 190         static int     lengthI(int[]     a)                       { return a.length; }
 191         static int     lengthJ(long[]    a)                       { return a.length; }
 192         static int     lengthF(float[]   a)                       { return a.length; }
 193         static int     lengthD(double[]  a)                       { return a.length; }
 194         static int     lengthZ(boolean[] a)                       { return a.length; }
 195         static int     lengthB(byte[]    a)                       { return a.length; }
 196         static int     lengthS(short[]   a)                       { return a.length; }
 197         static int     lengthC(char[]    a)                       { return a.length; }
 198         static int     lengthL(Object[]  a)                       { return a.length; }
 199 
 200         static String name(Class<?> arrayClass, ArrayAccess access) {
 201             Class<?> elemClass = arrayClass.getComponentType();
 202             if (elemClass == null)  throw newIllegalArgumentException("not an array", arrayClass);
 203             return ArrayAccess.opName(access) + Wrapper.basicTypeChar(elemClass);
 204         }
 205         static MethodType type(Class<?> arrayClass, ArrayAccess access) {
 206             Class<?> elemClass = arrayClass.getComponentType();
 207             Class<?> arrayArgClass = arrayClass;
 208             if (!elemClass.isPrimitive()) {
 209                 arrayArgClass = Object[].class;
 210                 elemClass = Object.class;
 211             }
 212             switch (access) {
 213                 case GET:    return MethodType.methodType(elemClass,  arrayArgClass, int.class);
 214                 case SET:    return MethodType.methodType(void.class, arrayArgClass, int.class, elemClass);
 215                 case LENGTH: return MethodType.methodType(int.class,  arrayArgClass);
 216             }
 217             throw unmatchedArrayAccess(access);
 218         }
 219         static MethodType correctType(Class<?> arrayClass, ArrayAccess access) {
 220             Class<?> elemClass = arrayClass.getComponentType();
 221             switch (access) {
 222                 case GET:    return MethodType.methodType(elemClass,  arrayClass, int.class);
 223                 case SET:    return MethodType.methodType(void.class, arrayClass, int.class, elemClass);
 224                 case LENGTH: return MethodType.methodType(int.class,  arrayClass);
 225             }
 226             throw unmatchedArrayAccess(access);
 227         }
 228         static MethodHandle getAccessor(Class<?> arrayClass, ArrayAccess access) {
 229             String     name = name(arrayClass, access);
 230             MethodType type = type(arrayClass, access);
 231             try {
 232                 return IMPL_LOOKUP.findStatic(ArrayAccessor.class, name, type);
 233             } catch (ReflectiveOperationException ex) {
 234                 throw uncaughtException(ex);
 235             }
 236         }
 237     }
 238 
 239     /**
 240      * Create a JVM-level adapter method handle to conform the given method
 241      * handle to the similar newType, using only pairwise argument conversions.
 242      * For each argument, convert incoming argument to the exact type needed.
 243      * The argument conversions allowed are casting, boxing and unboxing,
 244      * integral widening or narrowing, and floating point widening or narrowing.
 245      * @param srcType required call type
 246      * @param target original method handle
 247      * @param strict if true, only asType conversions are allowed; if false, explicitCastArguments conversions allowed
 248      * @param monobox if true, unboxing conversions are assumed to be exactly typed (Integer to int only, not long or double)
 249      * @return an adapter to the original handle with the desired new type,
 250      *          or the original target if the types are already identical
 251      *          or null if the adaptation cannot be made
 252      */
 253     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 254                                             boolean strict, boolean monobox) {
 255         MethodType dstType = target.type();
 256         if (srcType == dstType)
 257             return target;
 258         return makePairwiseConvertByEditor(target, srcType, strict, monobox);
 259     }
 260 
 261     private static int countNonNull(Object[] array) {
 262         int count = 0;
 263         if (array != null) {
 264             for (Object x : array) {
 265                 if (x != null) ++count;
 266             }
 267         }
 268         return count;
 269     }
 270 
 271     static MethodHandle makePairwiseConvertByEditor(MethodHandle target, MethodType srcType,
 272                                                     boolean strict, boolean monobox) {
 273         // In method types arguments start at index 0, while the LF
 274         // editor have the MH receiver at position 0 - adjust appropriately.
 275         final int MH_RECEIVER_OFFSET = 1;
 276         Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
 277         int convCount = countNonNull(convSpecs);
 278         if (convCount == 0)
 279             return target.viewAsType(srcType, strict);
 280         MethodType basicSrcType = srcType.basicType();
 281         MethodType midType = target.type().basicType();
 282         BoundMethodHandle mh = target.rebind();
 283 
 284         // Match each unique conversion to the positions at which it is to be applied
 285         var convSpecMap = new HashMap<Object, int[]>(((4 * convCount) / 3) + 1);
 286         for (int i = 0; i < convSpecs.length - MH_RECEIVER_OFFSET; i++) {
 287             Object convSpec = convSpecs[i];
 288             if (convSpec == null) continue;
 289             int[] positions = convSpecMap.get(convSpec);
 290             if (positions == null) {
 291                 positions = new int[] { i + MH_RECEIVER_OFFSET };
 292             } else {
 293                 positions = Arrays.copyOf(positions, positions.length + 1);
 294                 positions[positions.length - 1] = i + MH_RECEIVER_OFFSET;
 295             }
 296             convSpecMap.put(convSpec, positions);
 297         }
 298         for (var entry : convSpecMap.entrySet()) {
 299             Object convSpec = entry.getKey();
 300 
 301             MethodHandle fn;
 302             if (convSpec instanceof Class) {
 303                 fn = getConstantHandle(MH_cast).bindTo(convSpec);
 304             } else {
 305                 fn = (MethodHandle) convSpec;
 306             }
 307             int[] positions = entry.getValue();
 308             Class<?> newType = basicSrcType.parameterType(positions[0] - MH_RECEIVER_OFFSET);
 309             BasicType newBasicType = BasicType.basicType(newType);
 310             convCount -= positions.length;
 311             if (convCount == 0) {
 312                 midType = srcType;
 313             } else {
 314                 Class<?>[] ptypes = midType.ptypes().clone();
 315                 for (int pos : positions) {
 316                     ptypes[pos - 1] = newType;
 317                 }
 318                 midType = MethodType.makeImpl(midType.rtype(), ptypes, true);
 319             }
 320             LambdaForm form2;
 321             if (positions.length > 1) {
 322                 form2 = mh.editor().filterRepeatedArgumentForm(newBasicType, positions);
 323             } else {
 324                 form2 = mh.editor().filterArgumentForm(positions[0], newBasicType);
 325             }
 326             mh = mh.copyWithExtendL(midType, form2, fn);
 327         }
 328         Object convSpec = convSpecs[convSpecs.length - 1];
 329         if (convSpec != null) {
 330             MethodHandle fn;
 331             if (convSpec instanceof Class) {
 332                 if (convSpec == void.class)
 333                     fn = null;
 334                 else
 335                     fn = getConstantHandle(MH_cast).bindTo(convSpec);
 336             } else {
 337                 fn = (MethodHandle) convSpec;
 338             }
 339             Class<?> newType = basicSrcType.returnType();
 340             assert(--convCount == 0);
 341             midType = srcType;
 342             if (fn != null) {
 343                 mh = mh.rebind();  // rebind if too complex
 344                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), false);
 345                 mh = mh.copyWithExtendL(midType, form2, fn);
 346             } else {
 347                 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), true);
 348                 mh = mh.copyWith(midType, form2);
 349             }
 350         }
 351         assert(convCount == 0);
 352         assert(mh.type().equals(srcType));
 353         return mh;
 354     }
 355 
 356     static Object[] computeValueConversions(MethodType srcType, MethodType dstType,
 357                                             boolean strict, boolean monobox) {
 358         final int INARG_COUNT = srcType.parameterCount();
 359         Object[] convSpecs = null;
 360         for (int i = 0; i <= INARG_COUNT; i++) {
 361             boolean isRet = (i == INARG_COUNT);
 362             Class<?> src = isRet ? dstType.returnType() : srcType.parameterType(i);
 363             Class<?> dst = isRet ? srcType.returnType() : dstType.parameterType(i);
 364             if (!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)) {
 365                 if (convSpecs == null) {
 366                     convSpecs = new Object[INARG_COUNT + 1];
 367                 }
 368                 convSpecs[i] = valueConversion(src, dst, strict, monobox);
 369             }
 370         }
 371         return convSpecs;
 372     }
 373     static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
 374                                             boolean strict) {
 375         return makePairwiseConvert(target, srcType, strict, /*monobox=*/ false);
 376     }
 377 
 378     /**
 379      * Find a conversion function from the given source to the given destination.
 380      * This conversion function will be used as a LF NamedFunction.
 381      * Return a Class object if a simple cast is needed.
 382      * Return void.class if void is involved.
 383      */
 384     static Object valueConversion(Class<?> src, Class<?> dst, boolean strict, boolean monobox) {
 385         assert(!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict));  // caller responsibility
 386         if (dst == void.class)
 387             return dst;
 388         MethodHandle fn;
 389         if (src.isPrimitive()) {
 390             if (src == void.class) {
 391                 return void.class;  // caller must recognize this specially
 392             } else if (dst.isPrimitive()) {
 393                 // Examples: int->byte, byte->int, boolean->int (!strict)
 394                 fn = ValueConversions.convertPrimitive(src, dst);
 395             } else {
 396                 // Examples: int->Integer, boolean->Object, float->Number
 397                 Wrapper wsrc = Wrapper.forPrimitiveType(src);
 398                 fn = ValueConversions.boxExact(wsrc);
 399                 assert(fn.type().parameterType(0) == wsrc.primitiveType());
 400                 assert(fn.type().returnType() == wsrc.wrapperType());
 401                 if (!VerifyType.isNullConversion(wsrc.wrapperType(), dst, strict)) {
 402                     // Corner case, such as int->Long, which will probably fail.
 403                     MethodType mt = MethodType.methodType(dst, src);
 404                     if (strict)
 405                         fn = fn.asType(mt);
 406                     else
 407                         fn = MethodHandleImpl.makePairwiseConvert(fn, mt, /*strict=*/ false);
 408                 }
 409             }
 410         } else if (dst.isPrimitive()) {
 411             Wrapper wdst = Wrapper.forPrimitiveType(dst);
 412             if (monobox || src == wdst.wrapperType()) {
 413                 // Use a strongly-typed unboxer, if possible.
 414                 fn = ValueConversions.unboxExact(wdst, strict);
 415             } else {
 416                 // Examples:  Object->int, Number->int, Comparable->int, Byte->int
 417                 // must include additional conversions
 418                 // src must be examined at runtime, to detect Byte, Character, etc.
 419                 fn = (strict
 420                         ? ValueConversions.unboxWiden(wdst)
 421                         : ValueConversions.unboxCast(wdst));
 422             }
 423         } else {
 424             // Simple reference conversion.
 425             // Note:  Do not check for a class hierarchy relation
 426             // between src and dst.  In all cases a 'null' argument
 427             // will pass the cast conversion.
 428             return dst;
 429         }
 430         assert(fn.type().parameterCount() <= 1) : "pc"+Arrays.asList(src.getSimpleName(), dst.getSimpleName(), fn);
 431         return fn;
 432     }
 433 
 434     static MethodHandle makeVarargsCollector(MethodHandle target, Class<?> arrayType) {
 435         MethodType type = target.type();
 436         int last = type.parameterCount() - 1;
 437         if (type.parameterType(last) != arrayType)
 438             target = target.asType(type.changeParameterType(last, arrayType));
 439         target = target.asFixedArity();  // make sure this attribute is turned off
 440         return new AsVarargsCollector(target, arrayType);
 441     }
 442 
 443     private static final class AsVarargsCollector extends DelegatingMethodHandle {
 444         private final MethodHandle target;
 445         private final Class<?> arrayType;
 446         private @Stable MethodHandle asCollectorCache;
 447 
 448         AsVarargsCollector(MethodHandle target, Class<?> arrayType) {
 449             this(target.type(), target, arrayType);
 450         }
 451         AsVarargsCollector(MethodType type, MethodHandle target, Class<?> arrayType) {
 452             super(type, target);
 453             this.target = target;
 454             this.arrayType = arrayType;
 455         }
 456 
 457         @Override
 458         public boolean isVarargsCollector() {
 459             return true;
 460         }
 461 
 462         @Override
 463         protected MethodHandle getTarget() {
 464             return target;
 465         }
 466 
 467         @Override
 468         public MethodHandle asFixedArity() {
 469             return target;
 470         }
 471 
 472         @Override
 473         MethodHandle setVarargs(MemberName member) {
 474             if (member.isVarargs())  return this;
 475             return asFixedArity();
 476         }
 477 
 478         @Override
 479         public MethodHandle withVarargs(boolean makeVarargs) {
 480             if (makeVarargs)  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         @Override
 524         public Object invokeWithArguments(Object... arguments) throws Throwable {
 525             MethodType type = this.type();
 526             int argc;
 527             final int MAX_SAFE = 127;  // 127 longs require 254 slots, which is safe to spread
 528             if (arguments == null
 529                     || (argc = arguments.length) <= MAX_SAFE
 530                     || argc < type.parameterCount()) {
 531                 return super.invokeWithArguments(arguments);
 532             }
 533 
 534             // a jumbo invocation requires more explicit reboxing of the trailing arguments
 535             int uncollected = type.parameterCount() - 1;
 536             Class<?> elemType = arrayType.getComponentType();
 537             int collected = argc - uncollected;
 538             Object collArgs = (elemType == Object.class)
 539                 ? new Object[collected] : Array.newInstance(elemType, collected);
 540             if (!elemType.isPrimitive()) {
 541                 // simple cast:  just do some casting
 542                 try {
 543                     System.arraycopy(arguments, uncollected, collArgs, 0, collected);
 544                 } catch (ArrayStoreException ex) {
 545                     return super.invokeWithArguments(arguments);
 546                 }
 547             } else {
 548                 // corner case of flat array requires reflection (or specialized copy loop)
 549                 MethodHandle arraySetter = MethodHandles.arrayElementSetter(arrayType);
 550                 try {
 551                     for (int i = 0; i < collected; i++) {
 552                         arraySetter.invoke(collArgs, i, arguments[uncollected + i]);
 553                     }
 554                 } catch (WrongMethodTypeException|ClassCastException ex) {
 555                     return super.invokeWithArguments(arguments);
 556                 }
 557             }
 558 
 559             // chop the jumbo list down to size and call in non-varargs mode
 560             Object[] newArgs = new Object[uncollected + 1];
 561             System.arraycopy(arguments, 0, newArgs, 0, uncollected);
 562             newArgs[uncollected] = collArgs;
 563             return asFixedArity().invokeWithArguments(newArgs);
 564         }
 565     }
 566 
 567     /** Factory method:  Spread selected argument. */
 568     static MethodHandle makeSpreadArguments(MethodHandle target,
 569                                             Class<?> spreadArgType, int spreadArgPos, int spreadArgCount) {
 570         MethodType targetType = target.type();
 571 
 572         for (int i = 0; i < spreadArgCount; i++) {
 573             Class<?> arg = VerifyType.spreadArgElementType(spreadArgType, i);
 574             if (arg == null)  arg = Object.class;
 575             targetType = targetType.changeParameterType(spreadArgPos + i, arg);
 576         }
 577         target = target.asType(targetType);
 578 
 579         MethodType srcType = targetType
 580                 .replaceParameterTypes(spreadArgPos, spreadArgPos + spreadArgCount, spreadArgType);
 581         // Now build a LambdaForm.
 582         MethodType lambdaType = srcType.invokerType();
 583         Name[] names = arguments(spreadArgCount + 2, lambdaType);
 584         int nameCursor = lambdaType.parameterCount();
 585         int[] indexes = new int[targetType.parameterCount()];
 586 
 587         for (int i = 0, argIndex = 1; i < targetType.parameterCount() + 1; i++, argIndex++) {
 588             Class<?> src = lambdaType.parameterType(i);
 589             if (i == spreadArgPos) {
 590                 // Spread the array.
 591                 MethodHandle aload = MethodHandles.arrayElementGetter(spreadArgType);
 592                 Name array = names[argIndex];
 593                 names[nameCursor++] = new Name(getFunction(NF_checkSpreadArgument), array, spreadArgCount);
 594                 for (int j = 0; j < spreadArgCount; i++, j++) {
 595                     indexes[i] = nameCursor;
 596                     names[nameCursor++] = new Name(new NamedFunction(aload, Intrinsic.ARRAY_LOAD), array, j);
 597                 }
 598             } else if (i < indexes.length) {
 599                 indexes[i] = argIndex;
 600             }
 601         }
 602         assert(nameCursor == names.length-1);  // leave room for the final call
 603 
 604         // Build argument array for the call.
 605         Name[] targetArgs = new Name[targetType.parameterCount()];
 606         for (int i = 0; i < targetType.parameterCount(); i++) {
 607             int idx = indexes[i];
 608             targetArgs[i] = names[idx];
 609         }
 610         names[names.length - 1] = new Name(target, (Object[]) targetArgs);
 611 
 612         LambdaForm form = new LambdaForm(lambdaType.parameterCount(), names, Kind.SPREAD);
 613         return SimpleMethodHandle.make(srcType, form);
 614     }
 615 
 616     static void checkSpreadArgument(Object av, int n) {
 617         if (av == null && n == 0) {
 618             return;
 619         } else if (av == null) {
 620             throw new NullPointerException("null array reference");
 621         } else if (av instanceof Object[]) {
 622             int len = ((Object[])av).length;
 623             if (len == n)  return;
 624         } else {
 625             int len = java.lang.reflect.Array.getLength(av);
 626             if (len == n)  return;
 627         }
 628         // fall through to error:
 629         throw newIllegalArgumentException("array is not of length "+n);
 630     }
 631 
 632     /** Factory method:  Collect or filter selected argument(s). */
 633     static MethodHandle makeCollectArguments(MethodHandle target,
 634                 MethodHandle collector, int collectArgPos, boolean retainOriginalArgs) {
 635         MethodType targetType = target.type();          // (a..., c, [b...])=>r
 636         MethodType collectorType = collector.type();    // (b...)=>c
 637         int collectArgCount = collectorType.parameterCount();
 638         Class<?> collectValType = collectorType.returnType();
 639         int collectValCount = (collectValType == void.class ? 0 : 1);
 640         MethodType srcType = targetType                 // (a..., [b...])=>r
 641                 .dropParameterTypes(collectArgPos, collectArgPos+collectValCount);
 642         if (!retainOriginalArgs) {                      // (a..., b...)=>r
 643             srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterArray());
 644         }
 645         // in  arglist: [0: ...keep1 | cpos: collect...  | cpos+cacount: keep2... ]
 646         // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
 647         // out(retain): [0: ...keep1 | cpos: cV? coll... | cpos+cvc+cac: keep2... ]
 648 
 649         // Now build a LambdaForm.
 650         MethodType lambdaType = srcType.invokerType();
 651         Name[] names = arguments(2, lambdaType);
 652         final int collectNamePos = names.length - 2;
 653         final int targetNamePos  = names.length - 1;
 654 
 655         Name[] collectorArgs = Arrays.copyOfRange(names, 1 + collectArgPos, 1 + collectArgPos + collectArgCount);
 656         names[collectNamePos] = new Name(collector, (Object[]) collectorArgs);
 657 
 658         // Build argument array for the target.
 659         // Incoming LF args to copy are: [ (mh) headArgs collectArgs tailArgs ].
 660         // Output argument array is [ headArgs (collectVal)? (collectArgs)? tailArgs ].
 661         Name[] targetArgs = new Name[targetType.parameterCount()];
 662         int inputArgPos  = 1;  // incoming LF args to copy to target
 663         int targetArgPos = 0;  // fill pointer for targetArgs
 664         int chunk = collectArgPos;  // |headArgs|
 665         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 666         inputArgPos  += chunk;
 667         targetArgPos += chunk;
 668         if (collectValType != void.class) {
 669             targetArgs[targetArgPos++] = names[collectNamePos];
 670         }
 671         chunk = collectArgCount;
 672         if (retainOriginalArgs) {
 673             System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 674             targetArgPos += chunk;   // optionally pass on the collected chunk
 675         }
 676         inputArgPos += chunk;
 677         chunk = targetArgs.length - targetArgPos;  // all the rest
 678         System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
 679         assert(inputArgPos + chunk == collectNamePos);  // use of rest of input args also
 680         names[targetNamePos] = new Name(target, (Object[]) targetArgs);
 681 
 682         LambdaForm form = new LambdaForm(lambdaType.parameterCount(), names, Kind.COLLECT);
 683         return SimpleMethodHandle.make(srcType, form);
 684     }
 685 
 686     @Hidden
 687     static MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback) {
 688         if (testResult) {
 689             return target;
 690         } else {
 691             return fallback;
 692         }
 693     }
 694 
 695     // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
 696     @Hidden
 697     @jdk.internal.HotSpotIntrinsicCandidate
 698     static boolean profileBoolean(boolean result, int[] counters) {
 699         // Profile is int[2] where [0] and [1] correspond to false and true occurrences respectively.
 700         int idx = result ? 1 : 0;
 701         try {
 702             counters[idx] = Math.addExact(counters[idx], 1);
 703         } catch (ArithmeticException e) {
 704             // Avoid continuous overflow by halving the problematic count.
 705             counters[idx] = counters[idx] / 2;
 706         }
 707         return result;
 708     }
 709 
 710     // Intrinsified by C2. Returns true if obj is a compile-time constant.
 711     @Hidden
 712     @jdk.internal.HotSpotIntrinsicCandidate
 713     static boolean isCompileConstant(Object obj) {
 714         return false;
 715     }
 716 
 717     static MethodHandle makeGuardWithTest(MethodHandle test,
 718                                    MethodHandle target,
 719                                    MethodHandle fallback) {
 720         MethodType type = target.type();
 721         assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
 722         MethodType basicType = type.basicType();
 723         LambdaForm form = makeGuardWithTestForm(basicType);
 724         BoundMethodHandle mh;
 725         try {
 726             if (PROFILE_GWT) {
 727                 int[] counts = new int[2];
 728                 mh = (BoundMethodHandle)
 729                         BoundMethodHandle.speciesData_LLLL().factory().invokeBasic(type, form,
 730                                 (Object) test, (Object) profile(target), (Object) profile(fallback), counts);
 731             } else {
 732                 mh = (BoundMethodHandle)
 733                         BoundMethodHandle.speciesData_LLL().factory().invokeBasic(type, form,
 734                                 (Object) test, (Object) profile(target), (Object) profile(fallback));
 735             }
 736         } catch (Throwable ex) {
 737             throw uncaughtException(ex);
 738         }
 739         assert(mh.type() == type);
 740         return mh;
 741     }
 742 
 743 
 744     static MethodHandle profile(MethodHandle target) {
 745         if (DONT_INLINE_THRESHOLD >= 0) {
 746             return makeBlockInliningWrapper(target);
 747         } else {
 748             return target;
 749         }
 750     }
 751 
 752     /**
 753      * Block inlining during JIT-compilation of a target method handle if it hasn't been invoked enough times.
 754      * Corresponding LambdaForm has @DontInline when compiled into bytecode.
 755      */
 756     static MethodHandle makeBlockInliningWrapper(MethodHandle target) {
 757         LambdaForm lform;
 758         if (DONT_INLINE_THRESHOLD > 0) {
 759             lform = Makers.PRODUCE_BLOCK_INLINING_FORM.apply(target);
 760         } else {
 761             lform = Makers.PRODUCE_REINVOKER_FORM.apply(target);
 762         }
 763         return new CountingWrapper(target, lform,
 764                 Makers.PRODUCE_BLOCK_INLINING_FORM, Makers.PRODUCE_REINVOKER_FORM,
 765                                    DONT_INLINE_THRESHOLD);
 766     }
 767 
 768     private final static class Makers {
 769         /** Constructs reinvoker lambda form which block inlining during JIT-compilation for a particular method handle */
 770         static final Function<MethodHandle, LambdaForm> PRODUCE_BLOCK_INLINING_FORM = new Function<MethodHandle, LambdaForm>() {
 771             @Override
 772             public LambdaForm apply(MethodHandle target) {
 773                 return DelegatingMethodHandle.makeReinvokerForm(target,
 774                                    MethodTypeForm.LF_DELEGATE_BLOCK_INLINING, CountingWrapper.class, false,
 775                                    DelegatingMethodHandle.NF_getTarget, CountingWrapper.NF_maybeStopCounting);
 776             }
 777         };
 778 
 779         /** Constructs simple reinvoker lambda form for a particular method handle */
 780         static final Function<MethodHandle, LambdaForm> PRODUCE_REINVOKER_FORM = new Function<MethodHandle, LambdaForm>() {
 781             @Override
 782             public LambdaForm apply(MethodHandle target) {
 783                 return DelegatingMethodHandle.makeReinvokerForm(target,
 784                         MethodTypeForm.LF_DELEGATE, DelegatingMethodHandle.class, DelegatingMethodHandle.NF_getTarget);
 785             }
 786         };
 787 
 788         /** Maker of type-polymorphic varargs */
 789         static final ClassValue<MethodHandle[]> TYPED_COLLECTORS = new ClassValue<MethodHandle[]>() {
 790             @Override
 791             protected MethodHandle[] computeValue(Class<?> type) {
 792                 return new MethodHandle[MAX_JVM_ARITY + 1];
 793             }
 794         };
 795     }
 796 
 797     /**
 798      * Counting method handle. It has 2 states: counting and non-counting.
 799      * It is in counting state for the first n invocations and then transitions to non-counting state.
 800      * Behavior in counting and non-counting states is determined by lambda forms produced by
 801      * countingFormProducer & nonCountingFormProducer respectively.
 802      */
 803     static class CountingWrapper extends DelegatingMethodHandle {
 804         private final MethodHandle target;
 805         private int count;
 806         private Function<MethodHandle, LambdaForm> countingFormProducer;
 807         private Function<MethodHandle, LambdaForm> nonCountingFormProducer;
 808         private volatile boolean isCounting;
 809 
 810         private CountingWrapper(MethodHandle target, LambdaForm lform,
 811                                 Function<MethodHandle, LambdaForm> countingFromProducer,
 812                                 Function<MethodHandle, LambdaForm> nonCountingFormProducer,
 813                                 int count) {
 814             super(target.type(), lform);
 815             this.target = target;
 816             this.count = count;
 817             this.countingFormProducer = countingFromProducer;
 818             this.nonCountingFormProducer = nonCountingFormProducer;
 819             this.isCounting = (count > 0);
 820         }
 821 
 822         @Hidden
 823         @Override
 824         protected MethodHandle getTarget() {
 825             return target;
 826         }
 827 
 828         @Override
 829         public MethodHandle asTypeUncached(MethodType newType) {
 830             MethodHandle newTarget = target.asType(newType);
 831             MethodHandle wrapper;
 832             if (isCounting) {
 833                 LambdaForm lform;
 834                 lform = countingFormProducer.apply(newTarget);
 835                 wrapper = new CountingWrapper(newTarget, lform, countingFormProducer, nonCountingFormProducer, DONT_INLINE_THRESHOLD);
 836             } else {
 837                 wrapper = newTarget; // no need for a counting wrapper anymore
 838             }
 839             return (asTypeCache = wrapper);
 840         }
 841 
 842         // Customize target if counting happens for too long.
 843         private int invocations = CUSTOMIZE_THRESHOLD;
 844         private void maybeCustomizeTarget() {
 845             int c = invocations;
 846             if (c >= 0) {
 847                 if (c == 1) {
 848                     target.customize();
 849                 }
 850                 invocations = c - 1;
 851             }
 852         }
 853 
 854         boolean countDown() {
 855             int c = count;
 856             maybeCustomizeTarget();
 857             if (c <= 1) {
 858                 // Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
 859                 if (isCounting) {
 860                     isCounting = false;
 861                     return true;
 862                 } else {
 863                     return false;
 864                 }
 865             } else {
 866                 count = c - 1;
 867                 return false;
 868             }
 869         }
 870 
 871         @Hidden
 872         static void maybeStopCounting(Object o1) {
 873              CountingWrapper wrapper = (CountingWrapper) o1;
 874              if (wrapper.countDown()) {
 875                  // Reached invocation threshold. Replace counting behavior with a non-counting one.
 876                  LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
 877                  lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
 878                  wrapper.updateForm(lform);
 879              }
 880         }
 881 
 882         static final NamedFunction NF_maybeStopCounting;
 883         static {
 884             Class<?> THIS_CLASS = CountingWrapper.class;
 885             try {
 886                 NF_maybeStopCounting = new NamedFunction(THIS_CLASS.getDeclaredMethod("maybeStopCounting", Object.class));
 887             } catch (ReflectiveOperationException ex) {
 888                 throw newInternalError(ex);
 889             }
 890         }
 891     }
 892 
 893     static LambdaForm makeGuardWithTestForm(MethodType basicType) {
 894         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWT);
 895         if (lform != null)  return lform;
 896         final int THIS_MH      = 0;  // the BMH_LLL
 897         final int ARG_BASE     = 1;  // start of incoming arguments
 898         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 899         int nameCursor = ARG_LIMIT;
 900         final int GET_TEST     = nameCursor++;
 901         final int GET_TARGET   = nameCursor++;
 902         final int GET_FALLBACK = nameCursor++;
 903         final int GET_COUNTERS = PROFILE_GWT ? nameCursor++ : -1;
 904         final int CALL_TEST    = nameCursor++;
 905         final int PROFILE      = (GET_COUNTERS != -1) ? nameCursor++ : -1;
 906         final int TEST         = nameCursor-1; // previous statement: either PROFILE or CALL_TEST
 907         final int SELECT_ALT   = nameCursor++;
 908         final int CALL_TARGET  = nameCursor++;
 909         assert(CALL_TARGET == SELECT_ALT+1);  // must be true to trigger IBG.emitSelectAlternative
 910 
 911         MethodType lambdaType = basicType.invokerType();
 912         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 913 
 914         BoundMethodHandle.SpeciesData data =
 915                 (GET_COUNTERS != -1) ? BoundMethodHandle.speciesData_LLLL()
 916                                      : BoundMethodHandle.speciesData_LLL();
 917         names[THIS_MH] = names[THIS_MH].withConstraint(data);
 918         names[GET_TEST]     = new Name(data.getterFunction(0), names[THIS_MH]);
 919         names[GET_TARGET]   = new Name(data.getterFunction(1), names[THIS_MH]);
 920         names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
 921         if (GET_COUNTERS != -1) {
 922             names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
 923         }
 924         Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
 925 
 926         // call test
 927         MethodType testType = basicType.changeReturnType(boolean.class).basicType();
 928         invokeArgs[0] = names[GET_TEST];
 929         names[CALL_TEST] = new Name(testType, invokeArgs);
 930 
 931         // profile branch
 932         if (PROFILE != -1) {
 933             names[PROFILE] = new Name(getFunction(NF_profileBoolean), names[CALL_TEST], names[GET_COUNTERS]);
 934         }
 935         // call selectAlternative
 936         names[SELECT_ALT] = new Name(new NamedFunction(getConstantHandle(MH_selectAlternative), Intrinsic.SELECT_ALTERNATIVE), names[TEST], names[GET_TARGET], names[GET_FALLBACK]);
 937 
 938         // call target or fallback
 939         invokeArgs[0] = names[SELECT_ALT];
 940         names[CALL_TARGET] = new Name(basicType, invokeArgs);
 941 
 942         lform = new LambdaForm(lambdaType.parameterCount(), names, /*forceInline=*/true, Kind.GUARD);
 943 
 944         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
 945     }
 946 
 947     /**
 948      * The LambdaForm shape for catchException combinator is the following:
 949      * <blockquote><pre>{@code
 950      *  guardWithCatch=Lambda(a0:L,a1:L,a2:L)=>{
 951      *    t3:L=BoundMethodHandle$Species_LLLLL.argL0(a0:L);
 952      *    t4:L=BoundMethodHandle$Species_LLLLL.argL1(a0:L);
 953      *    t5:L=BoundMethodHandle$Species_LLLLL.argL2(a0:L);
 954      *    t6:L=BoundMethodHandle$Species_LLLLL.argL3(a0:L);
 955      *    t7:L=BoundMethodHandle$Species_LLLLL.argL4(a0:L);
 956      *    t8:L=MethodHandle.invokeBasic(t6:L,a1:L,a2:L);
 957      *    t9:L=MethodHandleImpl.guardWithCatch(t3:L,t4:L,t5:L,t8:L);
 958      *   t10:I=MethodHandle.invokeBasic(t7:L,t9:L);t10:I}
 959      * }</pre></blockquote>
 960      *
 961      * argL0 and argL2 are target and catcher method handles. argL1 is exception class.
 962      * argL3 and argL4 are auxiliary method handles: argL3 boxes arguments and wraps them into Object[]
 963      * (ValueConversions.array()) and argL4 unboxes result if necessary (ValueConversions.unbox()).
 964      *
 965      * Having t8 and t10 passed outside and not hardcoded into a lambda form allows to share lambda forms
 966      * among catchException combinators with the same basic type.
 967      */
 968     private static LambdaForm makeGuardWithCatchForm(MethodType basicType) {
 969         MethodType lambdaType = basicType.invokerType();
 970 
 971         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWC);
 972         if (lform != null) {
 973             return lform;
 974         }
 975         final int THIS_MH      = 0;  // the BMH_LLLLL
 976         final int ARG_BASE     = 1;  // start of incoming arguments
 977         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
 978 
 979         int nameCursor = ARG_LIMIT;
 980         final int GET_TARGET       = nameCursor++;
 981         final int GET_CLASS        = nameCursor++;
 982         final int GET_CATCHER      = nameCursor++;
 983         final int GET_COLLECT_ARGS = nameCursor++;
 984         final int GET_UNBOX_RESULT = nameCursor++;
 985         final int BOXED_ARGS       = nameCursor++;
 986         final int TRY_CATCH        = nameCursor++;
 987         final int UNBOX_RESULT     = nameCursor++;
 988 
 989         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
 990 
 991         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
 992         names[THIS_MH]          = names[THIS_MH].withConstraint(data);
 993         names[GET_TARGET]       = new Name(data.getterFunction(0), names[THIS_MH]);
 994         names[GET_CLASS]        = new Name(data.getterFunction(1), names[THIS_MH]);
 995         names[GET_CATCHER]      = new Name(data.getterFunction(2), names[THIS_MH]);
 996         names[GET_COLLECT_ARGS] = new Name(data.getterFunction(3), names[THIS_MH]);
 997         names[GET_UNBOX_RESULT] = new Name(data.getterFunction(4), names[THIS_MH]);
 998 
 999         // FIXME: rework argument boxing/result unboxing logic for LF interpretation
1000 
1001         // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
1002         MethodType collectArgsType = basicType.changeReturnType(Object.class);
1003         MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
1004         Object[] args = new Object[invokeBasic.type().parameterCount()];
1005         args[0] = names[GET_COLLECT_ARGS];
1006         System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT-ARG_BASE);
1007         names[BOXED_ARGS] = new Name(new NamedFunction(invokeBasic, Intrinsic.GUARD_WITH_CATCH), args);
1008 
1009         // t_{i+1}:L=MethodHandleImpl.guardWithCatch(target:L,exType:L,catcher:L,t_{i}:L);
1010         Object[] gwcArgs = new Object[] {names[GET_TARGET], names[GET_CLASS], names[GET_CATCHER], names[BOXED_ARGS]};
1011         names[TRY_CATCH] = new Name(getFunction(NF_guardWithCatch), gwcArgs);
1012 
1013         // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
1014         MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
1015         Object[] unboxArgs  = new Object[] {names[GET_UNBOX_RESULT], names[TRY_CATCH]};
1016         names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
1017 
1018         lform = new LambdaForm(lambdaType.parameterCount(), names, Kind.GUARD_WITH_CATCH);
1019 
1020         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWC, lform);
1021     }
1022 
1023     static MethodHandle makeGuardWithCatch(MethodHandle target,
1024                                     Class<? extends Throwable> exType,
1025                                     MethodHandle catcher) {
1026         MethodType type = target.type();
1027         LambdaForm form = makeGuardWithCatchForm(type.basicType());
1028 
1029         // Prepare auxiliary method handles used during LambdaForm interpretation.
1030         // Box arguments and wrap them into Object[]: ValueConversions.array().
1031         MethodType varargsType = type.changeReturnType(Object[].class);
1032         MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
1033         MethodHandle unboxResult = unboxResultHandle(type.returnType());
1034 
1035         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
1036         BoundMethodHandle mh;
1037         try {
1038             mh = (BoundMethodHandle) data.factory().invokeBasic(type, form, (Object) target, (Object) exType,
1039                     (Object) catcher, (Object) collectArgs, (Object) unboxResult);
1040         } catch (Throwable ex) {
1041             throw uncaughtException(ex);
1042         }
1043         assert(mh.type() == type);
1044         return mh;
1045     }
1046 
1047     /**
1048      * Intrinsified during LambdaForm compilation
1049      * (see {@link InvokerBytecodeGenerator#emitGuardWithCatch emitGuardWithCatch}).
1050      */
1051     @Hidden
1052     static Object guardWithCatch(MethodHandle target, Class<? extends Throwable> exType, MethodHandle catcher,
1053                                  Object... av) throws Throwable {
1054         // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case.
1055         try {
1056             return target.asFixedArity().invokeWithArguments(av);
1057         } catch (Throwable t) {
1058             if (!exType.isInstance(t)) throw t;
1059             return catcher.asFixedArity().invokeWithArguments(prepend(av, t));
1060         }
1061     }
1062 
1063     /** Prepend elements to an array. */
1064     @Hidden
1065     private static Object[] prepend(Object[] array, Object... elems) {
1066         int nArray = array.length;
1067         int nElems = elems.length;
1068         Object[] newArray = new Object[nArray + nElems];
1069         System.arraycopy(elems, 0, newArray, 0, nElems);
1070         System.arraycopy(array, 0, newArray, nElems, nArray);
1071         return newArray;
1072     }
1073 
1074     static MethodHandle throwException(MethodType type) {
1075         assert(Throwable.class.isAssignableFrom(type.parameterType(0)));
1076         int arity = type.parameterCount();
1077         if (arity > 1) {
1078             MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
1079             mh = MethodHandles.dropArguments(mh, 1, Arrays.copyOfRange(type.parameterArray(), 1, arity));
1080             return mh;
1081         }
1082         return makePairwiseConvert(getFunction(NF_throwException).resolvedHandle(), type, false, true);
1083     }
1084 
1085     static <T extends Throwable> Empty throwException(T t) throws T { throw t; }
1086 
1087     static MethodHandle[] FAKE_METHOD_HANDLE_INVOKE = new MethodHandle[2];
1088     static MethodHandle fakeMethodHandleInvoke(MemberName method) {
1089         int idx;
1090         assert(method.isMethodHandleInvoke());
1091         switch (method.getName()) {
1092         case "invoke":       idx = 0; break;
1093         case "invokeExact":  idx = 1; break;
1094         default:             throw new InternalError(method.getName());
1095         }
1096         MethodHandle mh = FAKE_METHOD_HANDLE_INVOKE[idx];
1097         if (mh != null)  return mh;
1098         MethodType type = MethodType.methodType(Object.class, UnsupportedOperationException.class,
1099                                                 MethodHandle.class, Object[].class);
1100         mh = throwException(type);
1101         mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke MethodHandle"));
1102         if (!method.getInvocationType().equals(mh.type()))
1103             throw new InternalError(method.toString());
1104         mh = mh.withInternalMemberName(method, false);
1105         mh = mh.withVarargs(true);
1106         assert(method.isVarargs());
1107         FAKE_METHOD_HANDLE_INVOKE[idx] = mh;
1108         return mh;
1109     }
1110     static MethodHandle fakeVarHandleInvoke(MemberName method) {
1111         // TODO caching, is it necessary?
1112         MethodType type = MethodType.methodType(method.getReturnType(), UnsupportedOperationException.class,
1113                                                 VarHandle.class, Object[].class);
1114         MethodHandle mh = throwException(type);
1115         mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke VarHandle"));
1116         if (!method.getInvocationType().equals(mh.type()))
1117             throw new InternalError(method.toString());
1118         mh = mh.withInternalMemberName(method, false);
1119         mh = mh.asVarargsCollector(Object[].class);
1120         assert(method.isVarargs());
1121         return mh;
1122     }
1123 
1124     /**
1125      * Create an alias for the method handle which, when called,
1126      * appears to be called from the same class loader and protection domain
1127      * as hostClass.
1128      * This is an expensive no-op unless the method which is called
1129      * is sensitive to its caller.  A small number of system methods
1130      * are in this category, including Class.forName and Method.invoke.
1131      */
1132     static MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1133         return BindCaller.bindCaller(mh, hostClass);
1134     }
1135 
1136     // Put the whole mess into its own nested class.
1137     // That way we can lazily load the code and set up the constants.
1138     private static class BindCaller {
1139         private static MethodType INVOKER_MT = MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1140 
1141         static MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1142             // Code in the boot layer should now be careful while creating method handles or
1143             // functional interface instances created from method references to @CallerSensitive  methods,
1144             // it needs to be ensured the handles or interface instances are kept safe and are not passed
1145             // from the boot layer to untrusted code.
1146             if (hostClass == null
1147                 ||    (hostClass.isArray() ||
1148                        hostClass.isPrimitive() ||
1149                        hostClass.getName().startsWith("java.lang.invoke."))) {
1150                 throw new InternalError();  // does not happen, and should not anyway
1151             }
1152             // For simplicity, convert mh to a varargs-like method.
1153             MethodHandle vamh = prepareForInvoker(mh);
1154             // Cache the result of makeInjectedInvoker once per argument class.
1155             MethodHandle bccInvoker = CV_makeInjectedInvoker.get(hostClass);
1156             return restoreToType(bccInvoker.bindTo(vamh), mh, hostClass);
1157         }
1158 
1159         private static MethodHandle makeInjectedInvoker(Class<?> hostClass) {
1160             try {
1161                 Class<?> invokerClass = UNSAFE.defineAnonymousClass(hostClass, INJECTED_INVOKER_TEMPLATE, null);
1162                 assert checkInjectedInvoker(hostClass, invokerClass);
1163                 return IMPL_LOOKUP.findStatic(invokerClass, "invoke_V", INVOKER_MT);
1164             } catch (ReflectiveOperationException ex) {
1165                 throw uncaughtException(ex);
1166             }
1167         }
1168 
1169         private static ClassValue<MethodHandle> CV_makeInjectedInvoker = new ClassValue<MethodHandle>() {
1170             @Override protected MethodHandle computeValue(Class<?> hostClass) {
1171                 return makeInjectedInvoker(hostClass);
1172             }
1173         };
1174 
1175         // Adapt mh so that it can be called directly from an injected invoker:
1176         private static MethodHandle prepareForInvoker(MethodHandle mh) {
1177             mh = mh.asFixedArity();
1178             MethodType mt = mh.type();
1179             int arity = mt.parameterCount();
1180             MethodHandle vamh = mh.asType(mt.generic());
1181             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1182             vamh = vamh.asSpreader(Object[].class, arity);
1183             vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
1184             return vamh;
1185         }
1186 
1187         // Undo the adapter effect of prepareForInvoker:
1188         private static MethodHandle restoreToType(MethodHandle vamh,
1189                                                   MethodHandle original,
1190                                                   Class<?> hostClass) {
1191             MethodType type = original.type();
1192             MethodHandle mh = vamh.asCollector(Object[].class, type.parameterCount());
1193             MemberName member = original.internalMemberName();
1194             mh = mh.asType(type);
1195             mh = new WrappedMember(mh, type, member, original.isInvokeSpecial(), hostClass);
1196             return mh;
1197         }
1198 
1199         private static boolean checkInjectedInvoker(Class<?> hostClass, Class<?> invokerClass) {
1200             assert (hostClass.getClassLoader() == invokerClass.getClassLoader()) : hostClass.getName()+" (CL)";
1201             try {
1202                 assert (hostClass.getProtectionDomain() == invokerClass.getProtectionDomain()) : hostClass.getName()+" (PD)";
1203             } catch (SecurityException ex) {
1204                 // Self-check was blocked by security manager. This is OK.
1205             }
1206             try {
1207                 // Test the invoker to ensure that it really injects into the right place.
1208                 MethodHandle invoker = IMPL_LOOKUP.findStatic(invokerClass, "invoke_V", INVOKER_MT);
1209                 MethodHandle vamh = prepareForInvoker(MH_checkCallerClass);
1210                 return (boolean)invoker.invoke(vamh, new Object[]{ invokerClass });
1211             } catch (Throwable ex) {
1212                 throw new InternalError(ex);
1213             }
1214         }
1215 
1216         private static final MethodHandle MH_checkCallerClass;
1217         static {
1218             final Class<?> THIS_CLASS = BindCaller.class;
1219             assert(checkCallerClass(THIS_CLASS));
1220             try {
1221                 MH_checkCallerClass = IMPL_LOOKUP
1222                     .findStatic(THIS_CLASS, "checkCallerClass",
1223                                 MethodType.methodType(boolean.class, Class.class));
1224                 assert((boolean) MH_checkCallerClass.invokeExact(THIS_CLASS));
1225             } catch (Throwable ex) {
1226                 throw new InternalError(ex);
1227             }
1228         }
1229 
1230         @CallerSensitive
1231         @ForceInline // to ensure Reflection.getCallerClass optimization
1232         private static boolean checkCallerClass(Class<?> expected) {
1233             // This method is called via MH_checkCallerClass and so it's correct to ask for the immediate caller here.
1234             Class<?> actual = Reflection.getCallerClass();
1235             if (actual != expected)
1236                 throw new InternalError("found " + actual.getName() + ", expected " + expected.getName());
1237             return true;
1238         }
1239 
1240         private static final byte[] INJECTED_INVOKER_TEMPLATE = generateInvokerTemplate();
1241 
1242         /** Produces byte code for a class that is used as an injected invoker. */
1243         private static byte[] generateInvokerTemplate() {
1244             ClassWriter cw = new ClassWriter(0);
1245 
1246             // private static class InjectedInvoker {
1247             //     @Hidden
1248             //     static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
1249             //        return vamh.invokeExact(args);
1250             //     }
1251             // }
1252             cw.visit(52, ACC_PRIVATE | ACC_SUPER, "InjectedInvoker", null, "java/lang/Object", null);
1253 
1254             MethodVisitor mv = cw.visitMethod(ACC_STATIC, "invoke_V",
1255                           "(Ljava/lang/invoke/MethodHandle;[Ljava/lang/Object;)Ljava/lang/Object;",
1256                           null, null);
1257 
1258             // Suppress invoker method in stack traces.
1259             AnnotationVisitor av0 = mv.visitAnnotation(InvokerBytecodeGenerator.HIDDEN_SIG, true);
1260             av0.visitEnd();
1261 
1262             mv.visitCode();
1263             mv.visitVarInsn(ALOAD, 0);
1264             mv.visitVarInsn(ALOAD, 1);
1265             mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/invoke/MethodHandle", "invokeExact",
1266                                "([Ljava/lang/Object;)Ljava/lang/Object;", false);
1267             mv.visitInsn(ARETURN);
1268             mv.visitMaxs(2, 2);
1269             mv.visitEnd();
1270 
1271             cw.visitEnd();
1272             return cw.toByteArray();
1273         }
1274     }
1275 
1276     /** This subclass allows a wrapped method handle to be re-associated with an arbitrary member name. */
1277     private static final class WrappedMember extends DelegatingMethodHandle {
1278         private final MethodHandle target;
1279         private final MemberName member;
1280         private final Class<?> callerClass;
1281         private final boolean isInvokeSpecial;
1282 
1283         private WrappedMember(MethodHandle target, MethodType type,
1284                               MemberName member, boolean isInvokeSpecial,
1285                               Class<?> callerClass) {
1286             super(type, target);
1287             this.target = target;
1288             this.member = member;
1289             this.callerClass = callerClass;
1290             this.isInvokeSpecial = isInvokeSpecial;
1291         }
1292 
1293         @Override
1294         MemberName internalMemberName() {
1295             return member;
1296         }
1297         @Override
1298         Class<?> internalCallerClass() {
1299             return callerClass;
1300         }
1301         @Override
1302         boolean isInvokeSpecial() {
1303             return isInvokeSpecial;
1304         }
1305         @Override
1306         protected MethodHandle getTarget() {
1307             return target;
1308         }
1309         @Override
1310         public MethodHandle asTypeUncached(MethodType newType) {
1311             // This MH is an alias for target, except for the MemberName
1312             // Drop the MemberName if there is any conversion.
1313             return asTypeCache = target.asType(newType);
1314         }
1315     }
1316 
1317     static MethodHandle makeWrappedMember(MethodHandle target, MemberName member, boolean isInvokeSpecial) {
1318         if (member.equals(target.internalMemberName()) && isInvokeSpecial == target.isInvokeSpecial())
1319             return target;
1320         return new WrappedMember(target, target.type(), member, isInvokeSpecial, null);
1321     }
1322 
1323     /** Intrinsic IDs */
1324     /*non-public*/
1325     enum Intrinsic {
1326         SELECT_ALTERNATIVE,
1327         GUARD_WITH_CATCH,
1328         TRY_FINALLY,
1329         LOOP,
1330         NEW_ARRAY,
1331         ARRAY_LOAD,
1332         ARRAY_STORE,
1333         ARRAY_LENGTH,
1334         IDENTITY,
1335         ZERO,
1336         NONE // no intrinsic associated
1337     }
1338 
1339     /** Mark arbitrary method handle as intrinsic.
1340      * InvokerBytecodeGenerator uses this info to produce more efficient bytecode shape. */
1341     static final class IntrinsicMethodHandle extends DelegatingMethodHandle {
1342         private final MethodHandle target;
1343         private final Intrinsic intrinsicName;
1344 
1345         IntrinsicMethodHandle(MethodHandle target, Intrinsic intrinsicName) {
1346             super(target.type(), target);
1347             this.target = target;
1348             this.intrinsicName = intrinsicName;
1349         }
1350 
1351         @Override
1352         protected MethodHandle getTarget() {
1353             return target;
1354         }
1355 
1356         @Override
1357         Intrinsic intrinsicName() {
1358             return intrinsicName;
1359         }
1360 
1361         @Override
1362         public MethodHandle asTypeUncached(MethodType newType) {
1363             // This MH is an alias for target, except for the intrinsic name
1364             // Drop the name if there is any conversion.
1365             return asTypeCache = target.asType(newType);
1366         }
1367 
1368         @Override
1369         String internalProperties() {
1370             return super.internalProperties() +
1371                     "\n& Intrinsic="+intrinsicName;
1372         }
1373 
1374         @Override
1375         public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
1376             if (intrinsicName == Intrinsic.IDENTITY) {
1377                 MethodType resultType = type().asCollectorType(arrayType, type().parameterCount() - 1, arrayLength);
1378                 MethodHandle newArray = MethodHandleImpl.varargsArray(arrayType, arrayLength);
1379                 return newArray.asType(resultType);
1380             }
1381             return super.asCollector(arrayType, arrayLength);
1382         }
1383     }
1384 
1385     static MethodHandle makeIntrinsic(MethodHandle target, Intrinsic intrinsicName) {
1386         if (intrinsicName == target.intrinsicName())
1387             return target;
1388         return new IntrinsicMethodHandle(target, intrinsicName);
1389     }
1390 
1391     static MethodHandle makeIntrinsic(MethodType type, LambdaForm form, Intrinsic intrinsicName) {
1392         return new IntrinsicMethodHandle(SimpleMethodHandle.make(type, form), intrinsicName);
1393     }
1394 
1395     /// Collection of multiple arguments.
1396 
1397     private static MethodHandle findCollector(String name, int nargs, Class<?> rtype, Class<?>... ptypes) {
1398         MethodType type = MethodType.genericMethodType(nargs)
1399                 .changeReturnType(rtype)
1400                 .insertParameterTypes(0, ptypes);
1401         try {
1402             return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, name, type);
1403         } catch (ReflectiveOperationException ex) {
1404             return null;
1405         }
1406     }
1407 
1408     private static final Object[] NO_ARGS_ARRAY = {};
1409     private static Object[] makeArray(Object... args) { return args; }
1410     private static Object[] array() { return NO_ARGS_ARRAY; }
1411     private static Object[] array(Object a0)
1412                 { return makeArray(a0); }
1413     private static Object[] array(Object a0, Object a1)
1414                 { return makeArray(a0, a1); }
1415     private static Object[] array(Object a0, Object a1, Object a2)
1416                 { return makeArray(a0, a1, a2); }
1417     private static Object[] array(Object a0, Object a1, Object a2, Object a3)
1418                 { return makeArray(a0, a1, a2, a3); }
1419     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1420                                   Object a4)
1421                 { return makeArray(a0, a1, a2, a3, a4); }
1422     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1423                                   Object a4, Object a5)
1424                 { return makeArray(a0, a1, a2, a3, a4, a5); }
1425     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1426                                   Object a4, Object a5, Object a6)
1427                 { return makeArray(a0, a1, a2, a3, a4, a5, a6); }
1428     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1429                                   Object a4, Object a5, Object a6, Object a7)
1430                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7); }
1431     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1432                                   Object a4, Object a5, Object a6, Object a7,
1433                                   Object a8)
1434                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8); }
1435     private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1436                                   Object a4, Object a5, Object a6, Object a7,
1437                                   Object a8, Object a9)
1438                 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); }
1439 
1440     private static final int ARRAYS_COUNT = 11;
1441     private static final @Stable MethodHandle[] ARRAYS = new MethodHandle[MAX_ARITY + 1];
1442 
1443     // filling versions of the above:
1444     // using Integer len instead of int len and no varargs to avoid bootstrapping problems
1445     private static Object[] fillNewArray(Integer len, Object[] /*not ...*/ args) {
1446         Object[] a = new Object[len];
1447         fillWithArguments(a, 0, args);
1448         return a;
1449     }
1450     private static Object[] fillNewTypedArray(Object[] example, Integer len, Object[] /*not ...*/ args) {
1451         Object[] a = Arrays.copyOf(example, len);
1452         assert(a.getClass() != Object[].class);
1453         fillWithArguments(a, 0, args);
1454         return a;
1455     }
1456     private static void fillWithArguments(Object[] a, int pos, Object... args) {
1457         System.arraycopy(args, 0, a, pos, args.length);
1458     }
1459     // using Integer pos instead of int pos to avoid bootstrapping problems
1460     private static Object[] fillArray(Integer pos, Object[] a, Object a0)
1461                 { fillWithArguments(a, pos, a0); return a; }
1462     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1)
1463                 { fillWithArguments(a, pos, a0, a1); return a; }
1464     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2)
1465                 { fillWithArguments(a, pos, a0, a1, a2); return a; }
1466     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3)
1467                 { fillWithArguments(a, pos, a0, a1, a2, a3); return a; }
1468     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1469                                   Object a4)
1470                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4); return a; }
1471     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1472                                   Object a4, Object a5)
1473                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5); return a; }
1474     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1475                                   Object a4, Object a5, Object a6)
1476                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6); return a; }
1477     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1478                                   Object a4, Object a5, Object a6, Object a7)
1479                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7); return a; }
1480     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1481                                   Object a4, Object a5, Object a6, Object a7,
1482                                   Object a8)
1483                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8); return a; }
1484     private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1485                                   Object a4, Object a5, Object a6, Object a7,
1486                                   Object a8, Object a9)
1487                 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); return a; }
1488 
1489     private static final int FILL_ARRAYS_COUNT = 11; // current number of fillArray methods
1490     private static final @Stable MethodHandle[] FILL_ARRAYS = new MethodHandle[FILL_ARRAYS_COUNT];
1491 
1492     private static MethodHandle getFillArray(int count) {
1493         assert (count > 0 && count < FILL_ARRAYS_COUNT);
1494         MethodHandle mh = FILL_ARRAYS[count];
1495         if (mh != null) {
1496             return mh;
1497         }
1498         mh = findCollector("fillArray", count, Object[].class, Integer.class, Object[].class);
1499         FILL_ARRAYS[count] = mh;
1500         return mh;
1501     }
1502 
1503     private static Object copyAsPrimitiveArray(Wrapper w, Object... boxes) {
1504         Object a = w.makeArray(boxes.length);
1505         w.copyArrayUnboxing(boxes, 0, a, 0, boxes.length);
1506         return a;
1507     }
1508 
1509     /** Return a method handle that takes the indicated number of Object
1510      *  arguments and returns an Object array of them, as if for varargs.
1511      */
1512     static MethodHandle varargsArray(int nargs) {
1513         MethodHandle mh = ARRAYS[nargs];
1514         if (mh != null) {
1515             return mh;
1516         }
1517         if (nargs < ARRAYS_COUNT) {
1518             mh = findCollector("array", nargs, Object[].class);
1519         } else {
1520             mh = buildVarargsArray(getConstantHandle(MH_fillNewArray),
1521                     getConstantHandle(MH_arrayIdentity), nargs);
1522         }
1523         assert(assertCorrectArity(mh, nargs));
1524         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1525         return ARRAYS[nargs] = mh;
1526     }
1527 
1528     private static boolean assertCorrectArity(MethodHandle mh, int arity) {
1529         assert(mh.type().parameterCount() == arity) : "arity != "+arity+": "+mh;
1530         return true;
1531     }
1532 
1533     // Array identity function (used as getConstantHandle(MH_arrayIdentity)).
1534     static <T> T[] identity(T[] x) {
1535         return x;
1536     }
1537 
1538     private static MethodHandle buildVarargsArray(MethodHandle newArray, MethodHandle finisher, int nargs) {
1539         // Build up the result mh as a sequence of fills like this:
1540         //   finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
1541         // The various fill(_,10*I,___*[J]) are reusable.
1542         int leftLen = Math.min(nargs, LEFT_ARGS);  // absorb some arguments immediately
1543         int rightLen = nargs - leftLen;
1544         MethodHandle leftCollector = newArray.bindTo(nargs);
1545         leftCollector = leftCollector.asCollector(Object[].class, leftLen);
1546         MethodHandle mh = finisher;
1547         if (rightLen > 0) {
1548             MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
1549             if (mh.equals(getConstantHandle(MH_arrayIdentity)))
1550                 mh = rightFiller;
1551             else
1552                 mh = MethodHandles.collectArguments(mh, 0, rightFiller);
1553         }
1554         if (mh.equals(getConstantHandle(MH_arrayIdentity)))
1555             mh = leftCollector;
1556         else
1557             mh = MethodHandles.collectArguments(mh, 0, leftCollector);
1558         return mh;
1559     }
1560 
1561     private static final int LEFT_ARGS = FILL_ARRAYS_COUNT - 1;
1562     private static final @Stable MethodHandle[] FILL_ARRAY_TO_RIGHT = new MethodHandle[MAX_ARITY + 1];
1563     /** fill_array_to_right(N).invoke(a, argL..arg[N-1])
1564      *  fills a[L]..a[N-1] with corresponding arguments,
1565      *  and then returns a.  The value L is a global constant (LEFT_ARGS).
1566      */
1567     private static MethodHandle fillToRight(int nargs) {
1568         MethodHandle filler = FILL_ARRAY_TO_RIGHT[nargs];
1569         if (filler != null)  return filler;
1570         filler = buildFiller(nargs);
1571         assert(assertCorrectArity(filler, nargs - LEFT_ARGS + 1));
1572         return FILL_ARRAY_TO_RIGHT[nargs] = filler;
1573     }
1574     private static MethodHandle buildFiller(int nargs) {
1575         if (nargs <= LEFT_ARGS)
1576             return getConstantHandle(MH_arrayIdentity);  // no args to fill; return the array unchanged
1577         // we need room for both mh and a in mh.invoke(a, arg*[nargs])
1578         final int CHUNK = LEFT_ARGS;
1579         int rightLen = nargs % CHUNK;
1580         int midLen = nargs - rightLen;
1581         if (rightLen == 0) {
1582             midLen = nargs - (rightLen = CHUNK);
1583             if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
1584                 // build some precursors from left to right
1585                 for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK)
1586                     if (j > LEFT_ARGS)  fillToRight(j);
1587             }
1588         }
1589         if (midLen < LEFT_ARGS) rightLen = nargs - (midLen = LEFT_ARGS);
1590         assert(rightLen > 0);
1591         MethodHandle midFill = fillToRight(midLen);  // recursive fill
1592         MethodHandle rightFill = getFillArray(rightLen).bindTo(midLen);  // [midLen..nargs-1]
1593         assert(midFill.type().parameterCount()   == 1 + midLen - LEFT_ARGS);
1594         assert(rightFill.type().parameterCount() == 1 + rightLen);
1595 
1596         // Combine the two fills:
1597         //   right(mid(a, x10..x19), x20..x23)
1598         // The final product will look like this:
1599         //   right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
1600         if (midLen == LEFT_ARGS)
1601             return rightFill;
1602         else
1603             return MethodHandles.collectArguments(rightFill, 0, midFill);
1604     }
1605 
1606     static final int MAX_JVM_ARITY = 255;  // limit imposed by the JVM
1607 
1608     /** Return a method handle that takes the indicated number of
1609      *  typed arguments and returns an array of them.
1610      *  The type argument is the array type.
1611      */
1612     static MethodHandle varargsArray(Class<?> arrayType, int nargs) {
1613         Class<?> elemType = arrayType.getComponentType();
1614         if (elemType == null)  throw new IllegalArgumentException("not an array: "+arrayType);
1615         // FIXME: Need more special casing and caching here.
1616         if (nargs >= MAX_JVM_ARITY/2 - 1) {
1617             int slots = nargs;
1618             final int MAX_ARRAY_SLOTS = MAX_JVM_ARITY - 1;  // 1 for receiver MH
1619             if (slots <= MAX_ARRAY_SLOTS && elemType.isPrimitive())
1620                 slots *= Wrapper.forPrimitiveType(elemType).stackSlots();
1621             if (slots > MAX_ARRAY_SLOTS)
1622                 throw new IllegalArgumentException("too many arguments: "+arrayType.getSimpleName()+", length "+nargs);
1623         }
1624         if (elemType == Object.class)
1625             return varargsArray(nargs);
1626         // other cases:  primitive arrays, subtypes of Object[]
1627         MethodHandle cache[] = Makers.TYPED_COLLECTORS.get(elemType);
1628         MethodHandle mh = nargs < cache.length ? cache[nargs] : null;
1629         if (mh != null)  return mh;
1630         if (nargs == 0) {
1631             Object example = java.lang.reflect.Array.newInstance(arrayType.getComponentType(), 0);
1632             mh = MethodHandles.constant(arrayType, example);
1633         } else if (elemType.isPrimitive()) {
1634             MethodHandle builder = getConstantHandle(MH_fillNewArray);
1635             MethodHandle producer = buildArrayProducer(arrayType);
1636             mh = buildVarargsArray(builder, producer, nargs);
1637         } else {
1638             Class<? extends Object[]> objArrayType = arrayType.asSubclass(Object[].class);
1639             Object[] example = Arrays.copyOf(NO_ARGS_ARRAY, 0, objArrayType);
1640             MethodHandle builder = getConstantHandle(MH_fillNewTypedArray).bindTo(example);
1641             MethodHandle producer = getConstantHandle(MH_arrayIdentity); // must be weakly typed
1642             mh = buildVarargsArray(builder, producer, nargs);
1643         }
1644         mh = mh.asType(MethodType.methodType(arrayType, Collections.<Class<?>>nCopies(nargs, elemType)));
1645         mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1646         assert(assertCorrectArity(mh, nargs));
1647         if (nargs < cache.length)
1648             cache[nargs] = mh;
1649         return mh;
1650     }
1651 
1652     private static MethodHandle buildArrayProducer(Class<?> arrayType) {
1653         Class<?> elemType = arrayType.getComponentType();
1654         assert(elemType.isPrimitive());
1655         return getConstantHandle(MH_copyAsPrimitiveArray).bindTo(Wrapper.forPrimitiveType(elemType));
1656     }
1657 
1658     /*non-public*/
1659     static void assertSame(Object mh1, Object mh2) {
1660         if (mh1 != mh2) {
1661             String msg = String.format("mh1 != mh2: mh1 = %s (form: %s); mh2 = %s (form: %s)",
1662                     mh1, ((MethodHandle)mh1).form,
1663                     mh2, ((MethodHandle)mh2).form);
1664             throw newInternalError(msg);
1665         }
1666     }
1667 
1668     // Local constant functions:
1669 
1670     /* non-public */
1671     static final byte NF_checkSpreadArgument = 0,
1672             NF_guardWithCatch = 1,
1673             NF_throwException = 2,
1674             NF_tryFinally = 3,
1675             NF_loop = 4,
1676             NF_profileBoolean = 5,
1677             NF_LIMIT = 6;
1678 
1679     private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT];
1680 
1681     static NamedFunction getFunction(byte func) {
1682         NamedFunction nf = NFS[func];
1683         if (nf != null) {
1684             return nf;
1685         }
1686         return NFS[func] = createFunction(func);
1687     }
1688 
1689     private static NamedFunction createFunction(byte func) {
1690         try {
1691             switch (func) {
1692                 case NF_checkSpreadArgument:
1693                     return new NamedFunction(MethodHandleImpl.class
1694                             .getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
1695                 case NF_guardWithCatch:
1696                     return new NamedFunction(MethodHandleImpl.class
1697                             .getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
1698                                     MethodHandle.class, Object[].class));
1699                 case NF_tryFinally:
1700                     return new NamedFunction(MethodHandleImpl.class
1701                             .getDeclaredMethod("tryFinally", MethodHandle.class, MethodHandle.class, Object[].class));
1702                 case NF_loop:
1703                     return new NamedFunction(MethodHandleImpl.class
1704                             .getDeclaredMethod("loop", BasicType[].class, LoopClauses.class, Object[].class));
1705                 case NF_throwException:
1706                     return new NamedFunction(MethodHandleImpl.class
1707                             .getDeclaredMethod("throwException", Throwable.class));
1708                 case NF_profileBoolean:
1709                     return new NamedFunction(MethodHandleImpl.class
1710                             .getDeclaredMethod("profileBoolean", boolean.class, int[].class));
1711                 default:
1712                     throw new InternalError("Undefined function: " + func);
1713             }
1714         } catch (ReflectiveOperationException ex) {
1715             throw newInternalError(ex);
1716         }
1717     }
1718 
1719     static {
1720         SharedSecrets.setJavaLangInvokeAccess(new JavaLangInvokeAccess() {
1721             @Override
1722             public Object newMemberName() {
1723                 return new MemberName();
1724             }
1725 
1726             @Override
1727             public String getName(Object mname) {
1728                 MemberName memberName = (MemberName)mname;
1729                 return memberName.getName();
1730             }
1731             @Override
1732             public Class<?> getDeclaringClass(Object mname) {
1733                 MemberName memberName = (MemberName)mname;
1734                 return memberName.getDeclaringClass();
1735             }
1736 
1737             @Override
1738             public MethodType getMethodType(Object mname) {
1739                 MemberName memberName = (MemberName)mname;
1740                 return memberName.getMethodType();
1741             }
1742 
1743             @Override
1744             public String getMethodDescriptor(Object mname) {
1745                 MemberName memberName = (MemberName)mname;
1746                 return memberName.getMethodDescriptor();
1747             }
1748 
1749             @Override
1750             public boolean isNative(Object mname) {
1751                 MemberName memberName = (MemberName)mname;
1752                 return memberName.isNative();
1753             }
1754 
1755             @Override
1756             public byte[] generateDirectMethodHandleHolderClassBytes(
1757                     String className, MethodType[] methodTypes, int[] types) {
1758                 return GenerateJLIClassesHelper
1759                         .generateDirectMethodHandleHolderClassBytes(
1760                                 className, methodTypes, types);
1761             }
1762 
1763             @Override
1764             public byte[] generateDelegatingMethodHandleHolderClassBytes(
1765                     String className, MethodType[] methodTypes) {
1766                 return GenerateJLIClassesHelper
1767                         .generateDelegatingMethodHandleHolderClassBytes(
1768                                 className, methodTypes);
1769             }
1770 
1771             @Override
1772             public Map.Entry<String, byte[]> generateConcreteBMHClassBytes(
1773                     final String types) {
1774                 return GenerateJLIClassesHelper
1775                         .generateConcreteBMHClassBytes(types);
1776             }
1777 
1778             @Override
1779             public byte[] generateBasicFormsClassBytes(final String className) {
1780                 return GenerateJLIClassesHelper
1781                         .generateBasicFormsClassBytes(className);
1782             }
1783 
1784             @Override
1785             public byte[] generateInvokersHolderClassBytes(final String className,
1786                     MethodType[] invokerMethodTypes,
1787                     MethodType[] callSiteMethodTypes) {
1788                 return GenerateJLIClassesHelper
1789                         .generateInvokersHolderClassBytes(className,
1790                                 invokerMethodTypes, callSiteMethodTypes);
1791             }
1792 






































1793         });
1794     }
1795 
1796     /** Result unboxing: ValueConversions.unbox() OR ValueConversions.identity() OR ValueConversions.ignore(). */
1797     private static MethodHandle unboxResultHandle(Class<?> returnType) {
1798         if (returnType.isPrimitive()) {
1799             if (returnType == void.class) {
1800                 return ValueConversions.ignore();
1801             } else {
1802                 Wrapper w = Wrapper.forPrimitiveType(returnType);
1803                 return ValueConversions.unboxExact(w);
1804             }
1805         } else {
1806             return MethodHandles.identity(Object.class);
1807         }
1808     }
1809 
1810     /**
1811      * Assembles a loop method handle from the given handles and type information.
1812      *
1813      * @param tloop the return type of the loop.
1814      * @param targs types of the arguments to be passed to the loop.
1815      * @param init sanitized array of initializers for loop-local variables.
1816      * @param step sanitited array of loop bodies.
1817      * @param pred sanitized array of predicates.
1818      * @param fini sanitized array of loop finalizers.
1819      *
1820      * @return a handle that, when invoked, will execute the loop.
1821      */
1822     static MethodHandle makeLoop(Class<?> tloop, List<Class<?>> targs, List<MethodHandle> init, List<MethodHandle> step,
1823                                  List<MethodHandle> pred, List<MethodHandle> fini) {
1824         MethodType type = MethodType.methodType(tloop, targs);
1825         BasicType[] initClauseTypes =
1826                 init.stream().map(h -> h.type().returnType()).map(BasicType::basicType).toArray(BasicType[]::new);
1827         LambdaForm form = makeLoopForm(type.basicType(), initClauseTypes);
1828 
1829         // Prepare auxiliary method handles used during LambdaForm interpretation.
1830         // Box arguments and wrap them into Object[]: ValueConversions.array().
1831         MethodType varargsType = type.changeReturnType(Object[].class);
1832         MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
1833         MethodHandle unboxResult = unboxResultHandle(tloop);
1834 
1835         LoopClauses clauseData =
1836                 new LoopClauses(new MethodHandle[][]{toArray(init), toArray(step), toArray(pred), toArray(fini)});
1837         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLL();
1838         BoundMethodHandle mh;
1839         try {
1840             mh = (BoundMethodHandle) data.factory().invokeBasic(type, form, (Object) clauseData,
1841                     (Object) collectArgs, (Object) unboxResult);
1842         } catch (Throwable ex) {
1843             throw uncaughtException(ex);
1844         }
1845         assert(mh.type() == type);
1846         return mh;
1847     }
1848 
1849     private static MethodHandle[] toArray(List<MethodHandle> l) {
1850         return l.toArray(new MethodHandle[0]);
1851     }
1852 
1853     /**
1854      * Loops introduce some complexity as they can have additional local state. Hence, LambdaForms for loops are
1855      * generated from a template. The LambdaForm template shape for the loop combinator is as follows (assuming one
1856      * reference parameter passed in {@code a1}, and a reference return type, with the return value represented by
1857      * {@code t12}):
1858      * <blockquote><pre>{@code
1859      *  loop=Lambda(a0:L,a1:L)=>{
1860      *    t2:L=BoundMethodHandle$Species_L3.argL0(a0:L);    // LoopClauses holding init, step, pred, fini handles
1861      *    t3:L=BoundMethodHandle$Species_L3.argL1(a0:L);    // helper handle to box the arguments into an Object[]
1862      *    t4:L=BoundMethodHandle$Species_L3.argL2(a0:L);    // helper handle to unbox the result
1863      *    t5:L=MethodHandle.invokeBasic(t3:L,a1:L);         // box the arguments into an Object[]
1864      *    t6:L=MethodHandleImpl.loop(null,t2:L,t3:L);       // call the loop executor
1865      *    t7:L=MethodHandle.invokeBasic(t4:L,t6:L);t7:L}    // unbox the result; return the result
1866      * }</pre></blockquote>
1867      * <p>
1868      * {@code argL0} is a LoopClauses instance holding, in a 2-dimensional array, the init, step, pred, and fini method
1869      * handles. {@code argL1} and {@code argL2} are auxiliary method handles: {@code argL1} boxes arguments and wraps
1870      * them into {@code Object[]} ({@code ValueConversions.array()}), and {@code argL2} unboxes the result if necessary
1871      * ({@code ValueConversions.unbox()}).
1872      * <p>
1873      * Having {@code t3} and {@code t4} passed in via a BMH and not hardcoded in the lambda form allows to share lambda
1874      * forms among loop combinators with the same basic type.
1875      * <p>
1876      * The above template is instantiated by using the {@link LambdaFormEditor} to replace the {@code null} argument to
1877      * the {@code loop} invocation with the {@code BasicType} array describing the loop clause types. This argument is
1878      * ignored in the loop invoker, but will be extracted and used in {@linkplain InvokerBytecodeGenerator#emitLoop(int)
1879      * bytecode generation}.
1880      */
1881     private static LambdaForm makeLoopForm(MethodType basicType, BasicType[] localVarTypes) {
1882         MethodType lambdaType = basicType.invokerType();
1883 
1884         final int THIS_MH = 0;  // the BMH_LLL
1885         final int ARG_BASE = 1; // start of incoming arguments
1886         final int ARG_LIMIT = ARG_BASE + basicType.parameterCount();
1887 
1888         int nameCursor = ARG_LIMIT;
1889         final int GET_CLAUSE_DATA = nameCursor++;
1890         final int GET_COLLECT_ARGS = nameCursor++;
1891         final int GET_UNBOX_RESULT = nameCursor++;
1892         final int BOXED_ARGS = nameCursor++;
1893         final int LOOP = nameCursor++;
1894         final int UNBOX_RESULT = nameCursor++;
1895 
1896         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_LOOP);
1897         if (lform == null) {
1898             Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
1899 
1900             BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLL();
1901             names[THIS_MH] = names[THIS_MH].withConstraint(data);
1902             names[GET_CLAUSE_DATA] = new Name(data.getterFunction(0), names[THIS_MH]);
1903             names[GET_COLLECT_ARGS] = new Name(data.getterFunction(1), names[THIS_MH]);
1904             names[GET_UNBOX_RESULT] = new Name(data.getterFunction(2), names[THIS_MH]);
1905 
1906             // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
1907             MethodType collectArgsType = basicType.changeReturnType(Object.class);
1908             MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
1909             Object[] args = new Object[invokeBasic.type().parameterCount()];
1910             args[0] = names[GET_COLLECT_ARGS];
1911             System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT - ARG_BASE);
1912             names[BOXED_ARGS] = new Name(new NamedFunction(invokeBasic, Intrinsic.LOOP), args);
1913 
1914             // t_{i+1}:L=MethodHandleImpl.loop(localTypes:L,clauses:L,t_{i}:L);
1915             Object[] lArgs =
1916                     new Object[]{null, // placeholder for BasicType[] localTypes - will be added by LambdaFormEditor
1917                             names[GET_CLAUSE_DATA], names[BOXED_ARGS]};
1918             names[LOOP] = new Name(getFunction(NF_loop), lArgs);
1919 
1920             // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
1921             MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
1922             Object[] unboxArgs = new Object[]{names[GET_UNBOX_RESULT], names[LOOP]};
1923             names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
1924 
1925             lform = basicType.form().setCachedLambdaForm(MethodTypeForm.LF_LOOP,
1926                     new LambdaForm(lambdaType.parameterCount(), names, Kind.LOOP));
1927         }
1928 
1929         // BOXED_ARGS is the index into the names array where the loop idiom starts
1930         return lform.editor().noteLoopLocalTypesForm(BOXED_ARGS, localVarTypes);
1931     }
1932 
1933     static class LoopClauses {
1934         @Stable final MethodHandle[][] clauses;
1935         LoopClauses(MethodHandle[][] clauses) {
1936             assert clauses.length == 4;
1937             this.clauses = clauses;
1938         }
1939         @Override
1940         public String toString() {
1941             StringBuffer sb = new StringBuffer("LoopClauses -- ");
1942             for (int i = 0; i < 4; ++i) {
1943                 if (i > 0) {
1944                     sb.append("       ");
1945                 }
1946                 sb.append('<').append(i).append(">: ");
1947                 MethodHandle[] hs = clauses[i];
1948                 for (int j = 0; j < hs.length; ++j) {
1949                     if (j > 0) {
1950                         sb.append("          ");
1951                     }
1952                     sb.append('*').append(j).append(": ").append(hs[j]).append('\n');
1953                 }
1954             }
1955             sb.append(" --\n");
1956             return sb.toString();
1957         }
1958     }
1959 
1960     /**
1961      * Intrinsified during LambdaForm compilation
1962      * (see {@link InvokerBytecodeGenerator#emitLoop(int)}).
1963      */
1964     @Hidden
1965     static Object loop(BasicType[] localTypes, LoopClauses clauseData, Object... av) throws Throwable {
1966         final MethodHandle[] init = clauseData.clauses[0];
1967         final MethodHandle[] step = clauseData.clauses[1];
1968         final MethodHandle[] pred = clauseData.clauses[2];
1969         final MethodHandle[] fini = clauseData.clauses[3];
1970         int varSize = (int) Stream.of(init).filter(h -> h.type().returnType() != void.class).count();
1971         int nArgs = init[0].type().parameterCount();
1972         Object[] varsAndArgs = new Object[varSize + nArgs];
1973         for (int i = 0, v = 0; i < init.length; ++i) {
1974             MethodHandle ih = init[i];
1975             if (ih.type().returnType() == void.class) {
1976                 ih.invokeWithArguments(av);
1977             } else {
1978                 varsAndArgs[v++] = ih.invokeWithArguments(av);
1979             }
1980         }
1981         System.arraycopy(av, 0, varsAndArgs, varSize, nArgs);
1982         final int nSteps = step.length;
1983         for (; ; ) {
1984             for (int i = 0, v = 0; i < nSteps; ++i) {
1985                 MethodHandle p = pred[i];
1986                 MethodHandle s = step[i];
1987                 MethodHandle f = fini[i];
1988                 if (s.type().returnType() == void.class) {
1989                     s.invokeWithArguments(varsAndArgs);
1990                 } else {
1991                     varsAndArgs[v++] = s.invokeWithArguments(varsAndArgs);
1992                 }
1993                 if (!(boolean) p.invokeWithArguments(varsAndArgs)) {
1994                     return f.invokeWithArguments(varsAndArgs);
1995                 }
1996             }
1997         }
1998     }
1999 
2000     /**
2001      * This method is bound as the predicate in {@linkplain MethodHandles#countedLoop(MethodHandle, MethodHandle,
2002      * MethodHandle) counting loops}.
2003      *
2004      * @param limit the upper bound of the parameter, statically bound at loop creation time.
2005      * @param counter the counter parameter, passed in during loop execution.
2006      *
2007      * @return whether the counter has reached the limit.
2008      */
2009     static boolean countedLoopPredicate(int limit, int counter) {
2010         return counter < limit;
2011     }
2012 
2013     /**
2014      * This method is bound as the step function in {@linkplain MethodHandles#countedLoop(MethodHandle, MethodHandle,
2015      * MethodHandle) counting loops} to increment the counter.
2016      *
2017      * @param limit the upper bound of the loop counter (ignored).
2018      * @param counter the loop counter.
2019      *
2020      * @return the loop counter incremented by 1.
2021      */
2022     static int countedLoopStep(int limit, int counter) {
2023         return counter + 1;
2024     }
2025 
2026     /**
2027      * This is bound to initialize the loop-local iterator in {@linkplain MethodHandles#iteratedLoop iterating loops}.
2028      *
2029      * @param it the {@link Iterable} over which the loop iterates.
2030      *
2031      * @return an {@link Iterator} over the argument's elements.
2032      */
2033     static Iterator<?> initIterator(Iterable<?> it) {
2034         return it.iterator();
2035     }
2036 
2037     /**
2038      * This method is bound as the predicate in {@linkplain MethodHandles#iteratedLoop iterating loops}.
2039      *
2040      * @param it the iterator to be checked.
2041      *
2042      * @return {@code true} iff there are more elements to iterate over.
2043      */
2044     static boolean iteratePredicate(Iterator<?> it) {
2045         return it.hasNext();
2046     }
2047 
2048     /**
2049      * This method is bound as the step for retrieving the current value from the iterator in {@linkplain
2050      * MethodHandles#iteratedLoop iterating loops}.
2051      *
2052      * @param it the iterator.
2053      *
2054      * @return the next element from the iterator.
2055      */
2056     static Object iterateNext(Iterator<?> it) {
2057         return it.next();
2058     }
2059 
2060     /**
2061      * Makes a {@code try-finally} handle that conforms to the type constraints.
2062      *
2063      * @param target the target to execute in a {@code try-finally} block.
2064      * @param cleanup the cleanup to execute in the {@code finally} block.
2065      * @param rtype the result type of the entire construct.
2066      * @param argTypes the types of the arguments.
2067      *
2068      * @return a handle on the constructed {@code try-finally} block.
2069      */
2070     static MethodHandle makeTryFinally(MethodHandle target, MethodHandle cleanup, Class<?> rtype, List<Class<?>> argTypes) {
2071         MethodType type = MethodType.methodType(rtype, argTypes);
2072         LambdaForm form = makeTryFinallyForm(type.basicType());
2073 
2074         // Prepare auxiliary method handles used during LambdaForm interpretation.
2075         // Box arguments and wrap them into Object[]: ValueConversions.array().
2076         MethodType varargsType = type.changeReturnType(Object[].class);
2077         MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
2078         MethodHandle unboxResult = unboxResultHandle(rtype);
2079 
2080         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLL();
2081         BoundMethodHandle mh;
2082         try {
2083             mh = (BoundMethodHandle) data.factory().invokeBasic(type, form, (Object) target, (Object) cleanup,
2084                     (Object) collectArgs, (Object) unboxResult);
2085         } catch (Throwable ex) {
2086             throw uncaughtException(ex);
2087         }
2088         assert(mh.type() == type);
2089         return mh;
2090     }
2091 
2092     /**
2093      * The LambdaForm shape for the tryFinally combinator is as follows (assuming one reference parameter passed in
2094      * {@code a1}, and a reference return type, with the return value represented by {@code t8}):
2095      * <blockquote><pre>{@code
2096      *  tryFinally=Lambda(a0:L,a1:L)=>{
2097      *    t2:L=BoundMethodHandle$Species_LLLL.argL0(a0:L);  // target method handle
2098      *    t3:L=BoundMethodHandle$Species_LLLL.argL1(a0:L);  // cleanup method handle
2099      *    t4:L=BoundMethodHandle$Species_LLLL.argL2(a0:L);  // helper handle to box the arguments into an Object[]
2100      *    t5:L=BoundMethodHandle$Species_LLLL.argL3(a0:L);  // helper handle to unbox the result
2101      *    t6:L=MethodHandle.invokeBasic(t4:L,a1:L);         // box the arguments into an Object[]
2102      *    t7:L=MethodHandleImpl.tryFinally(t2:L,t3:L,t6:L); // call the tryFinally executor
2103      *    t8:L=MethodHandle.invokeBasic(t5:L,t7:L);t8:L}    // unbox the result; return the result
2104      * }</pre></blockquote>
2105      * <p>
2106      * {@code argL0} and {@code argL1} are the target and cleanup method handles.
2107      * {@code argL2} and {@code argL3} are auxiliary method handles: {@code argL2} boxes arguments and wraps them into
2108      * {@code Object[]} ({@code ValueConversions.array()}), and {@code argL3} unboxes the result if necessary
2109      * ({@code ValueConversions.unbox()}).
2110      * <p>
2111      * Having {@code t4} and {@code t5} passed in via a BMH and not hardcoded in the lambda form allows to share lambda
2112      * forms among tryFinally combinators with the same basic type.
2113      */
2114     private static LambdaForm makeTryFinallyForm(MethodType basicType) {
2115         MethodType lambdaType = basicType.invokerType();
2116 
2117         LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_TF);
2118         if (lform != null) {
2119             return lform;
2120         }
2121         final int THIS_MH      = 0;  // the BMH_LLLL
2122         final int ARG_BASE     = 1;  // start of incoming arguments
2123         final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
2124 
2125         int nameCursor = ARG_LIMIT;
2126         final int GET_TARGET       = nameCursor++;
2127         final int GET_CLEANUP      = nameCursor++;
2128         final int GET_COLLECT_ARGS = nameCursor++;
2129         final int GET_UNBOX_RESULT = nameCursor++;
2130         final int BOXED_ARGS       = nameCursor++;
2131         final int TRY_FINALLY      = nameCursor++;
2132         final int UNBOX_RESULT     = nameCursor++;
2133 
2134         Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
2135 
2136         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLL();
2137         names[THIS_MH]          = names[THIS_MH].withConstraint(data);
2138         names[GET_TARGET]       = new Name(data.getterFunction(0), names[THIS_MH]);
2139         names[GET_CLEANUP]      = new Name(data.getterFunction(1), names[THIS_MH]);
2140         names[GET_COLLECT_ARGS] = new Name(data.getterFunction(2), names[THIS_MH]);
2141         names[GET_UNBOX_RESULT] = new Name(data.getterFunction(3), names[THIS_MH]);
2142 
2143         // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
2144         MethodType collectArgsType = basicType.changeReturnType(Object.class);
2145         MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
2146         Object[] args = new Object[invokeBasic.type().parameterCount()];
2147         args[0] = names[GET_COLLECT_ARGS];
2148         System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT-ARG_BASE);
2149         names[BOXED_ARGS] = new Name(new NamedFunction(invokeBasic, Intrinsic.TRY_FINALLY), args);
2150 
2151         // t_{i+1}:L=MethodHandleImpl.tryFinally(target:L,exType:L,catcher:L,t_{i}:L);
2152         Object[] tfArgs = new Object[] {names[GET_TARGET], names[GET_CLEANUP], names[BOXED_ARGS]};
2153         names[TRY_FINALLY] = new Name(getFunction(NF_tryFinally), tfArgs);
2154 
2155         // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
2156         MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
2157         Object[] unboxArgs  = new Object[] {names[GET_UNBOX_RESULT], names[TRY_FINALLY]};
2158         names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
2159 
2160         lform = new LambdaForm(lambdaType.parameterCount(), names, Kind.TRY_FINALLY);
2161 
2162         return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_TF, lform);
2163     }
2164 
2165     /**
2166      * Intrinsified during LambdaForm compilation
2167      * (see {@link InvokerBytecodeGenerator#emitTryFinally emitTryFinally}).
2168      */
2169     @Hidden
2170     static Object tryFinally(MethodHandle target, MethodHandle cleanup, Object... av) throws Throwable {
2171         Throwable t = null;
2172         Object r = null;
2173         try {
2174             r = target.invokeWithArguments(av);
2175         } catch (Throwable thrown) {
2176             t = thrown;
2177             throw t;
2178         } finally {
2179             Object[] args = target.type().returnType() == void.class ? prepend(av, t) : prepend(av, t, r);
2180             r = cleanup.invokeWithArguments(args);
2181         }
2182         return r;
2183     }
2184 
2185     // Indexes into constant method handles:
2186     static final int
2187             MH_cast                  =  0,
2188             MH_selectAlternative     =  1,
2189             MH_copyAsPrimitiveArray  =  2,
2190             MH_fillNewTypedArray     =  3,
2191             MH_fillNewArray          =  4,
2192             MH_arrayIdentity         =  5,
2193             MH_countedLoopPred       =  6,
2194             MH_countedLoopStep       =  7,
2195             MH_initIterator          =  8,
2196             MH_iteratePred           =  9,
2197             MH_iterateNext           = 10,
2198             MH_Array_newInstance     = 11,
2199             MH_LIMIT                 = 12;
2200 
2201     static MethodHandle getConstantHandle(int idx) {
2202         MethodHandle handle = HANDLES[idx];
2203         if (handle != null) {
2204             return handle;
2205         }
2206         return setCachedHandle(idx, makeConstantHandle(idx));
2207     }
2208 
2209     private static synchronized MethodHandle setCachedHandle(int idx, final MethodHandle method) {
2210         // Simulate a CAS, to avoid racy duplication of results.
2211         MethodHandle prev = HANDLES[idx];
2212         if (prev != null) {
2213             return prev;
2214         }
2215         HANDLES[idx] = method;
2216         return method;
2217     }
2218 
2219     // Local constant method handles:
2220     private static final @Stable MethodHandle[] HANDLES = new MethodHandle[MH_LIMIT];
2221 
2222     private static MethodHandle makeConstantHandle(int idx) {
2223         try {
2224             switch (idx) {
2225                 case MH_cast:
2226                     return IMPL_LOOKUP.findVirtual(Class.class, "cast",
2227                             MethodType.methodType(Object.class, Object.class));
2228                 case MH_copyAsPrimitiveArray:
2229                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "copyAsPrimitiveArray",
2230                             MethodType.methodType(Object.class, Wrapper.class, Object[].class));
2231                 case MH_arrayIdentity:
2232                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "identity",
2233                             MethodType.methodType(Object[].class, Object[].class));
2234                 case MH_fillNewArray:
2235                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "fillNewArray",
2236                             MethodType.methodType(Object[].class, Integer.class, Object[].class));
2237                 case MH_fillNewTypedArray:
2238                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "fillNewTypedArray",
2239                             MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
2240                 case MH_selectAlternative:
2241                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "selectAlternative",
2242                             MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class));
2243                 case MH_countedLoopPred:
2244                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "countedLoopPredicate",
2245                             MethodType.methodType(boolean.class, int.class, int.class));
2246                 case MH_countedLoopStep:
2247                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "countedLoopStep",
2248                             MethodType.methodType(int.class, int.class, int.class));
2249                 case MH_initIterator:
2250                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "initIterator",
2251                             MethodType.methodType(Iterator.class, Iterable.class));
2252                 case MH_iteratePred:
2253                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "iteratePredicate",
2254                             MethodType.methodType(boolean.class, Iterator.class));
2255                 case MH_iterateNext:
2256                     return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "iterateNext",
2257                             MethodType.methodType(Object.class, Iterator.class));
2258                 case MH_Array_newInstance:
2259                     return IMPL_LOOKUP.findStatic(Array.class, "newInstance",
2260                             MethodType.methodType(Object.class, Class.class, int.class));
2261             }
2262         } catch (ReflectiveOperationException ex) {
2263             throw newInternalError(ex);
2264         }
2265         throw newInternalError("Unknown function index: " + idx);
2266     }
2267 }
--- EOF ---