rev 15353 : 8164044: Generate the corresponding BoundMethodHandle to all generated DirectMethodHandles
Reviewed-by: vlivanov, mhaupt

   1 /*
   2  * Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang.invoke;
  27 
  28 import jdk.internal.perf.PerfCounter;
  29 import jdk.internal.vm.annotation.DontInline;
  30 import jdk.internal.vm.annotation.Stable;
  31 import sun.invoke.util.Wrapper;
  32 
  33 import java.lang.annotation.ElementType;
  34 import java.lang.annotation.Retention;
  35 import java.lang.annotation.RetentionPolicy;
  36 import java.lang.annotation.Target;
  37 import java.lang.reflect.Method;
  38 import java.util.Arrays;
  39 import java.util.HashMap;
  40 
  41 import static java.lang.invoke.LambdaForm.BasicType.*;
  42 import static java.lang.invoke.MethodHandleNatives.Constants.REF_invokeStatic;
  43 import static java.lang.invoke.MethodHandleStatics.*;

  44 
  45 /**
  46  * The symbolic, non-executable form of a method handle's invocation semantics.
  47  * It consists of a series of names.
  48  * The first N (N=arity) names are parameters,
  49  * while any remaining names are temporary values.
  50  * Each temporary specifies the application of a function to some arguments.
  51  * The functions are method handles, while the arguments are mixes of
  52  * constant values and local names.
  53  * The result of the lambda is defined as one of the names, often the last one.
  54  * <p>
  55  * Here is an approximate grammar:
  56  * <blockquote><pre>{@code
  57  * LambdaForm = "(" ArgName* ")=>{" TempName* Result "}"
  58  * ArgName = "a" N ":" T
  59  * TempName = "t" N ":" T "=" Function "(" Argument* ");"
  60  * Function = ConstantValue
  61  * Argument = NameRef | ConstantValue
  62  * Result = NameRef | "void"
  63  * NameRef = "a" N | "t" N
  64  * N = (any whole number)
  65  * T = "L" | "I" | "J" | "F" | "D" | "V"
  66  * }</pre></blockquote>
  67  * Names are numbered consecutively from left to right starting at zero.
  68  * (The letters are merely a taste of syntax sugar.)
  69  * Thus, the first temporary (if any) is always numbered N (where N=arity).
  70  * Every occurrence of a name reference in an argument list must refer to
  71  * a name previously defined within the same lambda.
  72  * A lambda has a void result if and only if its result index is -1.
  73  * If a temporary has the type "V", it cannot be the subject of a NameRef,
  74  * even though possesses a number.
  75  * Note that all reference types are erased to "L", which stands for {@code Object}.
  76  * All subword types (boolean, byte, short, char) are erased to "I" which is {@code int}.
  77  * The other types stand for the usual primitive types.
  78  * <p>
  79  * Function invocation closely follows the static rules of the Java verifier.
  80  * Arguments and return values must exactly match when their "Name" types are
  81  * considered.
  82  * Conversions are allowed only if they do not change the erased type.
  83  * <ul>
  84  * <li>L = Object: casts are used freely to convert into and out of reference types
  85  * <li>I = int: subword types are forcibly narrowed when passed as arguments (see {@code explicitCastArguments})
  86  * <li>J = long: no implicit conversions
  87  * <li>F = float: no implicit conversions
  88  * <li>D = double: no implicit conversions
  89  * <li>V = void: a function result may be void if and only if its Name is of type "V"
  90  * </ul>
  91  * Although implicit conversions are not allowed, explicit ones can easily be
  92  * encoded by using temporary expressions which call type-transformed identity functions.
  93  * <p>
  94  * Examples:
  95  * <blockquote><pre>{@code
  96  * (a0:J)=>{ a0 }
  97  *     == identity(long)
  98  * (a0:I)=>{ t1:V = System.out#println(a0); void }
  99  *     == System.out#println(int)
 100  * (a0:L)=>{ t1:V = System.out#println(a0); a0 }
 101  *     == identity, with printing side-effect
 102  * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
 103  *                 t3:L = BoundMethodHandle#target(a0);
 104  *                 t4:L = MethodHandle#invoke(t3, t2, a1); t4 }
 105  *     == general invoker for unary insertArgument combination
 106  * (a0:L, a1:L)=>{ t2:L = FilterMethodHandle#filter(a0);
 107  *                 t3:L = MethodHandle#invoke(t2, a1);
 108  *                 t4:L = FilterMethodHandle#target(a0);
 109  *                 t5:L = MethodHandle#invoke(t4, t3); t5 }
 110  *     == general invoker for unary filterArgument combination
 111  * (a0:L, a1:L)=>{ ...(same as previous example)...
 112  *                 t5:L = MethodHandle#invoke(t4, t3, a1); t5 }
 113  *     == general invoker for unary/unary foldArgument combination
 114  * (a0:L, a1:I)=>{ t2:I = identity(long).asType((int)->long)(a1); t2 }
 115  *     == invoker for identity method handle which performs i2l
 116  * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
 117  *                 t3:L = Class#cast(t2,a1); t3 }
 118  *     == invoker for identity method handle which performs cast
 119  * }</pre></blockquote>
 120  * <p>
 121  * @author John Rose, JSR 292 EG
 122  */
 123 class LambdaForm {
 124     final int arity;
 125     final int result;
 126     final boolean forceInline;
 127     final MethodHandle customized;
 128     @Stable final Name[] names;
 129     final String debugName;

 130     MemberName vmentry;   // low-level behavior, or null if not yet prepared
 131     private boolean isCompiled;
 132 
 133     // Either a LambdaForm cache (managed by LambdaFormEditor) or a link to uncustomized version (for customized LF)
 134     volatile Object transformCache;
 135 
 136     public static final int VOID_RESULT = -1, LAST_RESULT = -2;
 137 
 138     enum BasicType {
 139         L_TYPE('L', Object.class, Wrapper.OBJECT),  // all reference types
 140         I_TYPE('I', int.class,    Wrapper.INT),
 141         J_TYPE('J', long.class,   Wrapper.LONG),
 142         F_TYPE('F', float.class,  Wrapper.FLOAT),
 143         D_TYPE('D', double.class, Wrapper.DOUBLE),  // all primitive types
 144         V_TYPE('V', void.class,   Wrapper.VOID);    // not valid in all contexts
 145 
 146         static final BasicType[] ALL_TYPES = BasicType.values();
 147         static final BasicType[] ARG_TYPES = Arrays.copyOf(ALL_TYPES, ALL_TYPES.length-1);
 148 
 149         static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
 150         static final int TYPE_LIMIT = ALL_TYPES.length;
 151 
 152         final char btChar;
 153         final Class<?> btClass;
 154         final Wrapper btWrapper;
 155 
 156         private BasicType(char btChar, Class<?> btClass, Wrapper wrapper) {
 157             this.btChar = btChar;
 158             this.btClass = btClass;
 159             this.btWrapper = wrapper;
 160         }
 161 
 162         char basicTypeChar() {
 163             return btChar;
 164         }
 165         Class<?> basicTypeClass() {
 166             return btClass;
 167         }
 168         Wrapper basicTypeWrapper() {
 169             return btWrapper;
 170         }
 171         int basicTypeSlots() {
 172             return btWrapper.stackSlots();
 173         }
 174 
 175         static BasicType basicType(byte type) {
 176             return ALL_TYPES[type];
 177         }
 178         static BasicType basicType(char type) {
 179             switch (type) {
 180                 case 'L': return L_TYPE;
 181                 case 'I': return I_TYPE;
 182                 case 'J': return J_TYPE;
 183                 case 'F': return F_TYPE;
 184                 case 'D': return D_TYPE;
 185                 case 'V': return V_TYPE;
 186                 // all subword types are represented as ints
 187                 case 'Z':
 188                 case 'B':
 189                 case 'S':
 190                 case 'C':
 191                     return I_TYPE;
 192                 default:
 193                     throw newInternalError("Unknown type char: '"+type+"'");
 194             }
 195         }
 196         static BasicType basicType(Wrapper type) {
 197             char c = type.basicTypeChar();
 198             return basicType(c);
 199         }
 200         static BasicType basicType(Class<?> type) {
 201             if (!type.isPrimitive())  return L_TYPE;
 202             return basicType(Wrapper.forPrimitiveType(type));
 203         }
 204         static BasicType[] basicTypes(String types) {
 205             BasicType[] btypes = new BasicType[types.length()];
 206             for (int i = 0; i < btypes.length; i++) {
 207                 btypes[i] = basicType(types.charAt(i));
 208             }
 209             return btypes;
 210         }
 211         static String basicTypeDesc(BasicType[] types) {
 212             if (types == null) {
 213                 return null;
 214             }
 215             if (types.length == 0) {
 216                 return "";
 217             }
 218             StringBuilder sb = new StringBuilder();
 219             for (BasicType bt : types) {
 220                 sb.append(bt.basicTypeChar());
 221             }
 222             return sb.toString();
 223         }
 224         static int[] basicTypeOrds(BasicType[] types) {
 225             if (types == null) {
 226                 return null;
 227             }
 228             int[] a = new int[types.length];
 229             for(int i = 0; i < types.length; ++i) {
 230                 a[i] = types[i].ordinal();
 231             }
 232             return a;
 233         }
 234 
 235         static char basicTypeChar(Class<?> type) {
 236             return basicType(type).btChar;
 237         }
 238 
 239         static byte[] basicTypesOrd(Class<?>[] types) {
 240             byte[] ords = new byte[types.length];
 241             for (int i = 0; i < ords.length; i++) {
 242                 ords[i] = (byte)basicType(types[i]).ordinal();
 243             }
 244             return ords;
 245         }
 246 
 247         static boolean isBasicTypeChar(char c) {
 248             return "LIJFDV".indexOf(c) >= 0;
 249         }
 250         static boolean isArgBasicTypeChar(char c) {
 251             return "LIJFD".indexOf(c) >= 0;
 252         }
 253 
 254         static { assert(checkBasicType()); }
 255         private static boolean checkBasicType() {
 256             for (int i = 0; i < ARG_TYPE_LIMIT; i++) {
 257                 assert ARG_TYPES[i].ordinal() == i;
 258                 assert ARG_TYPES[i] == ALL_TYPES[i];
 259             }
 260             for (int i = 0; i < TYPE_LIMIT; i++) {
 261                 assert ALL_TYPES[i].ordinal() == i;
 262             }
 263             assert ALL_TYPES[TYPE_LIMIT - 1] == V_TYPE;
 264             assert !Arrays.asList(ARG_TYPES).contains(V_TYPE);
 265             return true;
 266         }
 267     }
 268 


























 269     LambdaForm(String debugName,
 270                int arity, Name[] names, int result) {
 271         this(debugName, arity, names, result, /*forceInline=*/true, /*customized=*/null);




 272     }
 273     LambdaForm(String debugName,
 274                int arity, Name[] names, int result, boolean forceInline, MethodHandle customized) {




 275         assert(namesOK(arity, names));
 276         this.arity = arity;
 277         this.result = fixResult(result, names);
 278         this.names = names.clone();
 279         this.debugName = fixDebugName(debugName);
 280         this.forceInline = forceInline;
 281         this.customized = customized;

 282         int maxOutArity = normalize();
 283         if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
 284             // Cannot use LF interpreter on very high arity expressions.
 285             assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
 286             compileToBytecode();
 287         }
 288     }
 289     LambdaForm(String debugName,
 290                int arity, Name[] names) {
 291         this(debugName, arity, names, LAST_RESULT, /*forceInline=*/true, /*customized=*/null);
 292     }
 293     LambdaForm(String debugName,
 294                int arity, Name[] names, boolean forceInline) {
 295         this(debugName, arity, names, LAST_RESULT, forceInline, /*customized=*/null);




 296     }
 297     LambdaForm(String debugName,
 298                Name[] formals, Name[] temps, Name result) {
 299         this(debugName,
 300              formals.length, buildNames(formals, temps, result), LAST_RESULT, /*forceInline=*/true, /*customized=*/null);
 301     }
 302     LambdaForm(String debugName,
 303                Name[] formals, Name[] temps, Name result, boolean forceInline) {
 304         this(debugName,
 305              formals.length, buildNames(formals, temps, result), LAST_RESULT, forceInline, /*customized=*/null);
 306     }
 307 
 308     private static Name[] buildNames(Name[] formals, Name[] temps, Name result) {
 309         int arity = formals.length;
 310         int length = arity + temps.length + (result == null ? 0 : 1);
 311         Name[] names = Arrays.copyOf(formals, length);
 312         System.arraycopy(temps, 0, names, arity, temps.length);
 313         if (result != null)
 314             names[length - 1] = result;
 315         return names;
 316     }
 317 
 318     private LambdaForm(MethodType mt) {
 319         // Make a blank lambda form, which returns a constant zero or null.
 320         // It is used as a template for managing the invocation of similar forms that are non-empty.
 321         // Called only from getPreparedForm.
 322         this.arity = mt.parameterCount();
 323         this.result = (mt.returnType() == void.class || mt.returnType() == Void.class) ? -1 : arity;
 324         this.names = buildEmptyNames(arity, mt, result == -1);
 325         this.debugName = "LF.zero";
 326         this.forceInline = true;
 327         this.customized = null;

 328         assert(nameRefsAreLegal());
 329         assert(isEmpty());
 330         String sig = null;
 331         assert(isValidSignature(sig = basicTypeSignature()));
 332         assert(sig.equals(basicTypeSignature())) : sig + " != " + basicTypeSignature();
 333     }
 334 
 335     private static Name[] buildEmptyNames(int arity, MethodType mt, boolean isVoid) {
 336         Name[] names = arguments(isVoid ? 0 : 1, mt);
 337         if (!isVoid) {
 338             Name zero = new Name(constantZero(basicType(mt.returnType())));
 339             names[arity] = zero.newIndex(arity);
 340         }
 341         return names;
 342     }
 343 
 344     private static int fixResult(int result, Name[] names) {
 345         if (result == LAST_RESULT)
 346             result = names.length - 1;  // might still be void
 347         if (result >= 0 && names[result].type == V_TYPE)
 348             result = VOID_RESULT;
 349         return result;
 350     }
 351 
 352     private static String fixDebugName(String debugName) {
 353         if (DEBUG_NAME_COUNTERS != null) {
 354             int under = debugName.indexOf('_');
 355             int length = debugName.length();
 356             if (under < 0)  under = length;
 357             String debugNameStem = debugName.substring(0, under);
 358             Integer ctr;
 359             synchronized (DEBUG_NAME_COUNTERS) {
 360                 ctr = DEBUG_NAME_COUNTERS.get(debugNameStem);
 361                 if (ctr == null)  ctr = 0;
 362                 DEBUG_NAME_COUNTERS.put(debugNameStem, ctr+1);
 363             }
 364             StringBuilder buf = new StringBuilder(debugNameStem);
 365             buf.append('_');
 366             int leadingZero = buf.length();
 367             buf.append((int) ctr);
 368             for (int i = buf.length() - leadingZero; i < 3; i++)
 369                 buf.insert(leadingZero, '0');
 370             if (under < length) {
 371                 ++under;    // skip "_"
 372                 while (under < length && Character.isDigit(debugName.charAt(under))) {
 373                     ++under;
 374                 }
 375                 if (under < length && debugName.charAt(under) == '_')  ++under;
 376                 if (under < length)
 377                     buf.append('_').append(debugName, under, length);
 378             }
 379             return buf.toString();
 380         }
 381         return debugName;
 382     }
 383 
 384     private static boolean namesOK(int arity, Name[] names) {
 385         for (int i = 0; i < names.length; i++) {
 386             Name n = names[i];
 387             assert(n != null) : "n is null";
 388             if (i < arity)
 389                 assert( n.isParam()) : n + " is not param at " + i;
 390             else
 391                 assert(!n.isParam()) : n + " is param at " + i;
 392         }
 393         return true;
 394     }
 395 
 396     /** Customize LambdaForm for a particular MethodHandle */
 397     LambdaForm customize(MethodHandle mh) {
 398         LambdaForm customForm = new LambdaForm(debugName, arity, names, result, forceInline, mh);
 399         if (COMPILE_THRESHOLD >= 0 && isCompiled) {
 400             // If shared LambdaForm has been compiled, compile customized version as well.
 401             customForm.compileToBytecode();
 402         }
 403         customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
 404         return customForm;
 405     }
 406 
 407     /** Get uncustomized flavor of the LambdaForm */
 408     LambdaForm uncustomize() {
 409         if (customized == null) {
 410             return this;
 411         }
 412         assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
 413         LambdaForm uncustomizedForm = (LambdaForm)transformCache;
 414         if (COMPILE_THRESHOLD >= 0 && isCompiled) {
 415             // If customized LambdaForm has been compiled, compile uncustomized version as well.
 416             uncustomizedForm.compileToBytecode();
 417         }
 418         return uncustomizedForm;
 419     }
 420 
 421     /** Renumber and/or replace params so that they are interned and canonically numbered.
 422      *  @return maximum argument list length among the names (since we have to pass over them anyway)
 423      */
 424     private int normalize() {
 425         Name[] oldNames = null;
 426         int maxOutArity = 0;
 427         int changesStart = 0;
 428         for (int i = 0; i < names.length; i++) {
 429             Name n = names[i];
 430             if (!n.initIndex(i)) {
 431                 if (oldNames == null) {
 432                     oldNames = names.clone();
 433                     changesStart = i;
 434                 }
 435                 names[i] = n.cloneWithIndex(i);
 436             }
 437             if (n.arguments != null && maxOutArity < n.arguments.length)
 438                 maxOutArity = n.arguments.length;
 439         }
 440         if (oldNames != null) {
 441             int startFixing = arity;
 442             if (startFixing <= changesStart)
 443                 startFixing = changesStart+1;
 444             for (int i = startFixing; i < names.length; i++) {
 445                 Name fixed = names[i].replaceNames(oldNames, names, changesStart, i);
 446                 names[i] = fixed.newIndex(i);
 447             }
 448         }
 449         assert(nameRefsAreLegal());
 450         int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
 451         boolean needIntern = false;
 452         for (int i = 0; i < maxInterned; i++) {
 453             Name n = names[i], n2 = internArgument(n);
 454             if (n != n2) {
 455                 names[i] = n2;
 456                 needIntern = true;
 457             }
 458         }
 459         if (needIntern) {
 460             for (int i = arity; i < names.length; i++) {
 461                 names[i].internArguments();
 462             }
 463         }
 464         assert(nameRefsAreLegal());
 465         return maxOutArity;
 466     }
 467 
 468     /**
 469      * Check that all embedded Name references are localizable to this lambda,
 470      * and are properly ordered after their corresponding definitions.
 471      * <p>
 472      * Note that a Name can be local to multiple lambdas, as long as
 473      * it possesses the same index in each use site.
 474      * This allows Name references to be freely reused to construct
 475      * fresh lambdas, without confusion.
 476      */
 477     boolean nameRefsAreLegal() {
 478         assert(arity >= 0 && arity <= names.length);
 479         assert(result >= -1 && result < names.length);
 480         // Do all names possess an index consistent with their local definition order?
 481         for (int i = 0; i < arity; i++) {
 482             Name n = names[i];
 483             assert(n.index() == i) : Arrays.asList(n.index(), i);
 484             assert(n.isParam());
 485         }
 486         // Also, do all local name references
 487         for (int i = arity; i < names.length; i++) {
 488             Name n = names[i];
 489             assert(n.index() == i);
 490             for (Object arg : n.arguments) {
 491                 if (arg instanceof Name) {
 492                     Name n2 = (Name) arg;
 493                     int i2 = n2.index;
 494                     assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
 495                     assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
 496                     assert(i2 < i);  // ref must come after def!
 497                 }
 498             }
 499         }
 500         return true;
 501     }
 502 
 503     /** Invoke this form on the given arguments. */
 504     // final Object invoke(Object... args) throws Throwable {
 505     //     // NYI: fit this into the fast path?
 506     //     return interpretWithArguments(args);
 507     // }
 508 
 509     /** Report the return type. */
 510     BasicType returnType() {
 511         if (result < 0)  return V_TYPE;
 512         Name n = names[result];
 513         return n.type;
 514     }
 515 
 516     /** Report the N-th argument type. */
 517     BasicType parameterType(int n) {
 518         return parameter(n).type;
 519     }
 520 
 521     /** Report the N-th argument name. */
 522     Name parameter(int n) {
 523         assert(n < arity);
 524         Name param = names[n];
 525         assert(param.isParam());
 526         return param;
 527     }
 528 
 529     /** Report the N-th argument type constraint. */
 530     Object parameterConstraint(int n) {
 531         return parameter(n).constraint;
 532     }
 533 
 534     /** Report the arity. */
 535     int arity() {
 536         return arity;
 537     }
 538 
 539     /** Report the number of expressions (non-parameter names). */
 540     int expressionCount() {
 541         return names.length - arity;
 542     }
 543 
 544     /** Return the method type corresponding to my basic type signature. */
 545     MethodType methodType() {
 546         Class<?>[] ptypes = new Class<?>[arity];
 547         for (int i = 0; i < arity; ++i) {
 548             ptypes[i] = parameterType(i).btClass;
 549         }
 550         return MethodType.methodType(returnType().btClass, ptypes);
 551     }
 552 
 553     /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
 554     final String basicTypeSignature() {
 555         StringBuilder buf = new StringBuilder(arity() + 3);
 556         for (int i = 0, a = arity(); i < a; i++)
 557             buf.append(parameterType(i).basicTypeChar());
 558         return buf.append('_').append(returnType().basicTypeChar()).toString();
 559     }
 560     static int signatureArity(String sig) {
 561         assert(isValidSignature(sig));
 562         return sig.indexOf('_');
 563     }
 564     static BasicType signatureReturn(String sig) {
 565         return basicType(sig.charAt(signatureArity(sig) + 1));
 566     }
 567     static boolean isValidSignature(String sig) {
 568         int arity = sig.indexOf('_');
 569         if (arity < 0)  return false;  // must be of the form *_*
 570         int siglen = sig.length();
 571         if (siglen != arity + 2)  return false;  // *_X
 572         for (int i = 0; i < siglen; i++) {
 573             if (i == arity)  continue;  // skip '_'
 574             char c = sig.charAt(i);
 575             if (c == 'V')
 576                 return (i == siglen - 1 && arity == siglen - 2);
 577             if (!isArgBasicTypeChar(c))  return false; // must be [LIJFD]
 578         }
 579         return true;  // [LIJFD]*_[LIJFDV]
 580     }
 581     static MethodType signatureType(String sig) {
 582         Class<?>[] ptypes = new Class<?>[signatureArity(sig)];
 583         for (int i = 0; i < ptypes.length; i++)
 584             ptypes[i] = basicType(sig.charAt(i)).btClass;
 585         Class<?> rtype = signatureReturn(sig).btClass;
 586         return MethodType.methodType(rtype, ptypes);
 587     }
 588 
 589     /**
 590      * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
 591      */
 592     boolean isSelectAlternative(int pos) {
 593         // selectAlternative idiom:
 594         //   t_{n}:L=MethodHandleImpl.selectAlternative(...)
 595         //   t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
 596         if (pos+1 >= names.length)  return false;
 597         Name name0 = names[pos];
 598         Name name1 = names[pos+1];
 599         return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
 600                 name1.isInvokeBasic() &&
 601                 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
 602                 lastUseIndex(name0) == pos+1;     // t_{n} is local: used only in t_{n+1}
 603     }
 604 
 605     private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
 606         if (pos+2 >= names.length)  return false;
 607         Name name0 = names[pos];
 608         Name name1 = names[pos+1];
 609         Name name2 = names[pos+2];
 610         return name1.refersTo(MethodHandleImpl.class, idiomName) &&
 611                 name0.isInvokeBasic() &&
 612                 name2.isInvokeBasic() &&
 613                 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
 614                 lastUseIndex(name0) == pos+1 &&       // t_{n} is local: used only in t_{n+1}
 615                 name2.lastUseIndex(name1) == 1 &&     // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 616                 lastUseIndex(name1) == pos+2;         // t_{n+1} is local: used only in t_{n+2}
 617     }
 618 
 619     /**
 620      * Check if i-th name is a start of GuardWithCatch idiom.
 621      */
 622     boolean isGuardWithCatch(int pos) {
 623         // GuardWithCatch idiom:
 624         //   t_{n}:L=MethodHandle.invokeBasic(...)
 625         //   t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
 626         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 627         return isMatchingIdiom(pos, "guardWithCatch", 3);
 628     }
 629 
 630     /**
 631      * Check if i-th name is a start of the tryFinally idiom.
 632      */
 633     boolean isTryFinally(int pos) {
 634         // tryFinally idiom:
 635         //   t_{n}:L=MethodHandle.invokeBasic(...)
 636         //   t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
 637         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 638         return isMatchingIdiom(pos, "tryFinally", 2);
 639     }
 640 
 641     /**
 642      * Check if i-th name is a start of the loop idiom.
 643      */
 644     boolean isLoop(int pos) {
 645         // loop idiom:
 646         //   t_{n}:L=MethodHandle.invokeBasic(...)
 647         //   t_{n+1}:L=MethodHandleImpl.loop(types, *, *, *, *, t_{n})
 648         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 649         return isMatchingIdiom(pos, "loop", 5);
 650     }
 651 
 652     /*
 653      * Code generation issues:
 654      *
 655      * Compiled LFs should be reusable in general.
 656      * The biggest issue is how to decide when to pull a name into
 657      * the bytecode, versus loading a reified form from the MH data.
 658      *
 659      * For example, an asType wrapper may require execution of a cast
 660      * after a call to a MH.  The target type of the cast can be placed
 661      * as a constant in the LF itself.  This will force the cast type
 662      * to be compiled into the bytecodes and native code for the MH.
 663      * Or, the target type of the cast can be erased in the LF, and
 664      * loaded from the MH data.  (Later on, if the MH as a whole is
 665      * inlined, the data will flow into the inlined instance of the LF,
 666      * as a constant, and the end result will be an optimal cast.)
 667      *
 668      * This erasure of cast types can be done with any use of
 669      * reference types.  It can also be done with whole method
 670      * handles.  Erasing a method handle might leave behind
 671      * LF code that executes correctly for any MH of a given
 672      * type, and load the required MH from the enclosing MH's data.
 673      * Or, the erasure might even erase the expected MT.
 674      *
 675      * Also, for direct MHs, the MemberName of the target
 676      * could be erased, and loaded from the containing direct MH.
 677      * As a simple case, a LF for all int-valued non-static
 678      * field getters would perform a cast on its input argument
 679      * (to non-constant base type derived from the MemberName)
 680      * and load an integer value from the input object
 681      * (at a non-constant offset also derived from the MemberName).
 682      * Such MN-erased LFs would be inlinable back to optimized
 683      * code, whenever a constant enclosing DMH is available
 684      * to supply a constant MN from its data.
 685      *
 686      * The main problem here is to keep LFs reasonably generic,
 687      * while ensuring that hot spots will inline good instances.
 688      * "Reasonably generic" means that we don't end up with
 689      * repeated versions of bytecode or machine code that do
 690      * not differ in their optimized form.  Repeated versions
 691      * of machine would have the undesirable overheads of
 692      * (a) redundant compilation work and (b) extra I$ pressure.
 693      * To control repeated versions, we need to be ready to
 694      * erase details from LFs and move them into MH data,
 695      * whevener those details are not relevant to significant
 696      * optimization.  "Significant" means optimization of
 697      * code that is actually hot.
 698      *
 699      * Achieving this may require dynamic splitting of MHs, by replacing
 700      * a generic LF with a more specialized one, on the same MH,
 701      * if (a) the MH is frequently executed and (b) the MH cannot
 702      * be inlined into a containing caller, such as an invokedynamic.
 703      *
 704      * Compiled LFs that are no longer used should be GC-able.
 705      * If they contain non-BCP references, they should be properly
 706      * interlinked with the class loader(s) that their embedded types
 707      * depend on.  This probably means that reusable compiled LFs
 708      * will be tabulated (indexed) on relevant class loaders,
 709      * or else that the tables that cache them will have weak links.
 710      */
 711 
 712     /**
 713      * Make this LF directly executable, as part of a MethodHandle.
 714      * Invariant:  Every MH which is invoked must prepare its LF
 715      * before invocation.
 716      * (In principle, the JVM could do this very lazily,
 717      * as a sort of pre-invocation linkage step.)
 718      */
 719     public void prepare() {
 720         if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
 721             compileToBytecode();
 722         }
 723         if (this.vmentry != null) {
 724             // already prepared (e.g., a primitive DMH invoker form)
 725             return;
 726         }
 727         MethodType mtype = methodType();
 728         LambdaForm prep = mtype.form().cachedLambdaForm(MethodTypeForm.LF_INTERPRET);
 729         if (prep == null) {
 730             assert (isValidSignature(basicTypeSignature()));
 731             prep = new LambdaForm(mtype);
 732             prep.vmentry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
 733             prep = mtype.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, prep);
 734         }
 735         this.vmentry = prep.vmentry;
 736         // TO DO: Maybe add invokeGeneric, invokeWithArguments
 737     }
 738 
 739     private static @Stable PerfCounter LF_FAILED;
 740 
 741     private static PerfCounter failedCompilationCounter() {
 742         if (LF_FAILED == null) {
 743             LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
 744         }
 745         return LF_FAILED;
 746     }
 747 
 748     /** Generate optimizable bytecode for this form. */
 749     void compileToBytecode() {
 750         if (forceInterpretation()) {
 751             return; // this should not be compiled
 752         }
 753         if (vmentry != null && isCompiled) {
 754             return;  // already compiled somehow
 755         }
 756         MethodType invokerType = methodType();
 757         assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
 758         try {
 759             vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
 760             if (TRACE_INTERPRETER)
 761                 traceInterpreter("compileToBytecode", this);
 762             isCompiled = true;
 763         } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
 764             // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
 765             invocationCounter = -1;
 766             failedCompilationCounter().increment();
 767             if (LOG_LF_COMPILATION_FAILURE) {
 768                 System.out.println("LambdaForm compilation failed: " + this);
 769                 bge.printStackTrace(System.out);
 770             }
 771         } catch (Error | Exception e) {
 772             throw newInternalError(this.toString(), e);
 773         }
 774     }
 775 
 776     /**
 777      * Generate optimizable bytecode for this form after first looking for a
 778      * pregenerated version in a specified class.
 779      */
 780     void compileToBytecode(Class<?> lookupClass) {
 781         if (vmentry != null && isCompiled) {
 782             return;  // already compiled somehow
 783         }
 784         MethodType invokerType = methodType();
 785         assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
 786         int dot = debugName.indexOf('.');
 787         String methodName = (dot > 0) ? debugName.substring(dot + 1) : debugName;
 788         MemberName member = new MemberName(lookupClass, methodName, invokerType, REF_invokeStatic);
 789         MemberName resolvedMember = MemberName.getFactory().resolveOrNull(REF_invokeStatic, member, lookupClass);
 790         if (resolvedMember != null) {
 791             vmentry = resolvedMember;
 792             isCompiled = true;
 793         } else {
 794             compileToBytecode();
 795         }
 796     }
 797 
 798     private static void computeInitialPreparedForms() {
 799         // Find all predefined invokers and associate them with canonical empty lambda forms.
 800         for (MemberName m : MemberName.getFactory().getMethods(LambdaForm.class, false, null, null, null)) {
 801             if (!m.isStatic() || !m.isPackage())  continue;
 802             MethodType mt = m.getMethodType();
 803             if (mt.parameterCount() > 0 &&
 804                 mt.parameterType(0) == MethodHandle.class &&
 805                 m.getName().startsWith("interpret_")) {
 806                 String sig = null;
 807                 assert((sig = basicTypeSignature(mt)) != null &&
 808                         m.getName().equals("interpret" + sig.substring(sig.indexOf('_'))));
 809                 LambdaForm form = new LambdaForm(mt);
 810                 form.vmentry = m;
 811                 form = mt.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, form);
 812             }
 813         }
 814     }
 815 
 816     // Set this false to disable use of the interpret_L methods defined in this file.
 817     private static final boolean USE_PREDEFINED_INTERPRET_METHODS = true;
 818 
 819     // The following are predefined exact invokers.  The system must build
 820     // a separate invoker for each distinct signature.
 821     static Object interpret_L(MethodHandle mh) throws Throwable {
 822         Object[] av = {mh};
 823         String sig = null;
 824         assert(argumentTypesMatch(sig = "L_L", av));
 825         Object res = mh.form.interpretWithArguments(av);
 826         assert(returnTypesMatch(sig, av, res));
 827         return res;
 828     }
 829     static Object interpret_L(MethodHandle mh, Object x1) throws Throwable {
 830         Object[] av = {mh, x1};
 831         String sig = null;
 832         assert(argumentTypesMatch(sig = "LL_L", av));
 833         Object res = mh.form.interpretWithArguments(av);
 834         assert(returnTypesMatch(sig, av, res));
 835         return res;
 836     }
 837     static Object interpret_L(MethodHandle mh, Object x1, Object x2) throws Throwable {
 838         Object[] av = {mh, x1, x2};
 839         String sig = null;
 840         assert(argumentTypesMatch(sig = "LLL_L", av));
 841         Object res = mh.form.interpretWithArguments(av);
 842         assert(returnTypesMatch(sig, av, res));
 843         return res;
 844     }
 845 
 846     // The next few routines are called only from assert expressions
 847     // They verify that the built-in invokers process the correct raw data types.
 848     private static boolean argumentTypesMatch(String sig, Object[] av) {
 849         int arity = signatureArity(sig);
 850         assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
 851         assert(av[0] instanceof MethodHandle) : "av[0] not instace of MethodHandle: " + av[0];
 852         MethodHandle mh = (MethodHandle) av[0];
 853         MethodType mt = mh.type();
 854         assert(mt.parameterCount() == arity-1);
 855         for (int i = 0; i < av.length; i++) {
 856             Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
 857             assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
 858         }
 859         return true;
 860     }
 861     private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
 862         // The following line is needed because (...)void method handles can use non-void invokers
 863         if (type == void.class)  tc = V_TYPE;   // can drop any kind of value
 864         assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
 865         switch (tc) {
 866         case I_TYPE: assert checkInt(type, x)   : "checkInt(" + type + "," + x +")";   break;
 867         case J_TYPE: assert x instanceof Long   : "instanceof Long: " + x;             break;
 868         case F_TYPE: assert x instanceof Float  : "instanceof Float: " + x;            break;
 869         case D_TYPE: assert x instanceof Double : "instanceof Double: " + x;           break;
 870         case L_TYPE: assert checkRef(type, x)   : "checkRef(" + type + "," + x + ")";  break;
 871         case V_TYPE: break;  // allow anything here; will be dropped
 872         default:  assert(false);
 873         }
 874         return true;
 875     }
 876     private static boolean returnTypesMatch(String sig, Object[] av, Object res) {
 877         MethodHandle mh = (MethodHandle) av[0];
 878         return valueMatches(signatureReturn(sig), mh.type().returnType(), res);
 879     }
 880     private static boolean checkInt(Class<?> type, Object x) {
 881         assert(x instanceof Integer);
 882         if (type == int.class)  return true;
 883         Wrapper w = Wrapper.forBasicType(type);
 884         assert(w.isSubwordOrInt());
 885         Object x1 = Wrapper.INT.wrap(w.wrap(x));
 886         return x.equals(x1);
 887     }
 888     private static boolean checkRef(Class<?> type, Object x) {
 889         assert(!type.isPrimitive());
 890         if (x == null)  return true;
 891         if (type.isInterface())  return true;
 892         return type.isInstance(x);
 893     }
 894 
 895     /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
 896     private static final int COMPILE_THRESHOLD;
 897     static {
 898         COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
 899     }
 900     private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
 901 
 902     private boolean forceInterpretation() {
 903         return invocationCounter == -1;
 904     }
 905 
 906     @Hidden
 907     @DontInline
 908     /** Interpretively invoke this form on the given arguments. */
 909     Object interpretWithArguments(Object... argumentValues) throws Throwable {
 910         if (TRACE_INTERPRETER)
 911             return interpretWithArgumentsTracing(argumentValues);
 912         checkInvocationCounter();
 913         assert(arityCheck(argumentValues));
 914         Object[] values = Arrays.copyOf(argumentValues, names.length);
 915         for (int i = argumentValues.length; i < values.length; i++) {
 916             values[i] = interpretName(names[i], values);
 917         }
 918         Object rv = (result < 0) ? null : values[result];
 919         assert(resultCheck(argumentValues, rv));
 920         return rv;
 921     }
 922 
 923     @Hidden
 924     @DontInline
 925     /** Evaluate a single Name within this form, applying its function to its arguments. */
 926     Object interpretName(Name name, Object[] values) throws Throwable {
 927         if (TRACE_INTERPRETER)
 928             traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
 929         Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
 930         for (int i = 0; i < arguments.length; i++) {
 931             Object a = arguments[i];
 932             if (a instanceof Name) {
 933                 int i2 = ((Name)a).index();
 934                 assert(names[i2] == a);
 935                 a = values[i2];
 936                 arguments[i] = a;
 937             }
 938         }
 939         return name.function.invokeWithArguments(arguments);
 940     }
 941 
 942     private void checkInvocationCounter() {
 943         if (COMPILE_THRESHOLD != 0 &&
 944             !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
 945             invocationCounter++;  // benign race
 946             if (invocationCounter >= COMPILE_THRESHOLD) {
 947                 // Replace vmentry with a bytecode version of this LF.
 948                 compileToBytecode();
 949             }
 950         }
 951     }
 952     Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
 953         traceInterpreter("[ interpretWithArguments", this, argumentValues);
 954         if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
 955             int ctr = invocationCounter++;  // benign race
 956             traceInterpreter("| invocationCounter", ctr);
 957             if (invocationCounter >= COMPILE_THRESHOLD) {
 958                 compileToBytecode();
 959             }
 960         }
 961         Object rval;
 962         try {
 963             assert(arityCheck(argumentValues));
 964             Object[] values = Arrays.copyOf(argumentValues, names.length);
 965             for (int i = argumentValues.length; i < values.length; i++) {
 966                 values[i] = interpretName(names[i], values);
 967             }
 968             rval = (result < 0) ? null : values[result];
 969         } catch (Throwable ex) {
 970             traceInterpreter("] throw =>", ex);
 971             throw ex;
 972         }
 973         traceInterpreter("] return =>", rval);
 974         return rval;
 975     }
 976 
 977     static void traceInterpreter(String event, Object obj, Object... args) {
 978         if (TRACE_INTERPRETER) {
 979             System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
 980         }
 981     }
 982     static void traceInterpreter(String event, Object obj) {
 983         traceInterpreter(event, obj, (Object[])null);
 984     }
 985     private boolean arityCheck(Object[] argumentValues) {
 986         assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
 987         // also check that the leading (receiver) argument is somehow bound to this LF:
 988         assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
 989         MethodHandle mh = (MethodHandle) argumentValues[0];
 990         assert(mh.internalForm() == this);
 991         // note:  argument #0 could also be an interface wrapper, in the future
 992         argumentTypesMatch(basicTypeSignature(), argumentValues);
 993         return true;
 994     }
 995     private boolean resultCheck(Object[] argumentValues, Object result) {
 996         MethodHandle mh = (MethodHandle) argumentValues[0];
 997         MethodType mt = mh.type();
 998         assert(valueMatches(returnType(), mt.returnType(), result));
 999         return true;
1000     }
1001 
1002     private boolean isEmpty() {
1003         if (result < 0)
1004             return (names.length == arity);
1005         else if (result == arity && names.length == arity + 1)
1006             return names[arity].isConstantZero();
1007         else
1008             return false;
1009     }
1010 
1011     public String toString() {
1012         StringBuilder buf = new StringBuilder(debugName+"=Lambda(");
1013         for (int i = 0; i < names.length; i++) {
1014             if (i == arity)  buf.append(")=>{");
1015             Name n = names[i];
1016             if (i >= arity)  buf.append("\n    ");
1017             buf.append(n.paramString());
1018             if (i < arity) {
1019                 if (i+1 < arity)  buf.append(",");
1020                 continue;
1021             }
1022             buf.append("=").append(n.exprString());
1023             buf.append(";");
1024         }
1025         if (arity == names.length)  buf.append(")=>{");
1026         buf.append(result < 0 ? "void" : names[result]).append("}");
1027         if (TRACE_INTERPRETER) {
1028             // Extra verbosity:
1029             buf.append(":").append(basicTypeSignature());
1030             buf.append("/").append(vmentry);
1031         }
1032         return buf.toString();
1033     }
1034 
1035     @Override
1036     public boolean equals(Object obj) {
1037         return obj instanceof LambdaForm && equals((LambdaForm)obj);
1038     }
1039     public boolean equals(LambdaForm that) {
1040         if (this.result != that.result)  return false;
1041         return Arrays.equals(this.names, that.names);
1042     }
1043     public int hashCode() {
1044         return result + 31 * Arrays.hashCode(names);
1045     }
1046     LambdaFormEditor editor() {
1047         return LambdaFormEditor.lambdaFormEditor(this);
1048     }
1049 
1050     boolean contains(Name name) {
1051         int pos = name.index();
1052         if (pos >= 0) {
1053             return pos < names.length && name.equals(names[pos]);
1054         }
1055         for (int i = arity; i < names.length; i++) {
1056             if (name.equals(names[i]))
1057                 return true;
1058         }
1059         return false;
1060     }
1061 
1062     static class NamedFunction {
1063         final MemberName member;
1064         private @Stable MethodHandle resolvedHandle;
1065         @Stable MethodHandle invoker;
1066 
1067         NamedFunction(MethodHandle resolvedHandle) {
1068             this(resolvedHandle.internalMemberName(), resolvedHandle);
1069         }
1070         NamedFunction(MemberName member, MethodHandle resolvedHandle) {
1071             this.member = member;
1072             this.resolvedHandle = resolvedHandle;
1073              // The following assert is almost always correct, but will fail for corner cases, such as PrivateInvokeTest.
1074              //assert(!isInvokeBasic(member));
1075         }
1076         NamedFunction(MethodType basicInvokerType) {
1077             assert(basicInvokerType == basicInvokerType.basicType()) : basicInvokerType;
1078             if (basicInvokerType.parameterSlotCount() < MethodType.MAX_MH_INVOKER_ARITY) {
1079                 this.resolvedHandle = basicInvokerType.invokers().basicInvoker();
1080                 this.member = resolvedHandle.internalMemberName();
1081             } else {
1082                 // necessary to pass BigArityTest
1083                 this.member = Invokers.invokeBasicMethod(basicInvokerType);
1084             }
1085             assert(isInvokeBasic(member));
1086         }
1087 
1088         private static boolean isInvokeBasic(MemberName member) {
1089             return member != null &&
1090                    member.getDeclaringClass() == MethodHandle.class &&
1091                   "invokeBasic".equals(member.getName());
1092         }
1093 
1094         // The next 2 constructors are used to break circular dependencies on MH.invokeStatic, etc.
1095         // Any LambdaForm containing such a member is not interpretable.
1096         // This is OK, since all such LFs are prepared with special primitive vmentry points.
1097         // And even without the resolvedHandle, the name can still be compiled and optimized.
1098         NamedFunction(Method method) {
1099             this(new MemberName(method));
1100         }
1101         NamedFunction(MemberName member) {
1102             this(member, null);
1103         }
1104 
1105         MethodHandle resolvedHandle() {
1106             if (resolvedHandle == null)  resolve();
1107             return resolvedHandle;
1108         }
1109 
1110         synchronized void resolve() {
1111             if (resolvedHandle == null) {
1112                 resolvedHandle = DirectMethodHandle.make(member);
1113             }
1114         }
1115 
1116         @Override
1117         public boolean equals(Object other) {
1118             if (this == other) return true;
1119             if (other == null) return false;
1120             if (!(other instanceof NamedFunction)) return false;
1121             NamedFunction that = (NamedFunction) other;
1122             return this.member != null && this.member.equals(that.member);
1123         }
1124 
1125         @Override
1126         public int hashCode() {
1127             if (member != null)
1128                 return member.hashCode();
1129             return super.hashCode();
1130         }
1131 
1132         // Put the predefined NamedFunction invokers into the table.
1133         static void initializeInvokers() {
1134             for (MemberName m : MemberName.getFactory().getMethods(NamedFunction.class, false, null, null, null)) {
1135                 if (!m.isStatic() || !m.isPackage())  continue;
1136                 MethodType type = m.getMethodType();
1137                 if (type.equals(INVOKER_METHOD_TYPE) &&
1138                     m.getName().startsWith("invoke_")) {
1139                     String sig = m.getName().substring("invoke_".length());
1140                     int arity = LambdaForm.signatureArity(sig);
1141                     MethodType srcType = MethodType.genericMethodType(arity);
1142                     if (LambdaForm.signatureReturn(sig) == V_TYPE)
1143                         srcType = srcType.changeReturnType(void.class);
1144                     MethodTypeForm typeForm = srcType.form();
1145                     typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, DirectMethodHandle.make(m));
1146                 }
1147             }
1148         }
1149 
1150         // The following are predefined NamedFunction invokers.  The system must build
1151         // a separate invoker for each distinct signature.
1152         /** void return type invokers. */
1153         @Hidden
1154         static Object invoke__V(MethodHandle mh, Object[] a) throws Throwable {
1155             assert(arityCheck(0, void.class, mh, a));
1156             mh.invokeBasic();
1157             return null;
1158         }
1159         @Hidden
1160         static Object invoke_L_V(MethodHandle mh, Object[] a) throws Throwable {
1161             assert(arityCheck(1, void.class, mh, a));
1162             mh.invokeBasic(a[0]);
1163             return null;
1164         }
1165         @Hidden
1166         static Object invoke_LL_V(MethodHandle mh, Object[] a) throws Throwable {
1167             assert(arityCheck(2, void.class, mh, a));
1168             mh.invokeBasic(a[0], a[1]);
1169             return null;
1170         }
1171         @Hidden
1172         static Object invoke_LLL_V(MethodHandle mh, Object[] a) throws Throwable {
1173             assert(arityCheck(3, void.class, mh, a));
1174             mh.invokeBasic(a[0], a[1], a[2]);
1175             return null;
1176         }
1177         @Hidden
1178         static Object invoke_LLLL_V(MethodHandle mh, Object[] a) throws Throwable {
1179             assert(arityCheck(4, void.class, mh, a));
1180             mh.invokeBasic(a[0], a[1], a[2], a[3]);
1181             return null;
1182         }
1183         @Hidden
1184         static Object invoke_LLLLL_V(MethodHandle mh, Object[] a) throws Throwable {
1185             assert(arityCheck(5, void.class, mh, a));
1186             mh.invokeBasic(a[0], a[1], a[2], a[3], a[4]);
1187             return null;
1188         }
1189         /** Object return type invokers. */
1190         @Hidden
1191         static Object invoke__L(MethodHandle mh, Object[] a) throws Throwable {
1192             assert(arityCheck(0, mh, a));
1193             return mh.invokeBasic();
1194         }
1195         @Hidden
1196         static Object invoke_L_L(MethodHandle mh, Object[] a) throws Throwable {
1197             assert(arityCheck(1, mh, a));
1198             return mh.invokeBasic(a[0]);
1199         }
1200         @Hidden
1201         static Object invoke_LL_L(MethodHandle mh, Object[] a) throws Throwable {
1202             assert(arityCheck(2, mh, a));
1203             return mh.invokeBasic(a[0], a[1]);
1204         }
1205         @Hidden
1206         static Object invoke_LLL_L(MethodHandle mh, Object[] a) throws Throwable {
1207             assert(arityCheck(3, mh, a));
1208             return mh.invokeBasic(a[0], a[1], a[2]);
1209         }
1210         @Hidden
1211         static Object invoke_LLLL_L(MethodHandle mh, Object[] a) throws Throwable {
1212             assert(arityCheck(4, mh, a));
1213             return mh.invokeBasic(a[0], a[1], a[2], a[3]);
1214         }
1215         @Hidden
1216         static Object invoke_LLLLL_L(MethodHandle mh, Object[] a) throws Throwable {
1217             assert(arityCheck(5, mh, a));
1218             return mh.invokeBasic(a[0], a[1], a[2], a[3], a[4]);
1219         }
1220         private static boolean arityCheck(int arity, MethodHandle mh, Object[] a) {
1221             return arityCheck(arity, Object.class, mh, a);
1222         }
1223         private static boolean arityCheck(int arity, Class<?> rtype, MethodHandle mh, Object[] a) {
1224             assert(a.length == arity)
1225                     : Arrays.asList(a.length, arity);
1226             assert(mh.type().basicType() == MethodType.genericMethodType(arity).changeReturnType(rtype))
1227                     : Arrays.asList(mh, rtype, arity);
1228             MemberName member = mh.internalMemberName();
1229             if (isInvokeBasic(member)) {
1230                 assert(arity > 0);
1231                 assert(a[0] instanceof MethodHandle);
1232                 MethodHandle mh2 = (MethodHandle) a[0];
1233                 assert(mh2.type().basicType() == MethodType.genericMethodType(arity-1).changeReturnType(rtype))
1234                         : Arrays.asList(member, mh2, rtype, arity);
1235             }
1236             return true;
1237         }
1238 
1239         static final MethodType INVOKER_METHOD_TYPE =
1240             MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1241 
1242         private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1243             typeForm = typeForm.basicType().form();  // normalize to basic type
1244             MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1245             if (mh != null)  return mh;
1246             MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm);  // this could take a while
1247             mh = DirectMethodHandle.make(invoker);
1248             MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1249             if (mh2 != null)  return mh2;  // benign race
1250             if (!mh.type().equals(INVOKER_METHOD_TYPE))
1251                 throw newInternalError(mh.debugString());
1252             return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1253         }
1254 
1255         @Hidden
1256         Object invokeWithArguments(Object... arguments) throws Throwable {
1257             // If we have a cached invoker, call it right away.
1258             // NOTE: The invoker always returns a reference value.
1259             if (TRACE_INTERPRETER)  return invokeWithArgumentsTracing(arguments);
1260             assert(checkArgumentTypes(arguments, methodType()));
1261             return invoker().invokeBasic(resolvedHandle(), arguments);
1262         }
1263 
1264         @Hidden
1265         Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1266             Object rval;
1267             try {
1268                 traceInterpreter("[ call", this, arguments);
1269                 if (invoker == null) {
1270                     traceInterpreter("| getInvoker", this);
1271                     invoker();
1272                 }
1273                 // resolvedHandle might be uninitialized, ok for tracing
1274                 if (resolvedHandle == null) {
1275                     traceInterpreter("| resolve", this);
1276                     resolvedHandle();
1277                 }
1278                 assert(checkArgumentTypes(arguments, methodType()));
1279                 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1280             } catch (Throwable ex) {
1281                 traceInterpreter("] throw =>", ex);
1282                 throw ex;
1283             }
1284             traceInterpreter("] return =>", rval);
1285             return rval;
1286         }
1287 
1288         private MethodHandle invoker() {
1289             if (invoker != null)  return invoker;
1290             // Get an invoker and cache it.
1291             return invoker = computeInvoker(methodType().form());
1292         }
1293 
1294         private static boolean checkArgumentTypes(Object[] arguments, MethodType methodType) {
1295             if (true)  return true;  // FIXME
1296             MethodType dstType = methodType.form().erasedType();
1297             MethodType srcType = dstType.basicType().wrap();
1298             Class<?>[] ptypes = new Class<?>[arguments.length];
1299             for (int i = 0; i < arguments.length; i++) {
1300                 Object arg = arguments[i];
1301                 Class<?> ptype = arg == null ? Object.class : arg.getClass();
1302                 // If the dest. type is a primitive we keep the
1303                 // argument type.
1304                 ptypes[i] = dstType.parameterType(i).isPrimitive() ? ptype : Object.class;
1305             }
1306             MethodType argType = MethodType.methodType(srcType.returnType(), ptypes).wrap();
1307             assert(argType.isConvertibleTo(srcType)) : "wrong argument types: cannot convert " + argType + " to " + srcType;
1308             return true;
1309         }
1310 
1311         MethodType methodType() {
1312             if (resolvedHandle != null)
1313                 return resolvedHandle.type();
1314             else
1315                 // only for certain internal LFs during bootstrapping
1316                 return member.getInvocationType();
1317         }
1318 
1319         MemberName member() {
1320             assert(assertMemberIsConsistent());
1321             return member;
1322         }
1323 
1324         // Called only from assert.
1325         private boolean assertMemberIsConsistent() {
1326             if (resolvedHandle instanceof DirectMethodHandle) {
1327                 MemberName m = resolvedHandle.internalMemberName();
1328                 assert(m.equals(member));
1329             }
1330             return true;
1331         }
1332 
1333         Class<?> memberDeclaringClassOrNull() {
1334             return (member == null) ? null : member.getDeclaringClass();
1335         }
1336 
1337         BasicType returnType() {
1338             return basicType(methodType().returnType());
1339         }
1340 
1341         BasicType parameterType(int n) {
1342             return basicType(methodType().parameterType(n));
1343         }
1344 
1345         int arity() {
1346             return methodType().parameterCount();
1347         }
1348 
1349         public String toString() {
1350             if (member == null)  return String.valueOf(resolvedHandle);
1351             return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1352         }
1353 
1354         public boolean isIdentity() {
1355             return this.equals(identity(returnType()));
1356         }
1357 
1358         public boolean isConstantZero() {
1359             return this.equals(constantZero(returnType()));
1360         }
1361 
1362         public MethodHandleImpl.Intrinsic intrinsicName() {
1363             return resolvedHandle == null ? MethodHandleImpl.Intrinsic.NONE
1364                                           : resolvedHandle.intrinsicName();
1365         }
1366     }
1367 
1368     public static String basicTypeSignature(MethodType type) {
1369         int params = type.parameterCount();
1370         char[] sig = new char[params + 2];
1371         int sigp = 0;
1372         while (sigp < params) {
1373             sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1374         }
1375         sig[sigp++] = '_';
1376         sig[sigp++] = basicTypeChar(type.returnType());
1377         assert(sigp == sig.length);
1378         return String.valueOf(sig);
1379     }
1380     public static String shortenSignature(String signature) {
1381         // Hack to make signatures more readable when they show up in method names.
1382         final int NO_CHAR = -1, MIN_RUN = 3;
1383         int c0, c1 = NO_CHAR, c1reps = 0;
1384         StringBuilder buf = null;
1385         int len = signature.length();
1386         if (len < MIN_RUN)  return signature;
1387         for (int i = 0; i <= len; i++) {
1388             // shift in the next char:
1389             c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1390             if (c1 == c0) { ++c1reps; continue; }
1391             // shift in the next count:
1392             int c0reps = c1reps; c1reps = 1;
1393             // end of a  character run
1394             if (c0reps < MIN_RUN) {
1395                 if (buf != null) {
1396                     while (--c0reps >= 0)
1397                         buf.append((char)c0);
1398                 }
1399                 continue;
1400             }
1401             // found three or more in a row
1402             if (buf == null)
1403                 buf = new StringBuilder().append(signature, 0, i - c0reps);
1404             buf.append((char)c0).append(c0reps);
1405         }
1406         return (buf == null) ? signature : buf.toString();
1407     }
1408 
1409     static final class Name {
1410         final BasicType type;
1411         @Stable short index;
1412         final NamedFunction function;
1413         final Object constraint;  // additional type information, if not null
1414         @Stable final Object[] arguments;
1415 
1416         private Name(int index, BasicType type, NamedFunction function, Object[] arguments) {
1417             this.index = (short)index;
1418             this.type = type;
1419             this.function = function;
1420             this.arguments = arguments;
1421             this.constraint = null;
1422             assert(this.index == index);
1423         }
1424         private Name(Name that, Object constraint) {
1425             this.index = that.index;
1426             this.type = that.type;
1427             this.function = that.function;
1428             this.arguments = that.arguments;
1429             this.constraint = constraint;
1430             assert(constraint == null || isParam());  // only params have constraints
1431             assert(constraint == null || constraint instanceof BoundMethodHandle.SpeciesData || constraint instanceof Class);
1432         }
1433         Name(MethodHandle function, Object... arguments) {
1434             this(new NamedFunction(function), arguments);
1435         }
1436         Name(MethodType functionType, Object... arguments) {
1437             this(new NamedFunction(functionType), arguments);
1438             assert(arguments[0] instanceof Name && ((Name)arguments[0]).type == L_TYPE);
1439         }
1440         Name(MemberName function, Object... arguments) {
1441             this(new NamedFunction(function), arguments);
1442         }
1443         Name(NamedFunction function, Object... arguments) {
1444             this(-1, function.returnType(), function, arguments = Arrays.copyOf(arguments, arguments.length, Object[].class));
1445             assert(typesMatch(function, arguments));
1446         }
1447         /** Create a raw parameter of the given type, with an expected index. */
1448         Name(int index, BasicType type) {
1449             this(index, type, null, null);
1450         }
1451         /** Create a raw parameter of the given type. */
1452         Name(BasicType type) { this(-1, type); }
1453 
1454         BasicType type() { return type; }
1455         int index() { return index; }
1456         boolean initIndex(int i) {
1457             if (index != i) {
1458                 if (index != -1)  return false;
1459                 index = (short)i;
1460             }
1461             return true;
1462         }
1463         char typeChar() {
1464             return type.btChar;
1465         }
1466 
1467         void resolve() {
1468             if (function != null)
1469                 function.resolve();
1470         }
1471 
1472         Name newIndex(int i) {
1473             if (initIndex(i))  return this;
1474             return cloneWithIndex(i);
1475         }
1476         Name cloneWithIndex(int i) {
1477             Object[] newArguments = (arguments == null) ? null : arguments.clone();
1478             return new Name(i, type, function, newArguments).withConstraint(constraint);
1479         }
1480         Name withConstraint(Object constraint) {
1481             if (constraint == this.constraint)  return this;
1482             return new Name(this, constraint);
1483         }
1484         Name replaceName(Name oldName, Name newName) {  // FIXME: use replaceNames uniformly
1485             if (oldName == newName)  return this;
1486             @SuppressWarnings("LocalVariableHidesMemberVariable")
1487             Object[] arguments = this.arguments;
1488             if (arguments == null)  return this;
1489             boolean replaced = false;
1490             for (int j = 0; j < arguments.length; j++) {
1491                 if (arguments[j] == oldName) {
1492                     if (!replaced) {
1493                         replaced = true;
1494                         arguments = arguments.clone();
1495                     }
1496                     arguments[j] = newName;
1497                 }
1498             }
1499             if (!replaced)  return this;
1500             return new Name(function, arguments);
1501         }
1502         /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1503          *  Limit such replacements to {@code start<=i<end}.  Return possibly changed self.
1504          */
1505         Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1506             if (start >= end)  return this;
1507             @SuppressWarnings("LocalVariableHidesMemberVariable")
1508             Object[] arguments = this.arguments;
1509             boolean replaced = false;
1510         eachArg:
1511             for (int j = 0; j < arguments.length; j++) {
1512                 if (arguments[j] instanceof Name) {
1513                     Name n = (Name) arguments[j];
1514                     int check = n.index;
1515                     // harmless check to see if the thing is already in newNames:
1516                     if (check >= 0 && check < newNames.length && n == newNames[check])
1517                         continue eachArg;
1518                     // n might not have the correct index: n != oldNames[n.index].
1519                     for (int i = start; i < end; i++) {
1520                         if (n == oldNames[i]) {
1521                             if (n == newNames[i])
1522                                 continue eachArg;
1523                             if (!replaced) {
1524                                 replaced = true;
1525                                 arguments = arguments.clone();
1526                             }
1527                             arguments[j] = newNames[i];
1528                             continue eachArg;
1529                         }
1530                     }
1531                 }
1532             }
1533             if (!replaced)  return this;
1534             return new Name(function, arguments);
1535         }
1536         void internArguments() {
1537             @SuppressWarnings("LocalVariableHidesMemberVariable")
1538             Object[] arguments = this.arguments;
1539             for (int j = 0; j < arguments.length; j++) {
1540                 if (arguments[j] instanceof Name) {
1541                     Name n = (Name) arguments[j];
1542                     if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1543                         arguments[j] = internArgument(n);
1544                 }
1545             }
1546         }
1547         boolean isParam() {
1548             return function == null;
1549         }
1550         boolean isConstantZero() {
1551             return !isParam() && arguments.length == 0 && function.isConstantZero();
1552         }
1553 
1554         boolean refersTo(Class<?> declaringClass, String methodName) {
1555             return function != null &&
1556                     function.member() != null && function.member().refersTo(declaringClass, methodName);
1557         }
1558 
1559         /**
1560          * Check if MemberName is a call to MethodHandle.invokeBasic.
1561          */
1562         boolean isInvokeBasic() {
1563             if (function == null)
1564                 return false;
1565             if (arguments.length < 1)
1566                 return false;  // must have MH argument
1567             MemberName member = function.member();
1568             return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1569                     !member.isPublic() && !member.isStatic();
1570         }
1571 
1572         /**
1573          * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1574          */
1575         boolean isLinkerMethodInvoke() {
1576             if (function == null)
1577                 return false;
1578             if (arguments.length < 1)
1579                 return false;  // must have MH argument
1580             MemberName member = function.member();
1581             return member != null &&
1582                     member.getDeclaringClass() == MethodHandle.class &&
1583                     !member.isPublic() && member.isStatic() &&
1584                     member.getName().startsWith("linkTo");
1585         }
1586 
1587         public String toString() {
1588             return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1589         }
1590         public String debugString() {
1591             String s = paramString();
1592             return (function == null) ? s : s + "=" + exprString();
1593         }
1594         public String paramString() {
1595             String s = toString();
1596             Object c = constraint;
1597             if (c == null)
1598                 return s;
1599             if (c instanceof Class)  c = ((Class<?>)c).getSimpleName();
1600             return s + "/" + c;
1601         }
1602         public String exprString() {
1603             if (function == null)  return toString();
1604             StringBuilder buf = new StringBuilder(function.toString());
1605             buf.append("(");
1606             String cma = "";
1607             for (Object a : arguments) {
1608                 buf.append(cma); cma = ",";
1609                 if (a instanceof Name || a instanceof Integer)
1610                     buf.append(a);
1611                 else
1612                     buf.append("(").append(a).append(")");
1613             }
1614             buf.append(")");
1615             return buf.toString();
1616         }
1617 
1618         private boolean typesMatch(NamedFunction function, Object ... arguments) {
1619             assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1620             for (int i = 0; i < arguments.length; i++) {
1621                 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1622             }
1623             return true;
1624         }
1625 
1626         private static boolean typesMatch(BasicType parameterType, Object object) {
1627             if (object instanceof Name) {
1628                 return ((Name)object).type == parameterType;
1629             }
1630             switch (parameterType) {
1631                 case I_TYPE:  return object instanceof Integer;
1632                 case J_TYPE:  return object instanceof Long;
1633                 case F_TYPE:  return object instanceof Float;
1634                 case D_TYPE:  return object instanceof Double;
1635             }
1636             assert(parameterType == L_TYPE);
1637             return true;
1638         }
1639 
1640         /** Return the index of the last occurrence of n in the argument array.
1641          *  Return -1 if the name is not used.
1642          */
1643         int lastUseIndex(Name n) {
1644             if (arguments == null)  return -1;
1645             for (int i = arguments.length; --i >= 0; ) {
1646                 if (arguments[i] == n)  return i;
1647             }
1648             return -1;
1649         }
1650 
1651         /** Return the number of occurrences of n in the argument array.
1652          *  Return 0 if the name is not used.
1653          */
1654         int useCount(Name n) {
1655             if (arguments == null)  return 0;
1656             int count = 0;
1657             for (int i = arguments.length; --i >= 0; ) {
1658                 if (arguments[i] == n)  ++count;
1659             }
1660             return count;
1661         }
1662 
1663         boolean contains(Name n) {
1664             return this == n || lastUseIndex(n) >= 0;
1665         }
1666 
1667         public boolean equals(Name that) {
1668             if (this == that)  return true;
1669             if (isParam())
1670                 // each parameter is a unique atom
1671                 return false;  // this != that
1672             return
1673                 //this.index == that.index &&
1674                 this.type == that.type &&
1675                 this.function.equals(that.function) &&
1676                 Arrays.equals(this.arguments, that.arguments);
1677         }
1678         @Override
1679         public boolean equals(Object x) {
1680             return x instanceof Name && equals((Name)x);
1681         }
1682         @Override
1683         public int hashCode() {
1684             if (isParam())
1685                 return index | (type.ordinal() << 8);
1686             return function.hashCode() ^ Arrays.hashCode(arguments);
1687         }
1688     }
1689 
1690     /** Return the index of the last name which contains n as an argument.
1691      *  Return -1 if the name is not used.  Return names.length if it is the return value.
1692      */
1693     int lastUseIndex(Name n) {
1694         int ni = n.index, nmax = names.length;
1695         assert(names[ni] == n);
1696         if (result == ni)  return nmax;  // live all the way beyond the end
1697         for (int i = nmax; --i > ni; ) {
1698             if (names[i].lastUseIndex(n) >= 0)
1699                 return i;
1700         }
1701         return -1;
1702     }
1703 
1704     /** Return the number of times n is used as an argument or return value. */
1705     int useCount(Name n) {
1706         int nmax = names.length;
1707         int end = lastUseIndex(n);
1708         if (end < 0)  return 0;
1709         int count = 0;
1710         if (end == nmax) { count++; end--; }
1711         int beg = n.index() + 1;
1712         if (beg < arity)  beg = arity;
1713         for (int i = beg; i <= end; i++) {
1714             count += names[i].useCount(n);
1715         }
1716         return count;
1717     }
1718 
1719     static Name argument(int which, BasicType type) {
1720         if (which >= INTERNED_ARGUMENT_LIMIT)
1721             return new Name(which, type);
1722         return INTERNED_ARGUMENTS[type.ordinal()][which];
1723     }
1724     static Name internArgument(Name n) {
1725         assert(n.isParam()) : "not param: " + n;
1726         assert(n.index < INTERNED_ARGUMENT_LIMIT);
1727         if (n.constraint != null)  return n;
1728         return argument(n.index, n.type);
1729     }
1730     static Name[] arguments(int extra, MethodType types) {
1731         int length = types.parameterCount();
1732         Name[] names = new Name[length + extra];
1733         for (int i = 0; i < length; i++)
1734             names[i] = argument(i, basicType(types.parameterType(i)));
1735         return names;
1736     }
1737     static final int INTERNED_ARGUMENT_LIMIT = 10;
1738     private static final Name[][] INTERNED_ARGUMENTS
1739             = new Name[ARG_TYPE_LIMIT][INTERNED_ARGUMENT_LIMIT];
1740     static {
1741         for (BasicType type : BasicType.ARG_TYPES) {
1742             int ord = type.ordinal();
1743             for (int i = 0; i < INTERNED_ARGUMENTS[ord].length; i++) {
1744                 INTERNED_ARGUMENTS[ord][i] = new Name(i, type);
1745             }
1746         }
1747     }
1748 
1749     private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
1750 
1751     static LambdaForm identityForm(BasicType type) {
1752         int ord = type.ordinal();
1753         LambdaForm form = LF_identity[ord];
1754         if (form != null) {
1755             return form;
1756         }
1757         createFormsFor(type);
1758         return LF_identity[ord];
1759     }
1760 
1761     static LambdaForm zeroForm(BasicType type) {
1762         int ord = type.ordinal();
1763         LambdaForm form = LF_zero[ord];
1764         if (form != null) {
1765             return form;
1766         }
1767         createFormsFor(type);
1768         return LF_zero[ord];
1769     }
1770 
1771     static NamedFunction identity(BasicType type) {
1772         int ord = type.ordinal();
1773         NamedFunction function = NF_identity[ord];
1774         if (function != null) {
1775             return function;
1776         }
1777         createFormsFor(type);
1778         return NF_identity[ord];
1779     }
1780 
1781     static NamedFunction constantZero(BasicType type) {
1782         int ord = type.ordinal();
1783         NamedFunction function = NF_zero[ord];
1784         if (function != null) {
1785             return function;
1786         }
1787         createFormsFor(type);
1788         return NF_zero[ord];
1789     }
1790 
1791     private static final @Stable LambdaForm[] LF_identity = new LambdaForm[TYPE_LIMIT];
1792     private static final @Stable LambdaForm[] LF_zero = new LambdaForm[TYPE_LIMIT];
1793     private static final @Stable NamedFunction[] NF_identity = new NamedFunction[TYPE_LIMIT];
1794     private static final @Stable NamedFunction[] NF_zero = new NamedFunction[TYPE_LIMIT];
1795 
1796     private static synchronized void createFormsFor(BasicType type) {
1797         final int ord = type.ordinal();
1798         LambdaForm idForm = LF_identity[ord];
1799         if (idForm != null) {
1800             return;
1801         }
1802         char btChar = type.basicTypeChar();
1803         boolean isVoid = (type == V_TYPE);
1804         Class<?> btClass = type.btClass;
1805         MethodType zeType = MethodType.methodType(btClass);
1806         MethodType idType = (isVoid) ? zeType : zeType.appendParameterTypes(btClass);
1807 
1808         // Look up symbolic names.  It might not be necessary to have these,
1809         // but if we need to emit direct references to bytecodes, it helps.
1810         // Zero is built from a call to an identity function with a constant zero input.
1811         MemberName idMem = new MemberName(LambdaForm.class, "identity_"+btChar, idType, REF_invokeStatic);
1812         MemberName zeMem = null;
1813         try {
1814             idMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, idMem, null, NoSuchMethodException.class);
1815             if (!isVoid) {
1816                 zeMem = new MemberName(LambdaForm.class, "zero_"+btChar, zeType, REF_invokeStatic);
1817                 zeMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, zeMem, null, NoSuchMethodException.class);
1818             }
1819         } catch (IllegalAccessException|NoSuchMethodException ex) {
1820             throw newInternalError(ex);
1821         }
1822 
1823         NamedFunction idFun;
1824         LambdaForm zeForm;
1825         NamedFunction zeFun;
1826 
1827         // Create the LFs and NamedFunctions. Precompiling LFs to byte code is needed to break circular
1828         // bootstrap dependency on this method in case we're interpreting LFs
1829         if (isVoid) {
1830             Name[] idNames = new Name[] { argument(0, L_TYPE) };
1831             idForm = new LambdaForm(idMem.getName(), 1, idNames, VOID_RESULT);
1832             idForm.compileToBytecode();
1833             idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1834 
1835             zeForm = idForm;
1836             zeFun = idFun;
1837         } else {
1838             Name[] idNames = new Name[] { argument(0, L_TYPE), argument(1, type) };
1839             idForm = new LambdaForm(idMem.getName(), 2, idNames, 1);
1840             idForm.compileToBytecode();
1841             idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1842 
1843             Object zeValue = Wrapper.forBasicType(btChar).zero();
1844             Name[] zeNames = new Name[] { argument(0, L_TYPE), new Name(idFun, zeValue) };
1845             zeForm = new LambdaForm(zeMem.getName(), 1, zeNames, 1);
1846             zeForm.compileToBytecode();
1847             zeFun = new NamedFunction(zeMem, SimpleMethodHandle.make(zeMem.getInvocationType(), zeForm));
1848         }
1849 
1850         LF_zero[ord] = zeForm;
1851         NF_zero[ord] = zeFun;
1852         LF_identity[ord] = idForm;
1853         NF_identity[ord] = idFun;
1854 
1855         assert(idFun.isIdentity());
1856         assert(zeFun.isConstantZero());
1857         assert(new Name(zeFun).isConstantZero());
1858     }
1859 
1860     // Avoid appealing to ValueConversions at bootstrap time:
1861     private static int identity_I(int x) { return x; }
1862     private static long identity_J(long x) { return x; }
1863     private static float identity_F(float x) { return x; }
1864     private static double identity_D(double x) { return x; }
1865     private static Object identity_L(Object x) { return x; }
1866     private static void identity_V() { return; }
1867     private static int zero_I() { return 0; }
1868     private static long zero_J() { return 0; }
1869     private static float zero_F() { return 0; }
1870     private static double zero_D() { return 0; }
1871     private static Object zero_L() { return null; }
1872 
1873     /**
1874      * Internal marker for byte-compiled LambdaForms.
1875      */
1876     /*non-public*/
1877     @Target(ElementType.METHOD)
1878     @Retention(RetentionPolicy.RUNTIME)
1879     @interface Compiled {
1880     }
1881 
1882     /**
1883      * Internal marker for LambdaForm interpreter frames.
1884      */
1885     /*non-public*/
1886     @Target(ElementType.METHOD)
1887     @Retention(RetentionPolicy.RUNTIME)
1888     @interface Hidden {
1889     }
1890 
1891     private static final HashMap<String,Integer> DEBUG_NAME_COUNTERS;
1892     static {
1893         if (debugEnabled())
1894             DEBUG_NAME_COUNTERS = new HashMap<>();
1895         else
1896             DEBUG_NAME_COUNTERS = null;
1897     }
1898 
1899     // Put this last, so that previous static inits can run before.
1900     static {
1901         if (USE_PREDEFINED_INTERPRET_METHODS)
1902             computeInitialPreparedForms();
1903         NamedFunction.initializeInvokers();
1904     }
1905 
1906     // The following hack is necessary in order to suppress TRACE_INTERPRETER
1907     // during execution of the static initializes of this class.
1908     // Turning on TRACE_INTERPRETER too early will cause
1909     // stack overflows and other misbehavior during attempts to trace events
1910     // that occur during LambdaForm.<clinit>.
1911     // Therefore, do not move this line higher in this file, and do not remove.
1912     private static final boolean TRACE_INTERPRETER = MethodHandleStatics.TRACE_INTERPRETER;
1913 }
--- EOF ---