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