1 /*
   2  * Copyright (c) 2011, 2020, 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.Hidden;
  31 import jdk.internal.vm.annotation.Stable;
  32 import sun.invoke.util.Wrapper;
  33 
  34 import java.lang.annotation.ElementType;
  35 import java.lang.annotation.Retention;
  36 import java.lang.annotation.RetentionPolicy;
  37 import java.lang.annotation.Target;
  38 import java.lang.reflect.Method;
  39 import java.util.Arrays;
  40 import java.util.HashMap;
  41 
  42 import static java.lang.invoke.LambdaForm.BasicType.*;
  43 import static java.lang.invoke.MethodHandleNatives.Constants.*;
  44 import static java.lang.invoke.MethodHandleStatics.*;
  45 
  46 /**
  47  * The symbolic, non-executable form of a method handle's invocation semantics.
  48  * It consists of a series of names.
  49  * The first N (N=arity) names are parameters,
  50  * while any remaining names are temporary values.
  51  * Each temporary specifies the application of a function to some arguments.
  52  * The functions are method handles, while the arguments are mixes of
  53  * constant values and local names.
  54  * The result of the lambda is defined as one of the names, often the last one.
  55  * <p>
  56  * Here is an approximate grammar:
  57  * <blockquote><pre>{@code
  58  * LambdaForm = "(" ArgName* ")=>{" TempName* Result "}"
  59  * ArgName = "a" N ":" T
  60  * TempName = "t" N ":" T "=" Function "(" Argument* ");"
  61  * Function = ConstantValue
  62  * Argument = NameRef | ConstantValue
  63  * Result = NameRef | "void"
  64  * NameRef = "a" N | "t" N
  65  * N = (any whole number)
  66  * T = "L" | "I" | "J" | "F" | "D" | "V"
  67  * }</pre></blockquote>
  68  * Names are numbered consecutively from left to right starting at zero.
  69  * (The letters are merely a taste of syntax sugar.)
  70  * Thus, the first temporary (if any) is always numbered N (where N=arity).
  71  * Every occurrence of a name reference in an argument list must refer to
  72  * a name previously defined within the same lambda.
  73  * A lambda has a void result if and only if its result index is -1.
  74  * If a temporary has the type "V", it cannot be the subject of a NameRef,
  75  * even though possesses a number.
  76  * Note that all reference types are erased to "L", which stands for {@code Object}.
  77  * All subword types (boolean, byte, short, char) are erased to "I" which is {@code int}.
  78  * The other types stand for the usual primitive types.
  79  * <p>
  80  * Function invocation closely follows the static rules of the Java verifier.
  81  * Arguments and return values must exactly match when their "Name" types are
  82  * considered.
  83  * Conversions are allowed only if they do not change the erased type.
  84  * <ul>
  85  * <li>L = Object: casts are used freely to convert into and out of reference types
  86  * <li>I = int: subword types are forcibly narrowed when passed as arguments (see {@code explicitCastArguments})
  87  * <li>J = long: no implicit conversions
  88  * <li>F = float: no implicit conversions
  89  * <li>D = double: no implicit conversions
  90  * <li>V = void: a function result may be void if and only if its Name is of type "V"
  91  * </ul>
  92  * Although implicit conversions are not allowed, explicit ones can easily be
  93  * encoded by using temporary expressions which call type-transformed identity functions.
  94  * <p>
  95  * Examples:
  96  * <blockquote><pre>{@code
  97  * (a0:J)=>{ a0 }
  98  *     == identity(long)
  99  * (a0:I)=>{ t1:V = System.out#println(a0); void }
 100  *     == System.out#println(int)
 101  * (a0:L)=>{ t1:V = System.out#println(a0); a0 }
 102  *     == identity, with printing side-effect
 103  * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
 104  *                 t3:L = BoundMethodHandle#target(a0);
 105  *                 t4:L = MethodHandle#invoke(t3, t2, a1); t4 }
 106  *     == general invoker for unary insertArgument combination
 107  * (a0:L, a1:L)=>{ t2:L = FilterMethodHandle#filter(a0);
 108  *                 t3:L = MethodHandle#invoke(t2, a1);
 109  *                 t4:L = FilterMethodHandle#target(a0);
 110  *                 t5:L = MethodHandle#invoke(t4, t3); t5 }
 111  *     == general invoker for unary filterArgument combination
 112  * (a0:L, a1:L)=>{ ...(same as previous example)...
 113  *                 t5:L = MethodHandle#invoke(t4, t3, a1); t5 }
 114  *     == general invoker for unary/unary foldArgument combination
 115  * (a0:L, a1:I)=>{ t2:I = identity(long).asType((int)->long)(a1); t2 }
 116  *     == invoker for identity method handle which performs i2l
 117  * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
 118  *                 t3:L = Class#cast(t2,a1); t3 }
 119  *     == invoker for identity method handle which performs cast
 120  * }</pre></blockquote>
 121  * <p>
 122  * @author John Rose, JSR 292 EG
 123  */
 124 class LambdaForm {
 125     final int arity;
 126     final int result;
 127     final boolean forceInline;
 128     final MethodHandle customized;
 129     @Stable final Name[] names;
 130     final Kind kind;
 131     MemberName vmentry;   // low-level behavior, or null if not yet prepared
 132     private boolean isCompiled;
 133 
 134     // Either a LambdaForm cache (managed by LambdaFormEditor) or a link to uncustomized version (for customized LF)
 135     volatile Object transformCache;
 136 
 137     public static final int VOID_RESULT = -1, LAST_RESULT = -2;
 138 
 139     enum BasicType {
 140         L_TYPE('L', Object.class, Wrapper.OBJECT),  // all reference types
 141         I_TYPE('I', int.class,    Wrapper.INT),
 142         J_TYPE('J', long.class,   Wrapper.LONG),
 143         F_TYPE('F', float.class,  Wrapper.FLOAT),
 144         D_TYPE('D', double.class, Wrapper.DOUBLE),  // all primitive types
 145         V_TYPE('V', void.class,   Wrapper.VOID);    // not valid in all contexts
 146 
 147         static final @Stable BasicType[] ALL_TYPES = BasicType.values();
 148         static final @Stable BasicType[] ARG_TYPES = Arrays.copyOf(ALL_TYPES, ALL_TYPES.length-1);
 149 
 150         static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
 151         static final int TYPE_LIMIT = ALL_TYPES.length;
 152 
 153         // Derived int constants, which (unlike the enums) can be constant folded.
 154         // We can remove them when JDK-8161245 is fixed.
 155         static final byte
 156                 L_TYPE_NUM = (byte) L_TYPE.ordinal(),
 157                 I_TYPE_NUM = (byte) I_TYPE.ordinal(),
 158                 J_TYPE_NUM = (byte) J_TYPE.ordinal(),
 159                 F_TYPE_NUM = (byte) F_TYPE.ordinal(),
 160                 D_TYPE_NUM = (byte) D_TYPE.ordinal(),
 161                 V_TYPE_NUM = (byte) V_TYPE.ordinal();
 162 
 163         final char btChar;
 164         final Class<?> btClass;
 165         final Wrapper btWrapper;
 166 
 167         private BasicType(char btChar, Class<?> btClass, Wrapper wrapper) {
 168             this.btChar = btChar;
 169             this.btClass = btClass;
 170             this.btWrapper = wrapper;
 171         }
 172 
 173         char basicTypeChar() {
 174             return btChar;
 175         }
 176         Class<?> basicTypeClass() {
 177             return btClass;
 178         }
 179         Wrapper basicTypeWrapper() {
 180             return btWrapper;
 181         }
 182         int basicTypeSlots() {
 183             return btWrapper.stackSlots();
 184         }
 185 
 186         static BasicType basicType(byte type) {
 187             return ALL_TYPES[type];
 188         }
 189         static BasicType basicType(char type) {
 190             return switch (type) {
 191                 case 'L' -> L_TYPE;
 192                 case 'I' -> I_TYPE;
 193                 case 'J' -> J_TYPE;
 194                 case 'F' -> F_TYPE;
 195                 case 'D' -> D_TYPE;
 196                 case 'V' -> V_TYPE;
 197                 // all subword types are represented as ints
 198                 case 'Z', 'B', 'S', 'C' -> I_TYPE;
 199                 default -> throw newInternalError("Unknown type char: '" + type + "'");
 200             };
 201         }
 202         static BasicType basicType(Wrapper type) {
 203             char c = type.basicTypeChar();
 204             return basicType(c);
 205         }
 206         static BasicType basicType(Class<?> type) {
 207             if (!type.isPrimitive())  return L_TYPE;
 208             return basicType(Wrapper.forPrimitiveType(type));
 209         }
 210         static int[] basicTypeOrds(BasicType[] types) {
 211             if (types == null) {
 212                 return null;
 213             }
 214             int[] a = new int[types.length];
 215             for(int i = 0; i < types.length; ++i) {
 216                 a[i] = types[i].ordinal();
 217             }
 218             return a;
 219         }
 220 
 221         static char basicTypeChar(Class<?> type) {
 222             return basicType(type).btChar;
 223         }
 224 
 225         static byte[] basicTypesOrd(Class<?>[] types) {
 226             byte[] ords = new byte[types.length];
 227             for (int i = 0; i < ords.length; i++) {
 228                 ords[i] = (byte)basicType(types[i]).ordinal();
 229             }
 230             return ords;
 231         }
 232 
 233         static boolean isBasicTypeChar(char c) {
 234             return "LIJFDV".indexOf(c) >= 0;
 235         }
 236         static boolean isArgBasicTypeChar(char c) {
 237             return "LIJFD".indexOf(c) >= 0;
 238         }
 239 
 240         static { assert(checkBasicType()); }
 241         private static boolean checkBasicType() {
 242             for (int i = 0; i < ARG_TYPE_LIMIT; i++) {
 243                 assert ARG_TYPES[i].ordinal() == i;
 244                 assert ARG_TYPES[i] == ALL_TYPES[i];
 245             }
 246             for (int i = 0; i < TYPE_LIMIT; i++) {
 247                 assert ALL_TYPES[i].ordinal() == i;
 248             }
 249             assert ALL_TYPES[TYPE_LIMIT - 1] == V_TYPE;
 250             assert !Arrays.asList(ARG_TYPES).contains(V_TYPE);
 251             return true;
 252         }
 253     }
 254 
 255     enum Kind {
 256         GENERIC("invoke"),
 257         ZERO("zero"),
 258         IDENTITY("identity"),
 259         BOUND_REINVOKER("BMH.reinvoke", "reinvoke"),
 260         REINVOKER("MH.reinvoke", "reinvoke"),
 261         DELEGATE("MH.delegate", "delegate"),
 262         EXACT_LINKER("MH.invokeExact_MT", "invokeExact_MT"),
 263         EXACT_INVOKER("MH.exactInvoker", "exactInvoker"),
 264         GENERIC_LINKER("MH.invoke_MT", "invoke_MT"),
 265         GENERIC_INVOKER("MH.invoker", "invoker"),
 266         LINK_TO_TARGET_METHOD("linkToTargetMethod"),
 267         LINK_TO_CALL_SITE("linkToCallSite"),
 268         DIRECT_INVOKE_VIRTUAL("DMH.invokeVirtual", "invokeVirtual"),
 269         DIRECT_INVOKE_SPECIAL("DMH.invokeSpecial", "invokeSpecial"),
 270         DIRECT_INVOKE_SPECIAL_IFC("DMH.invokeSpecialIFC", "invokeSpecialIFC"),
 271         DIRECT_INVOKE_STATIC("DMH.invokeStatic", "invokeStatic"),
 272         DIRECT_NEW_INVOKE_SPECIAL("DMH.newInvokeSpecial", "newInvokeSpecial"),
 273         DIRECT_INVOKE_INTERFACE("DMH.invokeInterface", "invokeInterface"),
 274         DIRECT_INVOKE_STATIC_INIT("DMH.invokeStaticInit", "invokeStaticInit"),
 275         GET_REFERENCE("getReference"),
 276         PUT_REFERENCE("putReference"),
 277         GET_REFERENCE_VOLATILE("getReferenceVolatile"),
 278         PUT_REFERENCE_VOLATILE("putReferenceVolatile"),
 279         GET_VALUE("getValue"),
 280         PUT_VALUE("putValue"),
 281         GET_VALUE_VOLATILE("getValueVolatile"),
 282         PUT_VALUE_VOLATILE("putValueVolatile"),
 283         GET_INT("getInt"),
 284         PUT_INT("putInt"),
 285         GET_INT_VOLATILE("getIntVolatile"),
 286         PUT_INT_VOLATILE("putIntVolatile"),
 287         GET_BOOLEAN("getBoolean"),
 288         PUT_BOOLEAN("putBoolean"),
 289         GET_BOOLEAN_VOLATILE("getBooleanVolatile"),
 290         PUT_BOOLEAN_VOLATILE("putBooleanVolatile"),
 291         GET_BYTE("getByte"),
 292         PUT_BYTE("putByte"),
 293         GET_BYTE_VOLATILE("getByteVolatile"),
 294         PUT_BYTE_VOLATILE("putByteVolatile"),
 295         GET_CHAR("getChar"),
 296         PUT_CHAR("putChar"),
 297         GET_CHAR_VOLATILE("getCharVolatile"),
 298         PUT_CHAR_VOLATILE("putCharVolatile"),
 299         GET_SHORT("getShort"),
 300         PUT_SHORT("putShort"),
 301         GET_SHORT_VOLATILE("getShortVolatile"),
 302         PUT_SHORT_VOLATILE("putShortVolatile"),
 303         GET_LONG("getLong"),
 304         PUT_LONG("putLong"),
 305         GET_LONG_VOLATILE("getLongVolatile"),
 306         PUT_LONG_VOLATILE("putLongVolatile"),
 307         GET_FLOAT("getFloat"),
 308         PUT_FLOAT("putFloat"),
 309         GET_FLOAT_VOLATILE("getFloatVolatile"),
 310         PUT_FLOAT_VOLATILE("putFloatVolatile"),
 311         GET_DOUBLE("getDouble"),
 312         PUT_DOUBLE("putDouble"),
 313         GET_DOUBLE_VOLATILE("getDoubleVolatile"),
 314         PUT_DOUBLE_VOLATILE("putDoubleVolatile"),
 315         TRY_FINALLY("tryFinally"),
 316         TABLE_SWITCH("tableSwitch"),
 317         COLLECT("collect"),
 318         COLLECTOR("collector"),
 319         CONVERT("convert"),
 320         SPREAD("spread"),
 321         LOOP("loop"),
 322         FIELD("field"),
 323         GUARD("guard"),
 324         GUARD_WITH_CATCH("guardWithCatch"),
 325         VARHANDLE_EXACT_INVOKER("VH.exactInvoker"),
 326         VARHANDLE_INVOKER("VH.invoker", "invoker"),
 327         VARHANDLE_LINKER("VH.invoke_MT", "invoke_MT");
 328 
 329         final String defaultLambdaName;
 330         final String methodName;
 331 
 332         private Kind(String defaultLambdaName) {
 333             this(defaultLambdaName, defaultLambdaName);
 334         }
 335 
 336         private Kind(String defaultLambdaName, String methodName) {
 337             this.defaultLambdaName = defaultLambdaName;
 338             this.methodName = methodName;
 339         }
 340     }
 341 
 342     LambdaForm(int arity, Name[] names, int result) {
 343         this(arity, names, result, /*forceInline=*/true, /*customized=*/null, Kind.GENERIC);
 344     }
 345     LambdaForm(int arity, Name[] names, int result, Kind kind) {
 346         this(arity, names, result, /*forceInline=*/true, /*customized=*/null, kind);
 347     }
 348     LambdaForm(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized) {
 349         this(arity, names, result, forceInline, customized, Kind.GENERIC);
 350     }
 351     LambdaForm(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized, Kind kind) {
 352         assert(namesOK(arity, names));
 353         this.arity = arity;
 354         this.result = fixResult(result, names);
 355         this.names = names.clone();
 356         this.forceInline = forceInline;
 357         this.customized = customized;
 358         this.kind = kind;
 359         int maxOutArity = normalize();
 360         if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
 361             // Cannot use LF interpreter on very high arity expressions.
 362             assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
 363             compileToBytecode();
 364         }
 365     }
 366     LambdaForm(int arity, Name[] names) {
 367         this(arity, names, LAST_RESULT, /*forceInline=*/true, /*customized=*/null, Kind.GENERIC);
 368     }
 369     LambdaForm(int arity, Name[] names, Kind kind) {
 370         this(arity, names, LAST_RESULT, /*forceInline=*/true, /*customized=*/null, kind);
 371     }
 372     LambdaForm(int arity, Name[] names, boolean forceInline, Kind kind) {
 373         this(arity, names, LAST_RESULT, forceInline, /*customized=*/null, kind);
 374     }
 375 
 376     private static Name[] buildNames(Name[] formals, Name[] temps, Name result) {
 377         int arity = formals.length;
 378         int length = arity + temps.length + (result == null ? 0 : 1);
 379         Name[] names = Arrays.copyOf(formals, length);
 380         System.arraycopy(temps, 0, names, arity, temps.length);
 381         if (result != null)
 382             names[length - 1] = result;
 383         return names;
 384     }
 385 
 386     private LambdaForm(MethodType mt) {
 387         // Make a blank lambda form, which returns a constant zero or null.
 388         // It is used as a template for managing the invocation of similar forms that are non-empty.
 389         // Called only from getPreparedForm.
 390         this.arity = mt.parameterCount();
 391         this.result = (mt.returnType() == void.class || mt.returnType() == Void.class) ? -1 : arity;
 392         this.names = buildEmptyNames(arity, mt, result == -1);
 393         this.forceInline = true;
 394         this.customized = null;
 395         this.kind = Kind.ZERO;
 396         assert(nameRefsAreLegal());
 397         assert(isEmpty());
 398         String sig = null;
 399         assert(isValidSignature(sig = basicTypeSignature()));
 400         assert(sig.equals(basicTypeSignature())) : sig + " != " + basicTypeSignature();
 401     }
 402 
 403     private static Name[] buildEmptyNames(int arity, MethodType mt, boolean isVoid) {
 404         Name[] names = arguments(isVoid ? 0 : 1, mt);
 405         if (!isVoid) {
 406             Name zero = new Name(constantZero(basicType(mt.returnType())));
 407             names[arity] = zero.newIndex(arity);
 408         }
 409         return names;
 410     }
 411 
 412     private static int fixResult(int result, Name[] names) {
 413         if (result == LAST_RESULT)
 414             result = names.length - 1;  // might still be void
 415         if (result >= 0 && names[result].type == V_TYPE)
 416             result = VOID_RESULT;
 417         return result;
 418     }
 419 
 420     static boolean debugNames() {
 421         return DEBUG_NAME_COUNTERS != null;
 422     }
 423 
 424     static void associateWithDebugName(LambdaForm form, String name) {
 425         assert (debugNames());
 426         synchronized (DEBUG_NAMES) {
 427             DEBUG_NAMES.put(form, name);
 428         }
 429     }
 430 
 431     String lambdaName() {
 432         if (DEBUG_NAMES != null) {
 433             synchronized (DEBUG_NAMES) {
 434                 String name = DEBUG_NAMES.get(this);
 435                 if (name == null) {
 436                     name = generateDebugName();
 437                 }
 438                 return name;
 439             }
 440         }
 441         return kind.defaultLambdaName;
 442     }
 443 
 444     private String generateDebugName() {
 445         assert (debugNames());
 446         String debugNameStem = kind.defaultLambdaName;
 447         Integer ctr = DEBUG_NAME_COUNTERS.getOrDefault(debugNameStem, 0);
 448         DEBUG_NAME_COUNTERS.put(debugNameStem, ctr + 1);
 449         StringBuilder buf = new StringBuilder(debugNameStem);
 450         int leadingZero = buf.length();
 451         buf.append((int) ctr);
 452         for (int i = buf.length() - leadingZero; i < 3; i++) {
 453             buf.insert(leadingZero, '0');
 454         }
 455         buf.append('_');
 456         buf.append(basicTypeSignature());
 457         String name = buf.toString();
 458         associateWithDebugName(this, name);
 459         return name;
 460     }
 461 
 462     private static boolean namesOK(int arity, Name[] names) {
 463         for (int i = 0; i < names.length; i++) {
 464             Name n = names[i];
 465             assert(n != null) : "n is null";
 466             if (i < arity)
 467                 assert( n.isParam()) : n + " is not param at " + i;
 468             else
 469                 assert(!n.isParam()) : n + " is param at " + i;
 470         }
 471         return true;
 472     }
 473 
 474     /** Customize LambdaForm for a particular MethodHandle */
 475     LambdaForm customize(MethodHandle mh) {
 476         if (customized == mh) {
 477             return this;
 478         }
 479         LambdaForm customForm = new LambdaForm(arity, names, result, forceInline, mh, kind);
 480         if (COMPILE_THRESHOLD >= 0 && isCompiled) {
 481             // If shared LambdaForm has been compiled, compile customized version as well.
 482             customForm.compileToBytecode();
 483         }
 484         customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
 485         return customForm;
 486     }
 487 
 488     /** Get uncustomized flavor of the LambdaForm */
 489     LambdaForm uncustomize() {
 490         if (customized == null) {
 491             return this;
 492         }
 493         assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
 494         LambdaForm uncustomizedForm = (LambdaForm)transformCache;
 495         if (COMPILE_THRESHOLD >= 0 && isCompiled) {
 496             // If customized LambdaForm has been compiled, compile uncustomized version as well.
 497             uncustomizedForm.compileToBytecode();
 498         }
 499         return uncustomizedForm;
 500     }
 501 
 502     /** Renumber and/or replace params so that they are interned and canonically numbered.
 503      *  @return maximum argument list length among the names (since we have to pass over them anyway)
 504      */
 505     private int normalize() {
 506         Name[] oldNames = null;
 507         int maxOutArity = 0;
 508         int changesStart = 0;
 509         for (int i = 0; i < names.length; i++) {
 510             Name n = names[i];
 511             if (!n.initIndex(i)) {
 512                 if (oldNames == null) {
 513                     oldNames = names.clone();
 514                     changesStart = i;
 515                 }
 516                 names[i] = n.cloneWithIndex(i);
 517             }
 518             if (n.arguments != null && maxOutArity < n.arguments.length)
 519                 maxOutArity = n.arguments.length;
 520         }
 521         if (oldNames != null) {
 522             int startFixing = arity;
 523             if (startFixing <= changesStart)
 524                 startFixing = changesStart+1;
 525             for (int i = startFixing; i < names.length; i++) {
 526                 Name fixed = names[i].replaceNames(oldNames, names, changesStart, i);
 527                 names[i] = fixed.newIndex(i);
 528             }
 529         }
 530         assert(nameRefsAreLegal());
 531         int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
 532         boolean needIntern = false;
 533         for (int i = 0; i < maxInterned; i++) {
 534             Name n = names[i], n2 = internArgument(n);
 535             if (n != n2) {
 536                 names[i] = n2;
 537                 needIntern = true;
 538             }
 539         }
 540         if (needIntern) {
 541             for (int i = arity; i < names.length; i++) {
 542                 names[i].internArguments();
 543             }
 544         }
 545         assert(nameRefsAreLegal());
 546         return maxOutArity;
 547     }
 548 
 549     /**
 550      * Check that all embedded Name references are localizable to this lambda,
 551      * and are properly ordered after their corresponding definitions.
 552      * <p>
 553      * Note that a Name can be local to multiple lambdas, as long as
 554      * it possesses the same index in each use site.
 555      * This allows Name references to be freely reused to construct
 556      * fresh lambdas, without confusion.
 557      */
 558     boolean nameRefsAreLegal() {
 559         assert(arity >= 0 && arity <= names.length);
 560         assert(result >= -1 && result < names.length);
 561         // Do all names possess an index consistent with their local definition order?
 562         for (int i = 0; i < arity; i++) {
 563             Name n = names[i];
 564             assert(n.index() == i) : Arrays.asList(n.index(), i);
 565             assert(n.isParam());
 566         }
 567         // Also, do all local name references
 568         for (int i = arity; i < names.length; i++) {
 569             Name n = names[i];
 570             assert(n.index() == i);
 571             for (Object arg : n.arguments) {
 572                 if (arg instanceof Name n2) {
 573                     int i2 = n2.index;
 574                     assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
 575                     assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
 576                     assert(i2 < i);  // ref must come after def!
 577                 }
 578             }
 579         }
 580         return true;
 581     }
 582 
 583     /** Invoke this form on the given arguments. */
 584     // final Object invoke(Object... args) throws Throwable {
 585     //     // NYI: fit this into the fast path?
 586     //     return interpretWithArguments(args);
 587     // }
 588 
 589     /** Report the return type. */
 590     BasicType returnType() {
 591         if (result < 0)  return V_TYPE;
 592         Name n = names[result];
 593         return n.type;
 594     }
 595 
 596     /** Report the N-th argument type. */
 597     BasicType parameterType(int n) {
 598         return parameter(n).type;
 599     }
 600 
 601     /** Report the N-th argument name. */
 602     Name parameter(int n) {
 603         Name param = names[n];
 604         assert(n < arity && param.isParam());
 605         return param;
 606     }
 607 
 608     /** Report the N-th argument type constraint. */
 609     Object parameterConstraint(int n) {
 610         return parameter(n).constraint;
 611     }
 612 
 613     /** Report the arity. */
 614     int arity() {
 615         return arity;
 616     }
 617 
 618     /** Report the number of expressions (non-parameter names). */
 619     int expressionCount() {
 620         return names.length - arity;
 621     }
 622 
 623     /** Return the method type corresponding to my basic type signature. */
 624     MethodType methodType() {
 625         Class<?>[] ptypes = new Class<?>[arity];
 626         for (int i = 0; i < arity; ++i) {
 627             ptypes[i] = parameterType(i).btClass;
 628         }
 629         return MethodType.makeImpl(returnType().btClass, ptypes, true);
 630     }
 631 
 632     /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
 633     final String basicTypeSignature() {
 634         StringBuilder buf = new StringBuilder(arity() + 3);
 635         for (int i = 0, a = arity(); i < a; i++)
 636             buf.append(parameterType(i).basicTypeChar());
 637         return buf.append('_').append(returnType().basicTypeChar()).toString();
 638     }
 639     static int signatureArity(String sig) {
 640         assert(isValidSignature(sig));
 641         return sig.indexOf('_');
 642     }
 643     static boolean isValidSignature(String sig) {
 644         int arity = sig.indexOf('_');
 645         if (arity < 0)  return false;  // must be of the form *_*
 646         int siglen = sig.length();
 647         if (siglen != arity + 2)  return false;  // *_X
 648         for (int i = 0; i < siglen; i++) {
 649             if (i == arity)  continue;  // skip '_'
 650             char c = sig.charAt(i);
 651             if (c == 'V')
 652                 return (i == siglen - 1 && arity == siglen - 2);
 653             if (!isArgBasicTypeChar(c))  return false; // must be [LIJFD]
 654         }
 655         return true;  // [LIJFD]*_[LIJFDV]
 656     }
 657 
 658     /**
 659      * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
 660      */
 661     boolean isSelectAlternative(int pos) {
 662         // selectAlternative idiom:
 663         //   t_{n}:L=MethodHandleImpl.selectAlternative(...)
 664         //   t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
 665         if (pos+1 >= names.length)  return false;
 666         Name name0 = names[pos];
 667         Name name1 = names[pos+1];
 668         return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
 669                 name1.isInvokeBasic() &&
 670                 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
 671                 lastUseIndex(name0) == pos+1;     // t_{n} is local: used only in t_{n+1}
 672     }
 673 
 674     private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
 675         if (pos+2 >= names.length)  return false;
 676         Name name0 = names[pos];
 677         Name name1 = names[pos+1];
 678         Name name2 = names[pos+2];
 679         return name1.refersTo(MethodHandleImpl.class, idiomName) &&
 680                 name0.isInvokeBasic() &&
 681                 name2.isInvokeBasic() &&
 682                 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
 683                 lastUseIndex(name0) == pos+1 &&       // t_{n} is local: used only in t_{n+1}
 684                 name2.lastUseIndex(name1) == 1 &&     // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 685                 lastUseIndex(name1) == pos+2;         // t_{n+1} is local: used only in t_{n+2}
 686     }
 687 
 688     /**
 689      * Check if i-th name is a start of GuardWithCatch idiom.
 690      */
 691     boolean isGuardWithCatch(int pos) {
 692         // GuardWithCatch idiom:
 693         //   t_{n}:L=MethodHandle.invokeBasic(...)
 694         //   t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
 695         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 696         return isMatchingIdiom(pos, "guardWithCatch", 3);
 697     }
 698 
 699     /**
 700      * Check if i-th name is a start of the tryFinally idiom.
 701      */
 702     boolean isTryFinally(int pos) {
 703         // tryFinally idiom:
 704         //   t_{n}:L=MethodHandle.invokeBasic(...)
 705         //   t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
 706         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 707         return isMatchingIdiom(pos, "tryFinally", 2);
 708     }
 709 
 710     /**
 711      * Check if i-th name is a start of the tableSwitch idiom.
 712      */
 713     boolean isTableSwitch(int pos) {
 714         // tableSwitch idiom:
 715         //   t_{n}:L=MethodHandle.invokeBasic(...)     // args
 716         //   t_{n+1}:L=MethodHandleImpl.tableSwitch(*, *, *, t_{n})
 717         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 718         if (pos + 2 >= names.length)  return false;
 719 
 720         final int POS_COLLECT_ARGS = pos;
 721         final int POS_TABLE_SWITCH = pos + 1;
 722         final int POS_UNBOX_RESULT = pos + 2;
 723 
 724         Name collectArgs = names[POS_COLLECT_ARGS];
 725         Name tableSwitch = names[POS_TABLE_SWITCH];
 726         Name unboxResult = names[POS_UNBOX_RESULT];
 727         return tableSwitch.refersTo(MethodHandleImpl.class, "tableSwitch") &&
 728                 collectArgs.isInvokeBasic() &&
 729                 unboxResult.isInvokeBasic() &&
 730                 tableSwitch.lastUseIndex(collectArgs) == 3 &&     // t_{n+1}:L=MethodHandleImpl.<invoker>(*, *, *, t_{n});
 731                 lastUseIndex(collectArgs) == POS_TABLE_SWITCH &&  // t_{n} is local: used only in t_{n+1}
 732                 unboxResult.lastUseIndex(tableSwitch) == 1 &&     // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 733                 lastUseIndex(tableSwitch) == POS_UNBOX_RESULT;    // t_{n+1} is local: used only in t_{n+2}
 734     }
 735 
 736     /**
 737      * Check if i-th name is a start of the loop idiom.
 738      */
 739     boolean isLoop(int pos) {
 740         // loop idiom:
 741         //   t_{n}:L=MethodHandle.invokeBasic(...)
 742         //   t_{n+1}:L=MethodHandleImpl.loop(types, *, t_{n})
 743         //   t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
 744         return isMatchingIdiom(pos, "loop", 2);
 745     }
 746 
 747     /*
 748      * Code generation issues:
 749      *
 750      * Compiled LFs should be reusable in general.
 751      * The biggest issue is how to decide when to pull a name into
 752      * the bytecode, versus loading a reified form from the MH data.
 753      *
 754      * For example, an asType wrapper may require execution of a cast
 755      * after a call to a MH.  The target type of the cast can be placed
 756      * as a constant in the LF itself.  This will force the cast type
 757      * to be compiled into the bytecodes and native code for the MH.
 758      * Or, the target type of the cast can be erased in the LF, and
 759      * loaded from the MH data.  (Later on, if the MH as a whole is
 760      * inlined, the data will flow into the inlined instance of the LF,
 761      * as a constant, and the end result will be an optimal cast.)
 762      *
 763      * This erasure of cast types can be done with any use of
 764      * reference types.  It can also be done with whole method
 765      * handles.  Erasing a method handle might leave behind
 766      * LF code that executes correctly for any MH of a given
 767      * type, and load the required MH from the enclosing MH's data.
 768      * Or, the erasure might even erase the expected MT.
 769      *
 770      * Also, for direct MHs, the MemberName of the target
 771      * could be erased, and loaded from the containing direct MH.
 772      * As a simple case, a LF for all int-valued non-static
 773      * field getters would perform a cast on its input argument
 774      * (to non-constant base type derived from the MemberName)
 775      * and load an integer value from the input object
 776      * (at a non-constant offset also derived from the MemberName).
 777      * Such MN-erased LFs would be inlinable back to optimized
 778      * code, whenever a constant enclosing DMH is available
 779      * to supply a constant MN from its data.
 780      *
 781      * The main problem here is to keep LFs reasonably generic,
 782      * while ensuring that hot spots will inline good instances.
 783      * "Reasonably generic" means that we don't end up with
 784      * repeated versions of bytecode or machine code that do
 785      * not differ in their optimized form.  Repeated versions
 786      * of machine would have the undesirable overheads of
 787      * (a) redundant compilation work and (b) extra I$ pressure.
 788      * To control repeated versions, we need to be ready to
 789      * erase details from LFs and move them into MH data,
 790      * whenever those details are not relevant to significant
 791      * optimization.  "Significant" means optimization of
 792      * code that is actually hot.
 793      *
 794      * Achieving this may require dynamic splitting of MHs, by replacing
 795      * a generic LF with a more specialized one, on the same MH,
 796      * if (a) the MH is frequently executed and (b) the MH cannot
 797      * be inlined into a containing caller, such as an invokedynamic.
 798      *
 799      * Compiled LFs that are no longer used should be GC-able.
 800      * If they contain non-BCP references, they should be properly
 801      * interlinked with the class loader(s) that their embedded types
 802      * depend on.  This probably means that reusable compiled LFs
 803      * will be tabulated (indexed) on relevant class loaders,
 804      * or else that the tables that cache them will have weak links.
 805      */
 806 
 807     /**
 808      * Make this LF directly executable, as part of a MethodHandle.
 809      * Invariant:  Every MH which is invoked must prepare its LF
 810      * before invocation.
 811      * (In principle, the JVM could do this very lazily,
 812      * as a sort of pre-invocation linkage step.)
 813      */
 814     public void prepare() {
 815         if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
 816             compileToBytecode();
 817         }
 818         if (this.vmentry != null) {
 819             // already prepared (e.g., a primitive DMH invoker form)
 820             return;
 821         }
 822         MethodType mtype = methodType();
 823         LambdaForm prep = mtype.form().cachedLambdaForm(MethodTypeForm.LF_INTERPRET);
 824         if (prep == null) {
 825             assert (isValidSignature(basicTypeSignature()));
 826             prep = new LambdaForm(mtype);
 827             prep.vmentry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
 828             prep = mtype.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, prep);
 829         }
 830         this.vmentry = prep.vmentry;
 831         // TO DO: Maybe add invokeGeneric, invokeWithArguments
 832     }
 833 
 834     private static @Stable PerfCounter LF_FAILED;
 835 
 836     private static PerfCounter failedCompilationCounter() {
 837         if (LF_FAILED == null) {
 838             LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
 839         }
 840         return LF_FAILED;
 841     }
 842 
 843     /** Generate optimizable bytecode for this form. */
 844     void compileToBytecode() {
 845         if (forceInterpretation()) {
 846             return; // this should not be compiled
 847         }
 848         if (vmentry != null && isCompiled) {
 849             return;  // already compiled somehow
 850         }
 851 
 852         // Obtain the invoker MethodType outside of the following try block.
 853         // This ensures that an IllegalArgumentException is directly thrown if the
 854         // type would have 256 or more parameters
 855         MethodType invokerType = methodType();
 856         assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
 857         try {
 858             vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
 859             if (TRACE_INTERPRETER)
 860                 traceInterpreter("compileToBytecode", this);
 861             isCompiled = true;
 862         } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
 863             // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
 864             invocationCounter = -1;
 865             failedCompilationCounter().increment();
 866             if (LOG_LF_COMPILATION_FAILURE) {
 867                 System.out.println("LambdaForm compilation failed: " + this);
 868                 bge.printStackTrace(System.out);
 869             }
 870         } catch (Error e) {
 871             // Pass through any error
 872             throw e;
 873         } catch (Exception e) {
 874             // Wrap any exception
 875             throw newInternalError(this.toString(), e);
 876         }
 877     }
 878 
 879     // The next few routines are called only from assert expressions
 880     // They verify that the built-in invokers process the correct raw data types.
 881     private static boolean argumentTypesMatch(String sig, Object[] av) {
 882         int arity = signatureArity(sig);
 883         assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
 884         assert(av[0] instanceof MethodHandle) : "av[0] not instance of MethodHandle: " + av[0];
 885         MethodHandle mh = (MethodHandle) av[0];
 886         MethodType mt = mh.type();
 887         assert(mt.parameterCount() == arity-1);
 888         for (int i = 0; i < av.length; i++) {
 889             Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
 890             assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
 891         }
 892         return true;
 893     }
 894     private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
 895         // The following line is needed because (...)void method handles can use non-void invokers
 896         if (type == void.class)  tc = V_TYPE;   // can drop any kind of value
 897         assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
 898         switch (tc) {
 899         case I_TYPE: assert checkInt(type, x)   : "checkInt(" + type + "," + x +")";   break;
 900         case J_TYPE: assert x instanceof Long   : "instanceof Long: " + x;             break;
 901         case F_TYPE: assert x instanceof Float  : "instanceof Float: " + x;            break;
 902         case D_TYPE: assert x instanceof Double : "instanceof Double: " + x;           break;
 903         case L_TYPE: assert checkRef(type, x)   : "checkRef(" + type + "," + x + ")";  break;
 904         case V_TYPE: break;  // allow anything here; will be dropped
 905         default:  assert(false);
 906         }
 907         return true;
 908     }
 909     private static boolean checkInt(Class<?> type, Object x) {
 910         assert(x instanceof Integer);
 911         if (type == int.class)  return true;
 912         Wrapper w = Wrapper.forBasicType(type);
 913         assert(w.isSubwordOrInt());
 914         Object x1 = Wrapper.INT.wrap(w.wrap(x));
 915         return x.equals(x1);
 916     }
 917     private static boolean checkRef(Class<?> type, Object x) {
 918         assert(!type.isPrimitive());
 919         if (x == null)  return true;
 920         if (type.isInterface())  return true;
 921         return type.isInstance(x);
 922     }
 923 
 924     /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
 925     private static final int COMPILE_THRESHOLD;
 926     static {
 927         COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
 928     }
 929     private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
 930 
 931     private boolean forceInterpretation() {
 932         return invocationCounter == -1;
 933     }
 934 
 935     @Hidden
 936     @DontInline
 937     /** Interpretively invoke this form on the given arguments. */
 938     Object interpretWithArguments(Object... argumentValues) throws Throwable {
 939         if (TRACE_INTERPRETER)
 940             return interpretWithArgumentsTracing(argumentValues);
 941         checkInvocationCounter();
 942         assert(arityCheck(argumentValues));
 943         Object[] values = Arrays.copyOf(argumentValues, names.length);
 944         for (int i = argumentValues.length; i < values.length; i++) {
 945             values[i] = interpretName(names[i], values);
 946         }
 947         Object rv = (result < 0) ? null : values[result];
 948         assert(resultCheck(argumentValues, rv));
 949         return rv;
 950     }
 951 
 952     @Hidden
 953     @DontInline
 954     /** Evaluate a single Name within this form, applying its function to its arguments. */
 955     Object interpretName(Name name, Object[] values) throws Throwable {
 956         if (TRACE_INTERPRETER)
 957             traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
 958         Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
 959         for (int i = 0; i < arguments.length; i++) {
 960             Object a = arguments[i];
 961             if (a instanceof Name) {
 962                 int i2 = ((Name)a).index();
 963                 assert(names[i2] == a);
 964                 a = values[i2];
 965                 arguments[i] = a;
 966             }
 967         }
 968         return name.function.invokeWithArguments(arguments);
 969     }
 970 
 971     private void checkInvocationCounter() {
 972         if (COMPILE_THRESHOLD != 0 &&
 973             !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
 974             invocationCounter++;  // benign race
 975             if (invocationCounter >= COMPILE_THRESHOLD) {
 976                 // Replace vmentry with a bytecode version of this LF.
 977                 compileToBytecode();
 978             }
 979         }
 980     }
 981     Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
 982         traceInterpreter("[ interpretWithArguments", this, argumentValues);
 983         if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
 984             int ctr = invocationCounter++;  // benign race
 985             traceInterpreter("| invocationCounter", ctr);
 986             if (invocationCounter >= COMPILE_THRESHOLD) {
 987                 compileToBytecode();
 988             }
 989         }
 990         Object rval;
 991         try {
 992             assert(arityCheck(argumentValues));
 993             Object[] values = Arrays.copyOf(argumentValues, names.length);
 994             for (int i = argumentValues.length; i < values.length; i++) {
 995                 values[i] = interpretName(names[i], values);
 996             }
 997             rval = (result < 0) ? null : values[result];
 998         } catch (Throwable ex) {
 999             traceInterpreter("] throw =>", ex);
1000             throw ex;
1001         }
1002         traceInterpreter("] return =>", rval);
1003         return rval;
1004     }
1005 
1006     static void traceInterpreter(String event, Object obj, Object... args) {
1007         if (TRACE_INTERPRETER) {
1008             System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
1009         }
1010     }
1011     static void traceInterpreter(String event, Object obj) {
1012         traceInterpreter(event, obj, (Object[])null);
1013     }
1014     private boolean arityCheck(Object[] argumentValues) {
1015         assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
1016         // also check that the leading (receiver) argument is somehow bound to this LF:
1017         assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
1018         MethodHandle mh = (MethodHandle) argumentValues[0];
1019         assert(mh.internalForm() == this);
1020         // note:  argument #0 could also be an interface wrapper, in the future
1021         argumentTypesMatch(basicTypeSignature(), argumentValues);
1022         return true;
1023     }
1024     private boolean resultCheck(Object[] argumentValues, Object result) {
1025         MethodHandle mh = (MethodHandle) argumentValues[0];
1026         MethodType mt = mh.type();
1027         assert(valueMatches(returnType(), mt.returnType(), result));
1028         return true;
1029     }
1030 
1031     private boolean isEmpty() {
1032         if (result < 0)
1033             return (names.length == arity);
1034         else if (result == arity && names.length == arity + 1)
1035             return names[arity].isConstantZero();
1036         else
1037             return false;
1038     }
1039 
1040     public String toString() {
1041         String lambdaName = lambdaName();
1042         StringBuilder buf = new StringBuilder(lambdaName + "=Lambda(");
1043         for (int i = 0; i < names.length; i++) {
1044             if (i == arity)  buf.append(")=>{");
1045             Name n = names[i];
1046             if (i >= arity)  buf.append("\n    ");
1047             buf.append(n.paramString());
1048             if (i < arity) {
1049                 if (i+1 < arity)  buf.append(",");
1050                 continue;
1051             }
1052             buf.append("=").append(n.exprString());
1053             buf.append(";");
1054         }
1055         if (arity == names.length)  buf.append(")=>{");
1056         buf.append(result < 0 ? "void" : names[result]).append("}");
1057         if (TRACE_INTERPRETER) {
1058             // Extra verbosity:
1059             buf.append(":").append(basicTypeSignature());
1060             buf.append("/").append(vmentry);
1061         }
1062         return buf.toString();
1063     }
1064 
1065     @Override
1066     public boolean equals(Object obj) {
1067         return obj instanceof LambdaForm && equals((LambdaForm)obj);
1068     }
1069     public boolean equals(LambdaForm that) {
1070         if (this.result != that.result)  return false;
1071         return Arrays.equals(this.names, that.names);
1072     }
1073     public int hashCode() {
1074         return result + 31 * Arrays.hashCode(names);
1075     }
1076     LambdaFormEditor editor() {
1077         return LambdaFormEditor.lambdaFormEditor(this);
1078     }
1079 
1080     boolean contains(Name name) {
1081         int pos = name.index();
1082         if (pos >= 0) {
1083             return pos < names.length && name.equals(names[pos]);
1084         }
1085         for (int i = arity; i < names.length; i++) {
1086             if (name.equals(names[i]))
1087                 return true;
1088         }
1089         return false;
1090     }
1091 
1092     static class NamedFunction {
1093         final MemberName member;
1094         private @Stable MethodHandle resolvedHandle;
1095         @Stable MethodHandle invoker;
1096 
1097         NamedFunction(MethodHandle resolvedHandle) {
1098             this(resolvedHandle.internalMemberName(), resolvedHandle);
1099         }
1100         NamedFunction(MemberName member, MethodHandle resolvedHandle) {
1101             this.member = member;
1102             this.resolvedHandle = resolvedHandle;
1103              // The following assert is almost always correct, but will fail for corner cases, such as PrivateInvokeTest.
1104              //assert(!isInvokeBasic(member));
1105         }
1106         NamedFunction(MethodType basicInvokerType) {
1107             assert(basicInvokerType == basicInvokerType.basicType()) : basicInvokerType;
1108             if (basicInvokerType.parameterSlotCount() < MethodType.MAX_MH_INVOKER_ARITY) {
1109                 this.resolvedHandle = basicInvokerType.invokers().basicInvoker();
1110                 this.member = resolvedHandle.internalMemberName();
1111             } else {
1112                 // necessary to pass BigArityTest
1113                 this.member = Invokers.invokeBasicMethod(basicInvokerType);
1114             }
1115             assert(isInvokeBasic(member));
1116         }
1117 
1118         private static boolean isInvokeBasic(MemberName member) {
1119             return member != null &&
1120                    member.getDeclaringClass() == MethodHandle.class &&
1121                   "invokeBasic".equals(member.getName());
1122         }
1123 
1124         // The next 2 constructors are used to break circular dependencies on MH.invokeStatic, etc.
1125         // Any LambdaForm containing such a member is not interpretable.
1126         // This is OK, since all such LFs are prepared with special primitive vmentry points.
1127         // And even without the resolvedHandle, the name can still be compiled and optimized.
1128         NamedFunction(Method method) {
1129             this(new MemberName(method));
1130         }
1131         NamedFunction(MemberName member) {
1132             this(member, null);
1133         }
1134 
1135         MethodHandle resolvedHandle() {
1136             if (resolvedHandle == null)  resolve();
1137             return resolvedHandle;
1138         }
1139 
1140         synchronized void resolve() {
1141             if (resolvedHandle == null) {
1142                 resolvedHandle = DirectMethodHandle.make(member);
1143             }
1144         }
1145 
1146         @Override
1147         public boolean equals(Object other) {
1148             if (this == other) return true;
1149             if (other == null) return false;
1150             return (other instanceof NamedFunction that)
1151                     && this.member != null
1152                     && this.member.equals(that.member);
1153         }
1154 
1155         @Override
1156         public int hashCode() {
1157             if (member != null)
1158                 return member.hashCode();
1159             return super.hashCode();
1160         }
1161 
1162         static final MethodType INVOKER_METHOD_TYPE =
1163             MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1164 
1165         private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1166             typeForm = typeForm.basicType().form();  // normalize to basic type
1167             MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1168             if (mh != null)  return mh;
1169             MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm);  // this could take a while
1170             mh = DirectMethodHandle.make(invoker);
1171             MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1172             if (mh2 != null)  return mh2;  // benign race
1173             if (!mh.type().equals(INVOKER_METHOD_TYPE))
1174                 throw newInternalError(mh.debugString());
1175             return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1176         }
1177 
1178         @Hidden
1179         Object invokeWithArguments(Object... arguments) throws Throwable {
1180             // If we have a cached invoker, call it right away.
1181             // NOTE: The invoker always returns a reference value.
1182             if (TRACE_INTERPRETER)  return invokeWithArgumentsTracing(arguments);
1183             return invoker().invokeBasic(resolvedHandle(), arguments);
1184         }
1185 
1186         @Hidden
1187         Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1188             Object rval;
1189             try {
1190                 traceInterpreter("[ call", this, arguments);
1191                 if (invoker == null) {
1192                     traceInterpreter("| getInvoker", this);
1193                     invoker();
1194                 }
1195                 // resolvedHandle might be uninitialized, ok for tracing
1196                 if (resolvedHandle == null) {
1197                     traceInterpreter("| resolve", this);
1198                     resolvedHandle();
1199                 }
1200                 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1201             } catch (Throwable ex) {
1202                 traceInterpreter("] throw =>", ex);
1203                 throw ex;
1204             }
1205             traceInterpreter("] return =>", rval);
1206             return rval;
1207         }
1208 
1209         private MethodHandle invoker() {
1210             if (invoker != null)  return invoker;
1211             // Get an invoker and cache it.
1212             return invoker = computeInvoker(methodType().form());
1213         }
1214 
1215         MethodType methodType() {
1216             if (resolvedHandle != null)
1217                 return resolvedHandle.type();
1218             else
1219                 // only for certain internal LFs during bootstrapping
1220                 return member.getInvocationType();
1221         }
1222 
1223         MemberName member() {
1224             assert(assertMemberIsConsistent());
1225             return member;
1226         }
1227 
1228         // Called only from assert.
1229         private boolean assertMemberIsConsistent() {
1230             if (resolvedHandle instanceof DirectMethodHandle) {
1231                 MemberName m = resolvedHandle.internalMemberName();
1232                 assert(m.equals(member));
1233             }
1234             return true;
1235         }
1236 
1237         Class<?> memberDeclaringClassOrNull() {
1238             return (member == null) ? null : member.getDeclaringClass();
1239         }
1240 
1241         BasicType returnType() {
1242             return basicType(methodType().returnType());
1243         }
1244 
1245         BasicType parameterType(int n) {
1246             return basicType(methodType().parameterType(n));
1247         }
1248 
1249         int arity() {
1250             return methodType().parameterCount();
1251         }
1252 
1253         public String toString() {
1254             if (member == null)  return String.valueOf(resolvedHandle);
1255             return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1256         }
1257 
1258         public boolean isIdentity() {
1259             return this.equals(identity(returnType()));
1260         }
1261 
1262         public boolean isConstantZero() {
1263             return this.equals(constantZero(returnType()));
1264         }
1265 
1266         public MethodHandleImpl.Intrinsic intrinsicName() {
1267             return resolvedHandle != null
1268                 ? resolvedHandle.intrinsicName()
1269                 : MethodHandleImpl.Intrinsic.NONE;
1270         }
1271 
1272         public Object intrinsicData() {
1273             return resolvedHandle != null
1274                 ? resolvedHandle.intrinsicData()
1275                 : null;
1276         }
1277     }
1278 
1279     public static String basicTypeSignature(MethodType type) {
1280         int params = type.parameterCount();
1281         char[] sig = new char[params + 2];
1282         int sigp = 0;
1283         while (sigp < params) {
1284             sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1285         }
1286         sig[sigp++] = '_';
1287         sig[sigp++] = basicTypeChar(type.returnType());
1288         assert(sigp == sig.length);
1289         return String.valueOf(sig);
1290     }
1291 
1292     /** Hack to make signatures more readable when they show up in method names.
1293      * Signature should start with a sequence of uppercase ASCII letters.
1294      * Runs of three or more are replaced by a single letter plus a decimal repeat count.
1295      * A tail of anything other than uppercase ASCII is passed through unchanged.
1296      * @param signature sequence of uppercase ASCII letters with possible repetitions
1297      * @return same sequence, with repetitions counted by decimal numerals
1298      */
1299     public static String shortenSignature(String signature) {
1300         final int NO_CHAR = -1, MIN_RUN = 3;
1301         int c0, c1 = NO_CHAR, c1reps = 0;
1302         StringBuilder buf = null;
1303         int len = signature.length();
1304         if (len < MIN_RUN)  return signature;
1305         for (int i = 0; i <= len; i++) {
1306             if (c1 != NO_CHAR && !('A' <= c1 && c1 <= 'Z')) {
1307                 // wrong kind of char; bail out here
1308                 if (buf != null) {
1309                     buf.append(signature, i - c1reps, len);
1310                 }
1311                 break;
1312             }
1313             // shift in the next char:
1314             c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1315             if (c1 == c0) { ++c1reps; continue; }
1316             // shift in the next count:
1317             int c0reps = c1reps; c1reps = 1;
1318             // end of a  character run
1319             if (c0reps < MIN_RUN) {
1320                 if (buf != null) {
1321                     while (--c0reps >= 0)
1322                         buf.append((char)c0);
1323                 }
1324                 continue;
1325             }
1326             // found three or more in a row
1327             if (buf == null)
1328                 buf = new StringBuilder().append(signature, 0, i - c0reps);
1329             buf.append((char)c0).append(c0reps);
1330         }
1331         return (buf == null) ? signature : buf.toString();
1332     }
1333 
1334     static final class Name {
1335         final BasicType type;
1336         @Stable short index;
1337         final NamedFunction function;
1338         final Object constraint;  // additional type information, if not null
1339         @Stable final Object[] arguments;
1340 
1341         private Name(int index, BasicType type, NamedFunction function, Object[] arguments) {
1342             this.index = (short)index;
1343             this.type = type;
1344             this.function = function;
1345             this.arguments = arguments;
1346             this.constraint = null;
1347             assert(this.index == index);
1348         }
1349         private Name(Name that, Object constraint) {
1350             this.index = that.index;
1351             this.type = that.type;
1352             this.function = that.function;
1353             this.arguments = that.arguments;
1354             this.constraint = constraint;
1355             assert(constraint == null || isParam());  // only params have constraints
1356             assert(constraint == null || constraint instanceof ClassSpecializer.SpeciesData || constraint instanceof Class);
1357         }
1358         Name(MethodHandle function, Object... arguments) {
1359             this(new NamedFunction(function), arguments);
1360         }
1361         Name(MethodType functionType, Object... arguments) {
1362             this(new NamedFunction(functionType), arguments);
1363             assert(arguments[0] instanceof Name && ((Name)arguments[0]).type == L_TYPE);
1364         }
1365         Name(MemberName function, Object... arguments) {
1366             this(new NamedFunction(function), arguments);
1367         }
1368         Name(NamedFunction function, Object... arguments) {
1369             this(-1, function.returnType(), function, arguments = Arrays.copyOf(arguments, arguments.length, Object[].class));
1370             assert(typesMatch(function, arguments));
1371         }
1372         /** Create a raw parameter of the given type, with an expected index. */
1373         Name(int index, BasicType type) {
1374             this(index, type, null, null);
1375         }
1376         /** Create a raw parameter of the given type. */
1377         Name(BasicType type) { this(-1, type); }
1378 
1379         BasicType type() { return type; }
1380         int index() { return index; }
1381         boolean initIndex(int i) {
1382             if (index != i) {
1383                 if (index != -1)  return false;
1384                 index = (short)i;
1385             }
1386             return true;
1387         }
1388         char typeChar() {
1389             return type.btChar;
1390         }
1391 
1392         Name newIndex(int i) {
1393             if (initIndex(i))  return this;
1394             return cloneWithIndex(i);
1395         }
1396         Name cloneWithIndex(int i) {
1397             Object[] newArguments = (arguments == null) ? null : arguments.clone();
1398             return new Name(i, type, function, newArguments).withConstraint(constraint);
1399         }
1400         Name withConstraint(Object constraint) {
1401             if (constraint == this.constraint)  return this;
1402             return new Name(this, constraint);
1403         }
1404         Name replaceName(Name oldName, Name newName) {  // FIXME: use replaceNames uniformly
1405             if (oldName == newName)  return this;
1406             @SuppressWarnings("LocalVariableHidesMemberVariable")
1407             Object[] arguments = this.arguments;
1408             if (arguments == null)  return this;
1409             boolean replaced = false;
1410             for (int j = 0; j < arguments.length; j++) {
1411                 if (arguments[j] == oldName) {
1412                     if (!replaced) {
1413                         replaced = true;
1414                         arguments = arguments.clone();
1415                     }
1416                     arguments[j] = newName;
1417                 }
1418             }
1419             if (!replaced)  return this;
1420             return new Name(function, arguments);
1421         }
1422         /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1423          *  Limit such replacements to {@code start<=i<end}.  Return possibly changed self.
1424          */
1425         Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1426             if (start >= end)  return this;
1427             @SuppressWarnings("LocalVariableHidesMemberVariable")
1428             Object[] arguments = this.arguments;
1429             boolean replaced = false;
1430         eachArg:
1431             for (int j = 0; j < arguments.length; j++) {
1432                 if (arguments[j] instanceof Name n) {
1433                     int check = n.index;
1434                     // harmless check to see if the thing is already in newNames:
1435                     if (check >= 0 && check < newNames.length && n == newNames[check])
1436                         continue eachArg;
1437                     // n might not have the correct index: n != oldNames[n.index].
1438                     for (int i = start; i < end; i++) {
1439                         if (n == oldNames[i]) {
1440                             if (n == newNames[i])
1441                                 continue eachArg;
1442                             if (!replaced) {
1443                                 replaced = true;
1444                                 arguments = arguments.clone();
1445                             }
1446                             arguments[j] = newNames[i];
1447                             continue eachArg;
1448                         }
1449                     }
1450                 }
1451             }
1452             if (!replaced)  return this;
1453             return new Name(function, arguments);
1454         }
1455         void internArguments() {
1456             @SuppressWarnings("LocalVariableHidesMemberVariable")
1457             Object[] arguments = this.arguments;
1458             for (int j = 0; j < arguments.length; j++) {
1459                 if (arguments[j] instanceof Name n) {
1460                     if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1461                         arguments[j] = internArgument(n);
1462                 }
1463             }
1464         }
1465         boolean isParam() {
1466             return function == null;
1467         }
1468         boolean isConstantZero() {
1469             return !isParam() && arguments.length == 0 && function.isConstantZero();
1470         }
1471 
1472         boolean refersTo(Class<?> declaringClass, String methodName) {
1473             return function != null &&
1474                     function.member() != null && function.member().refersTo(declaringClass, methodName);
1475         }
1476 
1477         /**
1478          * Check if MemberName is a call to MethodHandle.invokeBasic.
1479          */
1480         boolean isInvokeBasic() {
1481             if (function == null)
1482                 return false;
1483             if (arguments.length < 1)
1484                 return false;  // must have MH argument
1485             MemberName member = function.member();
1486             return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1487                     !member.isPublic() && !member.isStatic();
1488         }
1489 
1490         /**
1491          * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1492          */
1493         boolean isLinkerMethodInvoke() {
1494             if (function == null)
1495                 return false;
1496             if (arguments.length < 1)
1497                 return false;  // must have MH argument
1498             MemberName member = function.member();
1499             return member != null &&
1500                     member.getDeclaringClass() == MethodHandle.class &&
1501                     !member.isPublic() && member.isStatic() &&
1502                     member.getName().startsWith("linkTo");
1503         }
1504 
1505         public String toString() {
1506             return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1507         }
1508         public String debugString() {
1509             String s = paramString();
1510             return (function == null) ? s : s + "=" + exprString();
1511         }
1512         public String paramString() {
1513             String s = toString();
1514             Object c = constraint;
1515             if (c == null)
1516                 return s;
1517             if (c instanceof Class)  c = ((Class<?>)c).getSimpleName();
1518             return s + "/" + c;
1519         }
1520         public String exprString() {
1521             if (function == null)  return toString();
1522             StringBuilder buf = new StringBuilder(function.toString());
1523             buf.append("(");
1524             String cma = "";
1525             for (Object a : arguments) {
1526                 buf.append(cma); cma = ",";
1527                 if (a instanceof Name || a instanceof Integer)
1528                     buf.append(a);
1529                 else
1530                     buf.append("(").append(a).append(")");
1531             }
1532             buf.append(")");
1533             return buf.toString();
1534         }
1535 
1536         private boolean typesMatch(NamedFunction function, Object ... arguments) {
1537             assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1538             for (int i = 0; i < arguments.length; i++) {
1539                 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1540             }
1541             return true;
1542         }
1543 
1544         private static boolean typesMatch(BasicType parameterType, Object object) {
1545             if (object instanceof Name) {
1546                 return ((Name)object).type == parameterType;
1547             }
1548             switch (parameterType) {
1549                 case I_TYPE:  return object instanceof Integer;
1550                 case J_TYPE:  return object instanceof Long;
1551                 case F_TYPE:  return object instanceof Float;
1552                 case D_TYPE:  return object instanceof Double;
1553             }
1554             assert(parameterType == L_TYPE);
1555             return true;
1556         }
1557 
1558         /** Return the index of the last occurrence of n in the argument array.
1559          *  Return -1 if the name is not used.
1560          */
1561         int lastUseIndex(Name n) {
1562             if (arguments == null)  return -1;
1563             for (int i = arguments.length; --i >= 0; ) {
1564                 if (arguments[i] == n)  return i;
1565             }
1566             return -1;
1567         }
1568 
1569         /** Return the number of occurrences of n in the argument array.
1570          *  Return 0 if the name is not used.
1571          */
1572         int useCount(Name n) {
1573             int count = 0;
1574             if (arguments != null) {
1575                 for (Object argument : arguments) {
1576                     if (argument == n) {
1577                         count++;
1578                     }
1579                 }
1580             }
1581             return count;
1582         }
1583 
1584         public boolean equals(Name that) {
1585             if (this == that)  return true;
1586             if (isParam())
1587                 // each parameter is a unique atom
1588                 return false;  // this != that
1589             return
1590                 //this.index == that.index &&
1591                 this.type == that.type &&
1592                 this.function.equals(that.function) &&
1593                 Arrays.equals(this.arguments, that.arguments);
1594         }
1595         @Override
1596         public boolean equals(Object x) {
1597             return x instanceof Name && equals((Name)x);
1598         }
1599         @Override
1600         public int hashCode() {
1601             if (isParam())
1602                 return index | (type.ordinal() << 8);
1603             return function.hashCode() ^ Arrays.hashCode(arguments);
1604         }
1605     }
1606 
1607     /** Return the index of the last name which contains n as an argument.
1608      *  Return -1 if the name is not used.  Return names.length if it is the return value.
1609      */
1610     int lastUseIndex(Name n) {
1611         int ni = n.index, nmax = names.length;
1612         assert(names[ni] == n);
1613         if (result == ni)  return nmax;  // live all the way beyond the end
1614         for (int i = nmax; --i > ni; ) {
1615             if (names[i].lastUseIndex(n) >= 0)
1616                 return i;
1617         }
1618         return -1;
1619     }
1620 
1621     /** Return the number of times n is used as an argument or return value. */
1622     int useCount(Name n) {
1623         int count = (result == n.index) ? 1 : 0;
1624         int i = Math.max(n.index + 1, arity);
1625         while (i < names.length) {
1626             count += names[i++].useCount(n);
1627         }
1628         return count;
1629     }
1630 
1631     static Name argument(int which, BasicType type) {
1632         if (which >= INTERNED_ARGUMENT_LIMIT)
1633             return new Name(which, type);
1634         return INTERNED_ARGUMENTS[type.ordinal()][which];
1635     }
1636     static Name internArgument(Name n) {
1637         assert(n.isParam()) : "not param: " + n;
1638         assert(n.index < INTERNED_ARGUMENT_LIMIT);
1639         if (n.constraint != null)  return n;
1640         return argument(n.index, n.type);
1641     }
1642     static Name[] arguments(int extra, MethodType types) {
1643         int length = types.parameterCount();
1644         Name[] names = new Name[length + extra];
1645         for (int i = 0; i < length; i++)
1646             names[i] = argument(i, basicType(types.parameterType(i)));
1647         return names;
1648     }
1649     static final int INTERNED_ARGUMENT_LIMIT = 10;
1650     private static final Name[][] INTERNED_ARGUMENTS
1651             = new Name[ARG_TYPE_LIMIT][INTERNED_ARGUMENT_LIMIT];
1652     static {
1653         for (BasicType type : BasicType.ARG_TYPES) {
1654             int ord = type.ordinal();
1655             for (int i = 0; i < INTERNED_ARGUMENTS[ord].length; i++) {
1656                 INTERNED_ARGUMENTS[ord][i] = new Name(i, type);
1657             }
1658         }
1659     }
1660 
1661     private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
1662 
1663     static LambdaForm identityForm(BasicType type) {
1664         int ord = type.ordinal();
1665         LambdaForm form = LF_identity[ord];
1666         if (form != null) {
1667             return form;
1668         }
1669         createFormsFor(type);
1670         return LF_identity[ord];
1671     }
1672 
1673     static LambdaForm zeroForm(BasicType type) {
1674         int ord = type.ordinal();
1675         LambdaForm form = LF_zero[ord];
1676         if (form != null) {
1677             return form;
1678         }
1679         createFormsFor(type);
1680         return LF_zero[ord];
1681     }
1682 
1683     static NamedFunction identity(BasicType type) {
1684         int ord = type.ordinal();
1685         NamedFunction function = NF_identity[ord];
1686         if (function != null) {
1687             return function;
1688         }
1689         createFormsFor(type);
1690         return NF_identity[ord];
1691     }
1692 
1693     static NamedFunction constantZero(BasicType type) {
1694         int ord = type.ordinal();
1695         NamedFunction function = NF_zero[ord];
1696         if (function != null) {
1697             return function;
1698         }
1699         createFormsFor(type);
1700         return NF_zero[ord];
1701     }
1702 
1703     private static final @Stable LambdaForm[] LF_identity = new LambdaForm[TYPE_LIMIT];
1704     private static final @Stable LambdaForm[] LF_zero = new LambdaForm[TYPE_LIMIT];
1705     private static final @Stable NamedFunction[] NF_identity = new NamedFunction[TYPE_LIMIT];
1706     private static final @Stable NamedFunction[] NF_zero = new NamedFunction[TYPE_LIMIT];
1707 
1708     private static final Object createFormsLock = new Object();
1709     private static void createFormsFor(BasicType type) {
1710         // Avoid racy initialization during bootstrap
1711         UNSAFE.ensureClassInitialized(BoundMethodHandle.class);
1712         synchronized (createFormsLock) {
1713             final int ord = type.ordinal();
1714             LambdaForm idForm = LF_identity[ord];
1715             if (idForm != null) {
1716                 return;
1717             }
1718             char btChar = type.basicTypeChar();
1719             boolean isVoid = (type == V_TYPE);
1720             Class<?> btClass = type.btClass;
1721             MethodType zeType = MethodType.methodType(btClass);
1722             MethodType idType = (isVoid) ? zeType : MethodType.methodType(btClass, btClass);
1723 
1724             // Look up symbolic names.  It might not be necessary to have these,
1725             // but if we need to emit direct references to bytecodes, it helps.
1726             // Zero is built from a call to an identity function with a constant zero input.
1727             MemberName idMem = new MemberName(LambdaForm.class, "identity_"+btChar, idType, REF_invokeStatic);
1728             MemberName zeMem = null;
1729             try {
1730                 idMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, idMem, null, LM_TRUSTED, NoSuchMethodException.class);
1731                 if (!isVoid) {
1732                     zeMem = new MemberName(LambdaForm.class, "zero_"+btChar, zeType, REF_invokeStatic);
1733                     zeMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, zeMem, null, LM_TRUSTED, NoSuchMethodException.class);
1734                 }
1735             } catch (IllegalAccessException|NoSuchMethodException ex) {
1736                 throw newInternalError(ex);
1737             }
1738 
1739             NamedFunction idFun;
1740             LambdaForm zeForm;
1741             NamedFunction zeFun;
1742 
1743             // Create the LFs and NamedFunctions. Precompiling LFs to byte code is needed to break circular
1744             // bootstrap dependency on this method in case we're interpreting LFs
1745             if (isVoid) {
1746                 Name[] idNames = new Name[] { argument(0, L_TYPE) };
1747                 idForm = new LambdaForm(1, idNames, VOID_RESULT, Kind.IDENTITY);
1748                 idForm.compileToBytecode();
1749                 idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1750 
1751                 zeForm = idForm;
1752                 zeFun = idFun;
1753             } else {
1754                 Name[] idNames = new Name[] { argument(0, L_TYPE), argument(1, type) };
1755                 idForm = new LambdaForm(2, idNames, 1, Kind.IDENTITY);
1756                 idForm.compileToBytecode();
1757                 idFun = new NamedFunction(idMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(idMem.getInvocationType(), idForm),
1758                             MethodHandleImpl.Intrinsic.IDENTITY));
1759 
1760                 Object zeValue = Wrapper.forBasicType(btChar).zero();
1761                 Name[] zeNames = new Name[] { argument(0, L_TYPE), new Name(idFun, zeValue) };
1762                 zeForm = new LambdaForm(1, zeNames, 1, Kind.ZERO);
1763                 zeForm.compileToBytecode();
1764                 zeFun = new NamedFunction(zeMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(zeMem.getInvocationType(), zeForm),
1765                         MethodHandleImpl.Intrinsic.ZERO));
1766             }
1767 
1768             LF_zero[ord] = zeForm;
1769             NF_zero[ord] = zeFun;
1770             LF_identity[ord] = idForm;
1771             NF_identity[ord] = idFun;
1772 
1773             assert(idFun.isIdentity());
1774             assert(zeFun.isConstantZero());
1775             assert(new Name(zeFun).isConstantZero());
1776         }
1777     }
1778 
1779     // Avoid appealing to ValueConversions at bootstrap time:
1780     private static int identity_I(int x) { return x; }
1781     private static long identity_J(long x) { return x; }
1782     private static float identity_F(float x) { return x; }
1783     private static double identity_D(double x) { return x; }
1784     private static Object identity_L(Object x) { return x; }
1785     private static void identity_V() { return; }
1786     private static int zero_I() { return 0; }
1787     private static long zero_J() { return 0; }
1788     private static float zero_F() { return 0; }
1789     private static double zero_D() { return 0; }
1790     private static Object zero_L() { return null; }
1791 
1792     /**
1793      * Internal marker for byte-compiled LambdaForms.
1794      */
1795     /*non-public*/
1796     @Target(ElementType.METHOD)
1797     @Retention(RetentionPolicy.RUNTIME)
1798     @interface Compiled {
1799     }
1800 
1801     private static final HashMap<String,Integer> DEBUG_NAME_COUNTERS;
1802     private static final HashMap<LambdaForm,String> DEBUG_NAMES;
1803     static {
1804         if (debugEnabled()) {
1805             DEBUG_NAME_COUNTERS = new HashMap<>();
1806             DEBUG_NAMES = new HashMap<>();
1807         } else {
1808             DEBUG_NAME_COUNTERS = null;
1809             DEBUG_NAMES = null;
1810         }
1811     }
1812 
1813     static {
1814         // The Holder class will contain pre-generated forms resolved
1815         // using MemberName.getFactory(). However, that doesn't initialize the
1816         // class, which subtly breaks inlining etc. By forcing
1817         // initialization of the Holder class we avoid these issues.
1818         UNSAFE.ensureClassInitialized(Holder.class);
1819     }
1820 
1821     /* Placeholder class for zero and identity forms generated ahead of time */
1822     final class Holder {}
1823 
1824     // The following hack is necessary in order to suppress TRACE_INTERPRETER
1825     // during execution of the static initializes of this class.
1826     // Turning on TRACE_INTERPRETER too early will cause
1827     // stack overflows and other misbehavior during attempts to trace events
1828     // that occur during LambdaForm.<clinit>.
1829     // Therefore, do not move this line higher in this file, and do not remove.
1830     private static final boolean TRACE_INTERPRETER = MethodHandleStatics.TRACE_INTERPRETER;
1831 }