1 /*
2 * Copyright (c) 2011, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import java.lang.classfile.TypeKind;
29 import jdk.internal.perf.PerfCounter;
30 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
31 import jdk.internal.vm.annotation.DontInline;
32 import jdk.internal.vm.annotation.Hidden;
33 import jdk.internal.vm.annotation.Stable;
34 import sun.invoke.util.Wrapper;
35
36 import java.lang.annotation.ElementType;
37 import java.lang.annotation.Retention;
38 import java.lang.annotation.RetentionPolicy;
39 import java.lang.annotation.Target;
40 import java.lang.reflect.Method;
41 import java.util.Arrays;
42 import java.util.HashMap;
43
44 import static java.lang.invoke.LambdaForm.BasicType.*;
45 import static java.lang.invoke.MethodHandleNatives.Constants.*;
46 import static java.lang.invoke.MethodHandleStatics.*;
47
48 /**
49 * The symbolic, non-executable form of a method handle's invocation semantics.
50 * It consists of a series of names.
51 * The first N (N=arity) names are parameters,
52 * while any remaining names are temporary values.
53 * Each temporary specifies the application of a function to some arguments.
54 * The functions are method handles, while the arguments are mixes of
55 * constant values and local names.
56 * The result of the lambda is defined as one of the names, often the last one.
57 * <p>
58 * Here is an approximate grammar:
59 * <blockquote><pre>{@code
60 * LambdaForm = "(" ArgName* ")=>{" TempName* Result "}"
61 * ArgName = "a" N ":" T
62 * TempName = "t" N ":" T "=" Function "(" Argument* ");"
63 * Function = ConstantValue
64 * Argument = NameRef | ConstantValue
65 * Result = NameRef | "void"
66 * NameRef = "a" N | "t" N
67 * N = (any whole number)
68 * T = "L" | "I" | "J" | "F" | "D" | "V"
69 * }</pre></blockquote>
70 * Names are numbered consecutively from left to right starting at zero.
71 * (The letters are merely a taste of syntax sugar.)
72 * Thus, the first temporary (if any) is always numbered N (where N=arity).
73 * Every occurrence of a name reference in an argument list must refer to
74 * a name previously defined within the same lambda.
75 * A lambda has a void result if and only if its result index is -1.
76 * If a temporary has the type "V", it cannot be the subject of a NameRef,
77 * even though possesses a number.
78 * Note that all reference types are erased to "L", which stands for {@code Object}.
79 * All subword types (boolean, byte, short, char) are erased to "I" which is {@code int}.
80 * The other types stand for the usual primitive types.
81 * <p>
82 * Function invocation closely follows the static rules of the Java verifier.
83 * Arguments and return values must exactly match when their "Name" types are
84 * considered.
85 * Conversions are allowed only if they do not change the erased type.
86 * <ul>
87 * <li>L = Object: casts are used freely to convert into and out of reference types
88 * <li>I = int: subword types are forcibly narrowed when passed as arguments (see {@code explicitCastArguments})
89 * <li>J = long: no implicit conversions
90 * <li>F = float: no implicit conversions
91 * <li>D = double: no implicit conversions
92 * <li>V = void: a function result may be void if and only if its Name is of type "V"
93 * </ul>
94 * Although implicit conversions are not allowed, explicit ones can easily be
95 * encoded by using temporary expressions which call type-transformed identity functions.
96 * <p>
97 * Examples:
98 * <blockquote><pre>{@code
99 * (a0:J)=>{ a0 }
100 * == identity(long)
101 * (a0:I)=>{ t1:V = System.out#println(a0); void }
102 * == System.out#println(int)
103 * (a0:L)=>{ t1:V = System.out#println(a0); a0 }
104 * == identity, with printing side-effect
105 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
106 * t3:L = BoundMethodHandle#target(a0);
107 * t4:L = MethodHandle#invoke(t3, t2, a1); t4 }
108 * == general invoker for unary insertArgument combination
109 * (a0:L, a1:L)=>{ t2:L = FilterMethodHandle#filter(a0);
110 * t3:L = MethodHandle#invoke(t2, a1);
111 * t4:L = FilterMethodHandle#target(a0);
112 * t5:L = MethodHandle#invoke(t4, t3); t5 }
113 * == general invoker for unary filterArgument combination
114 * (a0:L, a1:L)=>{ ...(same as previous example)...
115 * t5:L = MethodHandle#invoke(t4, t3, a1); t5 }
116 * == general invoker for unary/unary foldArgument combination
117 * (a0:L, a1:I)=>{ t2:I = identity(long).asType((int)->long)(a1); t2 }
118 * == invoker for identity method handle which performs i2l
119 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
120 * t3:L = Class#cast(t2,a1); t3 }
121 * == invoker for identity method handle which performs cast
122 * }</pre></blockquote>
123 * <p>
124 * @author John Rose, JSR 292 EG
125 */
126 @AOTSafeClassInitializer
127 class LambdaForm {
128 final int arity;
129 final int result;
130 final boolean forceInline;
131 final MethodHandle customized;
132 @Stable final Name[] names;
133 final Kind kind;
134 MemberName vmentry; // low-level behavior, or null if not yet prepared
135 private boolean isCompiled;
136
137 // Either a LambdaForm cache (managed by LambdaFormEditor) or a link to uncustomized version (for customized LF)
138 volatile Object transformCache;
139
140 public static final int VOID_RESULT = -1, LAST_RESULT = -2;
141
142 enum BasicType {
143 L_TYPE('L', Object.class, Wrapper.OBJECT, TypeKind.REFERENCE), // all reference types
144 I_TYPE('I', int.class, Wrapper.INT, TypeKind.INT),
145 J_TYPE('J', long.class, Wrapper.LONG, TypeKind.LONG),
146 F_TYPE('F', float.class, Wrapper.FLOAT, TypeKind.FLOAT),
147 D_TYPE('D', double.class, Wrapper.DOUBLE, TypeKind.DOUBLE), // all primitive types
148 V_TYPE('V', void.class, Wrapper.VOID, TypeKind.VOID); // not valid in all contexts
149
150 static final @Stable BasicType[] ALL_TYPES = BasicType.values();
151 static final @Stable BasicType[] ARG_TYPES = Arrays.copyOf(ALL_TYPES, ALL_TYPES.length-1);
152
153 static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
154 static final int TYPE_LIMIT = ALL_TYPES.length;
155
156 final char btChar;
157 final Class<?> btClass;
158 final Wrapper btWrapper;
159 final TypeKind btKind;
160
161 private BasicType(char btChar, Class<?> btClass, Wrapper wrapper, TypeKind typeKind) {
162 this.btChar = btChar;
163 this.btClass = btClass;
164 this.btWrapper = wrapper;
165 this.btKind = typeKind;
166 }
167
168 char basicTypeChar() {
169 return btChar;
170 }
171 Class<?> basicTypeClass() {
172 return btClass;
173 }
174 Wrapper basicTypeWrapper() {
175 return btWrapper;
176 }
177 TypeKind basicTypeKind() {
178 return btKind;
179 }
180 int basicTypeSlots() {
181 return btWrapper.stackSlots();
182 }
183
184 static BasicType basicType(byte type) {
185 return ALL_TYPES[type];
186 }
187 static BasicType basicType(char type) {
188 return switch (type) {
189 case 'L' -> L_TYPE;
190 case 'I' -> I_TYPE;
191 case 'J' -> J_TYPE;
192 case 'F' -> F_TYPE;
193 case 'D' -> D_TYPE;
194 case 'V' -> V_TYPE;
195 // all subword types are represented as ints
196 case 'Z', 'B', 'S', 'C' -> I_TYPE;
197 default -> throw newInternalError("Unknown type char: '" + type + "'");
198 };
199 }
200 static BasicType basicType(Class<?> type) {
201 return basicType(Wrapper.basicTypeChar(type));
202 }
203 static int[] basicTypeOrds(BasicType[] types) {
204 if (types == null) {
205 return null;
206 }
207 int[] a = new int[types.length];
208 for(int i = 0; i < types.length; ++i) {
209 a[i] = types[i].ordinal();
210 }
211 return a;
212 }
213
214 static char basicTypeChar(Class<?> type) {
215 return basicType(type).btChar;
216 }
217
218 static int[] basicTypesOrd(Class<?>[] types) {
219 int[] ords = new int[types.length];
220 for (int i = 0; i < ords.length; i++) {
221 ords[i] = basicType(types[i]).ordinal();
222 }
223 return ords;
224 }
225
226 static boolean isBasicTypeChar(char c) {
227 return "LIJFDV".indexOf(c) >= 0;
228 }
229 static boolean isArgBasicTypeChar(char c) {
230 return "LIJFD".indexOf(c) >= 0;
231 }
232
233 static { assert(checkBasicType()); }
234 private static boolean checkBasicType() {
235 for (int i = 0; i < ARG_TYPE_LIMIT; i++) {
236 assert ARG_TYPES[i].ordinal() == i;
237 assert ARG_TYPES[i] == ALL_TYPES[i];
238 }
239 for (int i = 0; i < TYPE_LIMIT; i++) {
240 assert ALL_TYPES[i].ordinal() == i;
241 }
242 assert ALL_TYPES[TYPE_LIMIT - 1] == V_TYPE;
243 assert !Arrays.asList(ARG_TYPES).contains(V_TYPE);
244 return true;
245 }
246 }
247
248 enum Kind {
249 GENERIC("invoke"),
250 IDENTITY("identity"),
251 CONSTANT("constant"),
252 BOUND_REINVOKER("BMH.reinvoke", "reinvoke"),
253 REINVOKER("MH.reinvoke", "reinvoke"),
254 DELEGATE("MH.delegate", "delegate"),
255 EXACT_LINKER("MH.invokeExact_MT", "invokeExact_MT"),
256 EXACT_INVOKER("MH.exactInvoker", "exactInvoker"),
257 GENERIC_LINKER("MH.invoke_MT", "invoke_MT"),
258 GENERIC_INVOKER("MH.invoker", "invoker"),
259 LINK_TO_TARGET_METHOD("linkToTargetMethod"),
260 LINK_TO_CALL_SITE("linkToCallSite"),
261 DIRECT_INVOKE_VIRTUAL("DMH.invokeVirtual", "invokeVirtual"),
262 DIRECT_INVOKE_SPECIAL("DMH.invokeSpecial", "invokeSpecial"),
263 DIRECT_INVOKE_SPECIAL_IFC("DMH.invokeSpecialIFC", "invokeSpecialIFC"),
264 DIRECT_INVOKE_STATIC("DMH.invokeStatic", "invokeStatic"),
265 DIRECT_NEW_INVOKE_SPECIAL("DMH.newInvokeSpecial", "newInvokeSpecial"),
266 DIRECT_INVOKE_INTERFACE("DMH.invokeInterface", "invokeInterface"),
267 DIRECT_INVOKE_STATIC_INIT("DMH.invokeStaticInit", "invokeStaticInit"),
268 // Start field forms
269 // IJFDL, instance/static differ in method type, can share form
270 // init form only applicable to static
271 FIELD_ACCESS("fieldAccess"),
272 FIELD_ACCESS_INIT("fieldAccessInit"),
273 VOLATILE_FIELD_ACCESS("volatileFieldAccess"),
274 VOLATILE_FIELD_ACCESS_INIT("volatileFieldAccessInit"),
275 // BCSZ need own forms to avoid clashing with basic type I, +-init/volatile
276 FIELD_ACCESS_B("fieldAccessB"),
277 FIELD_ACCESS_INIT_B("fieldAccessInitB"),
278 VOLATILE_FIELD_ACCESS_B("volatileFieldAccessB"),
279 VOLATILE_FIELD_ACCESS_INIT_B("volatileFieldAccessInitB"),
280 FIELD_ACCESS_C("fieldAccessC"),
281 FIELD_ACCESS_INIT_C("fieldAccessInitC"),
282 VOLATILE_FIELD_ACCESS_C("volatileFieldAccessC"),
283 VOLATILE_FIELD_ACCESS_INIT_C("volatileFieldAccessInitC"),
284 FIELD_ACCESS_S("fieldAccessS"),
285 FIELD_ACCESS_INIT_S("fieldAccessInitS"),
286 VOLATILE_FIELD_ACCESS_S("volatileFieldAccessS"),
287 VOLATILE_FIELD_ACCESS_INIT_S("volatileFieldAccessInitS"),
288 FIELD_ACCESS_Z("fieldAccessZ"),
289 FIELD_ACCESS_INIT_Z("fieldAccessInitZ"),
290 VOLATILE_FIELD_ACCESS_Z("volatileFieldAccessZ"),
291 VOLATILE_FIELD_ACCESS_INIT_Z("volatileFieldAccessInitZ"),
292 // cast, nr, flat need their own forms to avoid clashing with L
293 FIELD_ACCESS_CAST("fieldAccessCast"),
294 FIELD_ACCESS_INIT_CAST("fieldAccessInitCast"),
295 VOLATILE_FIELD_ACCESS_CAST("volatileFieldAccessCast"),
296 VOLATILE_FIELD_ACCESS_INIT_CAST("volatileFieldAccessInitCast"),
297 // null-check and put reference, +-cast, +-init/volatile
298 // non-cast forms serve bytecode emulation purpose, which always enforces null checks
299 PUT_NULL_RESTRICTED_REFERENCE("putNullRestrictedReference"),
300 PUT_NULL_RESTRICTED_REFERENCE_INIT("putNullRestrictedReferenceInit"),
301 VOLATILE_PUT_NULL_RESTRICTED_REFERENCE("volatilePutNullRestrictedReference"),
302 VOLATILE_PUT_NULL_RESTRICTED_REFERENCE_INIT("volatilePutNullRestrictedReferenceInit"),
303 PUT_NULL_RESTRICTED_REFERENCE_CAST("putNullRestrictedReferenceCast"),
304 PUT_NULL_RESTRICTED_REFERENCE_CAST_INIT("putNullRestrictedReferenceInitCast"),
305 VOLATILE_PUT_NULL_RESTRICTED_REFERENCE_CAST("volatilePutNullRestrictedReferenceCast"),
306 VOLATILE_PUT_NULL_RESTRICTED_REFERENCE_CAST_INIT("volatilePutNullRestrictedReferenceCastInit"),
307 // flat implies cast, +-init/volatile
308 FIELD_ACCESS_FLAT("fieldAccessFlat"),
309 FIELD_ACCESS_INIT_FLAT("fieldAccessInitFlat"),
310 VOLATILE_FIELD_ACCESS_FLAT("volatileFieldAccessFlat"),
311 VOLATILE_FIELD_ACCESS_INIT_FLAT("volatileFieldAccessInitFlat"),
312 // write guard NR flat, implies cast; +-volatile; no init forms - no flat in static fields yet
313 PUT_NULL_RESTRICTED_FLAT_VALUE("putNullRestrictedFlatValue"),
314 VOLATILE_PUT_NULL_RESTRICTED_FLAT_VALUE("volatilePutNullRestrictedFlatValue"),
315 // End fields
316 TRY_FINALLY("tryFinally"),
317 TABLE_SWITCH("tableSwitch"),
318 COLLECTOR("collector"),
319 LOOP("loop"),
320 GUARD("guard"),
321 GUARD_WITH_CATCH("guardWithCatch"),
322 VARHANDLE_EXACT_INVOKER("VH.exactInvoker"),
323 VARHANDLE_INVOKER("VH.invoker", "invoker"),
324 VARHANDLE_LINKER("VH.invoke_MT", "invoke_MT");
325
326 final String defaultLambdaName;
327 final String methodName;
328
329 private Kind(String defaultLambdaName) {
330 this(defaultLambdaName, defaultLambdaName);
331 }
332
333 private Kind(String defaultLambdaName, String methodName) {
334 this.defaultLambdaName = defaultLambdaName;
335 this.methodName = methodName;
336 }
337 }
338
339 // private version that doesn't do checks or defensive copies
340 private LambdaForm(int arity, int result, boolean forceInline, MethodHandle customized, Name[] names, Kind kind) {
341 this.arity = arity;
342 this.result = result;
343 this.forceInline = forceInline;
344 this.customized = customized;
345 this.names = names;
346 this.kind = kind;
347 this.vmentry = null;
348 this.isCompiled = false;
349 }
350
351 // root factory pre/post processing and calls simple constructor
352 private static LambdaForm create(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized, Kind kind) {
353 names = names.clone();
354 assert(namesOK(arity, names));
355 result = fixResult(result, names);
356
357 boolean canInterpret = normalizeNames(arity, names);
358 LambdaForm form = new LambdaForm(arity, result, forceInline, customized, names, kind);
359 assert(form.nameRefsAreLegal());
360 if (!canInterpret) {
361 form.compileToBytecode();
362 }
363 return form;
364 }
365
366 // derived factories with defaults
367 private static final int DEFAULT_RESULT = LAST_RESULT;
368 private static final boolean DEFAULT_FORCE_INLINE = true;
369 private static final MethodHandle DEFAULT_CUSTOMIZED = null;
370 private static final Kind DEFAULT_KIND = Kind.GENERIC;
371
372 static LambdaForm create(int arity, Name[] names, int result) {
373 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
374 }
375 static LambdaForm create(int arity, Name[] names, int result, Kind kind) {
376 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
377 }
378 static LambdaForm create(int arity, Name[] names) {
379 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
380 }
381 static LambdaForm create(int arity, Name[] names, Kind kind) {
382 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
383 }
384 static LambdaForm create(int arity, Name[] names, boolean forceInline, Kind kind) {
385 return create(arity, names, DEFAULT_RESULT, forceInline, DEFAULT_CUSTOMIZED, kind);
386 }
387
388 private static int fixResult(int result, Name[] names) {
389 if (result == LAST_RESULT)
390 result = names.length - 1; // might still be void
391 if (result >= 0 && names[result].type == V_TYPE)
392 result = VOID_RESULT;
393 return result;
394 }
395
396 static boolean debugNames() {
397 return DEBUG_NAME_COUNTERS != null;
398 }
399
400 static void associateWithDebugName(LambdaForm form, String name) {
401 assert (debugNames());
402 synchronized (DEBUG_NAMES) {
403 DEBUG_NAMES.put(form, name);
404 }
405 }
406
407 String lambdaName() {
408 if (DEBUG_NAMES != null) {
409 synchronized (DEBUG_NAMES) {
410 String name = DEBUG_NAMES.get(this);
411 if (name == null) {
412 name = generateDebugName();
413 }
414 return name;
415 }
416 }
417 return kind.defaultLambdaName;
418 }
419
420 private String generateDebugName() {
421 assert (debugNames());
422 String debugNameStem = kind.defaultLambdaName;
423 Integer ctr = DEBUG_NAME_COUNTERS.getOrDefault(debugNameStem, 0);
424 DEBUG_NAME_COUNTERS.put(debugNameStem, ctr + 1);
425 StringBuilder buf = new StringBuilder(debugNameStem);
426 int leadingZero = buf.length();
427 buf.append((int) ctr);
428 for (int i = buf.length() - leadingZero; i < 3; i++) {
429 buf.insert(leadingZero, '0');
430 }
431 buf.append('_');
432 buf.append(basicTypeSignature());
433 String name = buf.toString();
434 associateWithDebugName(this, name);
435 return name;
436 }
437
438 private static boolean namesOK(int arity, Name[] names) {
439 for (int i = 0; i < names.length; i++) {
440 Name n = names[i];
441 assert(n != null) : "n is null";
442 if (i < arity)
443 assert( n.isParam()) : n + " is not param at " + i;
444 else
445 assert(!n.isParam()) : n + " is param at " + i;
446 }
447 return true;
448 }
449
450 /** Customize LambdaForm for a particular MethodHandle */
451 LambdaForm customize(MethodHandle mh) {
452 if (customized == mh) {
453 return this;
454 }
455 LambdaForm customForm = LambdaForm.create(arity, names, result, forceInline, mh, kind);
456 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
457 // If shared LambdaForm has been compiled, compile customized version as well.
458 customForm.compileToBytecode();
459 }
460 customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
461 return customForm;
462 }
463
464 /** Get uncustomized flavor of the LambdaForm */
465 LambdaForm uncustomize() {
466 if (customized == null) {
467 return this;
468 }
469 assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
470 LambdaForm uncustomizedForm = (LambdaForm)transformCache;
471 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
472 // If customized LambdaForm has been compiled, compile uncustomized version as well.
473 uncustomizedForm.compileToBytecode();
474 }
475 return uncustomizedForm;
476 }
477
478 /** Renumber and/or replace params so that they are interned and canonically numbered.
479 * @return true if we can interpret
480 */
481 private static boolean normalizeNames(int arity, Name[] names) {
482 Name[] oldNames = names.clone();
483 int maxOutArity = 0;
484 for (int i = 0; i < names.length; i++) {
485 Name n = names[i];
486 names[i] = n.withIndex(i);
487 if (n.arguments != null && maxOutArity < n.arguments.length)
488 maxOutArity = n.arguments.length;
489 }
490 if (oldNames != null) {
491 for (int i = Math.max(1, arity); i < names.length; i++) {
492 Name fixed = names[i].replaceNames(oldNames, names, 0, i);
493 names[i] = fixed.withIndex(i);
494 }
495 }
496 int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
497 boolean needIntern = false;
498 for (int i = 0; i < maxInterned; i++) {
499 Name n = names[i], n2 = internArgument(n);
500 if (n != n2) {
501 names[i] = n2;
502 needIntern = true;
503 }
504 }
505 if (needIntern) {
506 for (int i = arity; i < names.length; i++) {
507 names[i].internArguments();
508 }
509 }
510
511 // return true if we can interpret
512 if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
513 // Cannot use LF interpreter on very high arity expressions.
514 assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
515 return false;
516 }
517 return true;
518 }
519
520 /**
521 * Check that all embedded Name references are localizable to this lambda,
522 * and are properly ordered after their corresponding definitions.
523 * <p>
524 * Note that a Name can be local to multiple lambdas, as long as
525 * it possesses the same index in each use site.
526 * This allows Name references to be freely reused to construct
527 * fresh lambdas, without confusion.
528 */
529 boolean nameRefsAreLegal() {
530 assert(arity >= 0 && arity <= names.length);
531 assert(result >= -1 && result < names.length);
532 // Do all names possess an index consistent with their local definition order?
533 for (int i = 0; i < arity; i++) {
534 Name n = names[i];
535 assert(n.index() == i) : Arrays.asList(n.index(), i);
536 assert(n.isParam());
537 }
538 // Also, do all local name references
539 for (int i = arity; i < names.length; i++) {
540 Name n = names[i];
541 assert(n.index() == i);
542 for (Object arg : n.arguments) {
543 if (arg instanceof Name n2) {
544 int i2 = n2.index;
545 assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
546 assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
547 assert(i2 < i); // ref must come after def!
548 }
549 }
550 }
551 return true;
552 }
553
554 // /** Invoke this form on the given arguments. */
555 // final Object invoke(Object... args) throws Throwable {
556 // // NYI: fit this into the fast path?
557 // return interpretWithArguments(args);
558 // }
559
560 /** Report the return type. */
561 BasicType returnType() {
562 if (result < 0) return V_TYPE;
563 Name n = names[result];
564 return n.type;
565 }
566
567 /** Report the N-th argument type. */
568 BasicType parameterType(int n) {
569 return parameter(n).type;
570 }
571
572 /** Report the N-th argument name. */
573 Name parameter(int n) {
574 Name param = names[n];
575 assert(n < arity && param.isParam());
576 return param;
577 }
578
579 /** Report the N-th argument type constraint. */
580 Object parameterConstraint(int n) {
581 return parameter(n).constraint;
582 }
583
584 /** Report the arity. */
585 int arity() {
586 return arity;
587 }
588
589 /** Report the number of expressions (non-parameter names). */
590 int expressionCount() {
591 return names.length - arity;
592 }
593
594 /** Return the method type corresponding to my basic type signature. */
595 MethodType methodType() {
596 Class<?>[] ptypes = new Class<?>[arity];
597 for (int i = 0; i < arity; ++i) {
598 ptypes[i] = parameterType(i).btClass;
599 }
600 return MethodType.methodType(returnType().btClass, ptypes, true);
601 }
602
603 /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
604 final String basicTypeSignature() {
605 StringBuilder buf = new StringBuilder(arity() + 3);
606 for (int i = 0, a = arity(); i < a; i++)
607 buf.append(parameterType(i).basicTypeChar());
608 return buf.append('_').append(returnType().basicTypeChar()).toString();
609 }
610 static int signatureArity(String sig) {
611 assert(isValidSignature(sig));
612 return sig.indexOf('_');
613 }
614 static boolean isValidSignature(String sig) {
615 int arity = sig.indexOf('_');
616 if (arity < 0) return false; // must be of the form *_*
617 int siglen = sig.length();
618 if (siglen != arity + 2) return false; // *_X
619 for (int i = 0; i < siglen; i++) {
620 if (i == arity) continue; // skip '_'
621 char c = sig.charAt(i);
622 if (c == 'V')
623 return (i == siglen - 1 && arity == siglen - 2);
624 if (!isArgBasicTypeChar(c)) return false; // must be [LIJFD]
625 }
626 return true; // [LIJFD]*_[LIJFDV]
627 }
628
629 /**
630 * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
631 */
632 boolean isSelectAlternative(int pos) {
633 // selectAlternative idiom:
634 // t_{n}:L=MethodHandleImpl.selectAlternative(...)
635 // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
636 if (pos+1 >= names.length) return false;
637 Name name0 = names[pos];
638 Name name1 = names[pos+1];
639 return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
640 name1.isInvokeBasic() &&
641 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
642 lastUseIndex(name0) == pos+1; // t_{n} is local: used only in t_{n+1}
643 }
644
645 private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
646 if (pos+2 >= names.length) return false;
647 Name name0 = names[pos];
648 Name name1 = names[pos+1];
649 Name name2 = names[pos+2];
650 return name1.refersTo(MethodHandleImpl.class, idiomName) &&
651 name0.isInvokeBasic() &&
652 name2.isInvokeBasic() &&
653 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
654 lastUseIndex(name0) == pos+1 && // t_{n} is local: used only in t_{n+1}
655 name2.lastUseIndex(name1) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
656 lastUseIndex(name1) == pos+2; // t_{n+1} is local: used only in t_{n+2}
657 }
658
659 /**
660 * Check if i-th name is a start of GuardWithCatch idiom.
661 */
662 boolean isGuardWithCatch(int pos) {
663 // GuardWithCatch idiom:
664 // t_{n}:L=MethodHandle.invokeBasic(...)
665 // t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
666 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
667 return isMatchingIdiom(pos, "guardWithCatch", 3);
668 }
669
670 /**
671 * Check if i-th name is a start of the tryFinally idiom.
672 */
673 boolean isTryFinally(int pos) {
674 // tryFinally idiom:
675 // t_{n}:L=MethodHandle.invokeBasic(...)
676 // t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
677 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
678 return isMatchingIdiom(pos, "tryFinally", 2);
679 }
680
681 /**
682 * Check if i-th name is a start of the tableSwitch idiom.
683 */
684 boolean isTableSwitch(int pos) {
685 // tableSwitch idiom:
686 // t_{n}:L=MethodHandle.invokeBasic(...) // args
687 // t_{n+1}:L=MethodHandleImpl.tableSwitch(*, *, *, t_{n})
688 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
689 if (pos + 2 >= names.length) return false;
690
691 final int POS_COLLECT_ARGS = pos;
692 final int POS_TABLE_SWITCH = pos + 1;
693 final int POS_UNBOX_RESULT = pos + 2;
694
695 Name collectArgs = names[POS_COLLECT_ARGS];
696 Name tableSwitch = names[POS_TABLE_SWITCH];
697 Name unboxResult = names[POS_UNBOX_RESULT];
698 return tableSwitch.refersTo(MethodHandleImpl.class, "tableSwitch") &&
699 collectArgs.isInvokeBasic() &&
700 unboxResult.isInvokeBasic() &&
701 tableSwitch.lastUseIndex(collectArgs) == 3 && // t_{n+1}:L=MethodHandleImpl.<invoker>(*, *, *, t_{n});
702 lastUseIndex(collectArgs) == POS_TABLE_SWITCH && // t_{n} is local: used only in t_{n+1}
703 unboxResult.lastUseIndex(tableSwitch) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
704 lastUseIndex(tableSwitch) == POS_UNBOX_RESULT; // t_{n+1} is local: used only in t_{n+2}
705 }
706
707 /**
708 * Check if i-th name is a start of the loop idiom.
709 */
710 boolean isLoop(int pos) {
711 // loop idiom:
712 // t_{n}:L=MethodHandle.invokeBasic(...)
713 // t_{n+1}:L=MethodHandleImpl.loop(types, *, t_{n})
714 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
715 return isMatchingIdiom(pos, "loop", 2);
716 }
717
718 /*
719 * Code generation issues:
720 *
721 * Compiled LFs should be reusable in general.
722 * The biggest issue is how to decide when to pull a name into
723 * the bytecode, versus loading a reified form from the MH data.
724 *
725 * For example, an asType wrapper may require execution of a cast
726 * after a call to a MH. The target type of the cast can be placed
727 * as a constant in the LF itself. This will force the cast type
728 * to be compiled into the bytecodes and native code for the MH.
729 * Or, the target type of the cast can be erased in the LF, and
730 * loaded from the MH data. (Later on, if the MH as a whole is
731 * inlined, the data will flow into the inlined instance of the LF,
732 * as a constant, and the end result will be an optimal cast.)
733 *
734 * This erasure of cast types can be done with any use of
735 * reference types. It can also be done with whole method
736 * handles. Erasing a method handle might leave behind
737 * LF code that executes correctly for any MH of a given
738 * type, and load the required MH from the enclosing MH's data.
739 * Or, the erasure might even erase the expected MT.
740 *
741 * Also, for direct MHs, the MemberName of the target
742 * could be erased, and loaded from the containing direct MH.
743 * As a simple case, a LF for all int-valued non-static
744 * field getters would perform a cast on its input argument
745 * (to non-constant base type derived from the MemberName)
746 * and load an integer value from the input object
747 * (at a non-constant offset also derived from the MemberName).
748 * Such MN-erased LFs would be inlinable back to optimized
749 * code, whenever a constant enclosing DMH is available
750 * to supply a constant MN from its data.
751 *
752 * The main problem here is to keep LFs reasonably generic,
753 * while ensuring that hot spots will inline good instances.
754 * "Reasonably generic" means that we don't end up with
755 * repeated versions of bytecode or machine code that do
756 * not differ in their optimized form. Repeated versions
757 * of machine would have the undesirable overheads of
758 * (a) redundant compilation work and (b) extra I$ pressure.
759 * To control repeated versions, we need to be ready to
760 * erase details from LFs and move them into MH data,
761 * whenever those details are not relevant to significant
762 * optimization. "Significant" means optimization of
763 * code that is actually hot.
764 *
765 * Achieving this may require dynamic splitting of MHs, by replacing
766 * a generic LF with a more specialized one, on the same MH,
767 * if (a) the MH is frequently executed and (b) the MH cannot
768 * be inlined into a containing caller, such as an invokedynamic.
769 *
770 * Compiled LFs that are no longer used should be GC-able.
771 * If they contain non-BCP references, they should be properly
772 * interlinked with the class loader(s) that their embedded types
773 * depend on. This probably means that reusable compiled LFs
774 * will be tabulated (indexed) on relevant class loaders,
775 * or else that the tables that cache them will have weak links.
776 */
777
778 /**
779 * Make this LF directly executable, as part of a MethodHandle.
780 * Invariant: Every MH which is invoked must prepare its LF
781 * before invocation.
782 * (In principle, the JVM could do this very lazily,
783 * as a sort of pre-invocation linkage step.)
784 */
785 public void prepare() {
786 if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
787 compileToBytecode();
788 }
789 if (this.vmentry != null) {
790 // already prepared (e.g., a primitive DMH invoker form)
791 return;
792 }
793 MethodType mtype = methodType();
794 MethodTypeForm form = mtype.form();
795
796 MemberName entry = form.cachedInterpretEntry();
797 if (entry == null) {
798 assert (isValidSignature(basicTypeSignature()));
799 entry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
800 entry = form.setCachedInterpretEntry(entry);
801 }
802 this.vmentry = entry;
803 // TO DO: Maybe add invokeGeneric, invokeWithArguments
804 }
805
806 private static @Stable PerfCounter LF_FAILED;
807
808 private static PerfCounter failedCompilationCounter() {
809 if (LF_FAILED == null) {
810 LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
811 }
812 return LF_FAILED;
813 }
814
815 /** Generate optimizable bytecode for this form. */
816 void compileToBytecode() {
817 if (forceInterpretation()) {
818 return; // this should not be compiled
819 }
820 if (vmentry != null && isCompiled) {
821 return; // already compiled somehow
822 }
823
824 // Obtain the invoker MethodType outside of the following try block.
825 // This ensures that an IllegalArgumentException is directly thrown if the
826 // type would have 256 or more parameters
827 MethodType invokerType = methodType();
828 assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
829 try {
830 vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
831 if (TRACE_INTERPRETER)
832 traceInterpreter("compileToBytecode", this);
833 isCompiled = true;
834 } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
835 // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
836 invocationCounter = -1;
837 failedCompilationCounter().increment();
838 if (LOG_LF_COMPILATION_FAILURE) {
839 System.out.println("LambdaForm compilation failed: " + this);
840 bge.printStackTrace(System.out);
841 }
842 } catch (Error e) {
843 // Pass through any error
844 throw e;
845 } catch (Exception e) {
846 // Wrap any exception
847 throw newInternalError(this.toString(), e);
848 }
849 }
850
851 // The next few routines are called only from assert expressions
852 // They verify that the built-in invokers process the correct raw data types.
853 private static boolean argumentTypesMatch(String sig, Object[] av) {
854 int arity = signatureArity(sig);
855 assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
856 assert(av[0] instanceof MethodHandle) : "av[0] not instance of MethodHandle: " + av[0];
857 MethodHandle mh = (MethodHandle) av[0];
858 MethodType mt = mh.type();
859 assert(mt.parameterCount() == arity-1);
860 for (int i = 0; i < av.length; i++) {
861 Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
862 assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
863 }
864 return true;
865 }
866 private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
867 // The following line is needed because (...)void method handles can use non-void invokers
868 if (type == void.class) tc = V_TYPE; // can drop any kind of value
869 assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
870 switch (tc) {
871 case I_TYPE: assert checkInt(type, x) : "checkInt(" + type + "," + x +")"; break;
872 case J_TYPE: assert x instanceof Long : "instanceof Long: " + x; break;
873 case F_TYPE: assert x instanceof Float : "instanceof Float: " + x; break;
874 case D_TYPE: assert x instanceof Double : "instanceof Double: " + x; break;
875 case L_TYPE: assert checkRef(type, x) : "checkRef(" + type + "," + x + ")"; break;
876 case V_TYPE: break; // allow anything here; will be dropped
877 default: assert(false);
878 }
879 return true;
880 }
881 private static boolean checkInt(Class<?> type, Object x) {
882 assert(x instanceof Integer);
883 if (type == int.class) return true;
884 Wrapper w = Wrapper.forBasicType(type);
885 assert(w.isSubwordOrInt());
886 Object x1 = Wrapper.INT.wrap(w.wrap(x));
887 return x.equals(x1);
888 }
889 private static boolean checkRef(Class<?> type, Object x) {
890 assert(!type.isPrimitive());
891 if (x == null) return true;
892 if (type.isInterface()) return true;
893 return type.isInstance(x);
894 }
895
896 /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
897 private static final int COMPILE_THRESHOLD;
898 static {
899 COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
900 }
901 private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
902
903 private boolean forceInterpretation() {
904 return invocationCounter == -1;
905 }
906
907 /** Interpretively invoke this form on the given arguments. */
908 @Hidden
909 @DontInline
910 Object interpretWithArguments(Object... argumentValues) throws Throwable {
911 if (TRACE_INTERPRETER)
912 return interpretWithArgumentsTracing(argumentValues);
913 checkInvocationCounter();
914 assert(arityCheck(argumentValues));
915 Object[] values = Arrays.copyOf(argumentValues, names.length);
916 for (int i = argumentValues.length; i < values.length; i++) {
917 values[i] = interpretName(names[i], values);
918 }
919 Object rv = (result < 0) ? null : values[result];
920 assert(resultCheck(argumentValues, rv));
921 return rv;
922 }
923
924 /** Evaluate a single Name within this form, applying its function to its arguments. */
925 @Hidden
926 @DontInline
927 Object interpretName(Name name, Object[] values) throws Throwable {
928 if (TRACE_INTERPRETER)
929 traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
930 Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
931 for (int i = 0; i < arguments.length; i++) {
932 Object a = arguments[i];
933 if (a instanceof Name n) {
934 int i2 = n.index();
935 assert(names[i2] == a);
936 a = values[i2];
937 arguments[i] = a;
938 }
939 }
940 return name.function.invokeWithArguments(arguments);
941 }
942
943 private void checkInvocationCounter() {
944 if (COMPILE_THRESHOLD != 0 &&
945 !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
946 invocationCounter++; // benign race
947 if (invocationCounter >= COMPILE_THRESHOLD) {
948 // Replace vmentry with a bytecode version of this LF.
949 compileToBytecode();
950 }
951 }
952 }
953 Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
954 traceInterpreter("[ interpretWithArguments", this, argumentValues);
955 if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
956 int ctr = invocationCounter++; // benign race
957 traceInterpreter("| invocationCounter", ctr);
958 if (invocationCounter >= COMPILE_THRESHOLD) {
959 compileToBytecode();
960 }
961 }
962 Object rval;
963 try {
964 assert(arityCheck(argumentValues));
965 Object[] values = Arrays.copyOf(argumentValues, names.length);
966 for (int i = argumentValues.length; i < values.length; i++) {
967 values[i] = interpretName(names[i], values);
968 }
969 rval = (result < 0) ? null : values[result];
970 } catch (Throwable ex) {
971 traceInterpreter("] throw =>", ex);
972 throw ex;
973 }
974 traceInterpreter("] return =>", rval);
975 return rval;
976 }
977
978 static void traceInterpreter(String event, Object obj, Object... args) {
979 if (TRACE_INTERPRETER) {
980 System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
981 }
982 }
983 static void traceInterpreter(String event, Object obj) {
984 traceInterpreter(event, obj, (Object[])null);
985 }
986 private boolean arityCheck(Object[] argumentValues) {
987 assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
988 // also check that the leading (receiver) argument is somehow bound to this LF:
989 assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
990 MethodHandle mh = (MethodHandle) argumentValues[0];
991 assert(mh.internalForm() == this);
992 // note: argument #0 could also be an interface wrapper, in the future
993 argumentTypesMatch(basicTypeSignature(), argumentValues);
994 return true;
995 }
996 private boolean resultCheck(Object[] argumentValues, Object result) {
997 MethodHandle mh = (MethodHandle) argumentValues[0];
998 MethodType mt = mh.type();
999 assert(valueMatches(returnType(), mt.returnType(), result));
1000 return true;
1001 }
1002
1003 public String toString() {
1004 return debugString(-1);
1005 }
1006
1007 String debugString(int indentLevel) {
1008 String prefix = MethodHandle.debugPrefix(indentLevel);
1009 String lambdaName = lambdaName();
1010 StringBuilder buf = new StringBuilder(lambdaName);
1011 buf.append("=Lambda(");
1012 for (int i = 0; i < names.length; i++) {
1013 if (i == arity) buf.append(")=>{");
1014 Name n = names[i];
1015 if (i >= arity) buf.append("\n ").append(prefix);
1016 buf.append(n.paramString());
1017 if (i < arity) {
1018 if (i+1 < arity) buf.append(",");
1019 continue;
1020 }
1021 buf.append("=").append(n.exprString());
1022 buf.append(";");
1023 }
1024 if (arity == names.length) buf.append(")=>{");
1025 buf.append(result < 0 ? "void" : names[result]).append("}");
1026 if (TRACE_INTERPRETER) {
1027 // Extra verbosity:
1028 buf.append(":").append(basicTypeSignature());
1029 buf.append("/").append(vmentry);
1030 }
1031 return buf.toString();
1032 }
1033
1034 @Override
1035 public boolean equals(Object obj) {
1036 return obj instanceof LambdaForm lf && equals(lf);
1037 }
1038 public boolean equals(LambdaForm that) {
1039 if (this.result != that.result) return false;
1040 return Arrays.equals(this.names, that.names);
1041 }
1042 public int hashCode() {
1043 return result + 31 * Arrays.hashCode(names);
1044 }
1045 LambdaFormEditor editor() {
1046 return LambdaFormEditor.lambdaFormEditor(this);
1047 }
1048
1049 boolean contains(Name name) {
1050 int pos = name.index();
1051 if (pos >= 0) {
1052 return pos < names.length && name.equals(names[pos]);
1053 }
1054 for (int i = arity; i < names.length; i++) {
1055 if (name.equals(names[i]))
1056 return true;
1057 }
1058 return false;
1059 }
1060
1061 @AOTSafeClassInitializer
1062 static class NamedFunction {
1063 final MemberName member;
1064 private @Stable MethodHandle resolvedHandle;
1065 private @Stable MethodType type;
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 return (other instanceof NamedFunction that)
1121 && this.member != null
1122 && 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 static final MethodType INVOKER_METHOD_TYPE =
1133 MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1134
1135 private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1136 typeForm = typeForm.basicType().form(); // normalize to basic type
1137 MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1138 if (mh != null) return mh;
1139 MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm); // this could take a while
1140 mh = DirectMethodHandle.make(invoker);
1141 MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1142 if (mh2 != null) return mh2; // benign race
1143 if (!mh.type().equals(INVOKER_METHOD_TYPE))
1144 throw newInternalError(mh.debugString());
1145 return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1146 }
1147
1148 @Hidden
1149 Object invokeWithArguments(Object... arguments) throws Throwable {
1150 // If we have a cached invoker, call it right away.
1151 // NOTE: The invoker always returns a reference value.
1152 if (TRACE_INTERPRETER) return invokeWithArgumentsTracing(arguments);
1153 return invoker().invokeBasic(resolvedHandle(), arguments);
1154 }
1155
1156 @Hidden
1157 Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1158 Object rval;
1159 try {
1160 traceInterpreter("[ call", this, arguments);
1161 // resolvedHandle might be uninitialized, ok for tracing
1162 if (resolvedHandle == null) {
1163 traceInterpreter("| resolve", this);
1164 resolvedHandle();
1165 }
1166 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1167 } catch (Throwable ex) {
1168 traceInterpreter("] throw =>", ex);
1169 throw ex;
1170 }
1171 traceInterpreter("] return =>", rval);
1172 return rval;
1173 }
1174
1175 private MethodHandle invoker() {
1176 return computeInvoker(methodType().form());
1177 }
1178
1179 MethodType methodType() {
1180 MethodType type = this.type;
1181 if (type == null) {
1182 this.type = type = calculateMethodType(member, resolvedHandle);
1183 }
1184 return type;
1185 }
1186
1187 private static MethodType calculateMethodType(MemberName member, MethodHandle resolvedHandle) {
1188 if (resolvedHandle != null) {
1189 return resolvedHandle.type();
1190 } else {
1191 // only for certain internal LFs during bootstrapping
1192 return member.getInvocationType();
1193 }
1194 }
1195
1196 MemberName member() {
1197 assert(assertMemberIsConsistent());
1198 return member;
1199 }
1200
1201 // Called only from assert.
1202 private boolean assertMemberIsConsistent() {
1203 if (resolvedHandle instanceof DirectMethodHandle) {
1204 MemberName m = resolvedHandle.internalMemberName();
1205 assert(m.equals(member));
1206 }
1207 return true;
1208 }
1209
1210 Class<?> memberDeclaringClassOrNull() {
1211 return (member == null) ? null : member.getDeclaringClass();
1212 }
1213
1214 BasicType returnType() {
1215 return basicType(methodType().returnType());
1216 }
1217
1218 BasicType parameterType(int n) {
1219 return basicType(methodType().parameterType(n));
1220 }
1221
1222 int arity() {
1223 return methodType().parameterCount();
1224 }
1225
1226 public String toString() {
1227 if (member == null) return String.valueOf(resolvedHandle);
1228 return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1229 }
1230
1231 public boolean isIdentity() {
1232 return this.equals(identity(returnType()));
1233 }
1234
1235 public MethodHandleImpl.Intrinsic intrinsicName() {
1236 return resolvedHandle != null
1237 ? resolvedHandle.intrinsicName()
1238 : MethodHandleImpl.Intrinsic.NONE;
1239 }
1240
1241 public Object intrinsicData() {
1242 return resolvedHandle != null
1243 ? resolvedHandle.intrinsicData()
1244 : null;
1245 }
1246 }
1247
1248 public static String basicTypeSignature(MethodType type) {
1249 int params = type.parameterCount();
1250 char[] sig = new char[params + 2];
1251 int sigp = 0;
1252 while (sigp < params) {
1253 sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1254 }
1255 sig[sigp++] = '_';
1256 sig[sigp++] = basicTypeChar(type.returnType());
1257 assert(sigp == sig.length);
1258 return String.valueOf(sig);
1259 }
1260
1261 /** Hack to make signatures more readable when they show up in method names.
1262 * Signature should start with a sequence of uppercase ASCII letters.
1263 * Runs of three or more are replaced by a single letter plus a decimal repeat count.
1264 * A tail of anything other than uppercase ASCII is passed through unchanged.
1265 * @param signature sequence of uppercase ASCII letters with possible repetitions
1266 * @return same sequence, with repetitions counted by decimal numerals
1267 */
1268 public static String shortenSignature(String signature) {
1269 final int NO_CHAR = -1, MIN_RUN = 3;
1270 int c0, c1 = NO_CHAR, c1reps = 0;
1271 StringBuilder buf = null;
1272 int len = signature.length();
1273 if (len < MIN_RUN) return signature;
1274 for (int i = 0; i <= len; i++) {
1275 if (c1 != NO_CHAR && !('A' <= c1 && c1 <= 'Z')) {
1276 // wrong kind of char; bail out here
1277 if (buf != null) {
1278 buf.append(signature, i - c1reps, len);
1279 }
1280 break;
1281 }
1282 // shift in the next char:
1283 c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1284 if (c1 == c0) { ++c1reps; continue; }
1285 // shift in the next count:
1286 int c0reps = c1reps; c1reps = 1;
1287 // end of a character run
1288 if (c0reps < MIN_RUN) {
1289 if (buf != null) {
1290 while (--c0reps >= 0)
1291 buf.append((char)c0);
1292 }
1293 continue;
1294 }
1295 // found three or more in a row
1296 if (buf == null)
1297 buf = new StringBuilder().append(signature, 0, i - c0reps);
1298 buf.append((char)c0).append(c0reps);
1299 }
1300 return (buf == null) ? signature : buf.toString();
1301 }
1302
1303 static final class Name {
1304 final BasicType type;
1305 final short index;
1306 final NamedFunction function;
1307 final Object constraint; // additional type information, if not null
1308 @Stable final Object[] arguments;
1309
1310 private static final Object[] EMPTY_ARGS = new Object[0];
1311
1312 private Name(int index, BasicType type, NamedFunction function, Object[] arguments, Object constraint) {
1313 this.index = (short)index;
1314 this.type = type;
1315 this.function = function;
1316 this.arguments = arguments;
1317 this.constraint = constraint;
1318 assert(this.index == index && typesMatch(function, arguments));
1319 assert(constraint == null || isParam()); // only params have constraints
1320 assert(constraint == null || constraint instanceof ClassSpecializer.SpeciesData || constraint instanceof Class);
1321 }
1322
1323 Name(MethodHandle function, Object... arguments) {
1324 this(new NamedFunction(function), arguments);
1325 }
1326 Name(MethodType functionType, Object... arguments) {
1327 this(new NamedFunction(functionType), arguments);
1328 assert(arguments[0] instanceof Name name && name.type == L_TYPE);
1329 }
1330 Name(MemberName function, Object... arguments) {
1331 this(new NamedFunction(function), arguments);
1332 }
1333 Name(NamedFunction function) {
1334 this(-1, function.returnType(), function, EMPTY_ARGS, null);
1335 }
1336 Name(NamedFunction function, Object arg) {
1337 this(-1, function.returnType(), function, new Object[] { arg }, null);
1338 }
1339 Name(NamedFunction function, Object arg0, Object arg1) {
1340 this(-1, function.returnType(), function, new Object[] { arg0, arg1 }, null);
1341 }
1342 Name(NamedFunction function, Object... arguments) {
1343 this(-1, function.returnType(), function, Arrays.copyOf(arguments, arguments.length, Object[].class), null);
1344 }
1345 /** Create a raw parameter of the given type, with an expected index. */
1346 Name(int index, BasicType type) {
1347 this(index, type, null, null, null);
1348 }
1349 /** Create a raw parameter of the given type. */
1350 Name(BasicType type) { this(-1, type); }
1351
1352 BasicType type() { return type; }
1353 int index() { return index; }
1354
1355 char typeChar() {
1356 return type.btChar;
1357 }
1358
1359 Name withIndex(int i) {
1360 if (i == this.index) return this;
1361 return new Name(i, type, function, arguments, constraint);
1362 }
1363
1364 Name withConstraint(Object constraint) {
1365 if (constraint == this.constraint) return this;
1366 return new Name(index, type, function, arguments, constraint);
1367 }
1368
1369 Name replaceName(Name oldName, Name newName) { // FIXME: use replaceNames uniformly
1370 if (oldName == newName) return this;
1371 @SuppressWarnings("LocalVariableHidesMemberVariable")
1372 Object[] arguments = this.arguments;
1373 if (arguments == null) return this;
1374 boolean replaced = false;
1375 for (int j = 0; j < arguments.length; j++) {
1376 if (arguments[j] == oldName) {
1377 if (!replaced) {
1378 replaced = true;
1379 arguments = arguments.clone();
1380 }
1381 arguments[j] = newName;
1382 }
1383 }
1384 if (!replaced) return this;
1385 return new Name(function, arguments);
1386 }
1387 /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1388 * Limit such replacements to {@code start<=i<end}. Return possibly changed self.
1389 */
1390 Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1391 if (start >= end) return this;
1392 @SuppressWarnings("LocalVariableHidesMemberVariable")
1393 Object[] arguments = this.arguments;
1394 boolean replaced = false;
1395 eachArg:
1396 for (int j = 0; j < arguments.length; j++) {
1397 if (arguments[j] instanceof Name n) {
1398 int check = n.index;
1399 // harmless check to see if the thing is already in newNames:
1400 if (check >= 0 && check < newNames.length && n == newNames[check])
1401 continue eachArg;
1402 // n might not have the correct index: n != oldNames[n.index].
1403 for (int i = start; i < end; i++) {
1404 if (n == oldNames[i]) {
1405 if (n == newNames[i])
1406 continue eachArg;
1407 if (!replaced) {
1408 replaced = true;
1409 arguments = arguments.clone();
1410 }
1411 arguments[j] = newNames[i];
1412 continue eachArg;
1413 }
1414 }
1415 }
1416 }
1417 if (!replaced) return this;
1418 return new Name(function, arguments);
1419 }
1420 void internArguments() {
1421 @SuppressWarnings("LocalVariableHidesMemberVariable")
1422 Object[] arguments = this.arguments;
1423 for (int j = 0; j < arguments.length; j++) {
1424 if (arguments[j] instanceof Name n) {
1425 if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1426 arguments[j] = internArgument(n);
1427 }
1428 }
1429 }
1430 boolean isParam() {
1431 return function == null;
1432 }
1433
1434 boolean refersTo(Class<?> declaringClass, String methodName) {
1435 return function != null &&
1436 function.member() != null && function.member().refersTo(declaringClass, methodName);
1437 }
1438
1439 /**
1440 * Check if MemberName is a call to MethodHandle.invokeBasic.
1441 */
1442 boolean isInvokeBasic() {
1443 if (function == null)
1444 return false;
1445 if (arguments.length < 1)
1446 return false; // must have MH argument
1447 MemberName member = function.member();
1448 return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1449 !member.isPublic() && !member.isStatic();
1450 }
1451
1452 /**
1453 * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1454 */
1455 boolean isLinkerMethodInvoke() {
1456 if (function == null)
1457 return false;
1458 if (arguments.length < 1)
1459 return false; // must have MH argument
1460 MemberName member = function.member();
1461 return member != null &&
1462 member.getDeclaringClass() == MethodHandle.class &&
1463 !member.isPublic() && member.isStatic() &&
1464 member.getName().startsWith("linkTo");
1465 }
1466
1467 public String toString() {
1468 return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1469 }
1470 public String debugString() {
1471 String s = paramString();
1472 return (function == null) ? s : s + "=" + exprString();
1473 }
1474 public String paramString() {
1475 String s = toString();
1476 Object c = constraint;
1477 if (c == null)
1478 return s;
1479 if (c instanceof Class<?> cl) c = cl.getSimpleName();
1480 return s + "/" + c;
1481 }
1482 public String exprString() {
1483 if (function == null) return toString();
1484 StringBuilder buf = new StringBuilder(function.toString());
1485 buf.append("(");
1486 String cma = "";
1487 for (Object a : arguments) {
1488 buf.append(cma); cma = ",";
1489 if (a instanceof Name || a instanceof Integer)
1490 buf.append(a);
1491 else
1492 buf.append("(").append(a).append(")");
1493 }
1494 buf.append(")");
1495 return buf.toString();
1496 }
1497
1498 private boolean typesMatch(NamedFunction function, Object ... arguments) {
1499 if (arguments == null) {
1500 assert(function == null);
1501 return true;
1502 }
1503 assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1504 for (int i = 0; i < arguments.length; i++) {
1505 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1506 }
1507 return true;
1508 }
1509
1510 private static boolean typesMatch(BasicType parameterType, Object object) {
1511 if (object instanceof Name name) {
1512 return name.type == parameterType;
1513 }
1514 switch (parameterType) {
1515 case I_TYPE: return object instanceof Integer;
1516 case J_TYPE: return object instanceof Long;
1517 case F_TYPE: return object instanceof Float;
1518 case D_TYPE: return object instanceof Double;
1519 }
1520 assert(parameterType == L_TYPE);
1521 return true;
1522 }
1523
1524 /** Return the index of the last occurrence of n in the argument array.
1525 * Return -1 if the name is not used.
1526 */
1527 int lastUseIndex(Name n) {
1528 Object[] arguments = this.arguments;
1529 if (arguments == null) return -1;
1530 for (int i = arguments.length; --i >= 0; ) {
1531 if (arguments[i] == n) return i;
1532 }
1533 return -1;
1534 }
1535
1536 public boolean equals(Name that) {
1537 if (this == that) return true;
1538 if (isParam())
1539 // each parameter is a unique atom
1540 return false; // this != that
1541 return
1542 //this.index == that.index &&
1543 this.type == that.type &&
1544 this.function.equals(that.function) &&
1545 Arrays.equals(this.arguments, that.arguments);
1546 }
1547 @Override
1548 public boolean equals(Object x) {
1549 return x instanceof Name n && equals(n);
1550 }
1551 @Override
1552 public int hashCode() {
1553 if (isParam())
1554 return index | (type.ordinal() << 8);
1555 return function.hashCode() ^ Arrays.hashCode(arguments);
1556 }
1557 }
1558
1559 /** Return the index of the last name which contains n as an argument.
1560 * Return -1 if the name is not used. Return names.length if it is the return value.
1561 */
1562 int lastUseIndex(Name n) {
1563 int ni = n.index, nmax = names.length;
1564 assert(names[ni] == n);
1565 if (result == ni) return nmax; // live all the way beyond the end
1566 for (int i = nmax; --i > ni; ) {
1567 if (names[i].lastUseIndex(n) >= 0)
1568 return i;
1569 }
1570 return -1;
1571 }
1572
1573 /** Return the number of times n is used as an argument or return value. */
1574 int useCount(Name n) {
1575 int count = (result == n.index) ? 1 : 0;
1576 int i = Math.max(n.index + 1, arity);
1577 Name[] names = this.names;
1578 while (i < names.length) {
1579 Object[] arguments = names[i++].arguments;
1580 if (arguments != null) {
1581 for (Object argument : arguments) {
1582 if (argument == n) {
1583 count++;
1584 }
1585 }
1586 }
1587 }
1588 return count;
1589 }
1590
1591 static Name argument(int which, BasicType type) {
1592 if (which >= INTERNED_ARGUMENT_LIMIT)
1593 return new Name(which, type);
1594 return INTERNED_ARGUMENTS[type.ordinal()][which];
1595 }
1596 static Name internArgument(Name n) {
1597 assert(n.isParam()) : "not param: " + n;
1598 assert(n.index < INTERNED_ARGUMENT_LIMIT);
1599 if (n.constraint != null) return n;
1600 return argument(n.index, n.type);
1601 }
1602 static Name[] arguments(int extra, MethodType types) {
1603 int length = types.parameterCount();
1604 Name[] names = new Name[length + extra];
1605 for (int i = 0; i < length; i++)
1606 names[i] = argument(i, basicType(types.parameterType(i)));
1607 return names;
1608 }
1609
1610 static Name[] invokeArguments(int extra, MethodType types) {
1611 int length = types.parameterCount();
1612 Name[] names = new Name[length + extra + 1];
1613 names[0] = argument(0, L_TYPE);
1614 for (int i = 0; i < length; i++)
1615 names[i + 1] = argument(i + 1, basicType(types.parameterType(i)));
1616 return names;
1617 }
1618
1619 static final int INTERNED_ARGUMENT_LIMIT = 10;
1620 private static final Name[][] INTERNED_ARGUMENTS
1621 = new Name[ARG_TYPE_LIMIT][INTERNED_ARGUMENT_LIMIT];
1622 static {
1623 for (BasicType type : BasicType.ARG_TYPES) {
1624 int ord = type.ordinal();
1625 for (int i = 0; i < INTERNED_ARGUMENTS[ord].length; i++) {
1626 INTERNED_ARGUMENTS[ord][i] = new Name(i, type);
1627 }
1628 }
1629 }
1630
1631 private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
1632
1633 static LambdaForm identityForm(BasicType type) {
1634 int ord = type.ordinal();
1635 LambdaForm form = LF_identity[ord];
1636 if (form != null) {
1637 return form;
1638 }
1639 createIdentityForm(type);
1640 return LF_identity[ord];
1641 }
1642
1643 static NamedFunction identity(BasicType type) {
1644 int ord = type.ordinal();
1645 NamedFunction function = NF_identity[ord];
1646 if (function != null) {
1647 return function;
1648 }
1649 createIdentityForm(type);
1650 return NF_identity[ord];
1651 }
1652
1653 static LambdaForm constantForm(BasicType type) {
1654 assert type != null && type != V_TYPE : type;
1655 var cached = LF_constant[type.ordinal()];
1656 if (cached != null)
1657 return cached;
1658 return createConstantForm(type);
1659 }
1660
1661 private static LambdaForm createConstantForm(BasicType type) {
1662 UNSAFE.ensureClassInitialized(BoundMethodHandle.class); // defend access to SimpleMethodHandle
1663 var species = SimpleMethodHandle.BMH_SPECIES.extendWith(type);
1664 var carrier = argument(0, L_TYPE).withConstraint(species); // BMH bound with data
1665 Name[] constNames = new Name[] { carrier, new Name(species.getterFunction(0), carrier) };
1666 return LF_constant[type.ordinal()] = create(1, constNames, Kind.CONSTANT);
1667 }
1668
1669 private static final @Stable LambdaForm[] LF_identity = new LambdaForm[TYPE_LIMIT];
1670 private static final @Stable NamedFunction[] NF_identity = new NamedFunction[TYPE_LIMIT];
1671 private static final @Stable LambdaForm[] LF_constant = new LambdaForm[ARG_TYPE_LIMIT]; // no void
1672
1673 private static final Object createIdentityFormLock = new Object();
1674 private static void createIdentityForm(BasicType type) {
1675 // Avoid racy initialization during bootstrap
1676 UNSAFE.ensureClassInitialized(BoundMethodHandle.class);
1677 synchronized (createIdentityFormLock) {
1678 final int ord = type.ordinal();
1679 LambdaForm idForm = LF_identity[ord];
1680 if (idForm != null) {
1681 return;
1682 }
1683 char btChar = type.basicTypeChar();
1684 boolean isVoid = (type == V_TYPE);
1685 Class<?> btClass = type.btClass;
1686 MethodType idType = (isVoid) ? MethodType.methodType(btClass) : MethodType.methodType(btClass, btClass);
1687
1688 // Look up symbolic names. It might not be necessary to have these,
1689 // but if we need to emit direct references to bytecodes, it helps.
1690 MemberName idMem = new MemberName(LambdaForm.class, "identity_"+btChar, idType, REF_invokeStatic);
1691 try {
1692 idMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, idMem, null, LM_TRUSTED, NoSuchMethodException.class);
1693 } catch (IllegalAccessException|NoSuchMethodException ex) {
1694 throw newInternalError(ex);
1695 }
1696
1697 NamedFunction idFun;
1698
1699 // Create the LFs and NamedFunctions. Precompiling LFs to byte code is needed to break circular
1700 // bootstrap dependency on this method in case we're interpreting LFs
1701 if (isVoid) {
1702 Name[] idNames = new Name[] { argument(0, L_TYPE) };
1703 idForm = LambdaForm.create(1, idNames, VOID_RESULT, Kind.IDENTITY);
1704 idForm.compileToBytecode();
1705 idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1706 } else {
1707 Name[] idNames = new Name[] { argument(0, L_TYPE), argument(1, type) };
1708 idForm = LambdaForm.create(2, idNames, 1, Kind.IDENTITY);
1709 idForm.compileToBytecode();
1710 idFun = new NamedFunction(idMem, MethodHandleImpl.makeIntrinsic(idMem.getInvocationType(), idForm,
1711 MethodHandleImpl.Intrinsic.IDENTITY));
1712 }
1713
1714 LF_identity[ord] = idForm;
1715 NF_identity[ord] = idFun;
1716
1717 assert(idFun.isIdentity());
1718 }
1719 }
1720
1721 // Avoid appealing to ValueConversions at bootstrap time:
1722 private static int identity_I(int x) { return x; }
1723 private static long identity_J(long x) { return x; }
1724 private static float identity_F(float x) { return x; }
1725 private static double identity_D(double x) { return x; }
1726 private static Object identity_L(Object x) { return x; }
1727 private static void identity_V() { return; }
1728 /**
1729 * Internal marker for byte-compiled LambdaForms.
1730 */
1731 /*non-public*/
1732 @Target(ElementType.METHOD)
1733 @Retention(RetentionPolicy.RUNTIME)
1734 @interface Compiled {
1735 }
1736
1737 private static final HashMap<String,Integer> DEBUG_NAME_COUNTERS;
1738 private static final HashMap<LambdaForm,String> DEBUG_NAMES;
1739 static {
1740 if (debugEnabled()) {
1741 DEBUG_NAME_COUNTERS = new HashMap<>();
1742 DEBUG_NAMES = new HashMap<>();
1743 } else {
1744 DEBUG_NAME_COUNTERS = null;
1745 DEBUG_NAMES = null;
1746 }
1747 }
1748
1749 static {
1750 // The Holder class will contain pre-generated forms resolved
1751 // using MemberName.getFactory(). However, that doesn't initialize the
1752 // class, which subtly breaks inlining etc. By forcing
1753 // initialization of the Holder class we avoid these issues.
1754 UNSAFE.ensureClassInitialized(Holder.class);
1755 }
1756
1757 /* Placeholder class for identity and constant forms generated ahead of time */
1758 @AOTSafeClassInitializer
1759 final class Holder {}
1760
1761 // The following hack is necessary in order to suppress TRACE_INTERPRETER
1762 // during execution of the static initializes of this class.
1763 // Turning on TRACE_INTERPRETER too early will cause
1764 // stack overflows and other misbehavior during attempts to trace events
1765 // that occur during LambdaForm.<clinit>.
1766 // Therefore, do not move this line higher in this file, and do not remove.
1767 private static final boolean TRACE_INTERPRETER = MethodHandleStatics.TRACE_INTERPRETER;
1768 }