1 /*
2 * Copyright (c) 2011, 2024, 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.REFERENCE), // all reference types
142 I_TYPE('I', int.class, Wrapper.INT, TypeKind.INT),
143 J_TYPE('J', long.class, Wrapper.LONG, TypeKind.LONG),
144 F_TYPE('F', float.class, Wrapper.FLOAT, TypeKind.FLOAT),
145 D_TYPE('D', double.class, Wrapper.DOUBLE, TypeKind.DOUBLE), // all primitive types
146 V_TYPE('V', void.class, Wrapper.VOID, TypeKind.VOID); // 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 COLLECTOR("collector"),
305 LOOP("loop"),
306 GUARD("guard"),
307 GUARD_WITH_CATCH("guardWithCatch"),
308 VARHANDLE_EXACT_INVOKER("VH.exactInvoker"),
309 VARHANDLE_INVOKER("VH.invoker", "invoker"),
310 VARHANDLE_LINKER("VH.invoke_MT", "invoke_MT");
311
312 final String defaultLambdaName;
313 final String methodName;
314
315 private Kind(String defaultLambdaName) {
316 this(defaultLambdaName, defaultLambdaName);
317 }
318
319 private Kind(String defaultLambdaName, String methodName) {
320 this.defaultLambdaName = defaultLambdaName;
321 this.methodName = methodName;
322 }
323 }
324
325 // private version that doesn't do checks or defensive copies
326 private LambdaForm(int arity, int result, boolean forceInline, MethodHandle customized, Name[] names, Kind kind) {
327 this.arity = arity;
328 this.result = result;
329 this.forceInline = forceInline;
330 this.customized = customized;
331 this.names = names;
332 this.kind = kind;
333 this.vmentry = null;
334 this.isCompiled = false;
335 }
336
337 // root factory pre/post processing and calls simple constructor
338 private static LambdaForm create(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized, Kind kind) {
339 names = names.clone();
340 assert(namesOK(arity, names));
341 result = fixResult(result, names);
342
343 boolean canInterpret = normalizeNames(arity, names);
344 LambdaForm form = new LambdaForm(arity, result, forceInline, customized, names, kind);
345 assert(form.nameRefsAreLegal());
346 if (!canInterpret) {
347 form.compileToBytecode();
348 }
349 return form;
350 }
351
352 // derived factories with defaults
353 private static final int DEFAULT_RESULT = LAST_RESULT;
354 private static final boolean DEFAULT_FORCE_INLINE = true;
355 private static final MethodHandle DEFAULT_CUSTOMIZED = null;
356 private static final Kind DEFAULT_KIND = Kind.GENERIC;
357
358 static LambdaForm create(int arity, Name[] names, int result) {
359 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
360 }
361 static LambdaForm create(int arity, Name[] names, int result, Kind kind) {
362 return create(arity, names, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
363 }
364 static LambdaForm create(int arity, Name[] names) {
365 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, DEFAULT_KIND);
366 }
367 static LambdaForm create(int arity, Name[] names, Kind kind) {
368 return create(arity, names, DEFAULT_RESULT, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, kind);
369 }
370 static LambdaForm create(int arity, Name[] names, boolean forceInline, Kind kind) {
371 return create(arity, names, DEFAULT_RESULT, forceInline, DEFAULT_CUSTOMIZED, kind);
372 }
373
374 private static LambdaForm createBlankForType(MethodType mt) {
375 // Make a blank lambda form, which returns a constant zero or null.
376 // It is used as a template for managing the invocation of similar forms that are non-empty.
377 // Called only from getPreparedForm.
378 int arity = mt.parameterCount();
379 int result = (mt.returnType() == void.class || mt.returnType() == Void.class) ? VOID_RESULT : arity;
380 Name[] names = buildEmptyNames(arity, mt, result == VOID_RESULT);
381 boolean canInterpret = normalizeNames(arity, names);
382 LambdaForm form = new LambdaForm(arity, result, DEFAULT_FORCE_INLINE, DEFAULT_CUSTOMIZED, names, Kind.ZERO);
383 assert(form.nameRefsAreLegal() && form.isEmpty() && isValidSignature(form.basicTypeSignature()));
384 if (!canInterpret) {
385 form.compileToBytecode();
386 }
387 return form;
388 }
389
390 private static Name[] buildEmptyNames(int arity, MethodType mt, boolean isVoid) {
391 Name[] names = arguments(isVoid ? 0 : 1, mt);
392 if (!isVoid) {
393 Name zero = new Name(constantZero(basicType(mt.returnType())));
394 names[arity] = zero.withIndex(arity);
395 }
396 assert(namesOK(arity, names));
397 return names;
398 }
399
400 private static int fixResult(int result, Name[] names) {
401 if (result == LAST_RESULT)
402 result = names.length - 1; // might still be void
403 if (result >= 0 && names[result].type == V_TYPE)
404 result = VOID_RESULT;
405 return result;
406 }
407
408 static boolean debugNames() {
409 return DEBUG_NAME_COUNTERS != null;
410 }
411
412 static void associateWithDebugName(LambdaForm form, String name) {
413 assert (debugNames());
414 synchronized (DEBUG_NAMES) {
415 DEBUG_NAMES.put(form, name);
416 }
417 }
418
419 String lambdaName() {
420 if (DEBUG_NAMES != null) {
421 synchronized (DEBUG_NAMES) {
422 String name = DEBUG_NAMES.get(this);
423 if (name == null) {
424 name = generateDebugName();
425 }
426 return name;
427 }
428 }
429 return kind.defaultLambdaName;
430 }
431
432 private String generateDebugName() {
433 assert (debugNames());
434 String debugNameStem = kind.defaultLambdaName;
435 Integer ctr = DEBUG_NAME_COUNTERS.getOrDefault(debugNameStem, 0);
436 DEBUG_NAME_COUNTERS.put(debugNameStem, ctr + 1);
437 StringBuilder buf = new StringBuilder(debugNameStem);
438 int leadingZero = buf.length();
439 buf.append((int) ctr);
440 for (int i = buf.length() - leadingZero; i < 3; i++) {
441 buf.insert(leadingZero, '0');
442 }
443 buf.append('_');
444 buf.append(basicTypeSignature());
445 String name = buf.toString();
446 associateWithDebugName(this, name);
447 return name;
448 }
449
450 private static boolean namesOK(int arity, Name[] names) {
451 for (int i = 0; i < names.length; i++) {
452 Name n = names[i];
453 assert(n != null) : "n is null";
454 if (i < arity)
455 assert( n.isParam()) : n + " is not param at " + i;
456 else
457 assert(!n.isParam()) : n + " is param at " + i;
458 }
459 return true;
460 }
461
462 /** Customize LambdaForm for a particular MethodHandle */
463 LambdaForm customize(MethodHandle mh) {
464 if (customized == mh) {
465 return this;
466 }
467 LambdaForm customForm = LambdaForm.create(arity, names, result, forceInline, mh, kind);
468 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
469 // If shared LambdaForm has been compiled, compile customized version as well.
470 customForm.compileToBytecode();
471 }
472 customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
473 return customForm;
474 }
475
476 /** Get uncustomized flavor of the LambdaForm */
477 LambdaForm uncustomize() {
478 if (customized == null) {
479 return this;
480 }
481 assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
482 LambdaForm uncustomizedForm = (LambdaForm)transformCache;
483 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
484 // If customized LambdaForm has been compiled, compile uncustomized version as well.
485 uncustomizedForm.compileToBytecode();
486 }
487 return uncustomizedForm;
488 }
489
490 /** Renumber and/or replace params so that they are interned and canonically numbered.
491 * @return true if we can interpret
492 */
493 private static boolean normalizeNames(int arity, Name[] names) {
494 Name[] oldNames = names.clone();
495 int maxOutArity = 0;
496 for (int i = 0; i < names.length; i++) {
497 Name n = names[i];
498 names[i] = n.withIndex(i);
499 if (n.arguments != null && maxOutArity < n.arguments.length)
500 maxOutArity = n.arguments.length;
501 }
502 if (oldNames != null) {
503 for (int i = Math.max(1, arity); i < names.length; i++) {
504 Name fixed = names[i].replaceNames(oldNames, names, 0, i);
505 names[i] = fixed.withIndex(i);
506 }
507 }
508 int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
509 boolean needIntern = false;
510 for (int i = 0; i < maxInterned; i++) {
511 Name n = names[i], n2 = internArgument(n);
512 if (n != n2) {
513 names[i] = n2;
514 needIntern = true;
515 }
516 }
517 if (needIntern) {
518 for (int i = arity; i < names.length; i++) {
519 names[i].internArguments();
520 }
521 }
522
523 // return true if we can interpret
524 if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
525 // Cannot use LF interpreter on very high arity expressions.
526 assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
527 return false;
528 }
529 return true;
530 }
531
532 /**
533 * Check that all embedded Name references are localizable to this lambda,
534 * and are properly ordered after their corresponding definitions.
535 * <p>
536 * Note that a Name can be local to multiple lambdas, as long as
537 * it possesses the same index in each use site.
538 * This allows Name references to be freely reused to construct
539 * fresh lambdas, without confusion.
540 */
541 boolean nameRefsAreLegal() {
542 assert(arity >= 0 && arity <= names.length);
543 assert(result >= -1 && result < names.length);
544 // Do all names possess an index consistent with their local definition order?
545 for (int i = 0; i < arity; i++) {
546 Name n = names[i];
547 assert(n.index() == i) : Arrays.asList(n.index(), i);
548 assert(n.isParam());
549 }
550 // Also, do all local name references
551 for (int i = arity; i < names.length; i++) {
552 Name n = names[i];
553 assert(n.index() == i);
554 for (Object arg : n.arguments) {
555 if (arg instanceof Name n2) {
556 int i2 = n2.index;
557 assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
558 assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
559 assert(i2 < i); // ref must come after def!
560 }
561 }
562 }
563 return true;
564 }
565
566 // /** Invoke this form on the given arguments. */
567 // final Object invoke(Object... args) throws Throwable {
568 // // NYI: fit this into the fast path?
569 // return interpretWithArguments(args);
570 // }
571
572 /** Report the return type. */
573 BasicType returnType() {
574 if (result < 0) return V_TYPE;
575 Name n = names[result];
576 return n.type;
577 }
578
579 /** Report the N-th argument type. */
580 BasicType parameterType(int n) {
581 return parameter(n).type;
582 }
583
584 /** Report the N-th argument name. */
585 Name parameter(int n) {
586 Name param = names[n];
587 assert(n < arity && param.isParam());
588 return param;
589 }
590
591 /** Report the N-th argument type constraint. */
592 Object parameterConstraint(int n) {
593 return parameter(n).constraint;
594 }
595
596 /** Report the arity. */
597 int arity() {
598 return arity;
599 }
600
601 /** Report the number of expressions (non-parameter names). */
602 int expressionCount() {
603 return names.length - arity;
604 }
605
606 /** Return the method type corresponding to my basic type signature. */
607 MethodType methodType() {
608 Class<?>[] ptypes = new Class<?>[arity];
609 for (int i = 0; i < arity; ++i) {
610 ptypes[i] = parameterType(i).btClass;
611 }
612 return MethodType.methodType(returnType().btClass, ptypes, true);
613 }
614
615 /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
616 final String basicTypeSignature() {
617 StringBuilder buf = new StringBuilder(arity() + 3);
618 for (int i = 0, a = arity(); i < a; i++)
619 buf.append(parameterType(i).basicTypeChar());
620 return buf.append('_').append(returnType().basicTypeChar()).toString();
621 }
622 static int signatureArity(String sig) {
623 assert(isValidSignature(sig));
624 return sig.indexOf('_');
625 }
626 static boolean isValidSignature(String sig) {
627 int arity = sig.indexOf('_');
628 if (arity < 0) return false; // must be of the form *_*
629 int siglen = sig.length();
630 if (siglen != arity + 2) return false; // *_X
631 for (int i = 0; i < siglen; i++) {
632 if (i == arity) continue; // skip '_'
633 char c = sig.charAt(i);
634 if (c == 'V')
635 return (i == siglen - 1 && arity == siglen - 2);
636 if (!isArgBasicTypeChar(c)) return false; // must be [LIJFD]
637 }
638 return true; // [LIJFD]*_[LIJFDV]
639 }
640
641 /**
642 * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
643 */
644 boolean isSelectAlternative(int pos) {
645 // selectAlternative idiom:
646 // t_{n}:L=MethodHandleImpl.selectAlternative(...)
647 // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
648 if (pos+1 >= names.length) return false;
649 Name name0 = names[pos];
650 Name name1 = names[pos+1];
651 return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
652 name1.isInvokeBasic() &&
653 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
654 lastUseIndex(name0) == pos+1; // t_{n} is local: used only in t_{n+1}
655 }
656
657 private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
658 if (pos+2 >= names.length) return false;
659 Name name0 = names[pos];
660 Name name1 = names[pos+1];
661 Name name2 = names[pos+2];
662 return name1.refersTo(MethodHandleImpl.class, idiomName) &&
663 name0.isInvokeBasic() &&
664 name2.isInvokeBasic() &&
665 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
666 lastUseIndex(name0) == pos+1 && // t_{n} is local: used only in t_{n+1}
667 name2.lastUseIndex(name1) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
668 lastUseIndex(name1) == pos+2; // t_{n+1} is local: used only in t_{n+2}
669 }
670
671 /**
672 * Check if i-th name is a start of GuardWithCatch idiom.
673 */
674 boolean isGuardWithCatch(int pos) {
675 // GuardWithCatch idiom:
676 // t_{n}:L=MethodHandle.invokeBasic(...)
677 // t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
678 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
679 return isMatchingIdiom(pos, "guardWithCatch", 3);
680 }
681
682 /**
683 * Check if i-th name is a start of the tryFinally idiom.
684 */
685 boolean isTryFinally(int pos) {
686 // tryFinally idiom:
687 // t_{n}:L=MethodHandle.invokeBasic(...)
688 // t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
689 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
690 return isMatchingIdiom(pos, "tryFinally", 2);
691 }
692
693 /**
694 * Check if i-th name is a start of the tableSwitch idiom.
695 */
696 boolean isTableSwitch(int pos) {
697 // tableSwitch idiom:
698 // t_{n}:L=MethodHandle.invokeBasic(...) // args
699 // t_{n+1}:L=MethodHandleImpl.tableSwitch(*, *, *, t_{n})
700 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
701 if (pos + 2 >= names.length) return false;
702
703 final int POS_COLLECT_ARGS = pos;
704 final int POS_TABLE_SWITCH = pos + 1;
705 final int POS_UNBOX_RESULT = pos + 2;
706
707 Name collectArgs = names[POS_COLLECT_ARGS];
708 Name tableSwitch = names[POS_TABLE_SWITCH];
709 Name unboxResult = names[POS_UNBOX_RESULT];
710 return tableSwitch.refersTo(MethodHandleImpl.class, "tableSwitch") &&
711 collectArgs.isInvokeBasic() &&
712 unboxResult.isInvokeBasic() &&
713 tableSwitch.lastUseIndex(collectArgs) == 3 && // t_{n+1}:L=MethodHandleImpl.<invoker>(*, *, *, t_{n});
714 lastUseIndex(collectArgs) == POS_TABLE_SWITCH && // t_{n} is local: used only in t_{n+1}
715 unboxResult.lastUseIndex(tableSwitch) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
716 lastUseIndex(tableSwitch) == POS_UNBOX_RESULT; // t_{n+1} is local: used only in t_{n+2}
717 }
718
719 /**
720 * Check if i-th name is a start of the loop idiom.
721 */
722 boolean isLoop(int pos) {
723 // loop idiom:
724 // t_{n}:L=MethodHandle.invokeBasic(...)
725 // t_{n+1}:L=MethodHandleImpl.loop(types, *, t_{n})
726 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
727 return isMatchingIdiom(pos, "loop", 2);
728 }
729
730 /*
731 * Code generation issues:
732 *
733 * Compiled LFs should be reusable in general.
734 * The biggest issue is how to decide when to pull a name into
735 * the bytecode, versus loading a reified form from the MH data.
736 *
737 * For example, an asType wrapper may require execution of a cast
738 * after a call to a MH. The target type of the cast can be placed
739 * as a constant in the LF itself. This will force the cast type
740 * to be compiled into the bytecodes and native code for the MH.
741 * Or, the target type of the cast can be erased in the LF, and
742 * loaded from the MH data. (Later on, if the MH as a whole is
743 * inlined, the data will flow into the inlined instance of the LF,
744 * as a constant, and the end result will be an optimal cast.)
745 *
746 * This erasure of cast types can be done with any use of
747 * reference types. It can also be done with whole method
748 * handles. Erasing a method handle might leave behind
749 * LF code that executes correctly for any MH of a given
750 * type, and load the required MH from the enclosing MH's data.
751 * Or, the erasure might even erase the expected MT.
752 *
753 * Also, for direct MHs, the MemberName of the target
754 * could be erased, and loaded from the containing direct MH.
755 * As a simple case, a LF for all int-valued non-static
756 * field getters would perform a cast on its input argument
757 * (to non-constant base type derived from the MemberName)
758 * and load an integer value from the input object
759 * (at a non-constant offset also derived from the MemberName).
760 * Such MN-erased LFs would be inlinable back to optimized
761 * code, whenever a constant enclosing DMH is available
762 * to supply a constant MN from its data.
763 *
764 * The main problem here is to keep LFs reasonably generic,
765 * while ensuring that hot spots will inline good instances.
766 * "Reasonably generic" means that we don't end up with
767 * repeated versions of bytecode or machine code that do
768 * not differ in their optimized form. Repeated versions
769 * of machine would have the undesirable overheads of
770 * (a) redundant compilation work and (b) extra I$ pressure.
771 * To control repeated versions, we need to be ready to
772 * erase details from LFs and move them into MH data,
773 * whenever those details are not relevant to significant
774 * optimization. "Significant" means optimization of
775 * code that is actually hot.
776 *
777 * Achieving this may require dynamic splitting of MHs, by replacing
778 * a generic LF with a more specialized one, on the same MH,
779 * if (a) the MH is frequently executed and (b) the MH cannot
780 * be inlined into a containing caller, such as an invokedynamic.
781 *
782 * Compiled LFs that are no longer used should be GC-able.
783 * If they contain non-BCP references, they should be properly
784 * interlinked with the class loader(s) that their embedded types
785 * depend on. This probably means that reusable compiled LFs
786 * will be tabulated (indexed) on relevant class loaders,
787 * or else that the tables that cache them will have weak links.
788 */
789
790 /**
791 * Make this LF directly executable, as part of a MethodHandle.
792 * Invariant: Every MH which is invoked must prepare its LF
793 * before invocation.
794 * (In principle, the JVM could do this very lazily,
795 * as a sort of pre-invocation linkage step.)
796 */
797 public void prepare() {
798 if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
799 compileToBytecode();
800 }
801 if (this.vmentry != null) {
802 // already prepared (e.g., a primitive DMH invoker form)
803 return;
804 }
805 MethodType mtype = methodType();
806 LambdaForm prep = mtype.form().cachedLambdaForm(MethodTypeForm.LF_INTERPRET);
807 if (prep == null) {
808 assert (isValidSignature(basicTypeSignature()));
809 prep = LambdaForm.createBlankForType(mtype);
810 prep.vmentry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
811 prep = mtype.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, prep);
812 }
813 this.vmentry = prep.vmentry;
814 // TO DO: Maybe add invokeGeneric, invokeWithArguments
815 }
816
817 private static @Stable PerfCounter LF_FAILED;
818
819 private static PerfCounter failedCompilationCounter() {
820 if (LF_FAILED == null) {
821 LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
822 }
823 return LF_FAILED;
824 }
825
826 /** Generate optimizable bytecode for this form. */
827 void compileToBytecode() {
828 if (forceInterpretation()) {
829 return; // this should not be compiled
830 }
831 if (vmentry != null && isCompiled) {
832 return; // already compiled somehow
833 }
834
835 // Obtain the invoker MethodType outside of the following try block.
836 // This ensures that an IllegalArgumentException is directly thrown if the
837 // type would have 256 or more parameters
838 MethodType invokerType = methodType();
839 assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
840 try {
841 vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
842 if (TRACE_INTERPRETER)
843 traceInterpreter("compileToBytecode", this);
844 isCompiled = true;
845 } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
846 // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
847 invocationCounter = -1;
848 failedCompilationCounter().increment();
849 if (LOG_LF_COMPILATION_FAILURE) {
850 System.out.println("LambdaForm compilation failed: " + this);
851 bge.printStackTrace(System.out);
852 }
853 } catch (Error e) {
854 // Pass through any error
855 throw e;
856 } catch (Exception e) {
857 // Wrap any exception
858 throw newInternalError(this.toString(), e);
859 }
860 }
861
862 // The next few routines are called only from assert expressions
863 // They verify that the built-in invokers process the correct raw data types.
864 private static boolean argumentTypesMatch(String sig, Object[] av) {
865 int arity = signatureArity(sig);
866 assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
867 assert(av[0] instanceof MethodHandle) : "av[0] not instance of MethodHandle: " + av[0];
868 MethodHandle mh = (MethodHandle) av[0];
869 MethodType mt = mh.type();
870 assert(mt.parameterCount() == arity-1);
871 for (int i = 0; i < av.length; i++) {
872 Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
873 assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
874 }
875 return true;
876 }
877 private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
878 // The following line is needed because (...)void method handles can use non-void invokers
879 if (type == void.class) tc = V_TYPE; // can drop any kind of value
880 assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
881 switch (tc) {
882 case I_TYPE: assert checkInt(type, x) : "checkInt(" + type + "," + x +")"; break;
883 case J_TYPE: assert x instanceof Long : "instanceof Long: " + x; break;
884 case F_TYPE: assert x instanceof Float : "instanceof Float: " + x; break;
885 case D_TYPE: assert x instanceof Double : "instanceof Double: " + x; break;
886 case L_TYPE: assert checkRef(type, x) : "checkRef(" + type + "," + x + ")"; break;
887 case V_TYPE: break; // allow anything here; will be dropped
888 default: assert(false);
889 }
890 return true;
891 }
892 private static boolean checkInt(Class<?> type, Object x) {
893 assert(x instanceof Integer);
894 if (type == int.class) return true;
895 Wrapper w = Wrapper.forBasicType(type);
896 assert(w.isSubwordOrInt());
897 Object x1 = Wrapper.INT.wrap(w.wrap(x));
898 return x.equals(x1);
899 }
900 private static boolean checkRef(Class<?> type, Object x) {
901 assert(!type.isPrimitive());
902 if (x == null) return true;
903 if (type.isInterface()) return true;
904 return type.isInstance(x);
905 }
906
907 /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
908 private static final int COMPILE_THRESHOLD;
909 static {
910 COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
911 }
912 private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
913
914 private boolean forceInterpretation() {
915 return invocationCounter == -1;
916 }
917
918 /** Interpretively invoke this form on the given arguments. */
919 @Hidden
920 @DontInline
921 Object interpretWithArguments(Object... argumentValues) throws Throwable {
922 if (TRACE_INTERPRETER)
923 return interpretWithArgumentsTracing(argumentValues);
924 checkInvocationCounter();
925 assert(arityCheck(argumentValues));
926 Object[] values = Arrays.copyOf(argumentValues, names.length);
927 for (int i = argumentValues.length; i < values.length; i++) {
928 values[i] = interpretName(names[i], values);
929 }
930 Object rv = (result < 0) ? null : values[result];
931 assert(resultCheck(argumentValues, rv));
932 return rv;
933 }
934
935 /** Evaluate a single Name within this form, applying its function to its arguments. */
936 @Hidden
937 @DontInline
938 Object interpretName(Name name, Object[] values) throws Throwable {
939 if (TRACE_INTERPRETER)
940 traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
941 Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
942 for (int i = 0; i < arguments.length; i++) {
943 Object a = arguments[i];
944 if (a instanceof Name n) {
945 int i2 = n.index();
946 assert(names[i2] == a);
947 a = values[i2];
948 arguments[i] = a;
949 }
950 }
951 return name.function.invokeWithArguments(arguments);
952 }
953
954 private void checkInvocationCounter() {
955 if (COMPILE_THRESHOLD != 0 &&
956 !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
957 invocationCounter++; // benign race
958 if (invocationCounter >= COMPILE_THRESHOLD) {
959 // Replace vmentry with a bytecode version of this LF.
960 compileToBytecode();
961 }
962 }
963 }
964 Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
965 traceInterpreter("[ interpretWithArguments", this, argumentValues);
966 if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
967 int ctr = invocationCounter++; // benign race
968 traceInterpreter("| invocationCounter", ctr);
969 if (invocationCounter >= COMPILE_THRESHOLD) {
970 compileToBytecode();
971 }
972 }
973 Object rval;
974 try {
975 assert(arityCheck(argumentValues));
976 Object[] values = Arrays.copyOf(argumentValues, names.length);
977 for (int i = argumentValues.length; i < values.length; i++) {
978 values[i] = interpretName(names[i], values);
979 }
980 rval = (result < 0) ? null : values[result];
981 } catch (Throwable ex) {
982 traceInterpreter("] throw =>", ex);
983 throw ex;
984 }
985 traceInterpreter("] return =>", rval);
986 return rval;
987 }
988
989 static void traceInterpreter(String event, Object obj, Object... args) {
990 if (TRACE_INTERPRETER) {
991 System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
992 }
993 }
994 static void traceInterpreter(String event, Object obj) {
995 traceInterpreter(event, obj, (Object[])null);
996 }
997 private boolean arityCheck(Object[] argumentValues) {
998 assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
999 // also check that the leading (receiver) argument is somehow bound to this LF:
1000 assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
1001 MethodHandle mh = (MethodHandle) argumentValues[0];
1002 assert(mh.internalForm() == this);
1003 // note: argument #0 could also be an interface wrapper, in the future
1004 argumentTypesMatch(basicTypeSignature(), argumentValues);
1005 return true;
1006 }
1007 private boolean resultCheck(Object[] argumentValues, Object result) {
1008 MethodHandle mh = (MethodHandle) argumentValues[0];
1009 MethodType mt = mh.type();
1010 assert(valueMatches(returnType(), mt.returnType(), result));
1011 return true;
1012 }
1013
1014 private boolean isEmpty() {
1015 if (result < 0)
1016 return (names.length == arity);
1017 else if (result == arity && names.length == arity + 1)
1018 return names[arity].isConstantZero();
1019 else
1020 return false;
1021 }
1022
1023 public String toString() {
1024 return debugString(-1);
1025 }
1026
1027 String debugString(int indentLevel) {
1028 String prefix = MethodHandle.debugPrefix(indentLevel);
1029 String lambdaName = lambdaName();
1030 StringBuilder buf = new StringBuilder(lambdaName);
1031 buf.append("=Lambda(");
1032 for (int i = 0; i < names.length; i++) {
1033 if (i == arity) buf.append(")=>{");
1034 Name n = names[i];
1035 if (i >= arity) buf.append("\n ").append(prefix);
1036 buf.append(n.paramString());
1037 if (i < arity) {
1038 if (i+1 < arity) buf.append(",");
1039 continue;
1040 }
1041 buf.append("=").append(n.exprString());
1042 buf.append(";");
1043 }
1044 if (arity == names.length) buf.append(")=>{");
1045 buf.append(result < 0 ? "void" : names[result]).append("}");
1046 if (TRACE_INTERPRETER) {
1047 // Extra verbosity:
1048 buf.append(":").append(basicTypeSignature());
1049 buf.append("/").append(vmentry);
1050 }
1051 return buf.toString();
1052 }
1053
1054 @Override
1055 public boolean equals(Object obj) {
1056 return obj instanceof LambdaForm lf && equals(lf);
1057 }
1058 public boolean equals(LambdaForm that) {
1059 if (this.result != that.result) return false;
1060 return Arrays.equals(this.names, that.names);
1061 }
1062 public int hashCode() {
1063 return result + 31 * Arrays.hashCode(names);
1064 }
1065 LambdaFormEditor editor() {
1066 return LambdaFormEditor.lambdaFormEditor(this);
1067 }
1068
1069 boolean contains(Name name) {
1070 int pos = name.index();
1071 if (pos >= 0) {
1072 return pos < names.length && name.equals(names[pos]);
1073 }
1074 for (int i = arity; i < names.length; i++) {
1075 if (name.equals(names[i]))
1076 return true;
1077 }
1078 return false;
1079 }
1080
1081 static class NamedFunction {
1082 final MemberName member;
1083 private @Stable MethodHandle resolvedHandle;
1084 private @Stable MethodType type;
1085
1086 NamedFunction(MethodHandle resolvedHandle) {
1087 this(resolvedHandle.internalMemberName(), resolvedHandle);
1088 }
1089 NamedFunction(MemberName member, MethodHandle resolvedHandle) {
1090 this.member = member;
1091 this.resolvedHandle = resolvedHandle;
1092 // The following assert is almost always correct, but will fail for corner cases, such as PrivateInvokeTest.
1093 //assert(!isInvokeBasic(member));
1094 }
1095 NamedFunction(MethodType basicInvokerType) {
1096 assert(basicInvokerType == basicInvokerType.basicType()) : basicInvokerType;
1097 if (basicInvokerType.parameterSlotCount() < MethodType.MAX_MH_INVOKER_ARITY) {
1098 this.resolvedHandle = basicInvokerType.invokers().basicInvoker();
1099 this.member = resolvedHandle.internalMemberName();
1100 } else {
1101 // necessary to pass BigArityTest
1102 this.member = Invokers.invokeBasicMethod(basicInvokerType);
1103 }
1104 assert(isInvokeBasic(member));
1105 }
1106
1107 private static boolean isInvokeBasic(MemberName member) {
1108 return member != null &&
1109 member.getDeclaringClass() == MethodHandle.class &&
1110 "invokeBasic".equals(member.getName());
1111 }
1112
1113 // The next 2 constructors are used to break circular dependencies on MH.invokeStatic, etc.
1114 // Any LambdaForm containing such a member is not interpretable.
1115 // This is OK, since all such LFs are prepared with special primitive vmentry points.
1116 // And even without the resolvedHandle, the name can still be compiled and optimized.
1117 NamedFunction(Method method) {
1118 this(new MemberName(method));
1119 }
1120 NamedFunction(MemberName member) {
1121 this(member, null);
1122 }
1123
1124 MethodHandle resolvedHandle() {
1125 if (resolvedHandle == null) resolve();
1126 return resolvedHandle;
1127 }
1128
1129 synchronized void resolve() {
1130 if (resolvedHandle == null) {
1131 resolvedHandle = DirectMethodHandle.make(member);
1132 }
1133 }
1134
1135 @Override
1136 public boolean equals(Object other) {
1137 if (this == other) return true;
1138 if (other == null) return false;
1139 return (other instanceof NamedFunction that)
1140 && this.member != null
1141 && this.member.equals(that.member);
1142 }
1143
1144 @Override
1145 public int hashCode() {
1146 if (member != null)
1147 return member.hashCode();
1148 return super.hashCode();
1149 }
1150
1151 static final MethodType INVOKER_METHOD_TYPE =
1152 MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1153
1154 private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1155 typeForm = typeForm.basicType().form(); // normalize to basic type
1156 MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1157 if (mh != null) return mh;
1158 MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm); // this could take a while
1159 mh = DirectMethodHandle.make(invoker);
1160 MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1161 if (mh2 != null) return mh2; // benign race
1162 if (!mh.type().equals(INVOKER_METHOD_TYPE))
1163 throw newInternalError(mh.debugString());
1164 return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1165 }
1166
1167 @Hidden
1168 Object invokeWithArguments(Object... arguments) throws Throwable {
1169 // If we have a cached invoker, call it right away.
1170 // NOTE: The invoker always returns a reference value.
1171 if (TRACE_INTERPRETER) return invokeWithArgumentsTracing(arguments);
1172 return invoker().invokeBasic(resolvedHandle(), arguments);
1173 }
1174
1175 @Hidden
1176 Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1177 Object rval;
1178 try {
1179 traceInterpreter("[ call", this, arguments);
1180 // resolvedHandle might be uninitialized, ok for tracing
1181 if (resolvedHandle == null) {
1182 traceInterpreter("| resolve", this);
1183 resolvedHandle();
1184 }
1185 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1186 } catch (Throwable ex) {
1187 traceInterpreter("] throw =>", ex);
1188 throw ex;
1189 }
1190 traceInterpreter("] return =>", rval);
1191 return rval;
1192 }
1193
1194 private MethodHandle invoker() {
1195 return computeInvoker(methodType().form());
1196 }
1197
1198 MethodType methodType() {
1199 MethodType type = this.type;
1200 if (type == null) {
1201 this.type = type = calculateMethodType(member, resolvedHandle);
1202 }
1203 return type;
1204 }
1205
1206 private static MethodType calculateMethodType(MemberName member, MethodHandle resolvedHandle) {
1207 if (resolvedHandle != null) {
1208 return resolvedHandle.type();
1209 } else {
1210 // only for certain internal LFs during bootstrapping
1211 return member.getInvocationType();
1212 }
1213 }
1214
1215 MemberName member() {
1216 assert(assertMemberIsConsistent());
1217 return member;
1218 }
1219
1220 // Called only from assert.
1221 private boolean assertMemberIsConsistent() {
1222 if (resolvedHandle instanceof DirectMethodHandle) {
1223 MemberName m = resolvedHandle.internalMemberName();
1224 assert(m.equals(member));
1225 }
1226 return true;
1227 }
1228
1229 Class<?> memberDeclaringClassOrNull() {
1230 return (member == null) ? null : member.getDeclaringClass();
1231 }
1232
1233 BasicType returnType() {
1234 return basicType(methodType().returnType());
1235 }
1236
1237 BasicType parameterType(int n) {
1238 return basicType(methodType().parameterType(n));
1239 }
1240
1241 int arity() {
1242 return methodType().parameterCount();
1243 }
1244
1245 public String toString() {
1246 if (member == null) return String.valueOf(resolvedHandle);
1247 return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1248 }
1249
1250 public boolean isIdentity() {
1251 return this.equals(identity(returnType()));
1252 }
1253
1254 public boolean isConstantZero() {
1255 return this.equals(constantZero(returnType()));
1256 }
1257
1258 public MethodHandleImpl.Intrinsic intrinsicName() {
1259 return resolvedHandle != null
1260 ? resolvedHandle.intrinsicName()
1261 : MethodHandleImpl.Intrinsic.NONE;
1262 }
1263
1264 public Object intrinsicData() {
1265 return resolvedHandle != null
1266 ? resolvedHandle.intrinsicData()
1267 : null;
1268 }
1269 }
1270
1271 public static String basicTypeSignature(MethodType type) {
1272 int params = type.parameterCount();
1273 char[] sig = new char[params + 2];
1274 int sigp = 0;
1275 while (sigp < params) {
1276 sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1277 }
1278 sig[sigp++] = '_';
1279 sig[sigp++] = basicTypeChar(type.returnType());
1280 assert(sigp == sig.length);
1281 return String.valueOf(sig);
1282 }
1283
1284 /** Hack to make signatures more readable when they show up in method names.
1285 * Signature should start with a sequence of uppercase ASCII letters.
1286 * Runs of three or more are replaced by a single letter plus a decimal repeat count.
1287 * A tail of anything other than uppercase ASCII is passed through unchanged.
1288 * @param signature sequence of uppercase ASCII letters with possible repetitions
1289 * @return same sequence, with repetitions counted by decimal numerals
1290 */
1291 public static String shortenSignature(String signature) {
1292 final int NO_CHAR = -1, MIN_RUN = 3;
1293 int c0, c1 = NO_CHAR, c1reps = 0;
1294 StringBuilder buf = null;
1295 int len = signature.length();
1296 if (len < MIN_RUN) return signature;
1297 for (int i = 0; i <= len; i++) {
1298 if (c1 != NO_CHAR && !('A' <= c1 && c1 <= 'Z')) {
1299 // wrong kind of char; bail out here
1300 if (buf != null) {
1301 buf.append(signature, i - c1reps, len);
1302 }
1303 break;
1304 }
1305 // shift in the next char:
1306 c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1307 if (c1 == c0) { ++c1reps; continue; }
1308 // shift in the next count:
1309 int c0reps = c1reps; c1reps = 1;
1310 // end of a character run
1311 if (c0reps < MIN_RUN) {
1312 if (buf != null) {
1313 while (--c0reps >= 0)
1314 buf.append((char)c0);
1315 }
1316 continue;
1317 }
1318 // found three or more in a row
1319 if (buf == null)
1320 buf = new StringBuilder().append(signature, 0, i - c0reps);
1321 buf.append((char)c0).append(c0reps);
1322 }
1323 return (buf == null) ? signature : buf.toString();
1324 }
1325
1326 static final class Name {
1327 final BasicType type;
1328 final short index;
1329 final NamedFunction function;
1330 final Object constraint; // additional type information, if not null
1331 @Stable final Object[] arguments;
1332
1333 private static final Object[] EMPTY_ARGS = new Object[0];
1334
1335 private Name(int index, BasicType type, NamedFunction function, Object[] arguments, Object constraint) {
1336 this.index = (short)index;
1337 this.type = type;
1338 this.function = function;
1339 this.arguments = arguments;
1340 this.constraint = constraint;
1341 assert(this.index == index && typesMatch(function, arguments));
1342 assert(constraint == null || isParam()); // only params have constraints
1343 assert(constraint == null || constraint instanceof ClassSpecializer.SpeciesData || constraint instanceof Class);
1344 }
1345
1346 Name(MethodHandle function, Object... arguments) {
1347 this(new NamedFunction(function), arguments);
1348 }
1349 Name(MethodType functionType, Object... arguments) {
1350 this(new NamedFunction(functionType), arguments);
1351 assert(arguments[0] instanceof Name name && name.type == L_TYPE);
1352 }
1353 Name(MemberName function, Object... arguments) {
1354 this(new NamedFunction(function), arguments);
1355 }
1356 Name(NamedFunction function) {
1357 this(-1, function.returnType(), function, EMPTY_ARGS, null);
1358 }
1359 Name(NamedFunction function, Object arg) {
1360 this(-1, function.returnType(), function, new Object[] { arg }, null);
1361 }
1362 Name(NamedFunction function, Object arg0, Object arg1) {
1363 this(-1, function.returnType(), function, new Object[] { arg0, arg1 }, null);
1364 }
1365 Name(NamedFunction function, Object... arguments) {
1366 this(-1, function.returnType(), function, Arrays.copyOf(arguments, arguments.length, Object[].class), null);
1367 }
1368 /** Create a raw parameter of the given type, with an expected index. */
1369 Name(int index, BasicType type) {
1370 this(index, type, null, null, null);
1371 }
1372 /** Create a raw parameter of the given type. */
1373 Name(BasicType type) { this(-1, type); }
1374
1375 BasicType type() { return type; }
1376 int index() { return index; }
1377
1378 char typeChar() {
1379 return type.btChar;
1380 }
1381
1382 Name withIndex(int i) {
1383 if (i == this.index) return this;
1384 return new Name(i, type, function, arguments, constraint);
1385 }
1386
1387 Name withConstraint(Object constraint) {
1388 if (constraint == this.constraint) return this;
1389 return new Name(index, type, function, arguments, constraint);
1390 }
1391
1392 Name replaceName(Name oldName, Name newName) { // FIXME: use replaceNames uniformly
1393 if (oldName == newName) return this;
1394 @SuppressWarnings("LocalVariableHidesMemberVariable")
1395 Object[] arguments = this.arguments;
1396 if (arguments == null) return this;
1397 boolean replaced = false;
1398 for (int j = 0; j < arguments.length; j++) {
1399 if (arguments[j] == oldName) {
1400 if (!replaced) {
1401 replaced = true;
1402 arguments = arguments.clone();
1403 }
1404 arguments[j] = newName;
1405 }
1406 }
1407 if (!replaced) return this;
1408 return new Name(function, arguments);
1409 }
1410 /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1411 * Limit such replacements to {@code start<=i<end}. Return possibly changed self.
1412 */
1413 Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1414 if (start >= end) return this;
1415 @SuppressWarnings("LocalVariableHidesMemberVariable")
1416 Object[] arguments = this.arguments;
1417 boolean replaced = false;
1418 eachArg:
1419 for (int j = 0; j < arguments.length; j++) {
1420 if (arguments[j] instanceof Name n) {
1421 int check = n.index;
1422 // harmless check to see if the thing is already in newNames:
1423 if (check >= 0 && check < newNames.length && n == newNames[check])
1424 continue eachArg;
1425 // n might not have the correct index: n != oldNames[n.index].
1426 for (int i = start; i < end; i++) {
1427 if (n == oldNames[i]) {
1428 if (n == newNames[i])
1429 continue eachArg;
1430 if (!replaced) {
1431 replaced = true;
1432 arguments = arguments.clone();
1433 }
1434 arguments[j] = newNames[i];
1435 continue eachArg;
1436 }
1437 }
1438 }
1439 }
1440 if (!replaced) return this;
1441 return new Name(function, arguments);
1442 }
1443 void internArguments() {
1444 @SuppressWarnings("LocalVariableHidesMemberVariable")
1445 Object[] arguments = this.arguments;
1446 for (int j = 0; j < arguments.length; j++) {
1447 if (arguments[j] instanceof Name n) {
1448 if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1449 arguments[j] = internArgument(n);
1450 }
1451 }
1452 }
1453 boolean isParam() {
1454 return function == null;
1455 }
1456 boolean isConstantZero() {
1457 return !isParam() && arguments.length == 0 && function.isConstantZero();
1458 }
1459
1460 boolean refersTo(Class<?> declaringClass, String methodName) {
1461 return function != null &&
1462 function.member() != null && function.member().refersTo(declaringClass, methodName);
1463 }
1464
1465 /**
1466 * Check if MemberName is a call to MethodHandle.invokeBasic.
1467 */
1468 boolean isInvokeBasic() {
1469 if (function == null)
1470 return false;
1471 if (arguments.length < 1)
1472 return false; // must have MH argument
1473 MemberName member = function.member();
1474 return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1475 !member.isPublic() && !member.isStatic();
1476 }
1477
1478 /**
1479 * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1480 */
1481 boolean isLinkerMethodInvoke() {
1482 if (function == null)
1483 return false;
1484 if (arguments.length < 1)
1485 return false; // must have MH argument
1486 MemberName member = function.member();
1487 return member != null &&
1488 member.getDeclaringClass() == MethodHandle.class &&
1489 !member.isPublic() && member.isStatic() &&
1490 member.getName().startsWith("linkTo");
1491 }
1492
1493 public String toString() {
1494 return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1495 }
1496 public String debugString() {
1497 String s = paramString();
1498 return (function == null) ? s : s + "=" + exprString();
1499 }
1500 public String paramString() {
1501 String s = toString();
1502 Object c = constraint;
1503 if (c == null)
1504 return s;
1505 if (c instanceof Class<?> cl) c = cl.getSimpleName();
1506 return s + "/" + c;
1507 }
1508 public String exprString() {
1509 if (function == null) return toString();
1510 StringBuilder buf = new StringBuilder(function.toString());
1511 buf.append("(");
1512 String cma = "";
1513 for (Object a : arguments) {
1514 buf.append(cma); cma = ",";
1515 if (a instanceof Name || a instanceof Integer)
1516 buf.append(a);
1517 else
1518 buf.append("(").append(a).append(")");
1519 }
1520 buf.append(")");
1521 return buf.toString();
1522 }
1523
1524 private boolean typesMatch(NamedFunction function, Object ... arguments) {
1525 if (arguments == null) {
1526 assert(function == null);
1527 return true;
1528 }
1529 assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1530 for (int i = 0; i < arguments.length; i++) {
1531 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1532 }
1533 return true;
1534 }
1535
1536 private static boolean typesMatch(BasicType parameterType, Object object) {
1537 if (object instanceof Name name) {
1538 return name.type == parameterType;
1539 }
1540 switch (parameterType) {
1541 case I_TYPE: return object instanceof Integer;
1542 case J_TYPE: return object instanceof Long;
1543 case F_TYPE: return object instanceof Float;
1544 case D_TYPE: return object instanceof Double;
1545 }
1546 assert(parameterType == L_TYPE);
1547 return true;
1548 }
1549
1550 /** Return the index of the last occurrence of n in the argument array.
1551 * Return -1 if the name is not used.
1552 */
1553 int lastUseIndex(Name n) {
1554 Object[] arguments = this.arguments;
1555 if (arguments == null) return -1;
1556 for (int i = arguments.length; --i >= 0; ) {
1557 if (arguments[i] == n) return i;
1558 }
1559 return -1;
1560 }
1561
1562 public boolean equals(Name that) {
1563 if (this == that) return true;
1564 if (isParam())
1565 // each parameter is a unique atom
1566 return false; // this != that
1567 return
1568 //this.index == that.index &&
1569 this.type == that.type &&
1570 this.function.equals(that.function) &&
1571 Arrays.equals(this.arguments, that.arguments);
1572 }
1573 @Override
1574 public boolean equals(Object x) {
1575 return x instanceof Name n && equals(n);
1576 }
1577 @Override
1578 public int hashCode() {
1579 if (isParam())
1580 return index | (type.ordinal() << 8);
1581 return function.hashCode() ^ Arrays.hashCode(arguments);
1582 }
1583 }
1584
1585 /** Return the index of the last name which contains n as an argument.
1586 * Return -1 if the name is not used. Return names.length if it is the return value.
1587 */
1588 int lastUseIndex(Name n) {
1589 int ni = n.index, nmax = names.length;
1590 assert(names[ni] == n);
1591 if (result == ni) return nmax; // live all the way beyond the end
1592 for (int i = nmax; --i > ni; ) {
1593 if (names[i].lastUseIndex(n) >= 0)
1594 return i;
1595 }
1596 return -1;
1597 }
1598
1599 /** Return the number of times n is used as an argument or return value. */
1600 int useCount(Name n) {
1601 int count = (result == n.index) ? 1 : 0;
1602 int i = Math.max(n.index + 1, arity);
1603 Name[] names = this.names;
1604 while (i < names.length) {
1605 Object[] arguments = names[i++].arguments;
1606 if (arguments != null) {
1607 for (Object argument : arguments) {
1608 if (argument == n) {
1609 count++;
1610 }
1611 }
1612 }
1613 }
1614 return count;
1615 }
1616
1617 static Name argument(int which, BasicType type) {
1618 if (which >= INTERNED_ARGUMENT_LIMIT)
1619 return new Name(which, type);
1620 return INTERNED_ARGUMENTS[type.ordinal()][which];
1621 }
1622 static Name internArgument(Name n) {
1623 assert(n.isParam()) : "not param: " + n;
1624 assert(n.index < INTERNED_ARGUMENT_LIMIT);
1625 if (n.constraint != null) return n;
1626 return argument(n.index, n.type);
1627 }
1628 static Name[] arguments(int extra, MethodType types) {
1629 int length = types.parameterCount();
1630 Name[] names = new Name[length + extra];
1631 for (int i = 0; i < length; i++)
1632 names[i] = argument(i, basicType(types.parameterType(i)));
1633 return names;
1634 }
1635
1636 static Name[] invokeArguments(int extra, MethodType types) {
1637 int length = types.parameterCount();
1638 Name[] names = new Name[length + extra + 1];
1639 names[0] = argument(0, L_TYPE);
1640 for (int i = 0; i < length; i++)
1641 names[i + 1] = argument(i + 1, basicType(types.parameterType(i)));
1642 return names;
1643 }
1644
1645 static final int INTERNED_ARGUMENT_LIMIT = 10;
1646 private static final Name[][] INTERNED_ARGUMENTS
1647 = new Name[ARG_TYPE_LIMIT][INTERNED_ARGUMENT_LIMIT];
1648 static {
1649 for (BasicType type : BasicType.ARG_TYPES) {
1650 int ord = type.ordinal();
1651 for (int i = 0; i < INTERNED_ARGUMENTS[ord].length; i++) {
1652 INTERNED_ARGUMENTS[ord][i] = new Name(i, type);
1653 }
1654 }
1655 }
1656
1657 private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
1658
1659 static LambdaForm identityForm(BasicType type) {
1660 int ord = type.ordinal();
1661 LambdaForm form = LF_identity[ord];
1662 if (form != null) {
1663 return form;
1664 }
1665 createFormsFor(type);
1666 return LF_identity[ord];
1667 }
1668
1669 static LambdaForm zeroForm(BasicType type) {
1670 int ord = type.ordinal();
1671 LambdaForm form = LF_zero[ord];
1672 if (form != null) {
1673 return form;
1674 }
1675 createFormsFor(type);
1676 return LF_zero[ord];
1677 }
1678
1679 static NamedFunction identity(BasicType type) {
1680 int ord = type.ordinal();
1681 NamedFunction function = NF_identity[ord];
1682 if (function != null) {
1683 return function;
1684 }
1685 createFormsFor(type);
1686 return NF_identity[ord];
1687 }
1688
1689 static NamedFunction constantZero(BasicType type) {
1690 int ord = type.ordinal();
1691 NamedFunction function = NF_zero[ord];
1692 if (function != null) {
1693 return function;
1694 }
1695 createFormsFor(type);
1696 return NF_zero[ord];
1697 }
1698
1699 private static final @Stable LambdaForm[] LF_identity = new LambdaForm[TYPE_LIMIT];
1700 private static final @Stable LambdaForm[] LF_zero = new LambdaForm[TYPE_LIMIT];
1701 private static final @Stable NamedFunction[] NF_identity = new NamedFunction[TYPE_LIMIT];
1702 private static final @Stable NamedFunction[] NF_zero = new NamedFunction[TYPE_LIMIT];
1703
1704 private static final Object createFormsLock = new Object();
1705 private static void createFormsFor(BasicType type) {
1706 // Avoid racy initialization during bootstrap
1707 UNSAFE.ensureClassInitialized(BoundMethodHandle.class);
1708 synchronized (createFormsLock) {
1709 final int ord = type.ordinal();
1710 LambdaForm idForm = LF_identity[ord];
1711 if (idForm != null) {
1712 return;
1713 }
1714 char btChar = type.basicTypeChar();
1715 boolean isVoid = (type == V_TYPE);
1716 Class<?> btClass = type.btClass;
1717 MethodType zeType = MethodType.methodType(btClass);
1718 MethodType idType = (isVoid) ? zeType : MethodType.methodType(btClass, btClass);
1719
1720 // Look up symbolic names. It might not be necessary to have these,
1721 // but if we need to emit direct references to bytecodes, it helps.
1722 // Zero is built from a call to an identity function with a constant zero input.
1723 MemberName idMem = new MemberName(LambdaForm.class, "identity_"+btChar, idType, REF_invokeStatic);
1724 MemberName zeMem = null;
1725 try {
1726 idMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, idMem, null, LM_TRUSTED, NoSuchMethodException.class);
1727 if (!isVoid) {
1728 zeMem = new MemberName(LambdaForm.class, "zero_"+btChar, zeType, REF_invokeStatic);
1729 zeMem = IMPL_NAMES.resolveOrFail(REF_invokeStatic, zeMem, null, LM_TRUSTED, NoSuchMethodException.class);
1730 }
1731 } catch (IllegalAccessException|NoSuchMethodException ex) {
1732 throw newInternalError(ex);
1733 }
1734
1735 NamedFunction idFun;
1736 LambdaForm zeForm;
1737 NamedFunction zeFun;
1738
1739 // Create the LFs and NamedFunctions. Precompiling LFs to byte code is needed to break circular
1740 // bootstrap dependency on this method in case we're interpreting LFs
1741 if (isVoid) {
1742 Name[] idNames = new Name[] { argument(0, L_TYPE) };
1743 idForm = LambdaForm.create(1, idNames, VOID_RESULT, Kind.IDENTITY);
1744 idForm.compileToBytecode();
1745 idFun = new NamedFunction(idMem, SimpleMethodHandle.make(idMem.getInvocationType(), idForm));
1746
1747 zeForm = idForm;
1748 zeFun = idFun;
1749 } else {
1750 Name[] idNames = new Name[] { argument(0, L_TYPE), argument(1, type) };
1751 idForm = LambdaForm.create(2, idNames, 1, Kind.IDENTITY);
1752 idForm.compileToBytecode();
1753 idFun = new NamedFunction(idMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(idMem.getInvocationType(), idForm),
1754 MethodHandleImpl.Intrinsic.IDENTITY));
1755
1756 Object zeValue = Wrapper.forBasicType(btChar).zero();
1757 Name[] zeNames = new Name[] { argument(0, L_TYPE), new Name(idFun, zeValue) };
1758 zeForm = LambdaForm.create(1, zeNames, 1, Kind.ZERO);
1759 zeForm.compileToBytecode();
1760 zeFun = new NamedFunction(zeMem, MethodHandleImpl.makeIntrinsic(SimpleMethodHandle.make(zeMem.getInvocationType(), zeForm),
1761 MethodHandleImpl.Intrinsic.ZERO));
1762 }
1763
1764 LF_zero[ord] = zeForm;
1765 NF_zero[ord] = zeFun;
1766 LF_identity[ord] = idForm;
1767 NF_identity[ord] = idFun;
1768
1769 assert(idFun.isIdentity());
1770 assert(zeFun.isConstantZero());
1771 assert(new Name(zeFun).isConstantZero());
1772 }
1773 }
1774
1775 // Avoid appealing to ValueConversions at bootstrap time:
1776 private static int identity_I(int x) { return x; }
1777 private static long identity_J(long x) { return x; }
1778 private static float identity_F(float x) { return x; }
1779 private static double identity_D(double x) { return x; }
1780 private static Object identity_L(Object x) { return x; }
1781 private static void identity_V() { return; }
1782 private static int zero_I() { return 0; }
1783 private static long zero_J() { return 0; }
1784 private static float zero_F() { return 0; }
1785 private static double zero_D() { return 0; }
1786 private static Object zero_L() { return null; }
1787
1788 /**
1789 * Internal marker for byte-compiled LambdaForms.
1790 */
1791 /*non-public*/
1792 @Target(ElementType.METHOD)
1793 @Retention(RetentionPolicy.RUNTIME)
1794 @interface Compiled {
1795 }
1796
1797 private static final HashMap<String,Integer> DEBUG_NAME_COUNTERS;
1798 private static final HashMap<LambdaForm,String> DEBUG_NAMES;
1799 static {
1800 if (debugEnabled()) {
1801 DEBUG_NAME_COUNTERS = new HashMap<>();
1802 DEBUG_NAMES = new HashMap<>();
1803 } else {
1804 DEBUG_NAME_COUNTERS = null;
1805 DEBUG_NAMES = null;
1806 }
1807 }
1808
1809 static {
1810 // The Holder class will contain pre-generated forms resolved
1811 // using MemberName.getFactory(). However, that doesn't initialize the
1812 // class, which subtly breaks inlining etc. By forcing
1813 // initialization of the Holder class we avoid these issues.
1814 UNSAFE.ensureClassInitialized(Holder.class);
1815 }
1816
1817 /* Placeholder class for zero and identity forms generated ahead of time */
1818 final class Holder {}
1819
1820 // The following hack is necessary in order to suppress TRACE_INTERPRETER
1821 // during execution of the static initializes of this class.
1822 // Turning on TRACE_INTERPRETER too early will cause
1823 // stack overflows and other misbehavior during attempts to trace events
1824 // that occur during LambdaForm.<clinit>.
1825 // Therefore, do not move this line higher in this file, and do not remove.
1826 private static final boolean TRACE_INTERPRETER = MethodHandleStatics.TRACE_INTERPRETER;
1827 }