1 /*
2 * Copyright (c) 2011, 2023, 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.DontInline;
31 import jdk.internal.vm.annotation.Hidden;
32 import jdk.internal.vm.annotation.Stable;
33 import sun.invoke.util.Wrapper;
34
35 import java.lang.annotation.ElementType;
36 import java.lang.annotation.Retention;
37 import java.lang.annotation.RetentionPolicy;
38 import java.lang.annotation.Target;
39 import java.lang.reflect.Method;
40 import java.util.Arrays;
41 import java.util.HashMap;
42
43 import static java.lang.invoke.LambdaForm.BasicType.*;
44 import static java.lang.invoke.MethodHandleNatives.Constants.*;
45 import static java.lang.invoke.MethodHandleStatics.*;
46
47 /**
48 * The symbolic, non-executable form of a method handle's invocation semantics.
49 * It consists of a series of names.
50 * The first N (N=arity) names are parameters,
51 * while any remaining names are temporary values.
52 * Each temporary specifies the application of a function to some arguments.
53 * The functions are method handles, while the arguments are mixes of
54 * constant values and local names.
55 * The result of the lambda is defined as one of the names, often the last one.
56 * <p>
57 * Here is an approximate grammar:
58 * <blockquote><pre>{@code
59 * LambdaForm = "(" ArgName* ")=>{" TempName* Result "}"
60 * ArgName = "a" N ":" T
61 * TempName = "t" N ":" T "=" Function "(" Argument* ");"
62 * Function = ConstantValue
63 * Argument = NameRef | ConstantValue
64 * Result = NameRef | "void"
65 * NameRef = "a" N | "t" N
66 * N = (any whole number)
67 * T = "L" | "I" | "J" | "F" | "D" | "V"
68 * }</pre></blockquote>
69 * Names are numbered consecutively from left to right starting at zero.
70 * (The letters are merely a taste of syntax sugar.)
71 * Thus, the first temporary (if any) is always numbered N (where N=arity).
72 * Every occurrence of a name reference in an argument list must refer to
73 * a name previously defined within the same lambda.
74 * A lambda has a void result if and only if its result index is -1.
75 * If a temporary has the type "V", it cannot be the subject of a NameRef,
76 * even though possesses a number.
77 * Note that all reference types are erased to "L", which stands for {@code Object}.
78 * All subword types (boolean, byte, short, char) are erased to "I" which is {@code int}.
79 * The other types stand for the usual primitive types.
80 * <p>
81 * Function invocation closely follows the static rules of the Java verifier.
82 * Arguments and return values must exactly match when their "Name" types are
83 * considered.
84 * Conversions are allowed only if they do not change the erased type.
85 * <ul>
86 * <li>L = Object: casts are used freely to convert into and out of reference types
87 * <li>I = int: subword types are forcibly narrowed when passed as arguments (see {@code explicitCastArguments})
88 * <li>J = long: no implicit conversions
89 * <li>F = float: no implicit conversions
90 * <li>D = double: no implicit conversions
91 * <li>V = void: a function result may be void if and only if its Name is of type "V"
92 * </ul>
93 * Although implicit conversions are not allowed, explicit ones can easily be
94 * encoded by using temporary expressions which call type-transformed identity functions.
95 * <p>
96 * Examples:
97 * <blockquote><pre>{@code
98 * (a0:J)=>{ a0 }
99 * == identity(long)
100 * (a0:I)=>{ t1:V = System.out#println(a0); void }
101 * == System.out#println(int)
102 * (a0:L)=>{ t1:V = System.out#println(a0); a0 }
103 * == identity, with printing side-effect
104 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
105 * t3:L = BoundMethodHandle#target(a0);
106 * t4:L = MethodHandle#invoke(t3, t2, a1); t4 }
107 * == general invoker for unary insertArgument combination
108 * (a0:L, a1:L)=>{ t2:L = FilterMethodHandle#filter(a0);
109 * t3:L = MethodHandle#invoke(t2, a1);
110 * t4:L = FilterMethodHandle#target(a0);
111 * t5:L = MethodHandle#invoke(t4, t3); t5 }
112 * == general invoker for unary filterArgument combination
113 * (a0:L, a1:L)=>{ ...(same as previous example)...
114 * t5:L = MethodHandle#invoke(t4, t3, a1); t5 }
115 * == general invoker for unary/unary foldArgument combination
116 * (a0:L, a1:I)=>{ t2:I = identity(long).asType((int)->long)(a1); t2 }
117 * == invoker for identity method handle which performs i2l
118 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
119 * t3:L = Class#cast(t2,a1); t3 }
120 * == invoker for identity method handle which performs cast
121 * }</pre></blockquote>
122 * <p>
123 * @author John Rose, JSR 292 EG
124 */
125 class LambdaForm {
126 final int arity;
127 final int result;
128 final boolean forceInline;
129 final MethodHandle customized;
130 @Stable final Name[] names;
131 final Kind kind;
132 MemberName vmentry; // low-level behavior, or null if not yet prepared
133 private boolean isCompiled;
134
135 // Either a LambdaForm cache (managed by LambdaFormEditor) or a link to uncustomized version (for customized LF)
136 volatile Object transformCache;
137
138 public static final int VOID_RESULT = -1, LAST_RESULT = -2;
139
140 enum BasicType {
141 L_TYPE('L', Object.class, Wrapper.OBJECT, TypeKind.ReferenceType), // all reference types
142 I_TYPE('I', int.class, Wrapper.INT, TypeKind.IntType),
143 J_TYPE('J', long.class, Wrapper.LONG, TypeKind.LongType),
144 F_TYPE('F', float.class, Wrapper.FLOAT, TypeKind.FloatType),
145 D_TYPE('D', double.class, Wrapper.DOUBLE, TypeKind.DoubleType), // all primitive types
146 V_TYPE('V', void.class, Wrapper.VOID, TypeKind.VoidType); // not valid in all contexts
147
148 static final @Stable BasicType[] ALL_TYPES = BasicType.values();
149 static final @Stable BasicType[] ARG_TYPES = Arrays.copyOf(ALL_TYPES, ALL_TYPES.length-1);
150
151 static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
152 static final int TYPE_LIMIT = ALL_TYPES.length;
153
154 final char btChar;
155 final Class<?> btClass;
156 final Wrapper btWrapper;
157 final TypeKind btKind;
158
159 private BasicType(char btChar, Class<?> btClass, Wrapper wrapper, TypeKind typeKind) {
160 this.btChar = btChar;
161 this.btClass = btClass;
162 this.btWrapper = wrapper;
163 this.btKind = typeKind;
164 }
165
166 char basicTypeChar() {
167 return btChar;
168 }
169 Class<?> basicTypeClass() {
170 return btClass;
171 }
172 Wrapper basicTypeWrapper() {
173 return btWrapper;
174 }
175 TypeKind basicTypeKind() {
176 return btKind;
177 }
178 int basicTypeSlots() {
179 return btWrapper.stackSlots();
180 }
181
182 static BasicType basicType(byte type) {
183 return ALL_TYPES[type];
184 }
185 static BasicType basicType(char type) {
186 return switch (type) {
187 case 'L' -> L_TYPE;
188 case 'I' -> I_TYPE;
189 case 'J' -> J_TYPE;
190 case 'F' -> F_TYPE;
191 case 'D' -> D_TYPE;
192 case 'V' -> V_TYPE;
193 // all subword types are represented as ints
194 case 'Z', 'B', 'S', 'C' -> I_TYPE;
195 default -> throw newInternalError("Unknown type char: '" + type + "'");
196 };
197 }
198 static BasicType basicType(Class<?> type) {
199 return basicType(Wrapper.basicTypeChar(type));
200 }
201 static int[] basicTypeOrds(BasicType[] types) {
202 if (types == null) {
203 return null;
204 }
205 int[] a = new int[types.length];
206 for(int i = 0; i < types.length; ++i) {
207 a[i] = types[i].ordinal();
208 }
209 return a;
210 }
211
212 static char basicTypeChar(Class<?> type) {
213 return basicType(type).btChar;
214 }
215
216 static int[] basicTypesOrd(Class<?>[] types) {
217 int[] ords = new int[types.length];
218 for (int i = 0; i < ords.length; i++) {
219 ords[i] = basicType(types[i]).ordinal();
220 }
221 return ords;
222 }
223
224 static boolean isBasicTypeChar(char c) {
225 return "LIJFDV".indexOf(c) >= 0;
226 }
227 static boolean isArgBasicTypeChar(char c) {
228 return "LIJFD".indexOf(c) >= 0;
229 }
230
231 static { assert(checkBasicType()); }
232 private static boolean checkBasicType() {
233 for (int i = 0; i < ARG_TYPE_LIMIT; i++) {
234 assert ARG_TYPES[i].ordinal() == i;
235 assert ARG_TYPES[i] == ALL_TYPES[i];
236 }
237 for (int i = 0; i < TYPE_LIMIT; i++) {
238 assert ALL_TYPES[i].ordinal() == i;
239 }
240 assert ALL_TYPES[TYPE_LIMIT - 1] == V_TYPE;
241 assert !Arrays.asList(ARG_TYPES).contains(V_TYPE);
242 return true;
243 }
244 }
245
246 enum Kind {
247 GENERIC("invoke"),
248 ZERO("zero"),
249 IDENTITY("identity"),
250 BOUND_REINVOKER("BMH.reinvoke", "reinvoke"),
251 REINVOKER("MH.reinvoke", "reinvoke"),
252 DELEGATE("MH.delegate", "delegate"),
253 EXACT_LINKER("MH.invokeExact_MT", "invokeExact_MT"),
254 EXACT_INVOKER("MH.exactInvoker", "exactInvoker"),
255 GENERIC_LINKER("MH.invoke_MT", "invoke_MT"),
256 GENERIC_INVOKER("MH.invoker", "invoker"),
257 LINK_TO_TARGET_METHOD("linkToTargetMethod"),
258 LINK_TO_CALL_SITE("linkToCallSite"),
259 DIRECT_INVOKE_VIRTUAL("DMH.invokeVirtual", "invokeVirtual"),
260 DIRECT_INVOKE_SPECIAL("DMH.invokeSpecial", "invokeSpecial"),
261 DIRECT_INVOKE_SPECIAL_IFC("DMH.invokeSpecialIFC", "invokeSpecialIFC"),
262 DIRECT_INVOKE_STATIC("DMH.invokeStatic", "invokeStatic"),
263 DIRECT_NEW_INVOKE_SPECIAL("DMH.newInvokeSpecial", "newInvokeSpecial"),
264 DIRECT_INVOKE_INTERFACE("DMH.invokeInterface", "invokeInterface"),
265 DIRECT_INVOKE_STATIC_INIT("DMH.invokeStaticInit", "invokeStaticInit"),
266 GET_REFERENCE("getReference"),
267 PUT_REFERENCE("putReference"),
268 GET_REFERENCE_VOLATILE("getReferenceVolatile"),
269 PUT_REFERENCE_VOLATILE("putReferenceVolatile"),
270 GET_INT("getInt"),
271 PUT_INT("putInt"),
272 GET_INT_VOLATILE("getIntVolatile"),
273 PUT_INT_VOLATILE("putIntVolatile"),
274 GET_BOOLEAN("getBoolean"),
275 PUT_BOOLEAN("putBoolean"),
276 GET_BOOLEAN_VOLATILE("getBooleanVolatile"),
277 PUT_BOOLEAN_VOLATILE("putBooleanVolatile"),
278 GET_BYTE("getByte"),
279 PUT_BYTE("putByte"),
280 GET_BYTE_VOLATILE("getByteVolatile"),
281 PUT_BYTE_VOLATILE("putByteVolatile"),
282 GET_CHAR("getChar"),
283 PUT_CHAR("putChar"),
284 GET_CHAR_VOLATILE("getCharVolatile"),
285 PUT_CHAR_VOLATILE("putCharVolatile"),
286 GET_SHORT("getShort"),
287 PUT_SHORT("putShort"),
288 GET_SHORT_VOLATILE("getShortVolatile"),
289 PUT_SHORT_VOLATILE("putShortVolatile"),
290 GET_LONG("getLong"),
291 PUT_LONG("putLong"),
292 GET_LONG_VOLATILE("getLongVolatile"),
293 PUT_LONG_VOLATILE("putLongVolatile"),
294 GET_FLOAT("getFloat"),
295 PUT_FLOAT("putFloat"),
296 GET_FLOAT_VOLATILE("getFloatVolatile"),
297 PUT_FLOAT_VOLATILE("putFloatVolatile"),
298 GET_DOUBLE("getDouble"),
299 PUT_DOUBLE("putDouble"),
300 GET_DOUBLE_VOLATILE("getDoubleVolatile"),
301 PUT_DOUBLE_VOLATILE("putDoubleVolatile"),
302 TRY_FINALLY("tryFinally"),
303 TABLE_SWITCH("tableSwitch"),
304 COLLECT("collect"),
305 COLLECTOR("collector"),
306 CONVERT("convert"),
307 SPREAD("spread"),
308 LOOP("loop"),
309 FIELD("field"),
310 GUARD("guard"),
311 GUARD_WITH_CATCH("guardWithCatch"),
312 VARHANDLE_EXACT_INVOKER("VH.exactInvoker"),
313 VARHANDLE_INVOKER("VH.invoker", "invoker"),
314 VARHANDLE_LINKER("VH.invoke_MT", "invoke_MT");
315
316 final String defaultLambdaName;
317 final String methodName;
318
319 private Kind(String defaultLambdaName) {
320 this(defaultLambdaName, defaultLambdaName);
321 }
322
323 private Kind(String defaultLambdaName, String methodName) {
324 this.defaultLambdaName = defaultLambdaName;
325 this.methodName = methodName;
326 }
327 }
328
329 // private version that doesn't do checks or defensive copies
330 private LambdaForm(int arity, int result, boolean forceInline, MethodHandle customized, Name[] names, Kind kind) {
331 this.arity = arity;
332 this.result = result;
333 this.forceInline = forceInline;
334 this.customized = customized;
335 this.names = names;
336 this.kind = kind;
337 this.vmentry = null;
338 this.isCompiled = false;
339 }
340
341 // root factory pre/post processing and calls simple constructor
342 private static LambdaForm create(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized, Kind kind) {
343 names = names.clone();
344 assert(namesOK(arity, names));
345 result = fixResult(result, names);
346
347 boolean canInterpret = normalizeNames(arity, names);
348 LambdaForm form = new LambdaForm(arity, result, forceInline, customized, names, kind);
349 assert(form.nameRefsAreLegal());
350 if (!canInterpret) {
351 form.compileToBytecode();
352 }
353 return form;
354 }
355
356 // derived factories with defaults
357 private static final int DEFAULT_RESULT = LAST_RESULT;
358 private static final boolean DEFAULT_FORCE_INLINE = true;
359 private static final MethodHandle DEFAULT_CUSTOMIZED = null;
360 private static final Kind DEFAULT_KIND = Kind.GENERIC;
361
362 static LambdaForm create(int arity, Name[] names, int result) {
363 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
364 }
365 static LambdaForm create(int arity, Name[] names, int result, Kind kind) {
366 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
367 }
368 static LambdaForm create(int arity, Name[] names) {
369 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
370 }
371 static LambdaForm create(int arity, Name[] names, Kind kind) {
372 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
373 }
374 static LambdaForm create(int arity, Name[] names, boolean forceInline, Kind kind) {
375 return create(arity, names, DEFAULT_RESULT, forceInline, DEFAULT_CUSTOMIZED, kind);
376 }
377
378 private static LambdaForm createBlankForType(MethodType mt) {
379 // Make a blank lambda form, which returns a constant zero or null.
380 // It is used as a template for managing the invocation of similar forms that are non-empty.
381 // Called only from getPreparedForm.
382 int arity = mt.parameterCount();
383 int result = (mt.returnType() == void.class || mt.returnType() == Void.class) ? VOID_RESULT : arity;
384 Name[] names = buildEmptyNames(arity, mt, result == VOID_RESULT);
385 boolean canInterpret = normalizeNames(arity, names);
386 LambdaForm form = new LambdaForm(arity, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, names, Kind.ZERO);
387 assert(form.nameRefsAreLegal() && form.isEmpty() && isValidSignature(form.basicTypeSignature()));
388 if (!canInterpret) {
389 form.compileToBytecode();
390 }
391 return form;
392 }
393
394 private static Name[] buildEmptyNames(int arity, MethodType mt, boolean isVoid) {
395 Name[] names = arguments(isVoid ? 0 : 1, mt);
396 if (!isVoid) {
397 Name zero = new Name(constantZero(basicType(mt.returnType())));
398 names[arity] = zero.newIndex(arity);
399 }
400 assert(namesOK(arity, names));
401 return names;
402 }
403
404 private static int fixResult(int result, Name[] names) {
405 if (result == LAST_RESULT)
406 result = names.length - 1; // might still be void
407 if (result >= 0 && names[result].type == V_TYPE)
408 result = VOID_RESULT;
409 return result;
410 }
411
412 static boolean debugNames() {
413 return DEBUG_NAME_COUNTERS != null;
414 }
415
416 static void associateWithDebugName(LambdaForm form, String name) {
417 assert (debugNames());
418 synchronized (DEBUG_NAMES) {
419 DEBUG_NAMES.put(form, name);
420 }
421 }
422
423 String lambdaName() {
424 if (DEBUG_NAMES != null) {
425 synchronized (DEBUG_NAMES) {
426 String name = DEBUG_NAMES.get(this);
427 if (name == null) {
428 name = generateDebugName();
429 }
430 return name;
431 }
432 }
433 return kind.defaultLambdaName;
434 }
435
436 private String generateDebugName() {
437 assert (debugNames());
438 String debugNameStem = kind.defaultLambdaName;
439 Integer ctr = DEBUG_NAME_COUNTERS.getOrDefault(debugNameStem, 0);
440 DEBUG_NAME_COUNTERS.put(debugNameStem, ctr + 1);
441 StringBuilder buf = new StringBuilder(debugNameStem);
442 int leadingZero = buf.length();
443 buf.append((int) ctr);
444 for (int i = buf.length() - leadingZero; i < 3; i++) {
445 buf.insert(leadingZero, '0');
446 }
447 buf.append('_');
448 buf.append(basicTypeSignature());
449 String name = buf.toString();
450 associateWithDebugName(this, name);
451 return name;
452 }
453
454 private static boolean namesOK(int arity, Name[] names) {
455 for (int i = 0; i < names.length; i++) {
456 Name n = names[i];
457 assert(n != null) : "n is null";
458 if (i < arity)
459 assert( n.isParam()) : n + " is not param at " + i;
460 else
461 assert(!n.isParam()) : n + " is param at " + i;
462 }
463 return true;
464 }
465
466 /** Customize LambdaForm for a particular MethodHandle */
467 LambdaForm customize(MethodHandle mh) {
468 if (customized == mh) {
469 return this;
470 }
471 LambdaForm customForm = LambdaForm.create(arity, names, result, forceInline, mh, kind);
472 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
473 // If shared LambdaForm has been compiled, compile customized version as well.
474 customForm.compileToBytecode();
475 }
476 customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
477 return customForm;
478 }
479
480 /** Get uncustomized flavor of the LambdaForm */
481 LambdaForm uncustomize() {
482 if (customized == null) {
483 return this;
484 }
485 assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
486 LambdaForm uncustomizedForm = (LambdaForm)transformCache;
487 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
488 // If customized LambdaForm has been compiled, compile uncustomized version as well.
489 uncustomizedForm.compileToBytecode();
490 }
491 return uncustomizedForm;
492 }
493
494 /** Renumber and/or replace params so that they are interned and canonically numbered.
495 * @return true if we can interpret
496 */
497 private static boolean normalizeNames(int arity, Name[] names) {
498 Name[] oldNames = null;
499 int maxOutArity = 0;
500 int changesStart = 0;
501 for (int i = 0; i < names.length; i++) {
502 Name n = names[i];
503 if (!n.initIndex(i)) {
504 if (oldNames == null) {
505 oldNames = names.clone();
506 changesStart = i;
507 }
508 names[i] = n.cloneWithIndex(i);
509 }
510 if (n.arguments != null && maxOutArity < n.arguments.length)
511 maxOutArity = n.arguments.length;
512 }
513 if (oldNames != null) {
514 int startFixing = arity;
515 if (startFixing <= changesStart)
516 startFixing = changesStart+1;
517 for (int i = startFixing; i < names.length; i++) {
518 Name fixed = names[i].replaceNames(oldNames, names, changesStart, i);
519 names[i] = fixed.newIndex(i);
520 }
521 }
522 int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
523 boolean needIntern = false;
524 for (int i = 0; i < maxInterned; i++) {
525 Name n = names[i], n2 = internArgument(n);
526 if (n != n2) {
527 names[i] = n2;
528 needIntern = true;
529 }
530 }
531 if (needIntern) {
532 for (int i = arity; i < names.length; i++) {
533 names[i].internArguments();
534 }
535 }
536
537 // return true if we can interpret
538 if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
539 // Cannot use LF interpreter on very high arity expressions.
540 assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
541 return false;
542 }
543 return true;
544 }
545
546 /**
547 * Check that all embedded Name references are localizable to this lambda,
548 * and are properly ordered after their corresponding definitions.
549 * <p>
550 * Note that a Name can be local to multiple lambdas, as long as
551 * it possesses the same index in each use site.
552 * This allows Name references to be freely reused to construct
553 * fresh lambdas, without confusion.
554 */
555 boolean nameRefsAreLegal() {
556 assert(arity >= 0 && arity <= names.length);
557 assert(result >= -1 && result < names.length);
558 // Do all names possess an index consistent with their local definition order?
559 for (int i = 0; i < arity; i++) {
560 Name n = names[i];
561 assert(n.index() == i) : Arrays.asList(n.index(), i);
562 assert(n.isParam());
563 }
564 // Also, do all local name references
565 for (int i = arity; i < names.length; i++) {
566 Name n = names[i];
567 assert(n.index() == i);
568 for (Object arg : n.arguments) {
569 if (arg instanceof Name n2) {
570 int i2 = n2.index;
571 assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
572 assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
573 assert(i2 < i); // ref must come after def!
574 }
575 }
576 }
577 return true;
578 }
579
580 // /** Invoke this form on the given arguments. */
581 // final Object invoke(Object... args) throws Throwable {
582 // // NYI: fit this into the fast path?
583 // return interpretWithArguments(args);
584 // }
585
586 /** Report the return type. */
587 BasicType returnType() {
588 if (result < 0) return V_TYPE;
589 Name n = names[result];
590 return n.type;
591 }
592
593 /** Report the N-th argument type. */
594 BasicType parameterType(int n) {
595 return parameter(n).type;
596 }
597
598 /** Report the N-th argument name. */
599 Name parameter(int n) {
600 Name param = names[n];
601 assert(n < arity && param.isParam());
602 return param;
603 }
604
605 /** Report the N-th argument type constraint. */
606 Object parameterConstraint(int n) {
607 return parameter(n).constraint;
608 }
609
610 /** Report the arity. */
611 int arity() {
612 return arity;
613 }
614
615 /** Report the number of expressions (non-parameter names). */
616 int expressionCount() {
617 return names.length - arity;
618 }
619
620 /** Return the method type corresponding to my basic type signature. */
621 MethodType methodType() {
622 Class<?>[] ptypes = new Class<?>[arity];
623 for (int i = 0; i < arity; ++i) {
624 ptypes[i] = parameterType(i).btClass;
625 }
626 return MethodType.methodType(returnType().btClass, ptypes, true);
627 }
628
629 /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
630 final String basicTypeSignature() {
631 StringBuilder buf = new StringBuilder(arity() + 3);
632 for (int i = 0, a = arity(); i < a; i++)
633 buf.append(parameterType(i).basicTypeChar());
634 return buf.append('_').append(returnType().basicTypeChar()).toString();
635 }
636 static int signatureArity(String sig) {
637 assert(isValidSignature(sig));
638 return sig.indexOf('_');
639 }
640 static boolean isValidSignature(String sig) {
641 int arity = sig.indexOf('_');
642 if (arity < 0) return false; // must be of the form *_*
643 int siglen = sig.length();
644 if (siglen != arity + 2) return false; // *_X
645 for (int i = 0; i < siglen; i++) {
646 if (i == arity) continue; // skip '_'
647 char c = sig.charAt(i);
648 if (c == 'V')
649 return (i == siglen - 1 && arity == siglen - 2);
650 if (!isArgBasicTypeChar(c)) return false; // must be [LIJFD]
651 }
652 return true; // [LIJFD]*_[LIJFDV]
653 }
654
655 /**
656 * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
657 */
658 boolean isSelectAlternative(int pos) {
659 // selectAlternative idiom:
660 // t_{n}:L=MethodHandleImpl.selectAlternative(...)
661 // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
662 if (pos+1 >= names.length) return false;
663 Name name0 = names[pos];
664 Name name1 = names[pos+1];
665 return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
666 name1.isInvokeBasic() &&
667 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
668 lastUseIndex(name0) == pos+1; // t_{n} is local: used only in t_{n+1}
669 }
670
671 private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
672 if (pos+2 >= names.length) return false;
673 Name name0 = names[pos];
674 Name name1 = names[pos+1];
675 Name name2 = names[pos+2];
676 return name1.refersTo(MethodHandleImpl.class, idiomName) &&
677 name0.isInvokeBasic() &&
678 name2.isInvokeBasic() &&
679 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
680 lastUseIndex(name0) == pos+1 && // t_{n} is local: used only in t_{n+1}
681 name2.lastUseIndex(name1) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
682 lastUseIndex(name1) == pos+2; // t_{n+1} is local: used only in t_{n+2}
683 }
684
685 /**
686 * Check if i-th name is a start of GuardWithCatch idiom.
687 */
688 boolean isGuardWithCatch(int pos) {
689 // GuardWithCatch idiom:
690 // t_{n}:L=MethodHandle.invokeBasic(...)
691 // t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
692 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
693 return isMatchingIdiom(pos, "guardWithCatch", 3);
694 }
695
696 /**
697 * Check if i-th name is a start of the tryFinally idiom.
698 */
699 boolean isTryFinally(int pos) {
700 // tryFinally idiom:
701 // t_{n}:L=MethodHandle.invokeBasic(...)
702 // t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
703 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
704 return isMatchingIdiom(pos, "tryFinally", 2);
705 }
706
707 /**
708 * Check if i-th name is a start of the tableSwitch idiom.
709 */
710 boolean isTableSwitch(int pos) {
711 // tableSwitch idiom:
712 // t_{n}:L=MethodHandle.invokeBasic(...) // args
713 // t_{n+1}:L=MethodHandleImpl.tableSwitch(*, *, *, t_{n})
714 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
715 if (pos + 2 >= names.length) return false;
716
717 final int POS_COLLECT_ARGS = pos;
718 final int POS_TABLE_SWITCH = pos + 1;
719 final int POS_UNBOX_RESULT = pos + 2;
720
721 Name collectArgs = names[POS_COLLECT_ARGS];
722 Name tableSwitch = names[POS_TABLE_SWITCH];
723 Name unboxResult = names[POS_UNBOX_RESULT];
724 return tableSwitch.refersTo(MethodHandleImpl.class, "tableSwitch") &&
725 collectArgs.isInvokeBasic() &&
726 unboxResult.isInvokeBasic() &&
727 tableSwitch.lastUseIndex(collectArgs) == 3 && // t_{n+1}:L=MethodHandleImpl.<invoker>(*, *, *, t_{n});
728 lastUseIndex(collectArgs) == POS_TABLE_SWITCH && // t_{n} is local: used only in t_{n+1}
729 unboxResult.lastUseIndex(tableSwitch) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
730 lastUseIndex(tableSwitch) == POS_UNBOX_RESULT; // t_{n+1} is local: used only in t_{n+2}
731 }
732
733 /**
734 * Check if i-th name is a start of the loop idiom.
735 */
736 boolean isLoop(int pos) {
737 // loop idiom:
738 // t_{n}:L=MethodHandle.invokeBasic(...)
739 // t_{n+1}:L=MethodHandleImpl.loop(types, *, t_{n})
740 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
741 return isMatchingIdiom(pos, "loop", 2);
742 }
743
744 /*
745 * Code generation issues:
746 *
747 * Compiled LFs should be reusable in general.
748 * The biggest issue is how to decide when to pull a name into
749 * the bytecode, versus loading a reified form from the MH data.
750 *
751 * For example, an asType wrapper may require execution of a cast
752 * after a call to a MH. The target type of the cast can be placed
753 * as a constant in the LF itself. This will force the cast type
754 * to be compiled into the bytecodes and native code for the MH.
755 * Or, the target type of the cast can be erased in the LF, and
756 * loaded from the MH data. (Later on, if the MH as a whole is
757 * inlined, the data will flow into the inlined instance of the LF,
758 * as a constant, and the end result will be an optimal cast.)
759 *
760 * This erasure of cast types can be done with any use of
761 * reference types. It can also be done with whole method
762 * handles. Erasing a method handle might leave behind
763 * LF code that executes correctly for any MH of a given
764 * type, and load the required MH from the enclosing MH's data.
765 * Or, the erasure might even erase the expected MT.
766 *
767 * Also, for direct MHs, the MemberName of the target
768 * could be erased, and loaded from the containing direct MH.
769 * As a simple case, a LF for all int-valued non-static
770 * field getters would perform a cast on its input argument
771 * (to non-constant base type derived from the MemberName)
772 * and load an integer value from the input object
773 * (at a non-constant offset also derived from the MemberName).
774 * Such MN-erased LFs would be inlinable back to optimized
775 * code, whenever a constant enclosing DMH is available
776 * to supply a constant MN from its data.
777 *
778 * The main problem here is to keep LFs reasonably generic,
779 * while ensuring that hot spots will inline good instances.
780 * "Reasonably generic" means that we don't end up with
781 * repeated versions of bytecode or machine code that do
782 * not differ in their optimized form. Repeated versions
783 * of machine would have the undesirable overheads of
784 * (a) redundant compilation work and (b) extra I$ pressure.
785 * To control repeated versions, we need to be ready to
786 * erase details from LFs and move them into MH data,
787 * whenever those details are not relevant to significant
788 * optimization. "Significant" means optimization of
789 * code that is actually hot.
790 *
791 * Achieving this may require dynamic splitting of MHs, by replacing
792 * a generic LF with a more specialized one, on the same MH,
793 * if (a) the MH is frequently executed and (b) the MH cannot
794 * be inlined into a containing caller, such as an invokedynamic.
795 *
796 * Compiled LFs that are no longer used should be GC-able.
797 * If they contain non-BCP references, they should be properly
798 * interlinked with the class loader(s) that their embedded types
799 * depend on. This probably means that reusable compiled LFs
800 * will be tabulated (indexed) on relevant class loaders,
801 * or else that the tables that cache them will have weak links.
802 */
803
804 /**
805 * Make this LF directly executable, as part of a MethodHandle.
806 * Invariant: Every MH which is invoked must prepare its LF
807 * before invocation.
808 * (In principle, the JVM could do this very lazily,
809 * as a sort of pre-invocation linkage step.)
810 */
811 public void prepare() {
812 if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
813 compileToBytecode();
814 }
815 if (this.vmentry != null) {
816 // already prepared (e.g., a primitive DMH invoker form)
817 return;
818 }
819 MethodType mtype = methodType();
820 LambdaForm prep = mtype.form().cachedLambdaForm(MethodTypeForm.LF_INTERPRET);
821 if (prep == null) {
822 assert (isValidSignature(basicTypeSignature()));
823 prep = LambdaForm.createBlankForType(mtype);
824 prep.vmentry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
825 prep = mtype.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, prep);
826 }
827 this.vmentry = prep.vmentry;
828 // TO DO: Maybe add invokeGeneric, invokeWithArguments
829 }
830
831 private static @Stable PerfCounter LF_FAILED;
832
833 private static PerfCounter failedCompilationCounter() {
834 if (LF_FAILED == null) {
835 LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
836 }
837 return LF_FAILED;
838 }
839
840 /** Generate optimizable bytecode for this form. */
841 void compileToBytecode() {
842 if (forceInterpretation()) {
843 return; // this should not be compiled
844 }
845 if (vmentry != null && isCompiled) {
846 return; // already compiled somehow
847 }
848
849 // Obtain the invoker MethodType outside of the following try block.
850 // This ensures that an IllegalArgumentException is directly thrown if the
851 // type would have 256 or more parameters
852 MethodType invokerType = methodType();
853 assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
854 try {
855 vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
856 if (TRACE_INTERPRETER)
857 traceInterpreter("compileToBytecode", this);
858 isCompiled = true;
859 } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
860 // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
861 invocationCounter = -1;
862 failedCompilationCounter().increment();
863 if (LOG_LF_COMPILATION_FAILURE) {
864 System.out.println("LambdaForm compilation failed: " + this);
865 bge.printStackTrace(System.out);
866 }
867 } catch (Error e) {
868 // Pass through any error
869 throw e;
870 } catch (Exception e) {
871 // Wrap any exception
872 throw newInternalError(this.toString(), e);
873 }
874 }
875
876 // The next few routines are called only from assert expressions
877 // They verify that the built-in invokers process the correct raw data types.
878 private static boolean argumentTypesMatch(String sig, Object[] av) {
879 int arity = signatureArity(sig);
880 assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
881 assert(av[0] instanceof MethodHandle) : "av[0] not instance of MethodHandle: " + av[0];
882 MethodHandle mh = (MethodHandle) av[0];
883 MethodType mt = mh.type();
884 assert(mt.parameterCount() == arity-1);
885 for (int i = 0; i < av.length; i++) {
886 Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
887 assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
888 }
889 return true;
890 }
891 private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
892 // The following line is needed because (...)void method handles can use non-void invokers
893 if (type == void.class) tc = V_TYPE; // can drop any kind of value
894 assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
895 switch (tc) {
896 case I_TYPE: assert checkInt(type, x) : "checkInt(" + type + "," + x +")"; break;
897 case J_TYPE: assert x instanceof Long : "instanceof Long: " + x; break;
898 case F_TYPE: assert x instanceof Float : "instanceof Float: " + x; break;
899 case D_TYPE: assert x instanceof Double : "instanceof Double: " + x; break;
900 case L_TYPE: assert checkRef(type, x) : "checkRef(" + type + "," + x + ")"; break;
901 case V_TYPE: break; // allow anything here; will be dropped
902 default: assert(false);
903 }
904 return true;
905 }
906 private static boolean checkInt(Class<?> type, Object x) {
907 assert(x instanceof Integer);
908 if (type == int.class) return true;
909 Wrapper w = Wrapper.forBasicType(type);
910 assert(w.isSubwordOrInt());
911 Object x1 = Wrapper.INT.wrap(w.wrap(x));
912 return x.equals(x1);
913 }
914 private static boolean checkRef(Class<?> type, Object x) {
915 assert(!type.isPrimitive());
916 if (x == null) return true;
917 if (type.isInterface()) return true;
918 return type.isInstance(x);
919 }
920
921 /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
922 private static final int COMPILE_THRESHOLD;
923 static {
924 COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
925 }
926 private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
927
928 private boolean forceInterpretation() {
929 return invocationCounter == -1;
930 }
931
932 /** Interpretively invoke this form on the given arguments. */
933 @Hidden
934 @DontInline
935 Object interpretWithArguments(Object... argumentValues) throws Throwable {
936 if (TRACE_INTERPRETER)
937 return interpretWithArgumentsTracing(argumentValues);
938 checkInvocationCounter();
939 assert(arityCheck(argumentValues));
940 Object[] values = Arrays.copyOf(argumentValues, names.length);
941 for (int i = argumentValues.length; i < values.length; i++) {
942 values[i] = interpretName(names[i], values);
943 }
944 Object rv = (result < 0) ? null : values[result];
945 assert(resultCheck(argumentValues, rv));
946 return rv;
947 }
948
949 /** Evaluate a single Name within this form, applying its function to its arguments. */
950 @Hidden
951 @DontInline
952 Object interpretName(Name name, Object[] values) throws Throwable {
953 if (TRACE_INTERPRETER)
954 traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
955 Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
956 for (int i = 0; i < arguments.length; i++) {
957 Object a = arguments[i];
958 if (a instanceof Name n) {
959 int i2 = n.index();
960 assert(names[i2] == a);
961 a = values[i2];
962 arguments[i] = a;
963 }
964 }
965 return name.function.invokeWithArguments(arguments);
966 }
967
968 private void checkInvocationCounter() {
969 if (COMPILE_THRESHOLD != 0 &&
970 !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
971 invocationCounter++; // benign race
972 if (invocationCounter >= COMPILE_THRESHOLD) {
973 // Replace vmentry with a bytecode version of this LF.
974 compileToBytecode();
975 }
976 }
977 }
978 Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
979 traceInterpreter("[ interpretWithArguments", this, argumentValues);
980 if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
981 int ctr = invocationCounter++; // benign race
982 traceInterpreter("| invocationCounter", ctr);
983 if (invocationCounter >= COMPILE_THRESHOLD) {
984 compileToBytecode();
985 }
986 }
987 Object rval;
988 try {
989 assert(arityCheck(argumentValues));
990 Object[] values = Arrays.copyOf(argumentValues, names.length);
991 for (int i = argumentValues.length; i < values.length; i++) {
992 values[i] = interpretName(names[i], values);
993 }
994 rval = (result < 0) ? null : values[result];
995 } catch (Throwable ex) {
996 traceInterpreter("] throw =>", ex);
997 throw ex;
998 }
999 traceInterpreter("] return =>", rval);
1000 return rval;
1001 }
1002
1003 static void traceInterpreter(String event, Object obj, Object... args) {
1004 if (TRACE_INTERPRETER) {
1005 System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
1006 }
1007 }
1008 static void traceInterpreter(String event, Object obj) {
1009 traceInterpreter(event, obj, (Object[])null);
1010 }
1011 private boolean arityCheck(Object[] argumentValues) {
1012 assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
1013 // also check that the leading (receiver) argument is somehow bound to this LF:
1014 assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
1015 MethodHandle mh = (MethodHandle) argumentValues[0];
1016 assert(mh.internalForm() == this);
1017 // note: argument #0 could also be an interface wrapper, in the future
1018 argumentTypesMatch(basicTypeSignature(), argumentValues);
1019 return true;
1020 }
1021 private boolean resultCheck(Object[] argumentValues, Object result) {
1022 MethodHandle mh = (MethodHandle) argumentValues[0];
1023 MethodType mt = mh.type();
1024 assert(valueMatches(returnType(), mt.returnType(), result));
1025 return true;
1026 }
1027
1028 private boolean isEmpty() {
1029 if (result < 0)
1030 return (names.length == arity);
1031 else if (result == arity && names.length == arity + 1)
1032 return names[arity].isConstantZero();
1033 else
1034 return false;
1035 }
1036
1037 public String toString() {
1038 return debugString(-1);
1039 }
1040
1041 String debugString(int indentLevel) {
1042 String prefix = MethodHandle.debugPrefix(indentLevel);
1043 String lambdaName = lambdaName();
1044 StringBuilder buf = new StringBuilder(lambdaName);
1045 buf.append("=Lambda(");
1046 for (int i = 0; i < names.length; i++) {
1047 if (i == arity) buf.append(")=>{");
1048 Name n = names[i];
1049 if (i >= arity) buf.append("\n ").append(prefix);
1050 buf.append(n.paramString());
1051 if (i < arity) {
1052 if (i+1 < arity) buf.append(",");
1053 continue;
1054 }
1055 buf.append("=").append(n.exprString());
1056 buf.append(";");
1057 }
1058 if (arity == names.length) buf.append(")=>{");
1059 buf.append(result < 0 ? "void" : names[result]).append("}");
1060 if (TRACE_INTERPRETER) {
1061 // Extra verbosity:
1062 buf.append(":").append(basicTypeSignature());
1063 buf.append("/").append(vmentry);
1064 }
1065 return buf.toString();
1066 }
1067
1068 @Override
1069 public boolean equals(Object obj) {
1070 return obj instanceof LambdaForm lf && equals(lf);
1071 }
1072 public boolean equals(LambdaForm that) {
1073 if (this.result != that.result) return false;
1074 return Arrays.equals(this.names, that.names);
1075 }
1076 public int hashCode() {
1077 return result + 31 * Arrays.hashCode(names);
1078 }
1079 LambdaFormEditor editor() {
1080 return LambdaFormEditor.lambdaFormEditor(this);
1081 }
1082
1083 boolean contains(Name name) {
1084 int pos = name.index();
1085 if (pos >= 0) {
1086 return pos < names.length && name.equals(names[pos]);
1087 }
1088 for (int i = arity; i < names.length; i++) {
1089 if (name.equals(names[i]))
1090 return true;
1091 }
1092 return false;
1093 }
1094
1095 static class NamedFunction {
1096 final MemberName member;
1097 private @Stable MethodHandle resolvedHandle;
1098 private @Stable MethodType type;
1099
1100 NamedFunction(MethodHandle resolvedHandle) {
1101 this(resolvedHandle.internalMemberName(), resolvedHandle);
1102 }
1103 NamedFunction(MemberName member, MethodHandle resolvedHandle) {
1104 this.member = member;
1105 this.resolvedHandle = resolvedHandle;
1106 // The following assert is almost always correct, but will fail for corner cases, such as PrivateInvokeTest.
1107 //assert(!isInvokeBasic(member));
1108 }
1109 NamedFunction(MethodType basicInvokerType) {
1110 assert(basicInvokerType == basicInvokerType.basicType()) : basicInvokerType;
1111 if (basicInvokerType.parameterSlotCount() < MethodType.MAX_MH_INVOKER_ARITY) {
1112 this.resolvedHandle = basicInvokerType.invokers().basicInvoker();
1113 this.member = resolvedHandle.internalMemberName();
1114 } else {
1115 // necessary to pass BigArityTest
1116 this.member = Invokers.invokeBasicMethod(basicInvokerType);
1117 }
1118 assert(isInvokeBasic(member));
1119 }
1120
1121 private static boolean isInvokeBasic(MemberName member) {
1122 return member != null &&
1123 member.getDeclaringClass() == MethodHandle.class &&
1124 "invokeBasic".equals(member.getName());
1125 }
1126
1127 // The next 2 constructors are used to break circular dependencies on MH.invokeStatic, etc.
1128 // Any LambdaForm containing such a member is not interpretable.
1129 // This is OK, since all such LFs are prepared with special primitive vmentry points.
1130 // And even without the resolvedHandle, the name can still be compiled and optimized.
1131 NamedFunction(Method method) {
1132 this(new MemberName(method));
1133 }
1134 NamedFunction(MemberName member) {
1135 this(member, null);
1136 }
1137
1138 MethodHandle resolvedHandle() {
1139 if (resolvedHandle == null) resolve();
1140 return resolvedHandle;
1141 }
1142
1143 synchronized void resolve() {
1144 if (resolvedHandle == null) {
1145 resolvedHandle = DirectMethodHandle.make(member);
1146 }
1147 }
1148
1149 @Override
1150 public boolean equals(Object other) {
1151 if (this == other) return true;
1152 if (other == null) return false;
1153 return (other instanceof NamedFunction that)
1154 && this.member != null
1155 && this.member.equals(that.member);
1156 }
1157
1158 @Override
1159 public int hashCode() {
1160 if (member != null)
1161 return member.hashCode();
1162 return super.hashCode();
1163 }
1164
1165 static final MethodType INVOKER_METHOD_TYPE =
1166 MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1167
1168 private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1169 typeForm = typeForm.basicType().form(); // normalize to basic type
1170 MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1171 if (mh != null) return mh;
1172 MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm); // this could take a while
1173 mh = DirectMethodHandle.make(invoker);
1174 MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1175 if (mh2 != null) return mh2; // benign race
1176 if (!mh.type().equals(INVOKER_METHOD_TYPE))
1177 throw newInternalError(mh.debugString());
1178 return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1179 }
1180
1181 @Hidden
1182 Object invokeWithArguments(Object... arguments) throws Throwable {
1183 // If we have a cached invoker, call it right away.
1184 // NOTE: The invoker always returns a reference value.
1185 if (TRACE_INTERPRETER) return invokeWithArgumentsTracing(arguments);
1186 return invoker().invokeBasic(resolvedHandle(), arguments);
1187 }
1188
1189 @Hidden
1190 Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1191 Object rval;
1192 try {
1193 traceInterpreter("[ call", this, arguments);
1194 // resolvedHandle might be uninitialized, ok for tracing
1195 if (resolvedHandle == null) {
1196 traceInterpreter("| resolve", this);
1197 resolvedHandle();
1198 }
1199 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1200 } catch (Throwable ex) {
1201 traceInterpreter("] throw =>", ex);
1202 throw ex;
1203 }
1204 traceInterpreter("] return =>", rval);
1205 return rval;
1206 }
1207
1208 private MethodHandle invoker() {
1209 return computeInvoker(methodType().form());
1210 }
1211
1212 MethodType methodType() {
1213 MethodType type = this.type;
1214 if (type == null) {
1215 this.type = type = calculateMethodType(member, resolvedHandle);
1216 }
1217 return type;
1218 }
1219
1220 private static MethodType calculateMethodType(MemberName member, MethodHandle resolvedHandle) {
1221 if (resolvedHandle != null) {
1222 return resolvedHandle.type();
1223 } else {
1224 // only for certain internal LFs during bootstrapping
1225 return member.getInvocationType();
1226 }
1227 }
1228
1229 MemberName member() {
1230 assert(assertMemberIsConsistent());
1231 return member;
1232 }
1233
1234 // Called only from assert.
1235 private boolean assertMemberIsConsistent() {
1236 if (resolvedHandle instanceof DirectMethodHandle) {
1237 MemberName m = resolvedHandle.internalMemberName();
1238 assert(m.equals(member));
1239 }
1240 return true;
1241 }
1242
1243 Class<?> memberDeclaringClassOrNull() {
1244 return (member == null) ? null : member.getDeclaringClass();
1245 }
1246
1247 BasicType returnType() {
1248 return basicType(methodType().returnType());
1249 }
1250
1251 BasicType parameterType(int n) {
1252 return basicType(methodType().parameterType(n));
1253 }
1254
1255 int arity() {
1256 return methodType().parameterCount();
1257 }
1258
1259 public String toString() {
1260 if (member == null) return String.valueOf(resolvedHandle);
1261 return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1262 }
1263
1264 public boolean isIdentity() {
1265 return this.equals(identity(returnType()));
1266 }
1267
1268 public boolean isConstantZero() {
1269 return this.equals(constantZero(returnType()));
1270 }
1271
1272 public MethodHandleImpl.Intrinsic intrinsicName() {
1273 return resolvedHandle != null
1274 ? resolvedHandle.intrinsicName()
1275 : MethodHandleImpl.Intrinsic.NONE;
1276 }
1277
1278 public Object intrinsicData() {
1279 return resolvedHandle != null
1280 ? resolvedHandle.intrinsicData()
1281 : null;
1282 }
1283 }
1284
1285 public static String basicTypeSignature(MethodType type) {
1286 int params = type.parameterCount();
1287 char[] sig = new char[params + 2];
1288 int sigp = 0;
1289 while (sigp < params) {
1290 sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1291 }
1292 sig[sigp++] = '_';
1293 sig[sigp++] = basicTypeChar(type.returnType());
1294 assert(sigp == sig.length);
1295 return String.valueOf(sig);
1296 }
1297
1298 /** Hack to make signatures more readable when they show up in method names.
1299 * Signature should start with a sequence of uppercase ASCII letters.
1300 * Runs of three or more are replaced by a single letter plus a decimal repeat count.
1301 * A tail of anything other than uppercase ASCII is passed through unchanged.
1302 * @param signature sequence of uppercase ASCII letters with possible repetitions
1303 * @return same sequence, with repetitions counted by decimal numerals
1304 */
1305 public static String shortenSignature(String signature) {
1306 final int NO_CHAR = -1, MIN_RUN = 3;
1307 int c0, c1 = NO_CHAR, c1reps = 0;
1308 StringBuilder buf = null;
1309 int len = signature.length();
1310 if (len < MIN_RUN) return signature;
1311 for (int i = 0; i <= len; i++) {
1312 if (c1 != NO_CHAR && !('A' <= c1 && c1 <= 'Z')) {
1313 // wrong kind of char; bail out here
1314 if (buf != null) {
1315 buf.append(signature, i - c1reps, len);
1316 }
1317 break;
1318 }
1319 // shift in the next char:
1320 c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1321 if (c1 == c0) { ++c1reps; continue; }
1322 // shift in the next count:
1323 int c0reps = c1reps; c1reps = 1;
1324 // end of a character run
1325 if (c0reps < MIN_RUN) {
1326 if (buf != null) {
1327 while (--c0reps >= 0)
1328 buf.append((char)c0);
1329 }
1330 continue;
1331 }
1332 // found three or more in a row
1333 if (buf == null)
1334 buf = new StringBuilder().append(signature, 0, i - c0reps);
1335 buf.append((char)c0).append(c0reps);
1336 }
1337 return (buf == null) ? signature : buf.toString();
1338 }
1339
1340 static final class Name {
1341 final BasicType type;
1342 @Stable short index;
1343 final NamedFunction function;
1344 final Object constraint; // additional type information, if not null
1345 @Stable final Object[] arguments;
1346
1347 private static final Object[] EMPTY_ARGS = new Object[0];
1348
1349 private Name(int index, BasicType type, NamedFunction function, Object[] arguments) {
1350 this.index = (short)index;
1351 this.type = type;
1352 this.function = function;
1353 this.arguments = arguments;
1354 this.constraint = null;
1355 assert(this.index == index && typesMatch(function, this.arguments));
1356 }
1357 private Name(Name that, Object constraint) {
1358 this.index = that.index;
1359 this.type = that.type;
1360 this.function = that.function;
1361 this.arguments = that.arguments;
1362 this.constraint = constraint;
1363 assert(constraint == null || isParam()); // only params have constraints
1364 assert(constraint == null || constraint instanceof ClassSpecializer.SpeciesData || constraint instanceof Class);
1365 }
1366 Name(MethodHandle function, Object... arguments) {
1367 this(new NamedFunction(function), arguments);
1368 }
1369 Name(MethodType functionType, Object... arguments) {
1370 this(new NamedFunction(functionType), arguments);
1371 assert(arguments[0] instanceof Name name && name.type == L_TYPE);
1372 }
1373 Name(MemberName function, Object... arguments) {
1374 this(new NamedFunction(function), arguments);
1375 }
1376 Name(NamedFunction function) {
1377 this(-1, function.returnType(), function, EMPTY_ARGS);
1378 }
1379 Name(NamedFunction function, Object arg) {
1380 this(-1, function.returnType(), function, new Object[] { arg });
1381 }
1382 Name(NamedFunction function, Object arg0, Object arg1) {
1383 this(-1, function.returnType(), function, new Object[] { arg0, arg1 });
1384 }
1385 Name(NamedFunction function, Object... arguments) {
1386 this(-1, function.returnType(), function, Arrays.copyOf(arguments, arguments.length, Object[].class));
1387 }
1388 /** Create a raw parameter of the given type, with an expected index. */
1389 Name(int index, BasicType type) {
1390 this(index, type, null, null);
1391 }
1392 /** Create a raw parameter of the given type. */
1393 Name(BasicType type) { this(-1, type); }
1394
1395 BasicType type() { return type; }
1396 int index() { return index; }
1397 boolean initIndex(int i) {
1398 if (index != i) {
1399 if (index != -1) return false;
1400 index = (short)i;
1401 }
1402 return true;
1403 }
1404 char typeChar() {
1405 return type.btChar;
1406 }
1407
1408 Name newIndex(int i) {
1409 if (initIndex(i)) return this;
1410 return cloneWithIndex(i);
1411 }
1412 Name cloneWithIndex(int i) {
1413 Object[] newArguments = (arguments == null) ? null : arguments.clone();
1414 return new Name(i, type, function, newArguments).withConstraint(constraint);
1415 }
1416 Name withConstraint(Object constraint) {
1417 if (constraint == this.constraint) return this;
1418 return new Name(this, constraint);
1419 }
1420 Name replaceName(Name oldName, Name newName) { // FIXME: use replaceNames uniformly
1421 if (oldName == newName) return this;
1422 @SuppressWarnings("LocalVariableHidesMemberVariable")
1423 Object[] arguments = this.arguments;
1424 if (arguments == null) return this;
1425 boolean replaced = false;
1426 for (int j = 0; j < arguments.length; j++) {
1427 if (arguments[j] == oldName) {
1428 if (!replaced) {
1429 replaced = true;
1430 arguments = arguments.clone();
1431 }
1432 arguments[j] = newName;
1433 }
1434 }
1435 if (!replaced) return this;
1436 return new Name(function, arguments);
1437 }
1438 /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1439 * Limit such replacements to {@code start<=i<end}. Return possibly changed self.
1440 */
1441 Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1442 if (start >= end) return this;
1443 @SuppressWarnings("LocalVariableHidesMemberVariable")
1444 Object[] arguments = this.arguments;
1445 boolean replaced = false;
1446 eachArg:
1447 for (int j = 0; j < arguments.length; j++) {
1448 if (arguments[j] instanceof Name n) {
1449 int check = n.index;
1450 // harmless check to see if the thing is already in newNames:
1451 if (check >= 0 && check < newNames.length && n == newNames[check])
1452 continue eachArg;
1453 // n might not have the correct index: n != oldNames[n.index].
1454 for (int i = start; i < end; i++) {
1455 if (n == oldNames[i]) {
1456 if (n == newNames[i])
1457 continue eachArg;
1458 if (!replaced) {
1459 replaced = true;
1460 arguments = arguments.clone();
1461 }
1462 arguments[j] = newNames[i];
1463 continue eachArg;
1464 }
1465 }
1466 }
1467 }
1468 if (!replaced) return this;
1469 return new Name(function, arguments);
1470 }
1471 void internArguments() {
1472 @SuppressWarnings("LocalVariableHidesMemberVariable")
1473 Object[] arguments = this.arguments;
1474 for (int j = 0; j < arguments.length; j++) {
1475 if (arguments[j] instanceof Name n) {
1476 if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1477 arguments[j] = internArgument(n);
1478 }
1479 }
1480 }
1481 boolean isParam() {
1482 return function == null;
1483 }
1484 boolean isConstantZero() {
1485 return !isParam() && arguments.length == 0 && function.isConstantZero();
1486 }
1487
1488 boolean refersTo(Class<?> declaringClass, String methodName) {
1489 return function != null &&
1490 function.member() != null && function.member().refersTo(declaringClass, methodName);
1491 }
1492
1493 /**
1494 * Check if MemberName is a call to MethodHandle.invokeBasic.
1495 */
1496 boolean isInvokeBasic() {
1497 if (function == null)
1498 return false;
1499 if (arguments.length < 1)
1500 return false; // must have MH argument
1501 MemberName member = function.member();
1502 return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1503 !member.isPublic() && !member.isStatic();
1504 }
1505
1506 /**
1507 * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1508 */
1509 boolean isLinkerMethodInvoke() {
1510 if (function == null)
1511 return false;
1512 if (arguments.length < 1)
1513 return false; // must have MH argument
1514 MemberName member = function.member();
1515 return member != null &&
1516 member.getDeclaringClass() == MethodHandle.class &&
1517 !member.isPublic() && member.isStatic() &&
1518 member.getName().startsWith("linkTo");
1519 }
1520
1521 public String toString() {
1522 return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1523 }
1524 public String debugString() {
1525 String s = paramString();
1526 return (function == null) ? s : s + "=" + exprString();
1527 }
1528 public String paramString() {
1529 String s = toString();
1530 Object c = constraint;
1531 if (c == null)
1532 return s;
1533 if (c instanceof Class<?> cl) c = cl.getSimpleName();
1534 return s + "/" + c;
1535 }
1536 public String exprString() {
1537 if (function == null) return toString();
1538 StringBuilder buf = new StringBuilder(function.toString());
1539 buf.append("(");
1540 String cma = "";
1541 for (Object a : arguments) {
1542 buf.append(cma); cma = ",";
1543 if (a instanceof Name || a instanceof Integer)
1544 buf.append(a);
1545 else
1546 buf.append("(").append(a).append(")");
1547 }
1548 buf.append(")");
1549 return buf.toString();
1550 }
1551
1552 private boolean typesMatch(NamedFunction function, Object ... arguments) {
1553 if (arguments == null) {
1554 assert(function == null);
1555 return true;
1556 }
1557 assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1558 for (int i = 0; i < arguments.length; i++) {
1559 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1560 }
1561 return true;
1562 }
1563
1564 private static boolean typesMatch(BasicType parameterType, Object object) {
1565 if (object instanceof Name name) {
1566 return name.type == parameterType;
1567 }
1568 switch (parameterType) {
1569 case I_TYPE: return object instanceof Integer;
1570 case J_TYPE: return object instanceof Long;
1571 case F_TYPE: return object instanceof Float;
1572 case D_TYPE: return object instanceof Double;
1573 }
1574 assert(parameterType == L_TYPE);
1575 return true;
1576 }
1577
1578 /** Return the index of the last occurrence of n in the argument array.
1579 * Return -1 if the name is not used.
1580 */
1581 int lastUseIndex(Name n) {
1582 if (arguments == null) return -1;
1583 for (int i = arguments.length; --i >= 0; ) {
1584 if (arguments[i] == n) return i;
1585 }
1586 return -1;
1587 }
1588
1589 /** Return the number of occurrences of n in the argument array.
1590 * Return 0 if the name is not used.
1591 */
1592 int useCount(Name n) {
1593 int count = 0;
1594 if (arguments != null) {
1595 for (Object argument : arguments) {
1596 if (argument == n) {
1597 count++;
1598 }
1599 }
1600 }
1601 return count;
1602 }
1603
1604 public boolean equals(Name that) {
1605 if (this == that) return true;
1606 if (isParam())
1607 // each parameter is a unique atom
1608 return false; // this != that
1609 return
1610 //this.index == that.index &&
1611 this.type == that.type &&
1612 this.function.equals(that.function) &&
1613 Arrays.equals(this.arguments, that.arguments);
1614 }
1615 @Override
1616 public boolean equals(Object x) {
1617 return x instanceof Name n && equals(n);
1618 }
1619 @Override
1620 public int hashCode() {
1621 if (isParam())
1622 return index | (type.ordinal() << 8);
1623 return function.hashCode() ^ Arrays.hashCode(arguments);
1624 }
1625 }
1626
1627 /** Return the index of the last name which contains n as an argument.
1628 * Return -1 if the name is not used. Return names.length if it is the return value.
1629 */
1630 int lastUseIndex(Name n) {
1631 int ni = n.index, nmax = names.length;
1632 assert(names[ni] == n);
1633 if (result == ni) return nmax; // live all the way beyond the end
1634 for (int i = nmax; --i > ni; ) {
1635 if (names[i].lastUseIndex(n) >= 0)
1636 return i;
1637 }
1638 return -1;
1639 }
1640
1641 /** Return the number of times n is used as an argument or return value. */
1642 int useCount(Name n) {
1643 int count = (result == n.index) ? 1 : 0;
1644 int i = Math.max(n.index + 1, arity);
1645 while (i < names.length) {
1646 count += names[i++].useCount(n);
1647 }
1648 return count;
1649 }
1650
1651 static Name argument(int which, BasicType type) {
1652 if (which >= INTERNED_ARGUMENT_LIMIT)
1653 return new Name(which, type);
1654 return INTERNED_ARGUMENTS[type.ordinal()][which];
1655 }
1656 static Name internArgument(Name n) {
1657 assert(n.isParam()) : "not param: " + n;
1658 assert(n.index < INTERNED_ARGUMENT_LIMIT);
1659 if (n.constraint != null) return n;
1660 return argument(n.index, n.type);
1661 }
1662 static Name[] arguments(int extra, MethodType types) {
1663 int length = types.parameterCount();
1664 Name[] names = new Name[length + extra];
1665 for (int i = 0; i < length; i++)
1666 names[i] = argument(i, basicType(types.parameterType(i)));
1667 return names;
1668 }
1669 static final int INTERNED_ARGUMENT_LIMIT = 10;
1670 private static final Name[][] INTERNED_ARGUMENTS
1671 = new Name[ARG_TYPE_LIMIT][INTERNED_ARGUMENT_LIMIT];
1672 static {
1673 for (BasicType type : BasicType.ARG_TYPES) {
1674 int ord = type.ordinal();
1675 for (int i = 0; i < INTERNED_ARGUMENTS[ord].length; i++) {
1676 INTERNED_ARGUMENTS[ord][i] = new Name(i, type);
1677 }
1678 }
1679 }
1680
1681 private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
1682
1683 static LambdaForm identityForm(BasicType type) {
1684 int ord = type.ordinal();
1685 LambdaForm form = LF_identity[ord];
1686 if (form != null) {
1687 return form;
1688 }
1689 createFormsFor(type);
1690 return LF_identity[ord];
1691 }
1692
1693 static LambdaForm zeroForm(BasicType type) {
1694 int ord = type.ordinal();
1695 LambdaForm form = LF_zero[ord];
1696 if (form != null) {
1697 return form;
1698 }
1699 createFormsFor(type);
1700 return LF_zero[ord];
1701 }
1702
1703 static NamedFunction identity(BasicType type) {
1704 int ord = type.ordinal();
1705 NamedFunction function = NF_identity[ord];
1706 if (function != null) {
1707 return function;
1708 }
1709 createFormsFor(type);
1710 return NF_identity[ord];
1711 }
1712
1713 static NamedFunction constantZero(BasicType type) {
1714 int ord = type.ordinal();
1715 NamedFunction function = NF_zero[ord];
1716 if (function != null) {
1717 return function;
1718 }
1719 createFormsFor(type);
1720 return NF_zero[ord];
1721 }
1722
1723 private static final @Stable LambdaForm[] LF_identity = new LambdaForm[TYPE_LIMIT];
1724 private static final @Stable LambdaForm[] LF_zero = new LambdaForm[TYPE_LIMIT];
1725 private static final @Stable NamedFunction[] NF_identity = new NamedFunction[TYPE_LIMIT];
1726 private static final @Stable NamedFunction[] NF_zero = new NamedFunction[TYPE_LIMIT];
1727
1728 private static final Object createFormsLock = new Object();
1729 private static void createFormsFor(BasicType type) {
1730 // Avoid racy initialization during bootstrap
1731 UNSAFE.ensureClassInitialized(BoundMethodHandle.class);
1732 synchronized (createFormsLock) {
1733 final int ord = type.ordinal();
1734 LambdaForm idForm = LF_identity[ord];
1735 if (idForm != null) {
1736 return;
1737 }
1738 char btChar = type.basicTypeChar();
1739 boolean isVoid = (type == V_TYPE);
1740 Class<?> btClass = type.btClass;
1741 MethodType zeType = MethodType.methodType(btClass);
1742 MethodType idType = (isVoid) ? zeType : MethodType.methodType(btClass, btClass);
1743
1744 // Look up symbolic names. It might not be necessary to have these,
1745 // but if we need to emit direct references to bytecodes, it helps.
1746 // Zero is built from a call to an identity function with a constant zero input.
1747 MemberName idMem = new MemberName(LambdaForm.class, "identity_"+btChar, idType, REF_invokeStatic);
1748 MemberName zeMem = null;
1749 try {
1750 idMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, idMem, null, LM_TRUSTED, NoSuchMethodException.class);
1751 if (!isVoid) {
1752 zeMem = new MemberName(LambdaForm.class, "zero_"+btChar, zeType, REF_invokeStatic);
1753 zeMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, zeMem, null, LM_TRUSTED, NoSuchMethodException.class);
1754 }
1755 } catch (IllegalAccessException|NoSuchMethodException ex) {
1756 throw newInternalError(ex);
1757 }
1758
1759 NamedFunction idFun;
1760 LambdaForm zeForm;
1761 NamedFunction zeFun;
1762
1763 // Create the LFs and NamedFunctions. Precompiling LFs to byte code is needed to break circular
1764 // bootstrap dependency on this method in case we're interpreting LFs
1765 if (isVoid) {
1766 Name[] idNames = new Name[] { argument(0, L_TYPE) };
1767 idForm = LambdaForm.create(1, idNames, VOID_RESULT, Kind.IDENTITY);
1768 idForm.compileToBytecode();
1769 idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1770
1771 zeForm = idForm;
1772 zeFun = idFun;
1773 } else {
1774 Name[] idNames = new Name[] { argument(0, L_TYPE), argument(1, type) };
1775 idForm = LambdaForm.create(2, idNames, 1, Kind.IDENTITY);
1776 idForm.compileToBytecode();
1777 idFun = new NamedFunction(idMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(idMem.getInvocationType(), idForm),
1778 MethodHandleImpl.Intrinsic.IDENTITY));
1779
1780 Object zeValue = Wrapper.forBasicType(btChar).zero();
1781 Name[] zeNames = new Name[] { argument(0, L_TYPE), new Name(idFun, zeValue) };
1782 zeForm = LambdaForm.create(1, zeNames, 1, Kind.ZERO);
1783 zeForm.compileToBytecode();
1784 zeFun = new NamedFunction(zeMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(zeMem.getInvocationType(), zeForm),
1785 MethodHandleImpl.Intrinsic.ZERO));
1786 }
1787
1788 LF_zero[ord] = zeForm;
1789 NF_zero[ord] = zeFun;
1790 LF_identity[ord] = idForm;
1791 NF_identity[ord] = idFun;
1792
1793 assert(idFun.isIdentity());
1794 assert(zeFun.isConstantZero());
1795 assert(new Name(zeFun).isConstantZero());
1796 }
1797 }
1798
1799 // Avoid appealing to ValueConversions at bootstrap time:
1800 private static int identity_I(int x) { return x; }
1801 private static long identity_J(long x) { return x; }
1802 private static float identity_F(float x) { return x; }
1803 private static double identity_D(double x) { return x; }
1804 private static Object identity_L(Object x) { return x; }
1805 private static void identity_V() { return; }
1806 private static int zero_I() { return 0; }
1807 private static long zero_J() { return 0; }
1808 private static float zero_F() { return 0; }
1809 private static double zero_D() { return 0; }
1810 private static Object zero_L() { return null; }
1811
1812 /**
1813 * Internal marker for byte-compiled LambdaForms.
1814 */
1815 /*non-public*/
1816 @Target(ElementType.METHOD)
1817 @Retention(RetentionPolicy.RUNTIME)
1818 @interface Compiled {
1819 }
1820
1821 private static final HashMap<String,Integer> DEBUG_NAME_COUNTERS;
1822 private static final HashMap<LambdaForm,String> DEBUG_NAMES;
1823 static {
1824 if (debugEnabled()) {
1825 DEBUG_NAME_COUNTERS = new HashMap<>();
1826 DEBUG_NAMES = new HashMap<>();
1827 } else {
1828 DEBUG_NAME_COUNTERS = null;
1829 DEBUG_NAMES = null;
1830 }
1831 }
1832
1833 static {
1834 // The Holder class will contain pre-generated forms resolved
1835 // using MemberName.getFactory(). However, that doesn't initialize the
1836 // class, which subtly breaks inlining etc. By forcing
1837 // initialization of the Holder class we avoid these issues.
1838 UNSAFE.ensureClassInitialized(Holder.class);
1839 }
1840
1841 /* Placeholder class for zero and identity forms generated ahead of time */
1842 final class Holder {}
1843
1844 // The following hack is necessary in order to suppress TRACE_INTERPRETER
1845 // during execution of the static initializes of this class.
1846 // Turning on TRACE_INTERPRETER too early will cause
1847 // stack overflows and other misbehavior during attempts to trace events
1848 // that occur during LambdaForm.<clinit>.
1849 // Therefore, do not move this line higher in this file, and do not remove.
1850 private static final boolean TRACE_INTERPRETER = MethodHandleStatics.TRACE_INTERPRETER;
1851 }