1 /*
2 * Copyright (c) 2011, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import jdk.internal.perf.PerfCounter;
29 import jdk.internal.vm.annotation.DontInline;
30 import jdk.internal.vm.annotation.Hidden;
31 import jdk.internal.vm.annotation.Stable;
32 import sun.invoke.util.Wrapper;
33
34 import java.lang.annotation.ElementType;
35 import java.lang.annotation.Retention;
36 import java.lang.annotation.RetentionPolicy;
37 import java.lang.annotation.Target;
38 import java.lang.reflect.Method;
39 import java.util.Arrays;
40 import java.util.HashMap;
41
42 import static java.lang.invoke.LambdaForm.BasicType.*;
43 import static java.lang.invoke.MethodHandleNatives.Constants.*;
44 import static java.lang.invoke.MethodHandleStatics.*;
45
46 /**
47 * The symbolic, non-executable form of a method handle's invocation semantics.
48 * It consists of a series of names.
49 * The first N (N=arity) names are parameters,
50 * while any remaining names are temporary values.
51 * Each temporary specifies the application of a function to some arguments.
52 * The functions are method handles, while the arguments are mixes of
53 * constant values and local names.
54 * The result of the lambda is defined as one of the names, often the last one.
55 * <p>
56 * Here is an approximate grammar:
57 * <blockquote><pre>{@code
58 * LambdaForm = "(" ArgName* ")=>{" TempName* Result "}"
59 * ArgName = "a" N ":" T
60 * TempName = "t" N ":" T "=" Function "(" Argument* ");"
61 * Function = ConstantValue
62 * Argument = NameRef | ConstantValue
63 * Result = NameRef | "void"
64 * NameRef = "a" N | "t" N
65 * N = (any whole number)
66 * T = "L" | "I" | "J" | "F" | "D" | "V"
67 * }</pre></blockquote>
68 * Names are numbered consecutively from left to right starting at zero.
69 * (The letters are merely a taste of syntax sugar.)
70 * Thus, the first temporary (if any) is always numbered N (where N=arity).
71 * Every occurrence of a name reference in an argument list must refer to
72 * a name previously defined within the same lambda.
73 * A lambda has a void result if and only if its result index is -1.
74 * If a temporary has the type "V", it cannot be the subject of a NameRef,
75 * even though possesses a number.
76 * Note that all reference types are erased to "L", which stands for {@code Object}.
77 * All subword types (boolean, byte, short, char) are erased to "I" which is {@code int}.
78 * The other types stand for the usual primitive types.
79 * <p>
80 * Function invocation closely follows the static rules of the Java verifier.
81 * Arguments and return values must exactly match when their "Name" types are
82 * considered.
83 * Conversions are allowed only if they do not change the erased type.
84 * <ul>
85 * <li>L = Object: casts are used freely to convert into and out of reference types
86 * <li>I = int: subword types are forcibly narrowed when passed as arguments (see {@code explicitCastArguments})
87 * <li>J = long: no implicit conversions
88 * <li>F = float: no implicit conversions
89 * <li>D = double: no implicit conversions
90 * <li>V = void: a function result may be void if and only if its Name is of type "V"
91 * </ul>
92 * Although implicit conversions are not allowed, explicit ones can easily be
93 * encoded by using temporary expressions which call type-transformed identity functions.
94 * <p>
95 * Examples:
96 * <blockquote><pre>{@code
97 * (a0:J)=>{ a0 }
98 * == identity(long)
99 * (a0:I)=>{ t1:V = System.out#println(a0); void }
100 * == System.out#println(int)
101 * (a0:L)=>{ t1:V = System.out#println(a0); a0 }
102 * == identity, with printing side-effect
103 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
104 * t3:L = BoundMethodHandle#target(a0);
105 * t4:L = MethodHandle#invoke(t3, t2, a1); t4 }
106 * == general invoker for unary insertArgument combination
107 * (a0:L, a1:L)=>{ t2:L = FilterMethodHandle#filter(a0);
108 * t3:L = MethodHandle#invoke(t2, a1);
109 * t4:L = FilterMethodHandle#target(a0);
110 * t5:L = MethodHandle#invoke(t4, t3); t5 }
111 * == general invoker for unary filterArgument combination
112 * (a0:L, a1:L)=>{ ...(same as previous example)...
113 * t5:L = MethodHandle#invoke(t4, t3, a1); t5 }
114 * == general invoker for unary/unary foldArgument combination
115 * (a0:L, a1:I)=>{ t2:I = identity(long).asType((int)->long)(a1); t2 }
116 * == invoker for identity method handle which performs i2l
117 * (a0:L, a1:L)=>{ t2:L = BoundMethodHandle#argument(a0);
118 * t3:L = Class#cast(t2,a1); t3 }
119 * == invoker for identity method handle which performs cast
120 * }</pre></blockquote>
121 * <p>
122 * @author John Rose, JSR 292 EG
123 */
124 class LambdaForm {
125 final int arity;
126 final int result;
127 final boolean forceInline;
128 final MethodHandle customized;
129 @Stable final Name[] names;
130 final Kind kind;
131 MemberName vmentry; // low-level behavior, or null if not yet prepared
132 private boolean isCompiled;
133
134 // Either a LambdaForm cache (managed by LambdaFormEditor) or a link to uncustomized version (for customized LF)
135 volatile Object transformCache;
136
137 public static final int VOID_RESULT = -1, LAST_RESULT = -2;
138
139 enum BasicType {
140 L_TYPE('L', Object.class, Wrapper.OBJECT), // all reference types
141 I_TYPE('I', int.class, Wrapper.INT),
142 J_TYPE('J', long.class, Wrapper.LONG),
143 F_TYPE('F', float.class, Wrapper.FLOAT),
144 D_TYPE('D', double.class, Wrapper.DOUBLE), // all primitive types
145 V_TYPE('V', void.class, Wrapper.VOID); // not valid in all contexts
146
147 static final @Stable BasicType[] ALL_TYPES = BasicType.values();
148 static final @Stable BasicType[] ARG_TYPES = Arrays.copyOf(ALL_TYPES, ALL_TYPES.length-1);
149
150 static final int ARG_TYPE_LIMIT = ARG_TYPES.length;
151 static final int TYPE_LIMIT = ALL_TYPES.length;
152
153 // Derived int constants, which (unlike the enums) can be constant folded.
154 // We can remove them when JDK-8161245 is fixed.
155 static final byte
156 L_TYPE_NUM = (byte) L_TYPE.ordinal(),
157 I_TYPE_NUM = (byte) I_TYPE.ordinal(),
158 J_TYPE_NUM = (byte) J_TYPE.ordinal(),
159 F_TYPE_NUM = (byte) F_TYPE.ordinal(),
160 D_TYPE_NUM = (byte) D_TYPE.ordinal(),
161 V_TYPE_NUM = (byte) V_TYPE.ordinal();
162
163 final char btChar;
164 final Class<?> btClass;
165 final Wrapper btWrapper;
166
167 private BasicType(char btChar, Class<?> btClass, Wrapper wrapper) {
168 this.btChar = btChar;
169 this.btClass = btClass;
170 this.btWrapper = wrapper;
171 }
172
173 char basicTypeChar() {
174 return btChar;
175 }
176 Class<?> basicTypeClass() {
177 return btClass;
178 }
179 Wrapper basicTypeWrapper() {
180 return btWrapper;
181 }
182 int basicTypeSlots() {
183 return btWrapper.stackSlots();
184 }
185
186 static BasicType basicType(byte type) {
187 return ALL_TYPES[type];
188 }
189 static BasicType basicType(char type) {
190 return switch (type) {
191 case 'L' -> L_TYPE;
192 case 'I' -> I_TYPE;
193 case 'J' -> J_TYPE;
194 case 'F' -> F_TYPE;
195 case 'D' -> D_TYPE;
196 case 'V' -> V_TYPE;
197 // all subword types are represented as ints
198 case 'Z', 'B', 'S', 'C' -> I_TYPE;
199 default -> throw newInternalError("Unknown type char: '" + type + "'");
200 };
201 }
202 static BasicType basicType(Wrapper type) {
203 char c = type.basicTypeChar();
204 return basicType(c);
205 }
206 static BasicType basicType(Class<?> type) {
207 if (!type.isPrimitive()) return L_TYPE;
208 return basicType(Wrapper.forPrimitiveType(type));
209 }
210 static int[] basicTypeOrds(BasicType[] types) {
211 if (types == null) {
212 return null;
213 }
214 int[] a = new int[types.length];
215 for(int i = 0; i < types.length; ++i) {
216 a[i] = types[i].ordinal();
217 }
218 return a;
219 }
220
221 static char basicTypeChar(Class<?> type) {
222 return basicType(type).btChar;
223 }
224
225 static byte[] basicTypesOrd(Class<?>[] types) {
226 byte[] ords = new byte[types.length];
227 for (int i = 0; i < ords.length; i++) {
228 ords[i] = (byte)basicType(types[i]).ordinal();
229 }
230 return ords;
231 }
232
233 static boolean isBasicTypeChar(char c) {
234 return "LIJFDV".indexOf(c) >= 0;
235 }
236 static boolean isArgBasicTypeChar(char c) {
237 return "LIJFD".indexOf(c) >= 0;
238 }
239
240 static { assert(checkBasicType()); }
241 private static boolean checkBasicType() {
242 for (int i = 0; i < ARG_TYPE_LIMIT; i++) {
243 assert ARG_TYPES[i].ordinal() == i;
244 assert ARG_TYPES[i] == ALL_TYPES[i];
245 }
246 for (int i = 0; i < TYPE_LIMIT; i++) {
247 assert ALL_TYPES[i].ordinal() == i;
248 }
249 assert ALL_TYPES[TYPE_LIMIT - 1] == V_TYPE;
250 assert !Arrays.asList(ARG_TYPES).contains(V_TYPE);
251 return true;
252 }
253 }
254
255 enum Kind {
256 GENERIC("invoke"),
257 ZERO("zero"),
258 IDENTITY("identity"),
259 BOUND_REINVOKER("BMH.reinvoke", "reinvoke"),
260 REINVOKER("MH.reinvoke", "reinvoke"),
261 DELEGATE("MH.delegate", "delegate"),
262 EXACT_LINKER("MH.invokeExact_MT", "invokeExact_MT"),
263 EXACT_INVOKER("MH.exactInvoker", "exactInvoker"),
264 GENERIC_LINKER("MH.invoke_MT", "invoke_MT"),
265 GENERIC_INVOKER("MH.invoker", "invoker"),
266 LINK_TO_TARGET_METHOD("linkToTargetMethod"),
267 LINK_TO_CALL_SITE("linkToCallSite"),
268 DIRECT_INVOKE_VIRTUAL("DMH.invokeVirtual", "invokeVirtual"),
269 DIRECT_INVOKE_SPECIAL("DMH.invokeSpecial", "invokeSpecial"),
270 DIRECT_INVOKE_SPECIAL_IFC("DMH.invokeSpecialIFC", "invokeSpecialIFC"),
271 DIRECT_INVOKE_STATIC("DMH.invokeStatic", "invokeStatic"),
272 DIRECT_NEW_INVOKE_SPECIAL("DMH.newInvokeSpecial", "newInvokeSpecial"),
273 DIRECT_INVOKE_INTERFACE("DMH.invokeInterface", "invokeInterface"),
274 DIRECT_INVOKE_STATIC_INIT("DMH.invokeStaticInit", "invokeStaticInit"),
275 GET_REFERENCE("getReference"),
276 PUT_REFERENCE("putReference"),
277 GET_REFERENCE_VOLATILE("getReferenceVolatile"),
278 PUT_REFERENCE_VOLATILE("putReferenceVolatile"),
279 GET_INT("getInt"),
280 PUT_INT("putInt"),
281 GET_INT_VOLATILE("getIntVolatile"),
282 PUT_INT_VOLATILE("putIntVolatile"),
283 GET_BOOLEAN("getBoolean"),
284 PUT_BOOLEAN("putBoolean"),
285 GET_BOOLEAN_VOLATILE("getBooleanVolatile"),
286 PUT_BOOLEAN_VOLATILE("putBooleanVolatile"),
287 GET_BYTE("getByte"),
288 PUT_BYTE("putByte"),
289 GET_BYTE_VOLATILE("getByteVolatile"),
290 PUT_BYTE_VOLATILE("putByteVolatile"),
291 GET_CHAR("getChar"),
292 PUT_CHAR("putChar"),
293 GET_CHAR_VOLATILE("getCharVolatile"),
294 PUT_CHAR_VOLATILE("putCharVolatile"),
295 GET_SHORT("getShort"),
296 PUT_SHORT("putShort"),
297 GET_SHORT_VOLATILE("getShortVolatile"),
298 PUT_SHORT_VOLATILE("putShortVolatile"),
299 GET_LONG("getLong"),
300 PUT_LONG("putLong"),
301 GET_LONG_VOLATILE("getLongVolatile"),
302 PUT_LONG_VOLATILE("putLongVolatile"),
303 GET_FLOAT("getFloat"),
304 PUT_FLOAT("putFloat"),
305 GET_FLOAT_VOLATILE("getFloatVolatile"),
306 PUT_FLOAT_VOLATILE("putFloatVolatile"),
307 GET_DOUBLE("getDouble"),
308 PUT_DOUBLE("putDouble"),
309 GET_DOUBLE_VOLATILE("getDoubleVolatile"),
310 PUT_DOUBLE_VOLATILE("putDoubleVolatile"),
311 TRY_FINALLY("tryFinally"),
312 TABLE_SWITCH("tableSwitch"),
313 COLLECT("collect"),
314 COLLECTOR("collector"),
315 CONVERT("convert"),
316 SPREAD("spread"),
317 LOOP("loop"),
318 FIELD("field"),
319 GUARD("guard"),
320 GUARD_WITH_CATCH("guardWithCatch"),
321 VARHANDLE_EXACT_INVOKER("VH.exactInvoker"),
322 VARHANDLE_INVOKER("VH.invoker", "invoker"),
323 VARHANDLE_LINKER("VH.invoke_MT", "invoke_MT");
324
325 final String defaultLambdaName;
326 final String methodName;
327
328 private Kind(String defaultLambdaName) {
329 this(defaultLambdaName, defaultLambdaName);
330 }
331
332 private Kind(String defaultLambdaName, String methodName) {
333 this.defaultLambdaName = defaultLambdaName;
334 this.methodName = methodName;
335 }
336 }
337
338 LambdaForm(int arity, Name[] names, int result) {
339 this(arity, names, result, /*forceInline=*/true, /*customized=*/null, Kind.GENERIC);
340 }
341 LambdaForm(int arity, Name[] names, int result, Kind kind) {
342 this(arity, names, result, /*forceInline=*/true, /*customized=*/null, kind);
343 }
344 LambdaForm(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized) {
345 this(arity, names, result, forceInline, customized, Kind.GENERIC);
346 }
347 LambdaForm(int arity, Name[] names, int result, boolean forceInline, MethodHandle customized, Kind kind) {
348 assert(namesOK(arity, names));
349 this.arity = arity;
350 this.result = fixResult(result, names);
351 this.names = names.clone();
352 this.forceInline = forceInline;
353 this.customized = customized;
354 this.kind = kind;
355 int maxOutArity = normalize();
356 if (maxOutArity > MethodType.MAX_MH_INVOKER_ARITY) {
357 // Cannot use LF interpreter on very high arity expressions.
358 assert(maxOutArity <= MethodType.MAX_JVM_ARITY);
359 compileToBytecode();
360 }
361 }
362 LambdaForm(int arity, Name[] names) {
363 this(arity, names, LAST_RESULT, /*forceInline=*/true, /*customized=*/null, Kind.GENERIC);
364 }
365 LambdaForm(int arity, Name[] names, Kind kind) {
366 this(arity, names, LAST_RESULT, /*forceInline=*/true, /*customized=*/null, kind);
367 }
368 LambdaForm(int arity, Name[] names, boolean forceInline, Kind kind) {
369 this(arity, names, LAST_RESULT, forceInline, /*customized=*/null, kind);
370 }
371
372 private static Name[] buildNames(Name[] formals, Name[] temps, Name result) {
373 int arity = formals.length;
374 int length = arity + temps.length + (result == null ? 0 : 1);
375 Name[] names = Arrays.copyOf(formals, length);
376 System.arraycopy(temps, 0, names, arity, temps.length);
377 if (result != null)
378 names[length - 1] = result;
379 return names;
380 }
381
382 private LambdaForm(MethodType mt) {
383 // Make a blank lambda form, which returns a constant zero or null.
384 // It is used as a template for managing the invocation of similar forms that are non-empty.
385 // Called only from getPreparedForm.
386 this.arity = mt.parameterCount();
387 this.result = (mt.returnType() == void.class || mt.returnType() == Void.class) ? -1 : arity;
388 this.names = buildEmptyNames(arity, mt, result == -1);
389 this.forceInline = true;
390 this.customized = null;
391 this.kind = Kind.ZERO;
392 assert(nameRefsAreLegal());
393 assert(isEmpty());
394 String sig = null;
395 assert(isValidSignature(sig = basicTypeSignature()));
396 assert(sig.equals(basicTypeSignature())) : sig + " != " + basicTypeSignature();
397 }
398
399 private static Name[] buildEmptyNames(int arity, MethodType mt, boolean isVoid) {
400 Name[] names = arguments(isVoid ? 0 : 1, mt);
401 if (!isVoid) {
402 Name zero = new Name(constantZero(basicType(mt.returnType())));
403 names[arity] = zero.newIndex(arity);
404 }
405 return names;
406 }
407
408 private static int fixResult(int result, Name[] names) {
409 if (result == LAST_RESULT)
410 result = names.length - 1; // might still be void
411 if (result >= 0 && names[result].type == V_TYPE)
412 result = VOID_RESULT;
413 return result;
414 }
415
416 static boolean debugNames() {
417 return DEBUG_NAME_COUNTERS != null;
418 }
419
420 static void associateWithDebugName(LambdaForm form, String name) {
421 assert (debugNames());
422 synchronized (DEBUG_NAMES) {
423 DEBUG_NAMES.put(form, name);
424 }
425 }
426
427 String lambdaName() {
428 if (DEBUG_NAMES != null) {
429 synchronized (DEBUG_NAMES) {
430 String name = DEBUG_NAMES.get(this);
431 if (name == null) {
432 name = generateDebugName();
433 }
434 return name;
435 }
436 }
437 return kind.defaultLambdaName;
438 }
439
440 private String generateDebugName() {
441 assert (debugNames());
442 String debugNameStem = kind.defaultLambdaName;
443 Integer ctr = DEBUG_NAME_COUNTERS.getOrDefault(debugNameStem, 0);
444 DEBUG_NAME_COUNTERS.put(debugNameStem, ctr + 1);
445 StringBuilder buf = new StringBuilder(debugNameStem);
446 int leadingZero = buf.length();
447 buf.append((int) ctr);
448 for (int i = buf.length() - leadingZero; i < 3; i++) {
449 buf.insert(leadingZero, '0');
450 }
451 buf.append('_');
452 buf.append(basicTypeSignature());
453 String name = buf.toString();
454 associateWithDebugName(this, name);
455 return name;
456 }
457
458 private static boolean namesOK(int arity, Name[] names) {
459 for (int i = 0; i < names.length; i++) {
460 Name n = names[i];
461 assert(n != null) : "n is null";
462 if (i < arity)
463 assert( n.isParam()) : n + " is not param at " + i;
464 else
465 assert(!n.isParam()) : n + " is param at " + i;
466 }
467 return true;
468 }
469
470 /** Customize LambdaForm for a particular MethodHandle */
471 LambdaForm customize(MethodHandle mh) {
472 if (customized == mh) {
473 return this;
474 }
475 LambdaForm customForm = new LambdaForm(arity, names, result, forceInline, mh, kind);
476 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
477 // If shared LambdaForm has been compiled, compile customized version as well.
478 customForm.compileToBytecode();
479 }
480 customForm.transformCache = this; // LambdaFormEditor should always use uncustomized form.
481 return customForm;
482 }
483
484 /** Get uncustomized flavor of the LambdaForm */
485 LambdaForm uncustomize() {
486 if (customized == null) {
487 return this;
488 }
489 assert(transformCache != null); // Customized LambdaForm should always has a link to uncustomized version.
490 LambdaForm uncustomizedForm = (LambdaForm)transformCache;
491 if (COMPILE_THRESHOLD >= 0 && isCompiled) {
492 // If customized LambdaForm has been compiled, compile uncustomized version as well.
493 uncustomizedForm.compileToBytecode();
494 }
495 return uncustomizedForm;
496 }
497
498 /** Renumber and/or replace params so that they are interned and canonically numbered.
499 * @return maximum argument list length among the names (since we have to pass over them anyway)
500 */
501 private int normalize() {
502 Name[] oldNames = null;
503 int maxOutArity = 0;
504 int changesStart = 0;
505 for (int i = 0; i < names.length; i++) {
506 Name n = names[i];
507 if (!n.initIndex(i)) {
508 if (oldNames == null) {
509 oldNames = names.clone();
510 changesStart = i;
511 }
512 names[i] = n.cloneWithIndex(i);
513 }
514 if (n.arguments != null && maxOutArity < n.arguments.length)
515 maxOutArity = n.arguments.length;
516 }
517 if (oldNames != null) {
518 int startFixing = arity;
519 if (startFixing <= changesStart)
520 startFixing = changesStart+1;
521 for (int i = startFixing; i < names.length; i++) {
522 Name fixed = names[i].replaceNames(oldNames, names, changesStart, i);
523 names[i] = fixed.newIndex(i);
524 }
525 }
526 assert(nameRefsAreLegal());
527 int maxInterned = Math.min(arity, INTERNED_ARGUMENT_LIMIT);
528 boolean needIntern = false;
529 for (int i = 0; i < maxInterned; i++) {
530 Name n = names[i], n2 = internArgument(n);
531 if (n != n2) {
532 names[i] = n2;
533 needIntern = true;
534 }
535 }
536 if (needIntern) {
537 for (int i = arity; i < names.length; i++) {
538 names[i].internArguments();
539 }
540 }
541 assert(nameRefsAreLegal());
542 return maxOutArity;
543 }
544
545 /**
546 * Check that all embedded Name references are localizable to this lambda,
547 * and are properly ordered after their corresponding definitions.
548 * <p>
549 * Note that a Name can be local to multiple lambdas, as long as
550 * it possesses the same index in each use site.
551 * This allows Name references to be freely reused to construct
552 * fresh lambdas, without confusion.
553 */
554 boolean nameRefsAreLegal() {
555 assert(arity >= 0 && arity <= names.length);
556 assert(result >= -1 && result < names.length);
557 // Do all names possess an index consistent with their local definition order?
558 for (int i = 0; i < arity; i++) {
559 Name n = names[i];
560 assert(n.index() == i) : Arrays.asList(n.index(), i);
561 assert(n.isParam());
562 }
563 // Also, do all local name references
564 for (int i = arity; i < names.length; i++) {
565 Name n = names[i];
566 assert(n.index() == i);
567 for (Object arg : n.arguments) {
568 if (arg instanceof Name n2) {
569 int i2 = n2.index;
570 assert(0 <= i2 && i2 < names.length) : n.debugString() + ": 0 <= i2 && i2 < names.length: 0 <= " + i2 + " < " + names.length;
571 assert(names[i2] == n2) : Arrays.asList("-1-", i, "-2-", n.debugString(), "-3-", i2, "-4-", n2.debugString(), "-5-", names[i2].debugString(), "-6-", this);
572 assert(i2 < i); // ref must come after def!
573 }
574 }
575 }
576 return true;
577 }
578
579 /** Invoke this form on the given arguments. */
580 // final Object invoke(Object... args) throws Throwable {
581 // // NYI: fit this into the fast path?
582 // return interpretWithArguments(args);
583 // }
584
585 /** Report the return type. */
586 BasicType returnType() {
587 if (result < 0) return V_TYPE;
588 Name n = names[result];
589 return n.type;
590 }
591
592 /** Report the N-th argument type. */
593 BasicType parameterType(int n) {
594 return parameter(n).type;
595 }
596
597 /** Report the N-th argument name. */
598 Name parameter(int n) {
599 Name param = names[n];
600 assert(n < arity && param.isParam());
601 return param;
602 }
603
604 /** Report the N-th argument type constraint. */
605 Object parameterConstraint(int n) {
606 return parameter(n).constraint;
607 }
608
609 /** Report the arity. */
610 int arity() {
611 return arity;
612 }
613
614 /** Report the number of expressions (non-parameter names). */
615 int expressionCount() {
616 return names.length - arity;
617 }
618
619 /** Return the method type corresponding to my basic type signature. */
620 MethodType methodType() {
621 Class<?>[] ptypes = new Class<?>[arity];
622 for (int i = 0; i < arity; ++i) {
623 ptypes[i] = parameterType(i).btClass;
624 }
625 return MethodType.makeImpl(returnType().btClass, ptypes, true);
626 }
627
628 /** Return ABC_Z, where the ABC are parameter type characters, and Z is the return type character. */
629 final String basicTypeSignature() {
630 StringBuilder buf = new StringBuilder(arity() + 3);
631 for (int i = 0, a = arity(); i < a; i++)
632 buf.append(parameterType(i).basicTypeChar());
633 return buf.append('_').append(returnType().basicTypeChar()).toString();
634 }
635 static int signatureArity(String sig) {
636 assert(isValidSignature(sig));
637 return sig.indexOf('_');
638 }
639 static boolean isValidSignature(String sig) {
640 int arity = sig.indexOf('_');
641 if (arity < 0) return false; // must be of the form *_*
642 int siglen = sig.length();
643 if (siglen != arity + 2) return false; // *_X
644 for (int i = 0; i < siglen; i++) {
645 if (i == arity) continue; // skip '_'
646 char c = sig.charAt(i);
647 if (c == 'V')
648 return (i == siglen - 1 && arity == siglen - 2);
649 if (!isArgBasicTypeChar(c)) return false; // must be [LIJFD]
650 }
651 return true; // [LIJFD]*_[LIJFDV]
652 }
653
654 /**
655 * Check if i-th name is a call to MethodHandleImpl.selectAlternative.
656 */
657 boolean isSelectAlternative(int pos) {
658 // selectAlternative idiom:
659 // t_{n}:L=MethodHandleImpl.selectAlternative(...)
660 // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
661 if (pos+1 >= names.length) return false;
662 Name name0 = names[pos];
663 Name name1 = names[pos+1];
664 return name0.refersTo(MethodHandleImpl.class, "selectAlternative") &&
665 name1.isInvokeBasic() &&
666 name1.lastUseIndex(name0) == 0 && // t_{n+1}:?=MethodHandle.invokeBasic(t_{n}, ...)
667 lastUseIndex(name0) == pos+1; // t_{n} is local: used only in t_{n+1}
668 }
669
670 private boolean isMatchingIdiom(int pos, String idiomName, int nArgs) {
671 if (pos+2 >= names.length) return false;
672 Name name0 = names[pos];
673 Name name1 = names[pos+1];
674 Name name2 = names[pos+2];
675 return name1.refersTo(MethodHandleImpl.class, idiomName) &&
676 name0.isInvokeBasic() &&
677 name2.isInvokeBasic() &&
678 name1.lastUseIndex(name0) == nArgs && // t_{n+1}:L=MethodHandleImpl.<invoker>(<args>, t_{n});
679 lastUseIndex(name0) == pos+1 && // t_{n} is local: used only in t_{n+1}
680 name2.lastUseIndex(name1) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
681 lastUseIndex(name1) == pos+2; // t_{n+1} is local: used only in t_{n+2}
682 }
683
684 /**
685 * Check if i-th name is a start of GuardWithCatch idiom.
686 */
687 boolean isGuardWithCatch(int pos) {
688 // GuardWithCatch idiom:
689 // t_{n}:L=MethodHandle.invokeBasic(...)
690 // t_{n+1}:L=MethodHandleImpl.guardWithCatch(*, *, *, t_{n});
691 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
692 return isMatchingIdiom(pos, "guardWithCatch", 3);
693 }
694
695 /**
696 * Check if i-th name is a start of the tryFinally idiom.
697 */
698 boolean isTryFinally(int pos) {
699 // tryFinally idiom:
700 // t_{n}:L=MethodHandle.invokeBasic(...)
701 // t_{n+1}:L=MethodHandleImpl.tryFinally(*, *, t_{n})
702 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
703 return isMatchingIdiom(pos, "tryFinally", 2);
704 }
705
706 /**
707 * Check if i-th name is a start of the tableSwitch idiom.
708 */
709 boolean isTableSwitch(int pos) {
710 // tableSwitch idiom:
711 // t_{n}:L=MethodHandle.invokeBasic(...) // args
712 // t_{n+1}:L=MethodHandleImpl.tableSwitch(*, *, *, t_{n})
713 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
714 if (pos + 2 >= names.length) return false;
715
716 final int POS_COLLECT_ARGS = pos;
717 final int POS_TABLE_SWITCH = pos + 1;
718 final int POS_UNBOX_RESULT = pos + 2;
719
720 Name collectArgs = names[POS_COLLECT_ARGS];
721 Name tableSwitch = names[POS_TABLE_SWITCH];
722 Name unboxResult = names[POS_UNBOX_RESULT];
723 return tableSwitch.refersTo(MethodHandleImpl.class, "tableSwitch") &&
724 collectArgs.isInvokeBasic() &&
725 unboxResult.isInvokeBasic() &&
726 tableSwitch.lastUseIndex(collectArgs) == 3 && // t_{n+1}:L=MethodHandleImpl.<invoker>(*, *, *, t_{n});
727 lastUseIndex(collectArgs) == POS_TABLE_SWITCH && // t_{n} is local: used only in t_{n+1}
728 unboxResult.lastUseIndex(tableSwitch) == 1 && // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
729 lastUseIndex(tableSwitch) == POS_UNBOX_RESULT; // t_{n+1} is local: used only in t_{n+2}
730 }
731
732 /**
733 * Check if i-th name is a start of the loop idiom.
734 */
735 boolean isLoop(int pos) {
736 // loop idiom:
737 // t_{n}:L=MethodHandle.invokeBasic(...)
738 // t_{n+1}:L=MethodHandleImpl.loop(types, *, t_{n})
739 // t_{n+2}:?=MethodHandle.invokeBasic(*, t_{n+1})
740 return isMatchingIdiom(pos, "loop", 2);
741 }
742
743 /*
744 * Code generation issues:
745 *
746 * Compiled LFs should be reusable in general.
747 * The biggest issue is how to decide when to pull a name into
748 * the bytecode, versus loading a reified form from the MH data.
749 *
750 * For example, an asType wrapper may require execution of a cast
751 * after a call to a MH. The target type of the cast can be placed
752 * as a constant in the LF itself. This will force the cast type
753 * to be compiled into the bytecodes and native code for the MH.
754 * Or, the target type of the cast can be erased in the LF, and
755 * loaded from the MH data. (Later on, if the MH as a whole is
756 * inlined, the data will flow into the inlined instance of the LF,
757 * as a constant, and the end result will be an optimal cast.)
758 *
759 * This erasure of cast types can be done with any use of
760 * reference types. It can also be done with whole method
761 * handles. Erasing a method handle might leave behind
762 * LF code that executes correctly for any MH of a given
763 * type, and load the required MH from the enclosing MH's data.
764 * Or, the erasure might even erase the expected MT.
765 *
766 * Also, for direct MHs, the MemberName of the target
767 * could be erased, and loaded from the containing direct MH.
768 * As a simple case, a LF for all int-valued non-static
769 * field getters would perform a cast on its input argument
770 * (to non-constant base type derived from the MemberName)
771 * and load an integer value from the input object
772 * (at a non-constant offset also derived from the MemberName).
773 * Such MN-erased LFs would be inlinable back to optimized
774 * code, whenever a constant enclosing DMH is available
775 * to supply a constant MN from its data.
776 *
777 * The main problem here is to keep LFs reasonably generic,
778 * while ensuring that hot spots will inline good instances.
779 * "Reasonably generic" means that we don't end up with
780 * repeated versions of bytecode or machine code that do
781 * not differ in their optimized form. Repeated versions
782 * of machine would have the undesirable overheads of
783 * (a) redundant compilation work and (b) extra I$ pressure.
784 * To control repeated versions, we need to be ready to
785 * erase details from LFs and move them into MH data,
786 * whenever those details are not relevant to significant
787 * optimization. "Significant" means optimization of
788 * code that is actually hot.
789 *
790 * Achieving this may require dynamic splitting of MHs, by replacing
791 * a generic LF with a more specialized one, on the same MH,
792 * if (a) the MH is frequently executed and (b) the MH cannot
793 * be inlined into a containing caller, such as an invokedynamic.
794 *
795 * Compiled LFs that are no longer used should be GC-able.
796 * If they contain non-BCP references, they should be properly
797 * interlinked with the class loader(s) that their embedded types
798 * depend on. This probably means that reusable compiled LFs
799 * will be tabulated (indexed) on relevant class loaders,
800 * or else that the tables that cache them will have weak links.
801 */
802
803 /**
804 * Make this LF directly executable, as part of a MethodHandle.
805 * Invariant: Every MH which is invoked must prepare its LF
806 * before invocation.
807 * (In principle, the JVM could do this very lazily,
808 * as a sort of pre-invocation linkage step.)
809 */
810 public void prepare() {
811 if (COMPILE_THRESHOLD == 0 && !forceInterpretation() && !isCompiled) {
812 compileToBytecode();
813 }
814 if (this.vmentry != null) {
815 // already prepared (e.g., a primitive DMH invoker form)
816 return;
817 }
818 MethodType mtype = methodType();
819 LambdaForm prep = mtype.form().cachedLambdaForm(MethodTypeForm.LF_INTERPRET);
820 if (prep == null) {
821 assert (isValidSignature(basicTypeSignature()));
822 prep = new LambdaForm(mtype);
823 prep.vmentry = InvokerBytecodeGenerator.generateLambdaFormInterpreterEntryPoint(mtype);
824 prep = mtype.form().setCachedLambdaForm(MethodTypeForm.LF_INTERPRET, prep);
825 }
826 this.vmentry = prep.vmentry;
827 // TO DO: Maybe add invokeGeneric, invokeWithArguments
828 }
829
830 private static @Stable PerfCounter LF_FAILED;
831
832 private static PerfCounter failedCompilationCounter() {
833 if (LF_FAILED == null) {
834 LF_FAILED = PerfCounter.newPerfCounter("java.lang.invoke.failedLambdaFormCompilations");
835 }
836 return LF_FAILED;
837 }
838
839 /** Generate optimizable bytecode for this form. */
840 void compileToBytecode() {
841 if (forceInterpretation()) {
842 return; // this should not be compiled
843 }
844 if (vmentry != null && isCompiled) {
845 return; // already compiled somehow
846 }
847
848 // Obtain the invoker MethodType outside of the following try block.
849 // This ensures that an IllegalArgumentException is directly thrown if the
850 // type would have 256 or more parameters
851 MethodType invokerType = methodType();
852 assert(vmentry == null || vmentry.getMethodType().basicType().equals(invokerType));
853 try {
854 vmentry = InvokerBytecodeGenerator.generateCustomizedCode(this, invokerType);
855 if (TRACE_INTERPRETER)
856 traceInterpreter("compileToBytecode", this);
857 isCompiled = true;
858 } catch (InvokerBytecodeGenerator.BytecodeGenerationException bge) {
859 // bytecode generation failed - mark this LambdaForm as to be run in interpretation mode only
860 invocationCounter = -1;
861 failedCompilationCounter().increment();
862 if (LOG_LF_COMPILATION_FAILURE) {
863 System.out.println("LambdaForm compilation failed: " + this);
864 bge.printStackTrace(System.out);
865 }
866 } catch (Error e) {
867 // Pass through any error
868 throw e;
869 } catch (Exception e) {
870 // Wrap any exception
871 throw newInternalError(this.toString(), e);
872 }
873 }
874
875 // The next few routines are called only from assert expressions
876 // They verify that the built-in invokers process the correct raw data types.
877 private static boolean argumentTypesMatch(String sig, Object[] av) {
878 int arity = signatureArity(sig);
879 assert(av.length == arity) : "av.length == arity: av.length=" + av.length + ", arity=" + arity;
880 assert(av[0] instanceof MethodHandle) : "av[0] not instance of MethodHandle: " + av[0];
881 MethodHandle mh = (MethodHandle) av[0];
882 MethodType mt = mh.type();
883 assert(mt.parameterCount() == arity-1);
884 for (int i = 0; i < av.length; i++) {
885 Class<?> pt = (i == 0 ? MethodHandle.class : mt.parameterType(i-1));
886 assert(valueMatches(basicType(sig.charAt(i)), pt, av[i]));
887 }
888 return true;
889 }
890 private static boolean valueMatches(BasicType tc, Class<?> type, Object x) {
891 // The following line is needed because (...)void method handles can use non-void invokers
892 if (type == void.class) tc = V_TYPE; // can drop any kind of value
893 assert tc == basicType(type) : tc + " == basicType(" + type + ")=" + basicType(type);
894 switch (tc) {
895 case I_TYPE: assert checkInt(type, x) : "checkInt(" + type + "," + x +")"; break;
896 case J_TYPE: assert x instanceof Long : "instanceof Long: " + x; break;
897 case F_TYPE: assert x instanceof Float : "instanceof Float: " + x; break;
898 case D_TYPE: assert x instanceof Double : "instanceof Double: " + x; break;
899 case L_TYPE: assert checkRef(type, x) : "checkRef(" + type + "," + x + ")"; break;
900 case V_TYPE: break; // allow anything here; will be dropped
901 default: assert(false);
902 }
903 return true;
904 }
905 private static boolean checkInt(Class<?> type, Object x) {
906 assert(x instanceof Integer);
907 if (type == int.class) return true;
908 Wrapper w = Wrapper.forBasicType(type);
909 assert(w.isSubwordOrInt());
910 Object x1 = Wrapper.INT.wrap(w.wrap(x));
911 return x.equals(x1);
912 }
913 private static boolean checkRef(Class<?> type, Object x) {
914 assert(!type.isPrimitive());
915 if (x == null) return true;
916 if (type.isInterface()) return true;
917 return type.isInstance(x);
918 }
919
920 /** If the invocation count hits the threshold we spin bytecodes and call that subsequently. */
921 private static final int COMPILE_THRESHOLD;
922 static {
923 COMPILE_THRESHOLD = Math.max(-1, MethodHandleStatics.COMPILE_THRESHOLD);
924 }
925 private int invocationCounter = 0; // a value of -1 indicates LambdaForm interpretation mode forever
926
927 private boolean forceInterpretation() {
928 return invocationCounter == -1;
929 }
930
931 @Hidden
932 @DontInline
933 /** Interpretively invoke this form on the given arguments. */
934 Object interpretWithArguments(Object... argumentValues) throws Throwable {
935 if (TRACE_INTERPRETER)
936 return interpretWithArgumentsTracing(argumentValues);
937 checkInvocationCounter();
938 assert(arityCheck(argumentValues));
939 Object[] values = Arrays.copyOf(argumentValues, names.length);
940 for (int i = argumentValues.length; i < values.length; i++) {
941 values[i] = interpretName(names[i], values);
942 }
943 Object rv = (result < 0) ? null : values[result];
944 assert(resultCheck(argumentValues, rv));
945 return rv;
946 }
947
948 @Hidden
949 @DontInline
950 /** Evaluate a single Name within this form, applying its function to its arguments. */
951 Object interpretName(Name name, Object[] values) throws Throwable {
952 if (TRACE_INTERPRETER)
953 traceInterpreter("| interpretName", name.debugString(), (Object[]) null);
954 Object[] arguments = Arrays.copyOf(name.arguments, name.arguments.length, Object[].class);
955 for (int i = 0; i < arguments.length; i++) {
956 Object a = arguments[i];
957 if (a instanceof Name) {
958 int i2 = ((Name)a).index();
959 assert(names[i2] == a);
960 a = values[i2];
961 arguments[i] = a;
962 }
963 }
964 return name.function.invokeWithArguments(arguments);
965 }
966
967 private void checkInvocationCounter() {
968 if (COMPILE_THRESHOLD != 0 &&
969 !forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
970 invocationCounter++; // benign race
971 if (invocationCounter >= COMPILE_THRESHOLD) {
972 // Replace vmentry with a bytecode version of this LF.
973 compileToBytecode();
974 }
975 }
976 }
977 Object interpretWithArgumentsTracing(Object... argumentValues) throws Throwable {
978 traceInterpreter("[ interpretWithArguments", this, argumentValues);
979 if (!forceInterpretation() && invocationCounter < COMPILE_THRESHOLD) {
980 int ctr = invocationCounter++; // benign race
981 traceInterpreter("| invocationCounter", ctr);
982 if (invocationCounter >= COMPILE_THRESHOLD) {
983 compileToBytecode();
984 }
985 }
986 Object rval;
987 try {
988 assert(arityCheck(argumentValues));
989 Object[] values = Arrays.copyOf(argumentValues, names.length);
990 for (int i = argumentValues.length; i < values.length; i++) {
991 values[i] = interpretName(names[i], values);
992 }
993 rval = (result < 0) ? null : values[result];
994 } catch (Throwable ex) {
995 traceInterpreter("] throw =>", ex);
996 throw ex;
997 }
998 traceInterpreter("] return =>", rval);
999 return rval;
1000 }
1001
1002 static void traceInterpreter(String event, Object obj, Object... args) {
1003 if (TRACE_INTERPRETER) {
1004 System.out.println("LFI: "+event+" "+(obj != null ? obj : "")+(args != null && args.length != 0 ? Arrays.asList(args) : ""));
1005 }
1006 }
1007 static void traceInterpreter(String event, Object obj) {
1008 traceInterpreter(event, obj, (Object[])null);
1009 }
1010 private boolean arityCheck(Object[] argumentValues) {
1011 assert(argumentValues.length == arity) : arity+"!="+Arrays.asList(argumentValues)+".length";
1012 // also check that the leading (receiver) argument is somehow bound to this LF:
1013 assert(argumentValues[0] instanceof MethodHandle) : "not MH: " + argumentValues[0];
1014 MethodHandle mh = (MethodHandle) argumentValues[0];
1015 assert(mh.internalForm() == this);
1016 // note: argument #0 could also be an interface wrapper, in the future
1017 argumentTypesMatch(basicTypeSignature(), argumentValues);
1018 return true;
1019 }
1020 private boolean resultCheck(Object[] argumentValues, Object result) {
1021 MethodHandle mh = (MethodHandle) argumentValues[0];
1022 MethodType mt = mh.type();
1023 assert(valueMatches(returnType(), mt.returnType(), result));
1024 return true;
1025 }
1026
1027 private boolean isEmpty() {
1028 if (result < 0)
1029 return (names.length == arity);
1030 else if (result == arity && names.length == arity + 1)
1031 return names[arity].isConstantZero();
1032 else
1033 return false;
1034 }
1035
1036 public String toString() {
1037 String lambdaName = lambdaName();
1038 StringBuilder buf = new StringBuilder(lambdaName + "=Lambda(");
1039 for (int i = 0; i < names.length; i++) {
1040 if (i == arity) buf.append(")=>{");
1041 Name n = names[i];
1042 if (i >= arity) buf.append("\n ");
1043 buf.append(n.paramString());
1044 if (i < arity) {
1045 if (i+1 < arity) buf.append(",");
1046 continue;
1047 }
1048 buf.append("=").append(n.exprString());
1049 buf.append(";");
1050 }
1051 if (arity == names.length) buf.append(")=>{");
1052 buf.append(result < 0 ? "void" : names[result]).append("}");
1053 if (TRACE_INTERPRETER) {
1054 // Extra verbosity:
1055 buf.append(":").append(basicTypeSignature());
1056 buf.append("/").append(vmentry);
1057 }
1058 return buf.toString();
1059 }
1060
1061 @Override
1062 public boolean equals(Object obj) {
1063 return obj instanceof LambdaForm && equals((LambdaForm)obj);
1064 }
1065 public boolean equals(LambdaForm that) {
1066 if (this.result != that.result) return false;
1067 return Arrays.equals(this.names, that.names);
1068 }
1069 public int hashCode() {
1070 return result + 31 * Arrays.hashCode(names);
1071 }
1072 LambdaFormEditor editor() {
1073 return LambdaFormEditor.lambdaFormEditor(this);
1074 }
1075
1076 boolean contains(Name name) {
1077 int pos = name.index();
1078 if (pos >= 0) {
1079 return pos < names.length && name.equals(names[pos]);
1080 }
1081 for (int i = arity; i < names.length; i++) {
1082 if (name.equals(names[i]))
1083 return true;
1084 }
1085 return false;
1086 }
1087
1088 static class NamedFunction {
1089 final MemberName member;
1090 private @Stable MethodHandle resolvedHandle;
1091 @Stable MethodHandle invoker;
1092
1093 NamedFunction(MethodHandle resolvedHandle) {
1094 this(resolvedHandle.internalMemberName(), resolvedHandle);
1095 }
1096 NamedFunction(MemberName member, MethodHandle resolvedHandle) {
1097 this.member = member;
1098 this.resolvedHandle = resolvedHandle;
1099 // The following assert is almost always correct, but will fail for corner cases, such as PrivateInvokeTest.
1100 //assert(!isInvokeBasic(member));
1101 }
1102 NamedFunction(MethodType basicInvokerType) {
1103 assert(basicInvokerType == basicInvokerType.basicType()) : basicInvokerType;
1104 if (basicInvokerType.parameterSlotCount() < MethodType.MAX_MH_INVOKER_ARITY) {
1105 this.resolvedHandle = basicInvokerType.invokers().basicInvoker();
1106 this.member = resolvedHandle.internalMemberName();
1107 } else {
1108 // necessary to pass BigArityTest
1109 this.member = Invokers.invokeBasicMethod(basicInvokerType);
1110 }
1111 assert(isInvokeBasic(member));
1112 }
1113
1114 private static boolean isInvokeBasic(MemberName member) {
1115 return member != null &&
1116 member.getDeclaringClass() == MethodHandle.class &&
1117 "invokeBasic".equals(member.getName());
1118 }
1119
1120 // The next 2 constructors are used to break circular dependencies on MH.invokeStatic, etc.
1121 // Any LambdaForm containing such a member is not interpretable.
1122 // This is OK, since all such LFs are prepared with special primitive vmentry points.
1123 // And even without the resolvedHandle, the name can still be compiled and optimized.
1124 NamedFunction(Method method) {
1125 this(new MemberName(method));
1126 }
1127 NamedFunction(MemberName member) {
1128 this(member, null);
1129 }
1130
1131 MethodHandle resolvedHandle() {
1132 if (resolvedHandle == null) resolve();
1133 return resolvedHandle;
1134 }
1135
1136 synchronized void resolve() {
1137 if (resolvedHandle == null) {
1138 resolvedHandle = DirectMethodHandle.make(member);
1139 }
1140 }
1141
1142 @Override
1143 public boolean equals(Object other) {
1144 if (this == other) return true;
1145 if (other == null) return false;
1146 return (other instanceof NamedFunction that)
1147 && this.member != null
1148 && this.member.equals(that.member);
1149 }
1150
1151 @Override
1152 public int hashCode() {
1153 if (member != null)
1154 return member.hashCode();
1155 return super.hashCode();
1156 }
1157
1158 static final MethodType INVOKER_METHOD_TYPE =
1159 MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1160
1161 private static MethodHandle computeInvoker(MethodTypeForm typeForm) {
1162 typeForm = typeForm.basicType().form(); // normalize to basic type
1163 MethodHandle mh = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1164 if (mh != null) return mh;
1165 MemberName invoker = InvokerBytecodeGenerator.generateNamedFunctionInvoker(typeForm); // this could take a while
1166 mh = DirectMethodHandle.make(invoker);
1167 MethodHandle mh2 = typeForm.cachedMethodHandle(MethodTypeForm.MH_NF_INV);
1168 if (mh2 != null) return mh2; // benign race
1169 if (!mh.type().equals(INVOKER_METHOD_TYPE))
1170 throw newInternalError(mh.debugString());
1171 return typeForm.setCachedMethodHandle(MethodTypeForm.MH_NF_INV, mh);
1172 }
1173
1174 @Hidden
1175 Object invokeWithArguments(Object... arguments) throws Throwable {
1176 // If we have a cached invoker, call it right away.
1177 // NOTE: The invoker always returns a reference value.
1178 if (TRACE_INTERPRETER) return invokeWithArgumentsTracing(arguments);
1179 return invoker().invokeBasic(resolvedHandle(), arguments);
1180 }
1181
1182 @Hidden
1183 Object invokeWithArgumentsTracing(Object[] arguments) throws Throwable {
1184 Object rval;
1185 try {
1186 traceInterpreter("[ call", this, arguments);
1187 if (invoker == null) {
1188 traceInterpreter("| getInvoker", this);
1189 invoker();
1190 }
1191 // resolvedHandle might be uninitialized, ok for tracing
1192 if (resolvedHandle == null) {
1193 traceInterpreter("| resolve", this);
1194 resolvedHandle();
1195 }
1196 rval = invoker().invokeBasic(resolvedHandle(), arguments);
1197 } catch (Throwable ex) {
1198 traceInterpreter("] throw =>", ex);
1199 throw ex;
1200 }
1201 traceInterpreter("] return =>", rval);
1202 return rval;
1203 }
1204
1205 private MethodHandle invoker() {
1206 if (invoker != null) return invoker;
1207 // Get an invoker and cache it.
1208 return invoker = computeInvoker(methodType().form());
1209 }
1210
1211 MethodType methodType() {
1212 if (resolvedHandle != null)
1213 return resolvedHandle.type();
1214 else
1215 // only for certain internal LFs during bootstrapping
1216 return member.getInvocationType();
1217 }
1218
1219 MemberName member() {
1220 assert(assertMemberIsConsistent());
1221 return member;
1222 }
1223
1224 // Called only from assert.
1225 private boolean assertMemberIsConsistent() {
1226 if (resolvedHandle instanceof DirectMethodHandle) {
1227 MemberName m = resolvedHandle.internalMemberName();
1228 assert(m.equals(member));
1229 }
1230 return true;
1231 }
1232
1233 Class<?> memberDeclaringClassOrNull() {
1234 return (member == null) ? null : member.getDeclaringClass();
1235 }
1236
1237 BasicType returnType() {
1238 return basicType(methodType().returnType());
1239 }
1240
1241 BasicType parameterType(int n) {
1242 return basicType(methodType().parameterType(n));
1243 }
1244
1245 int arity() {
1246 return methodType().parameterCount();
1247 }
1248
1249 public String toString() {
1250 if (member == null) return String.valueOf(resolvedHandle);
1251 return member.getDeclaringClass().getSimpleName()+"."+member.getName();
1252 }
1253
1254 public boolean isIdentity() {
1255 return this.equals(identity(returnType()));
1256 }
1257
1258 public boolean isConstantZero() {
1259 return this.equals(constantZero(returnType()));
1260 }
1261
1262 public MethodHandleImpl.Intrinsic intrinsicName() {
1263 return resolvedHandle != null
1264 ? resolvedHandle.intrinsicName()
1265 : MethodHandleImpl.Intrinsic.NONE;
1266 }
1267
1268 public Object intrinsicData() {
1269 return resolvedHandle != null
1270 ? resolvedHandle.intrinsicData()
1271 : null;
1272 }
1273 }
1274
1275 public static String basicTypeSignature(MethodType type) {
1276 int params = type.parameterCount();
1277 char[] sig = new char[params + 2];
1278 int sigp = 0;
1279 while (sigp < params) {
1280 sig[sigp] = basicTypeChar(type.parameterType(sigp++));
1281 }
1282 sig[sigp++] = '_';
1283 sig[sigp++] = basicTypeChar(type.returnType());
1284 assert(sigp == sig.length);
1285 return String.valueOf(sig);
1286 }
1287
1288 /** Hack to make signatures more readable when they show up in method names.
1289 * Signature should start with a sequence of uppercase ASCII letters.
1290 * Runs of three or more are replaced by a single letter plus a decimal repeat count.
1291 * A tail of anything other than uppercase ASCII is passed through unchanged.
1292 * @param signature sequence of uppercase ASCII letters with possible repetitions
1293 * @return same sequence, with repetitions counted by decimal numerals
1294 */
1295 public static String shortenSignature(String signature) {
1296 final int NO_CHAR = -1, MIN_RUN = 3;
1297 int c0, c1 = NO_CHAR, c1reps = 0;
1298 StringBuilder buf = null;
1299 int len = signature.length();
1300 if (len < MIN_RUN) return signature;
1301 for (int i = 0; i <= len; i++) {
1302 if (c1 != NO_CHAR && !('A' <= c1 && c1 <= 'Z')) {
1303 // wrong kind of char; bail out here
1304 if (buf != null) {
1305 buf.append(signature, i - c1reps, len);
1306 }
1307 break;
1308 }
1309 // shift in the next char:
1310 c0 = c1; c1 = (i == len ? NO_CHAR : signature.charAt(i));
1311 if (c1 == c0) { ++c1reps; continue; }
1312 // shift in the next count:
1313 int c0reps = c1reps; c1reps = 1;
1314 // end of a character run
1315 if (c0reps < MIN_RUN) {
1316 if (buf != null) {
1317 while (--c0reps >= 0)
1318 buf.append((char)c0);
1319 }
1320 continue;
1321 }
1322 // found three or more in a row
1323 if (buf == null)
1324 buf = new StringBuilder().append(signature, 0, i - c0reps);
1325 buf.append((char)c0).append(c0reps);
1326 }
1327 return (buf == null) ? signature : buf.toString();
1328 }
1329
1330 static final class Name {
1331 final BasicType type;
1332 @Stable short index;
1333 final NamedFunction function;
1334 final Object constraint; // additional type information, if not null
1335 @Stable final Object[] arguments;
1336
1337 private Name(int index, BasicType type, NamedFunction function, Object[] arguments) {
1338 this.index = (short)index;
1339 this.type = type;
1340 this.function = function;
1341 this.arguments = arguments;
1342 this.constraint = null;
1343 assert(this.index == index);
1344 }
1345 private Name(Name that, Object constraint) {
1346 this.index = that.index;
1347 this.type = that.type;
1348 this.function = that.function;
1349 this.arguments = that.arguments;
1350 this.constraint = constraint;
1351 assert(constraint == null || isParam()); // only params have constraints
1352 assert(constraint == null || constraint instanceof ClassSpecializer.SpeciesData || constraint instanceof Class);
1353 }
1354 Name(MethodHandle function, Object... arguments) {
1355 this(new NamedFunction(function), arguments);
1356 }
1357 Name(MethodType functionType, Object... arguments) {
1358 this(new NamedFunction(functionType), arguments);
1359 assert(arguments[0] instanceof Name && ((Name)arguments[0]).type == L_TYPE);
1360 }
1361 Name(MemberName function, Object... arguments) {
1362 this(new NamedFunction(function), arguments);
1363 }
1364 Name(NamedFunction function, Object... arguments) {
1365 this(-1, function.returnType(), function, arguments = Arrays.copyOf(arguments, arguments.length, Object[].class));
1366 assert(typesMatch(function, arguments));
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);
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 boolean initIndex(int i) {
1378 if (index != i) {
1379 if (index != -1) return false;
1380 index = (short)i;
1381 }
1382 return true;
1383 }
1384 char typeChar() {
1385 return type.btChar;
1386 }
1387
1388 Name newIndex(int i) {
1389 if (initIndex(i)) return this;
1390 return cloneWithIndex(i);
1391 }
1392 Name cloneWithIndex(int i) {
1393 Object[] newArguments = (arguments == null) ? null : arguments.clone();
1394 return new Name(i, type, function, newArguments).withConstraint(constraint);
1395 }
1396 Name withConstraint(Object constraint) {
1397 if (constraint == this.constraint) return this;
1398 return new Name(this, constraint);
1399 }
1400 Name replaceName(Name oldName, Name newName) { // FIXME: use replaceNames uniformly
1401 if (oldName == newName) return this;
1402 @SuppressWarnings("LocalVariableHidesMemberVariable")
1403 Object[] arguments = this.arguments;
1404 if (arguments == null) return this;
1405 boolean replaced = false;
1406 for (int j = 0; j < arguments.length; j++) {
1407 if (arguments[j] == oldName) {
1408 if (!replaced) {
1409 replaced = true;
1410 arguments = arguments.clone();
1411 }
1412 arguments[j] = newName;
1413 }
1414 }
1415 if (!replaced) return this;
1416 return new Name(function, arguments);
1417 }
1418 /** In the arguments of this Name, replace oldNames[i] pairwise by newNames[i].
1419 * Limit such replacements to {@code start<=i<end}. Return possibly changed self.
1420 */
1421 Name replaceNames(Name[] oldNames, Name[] newNames, int start, int end) {
1422 if (start >= end) return this;
1423 @SuppressWarnings("LocalVariableHidesMemberVariable")
1424 Object[] arguments = this.arguments;
1425 boolean replaced = false;
1426 eachArg:
1427 for (int j = 0; j < arguments.length; j++) {
1428 if (arguments[j] instanceof Name n) {
1429 int check = n.index;
1430 // harmless check to see if the thing is already in newNames:
1431 if (check >= 0 && check < newNames.length && n == newNames[check])
1432 continue eachArg;
1433 // n might not have the correct index: n != oldNames[n.index].
1434 for (int i = start; i < end; i++) {
1435 if (n == oldNames[i]) {
1436 if (n == newNames[i])
1437 continue eachArg;
1438 if (!replaced) {
1439 replaced = true;
1440 arguments = arguments.clone();
1441 }
1442 arguments[j] = newNames[i];
1443 continue eachArg;
1444 }
1445 }
1446 }
1447 }
1448 if (!replaced) return this;
1449 return new Name(function, arguments);
1450 }
1451 void internArguments() {
1452 @SuppressWarnings("LocalVariableHidesMemberVariable")
1453 Object[] arguments = this.arguments;
1454 for (int j = 0; j < arguments.length; j++) {
1455 if (arguments[j] instanceof Name n) {
1456 if (n.isParam() && n.index < INTERNED_ARGUMENT_LIMIT)
1457 arguments[j] = internArgument(n);
1458 }
1459 }
1460 }
1461 boolean isParam() {
1462 return function == null;
1463 }
1464 boolean isConstantZero() {
1465 return !isParam() && arguments.length == 0 && function.isConstantZero();
1466 }
1467
1468 boolean refersTo(Class<?> declaringClass, String methodName) {
1469 return function != null &&
1470 function.member() != null && function.member().refersTo(declaringClass, methodName);
1471 }
1472
1473 /**
1474 * Check if MemberName is a call to MethodHandle.invokeBasic.
1475 */
1476 boolean isInvokeBasic() {
1477 if (function == null)
1478 return false;
1479 if (arguments.length < 1)
1480 return false; // must have MH argument
1481 MemberName member = function.member();
1482 return member != null && member.refersTo(MethodHandle.class, "invokeBasic") &&
1483 !member.isPublic() && !member.isStatic();
1484 }
1485
1486 /**
1487 * Check if MemberName is a call to MethodHandle.linkToStatic, etc.
1488 */
1489 boolean isLinkerMethodInvoke() {
1490 if (function == null)
1491 return false;
1492 if (arguments.length < 1)
1493 return false; // must have MH argument
1494 MemberName member = function.member();
1495 return member != null &&
1496 member.getDeclaringClass() == MethodHandle.class &&
1497 !member.isPublic() && member.isStatic() &&
1498 member.getName().startsWith("linkTo");
1499 }
1500
1501 public String toString() {
1502 return (isParam()?"a":"t")+(index >= 0 ? index : System.identityHashCode(this))+":"+typeChar();
1503 }
1504 public String debugString() {
1505 String s = paramString();
1506 return (function == null) ? s : s + "=" + exprString();
1507 }
1508 public String paramString() {
1509 String s = toString();
1510 Object c = constraint;
1511 if (c == null)
1512 return s;
1513 if (c instanceof Class) c = ((Class<?>)c).getSimpleName();
1514 return s + "/" + c;
1515 }
1516 public String exprString() {
1517 if (function == null) return toString();
1518 StringBuilder buf = new StringBuilder(function.toString());
1519 buf.append("(");
1520 String cma = "";
1521 for (Object a : arguments) {
1522 buf.append(cma); cma = ",";
1523 if (a instanceof Name || a instanceof Integer)
1524 buf.append(a);
1525 else
1526 buf.append("(").append(a).append(")");
1527 }
1528 buf.append(")");
1529 return buf.toString();
1530 }
1531
1532 private boolean typesMatch(NamedFunction function, Object ... arguments) {
1533 assert(arguments.length == function.arity()) : "arity mismatch: arguments.length=" + arguments.length + " == function.arity()=" + function.arity() + " in " + debugString();
1534 for (int i = 0; i < arguments.length; i++) {
1535 assert (typesMatch(function.parameterType(i), arguments[i])) : "types don't match: function.parameterType(" + i + ")=" + function.parameterType(i) + ", arguments[" + i + "]=" + arguments[i] + " in " + debugString();
1536 }
1537 return true;
1538 }
1539
1540 private static boolean typesMatch(BasicType parameterType, Object object) {
1541 if (object instanceof Name) {
1542 return ((Name)object).type == parameterType;
1543 }
1544 switch (parameterType) {
1545 case I_TYPE: return object instanceof Integer;
1546 case J_TYPE: return object instanceof Long;
1547 case F_TYPE: return object instanceof Float;
1548 case D_TYPE: return object instanceof Double;
1549 }
1550 assert(parameterType == L_TYPE);
1551 return true;
1552 }
1553
1554 /** Return the index of the last occurrence of n in the argument array.
1555 * Return -1 if the name is not used.
1556 */
1557 int lastUseIndex(Name n) {
1558 if (arguments == null) return -1;
1559 for (int i = arguments.length; --i >= 0; ) {
1560 if (arguments[i] == n) return i;
1561 }
1562 return -1;
1563 }
1564
1565 /** Return the number of occurrences of n in the argument array.
1566 * Return 0 if the name is not used.
1567 */
1568 int useCount(Name n) {
1569 int count = 0;
1570 if (arguments != null) {
1571 for (Object argument : arguments) {
1572 if (argument == n) {
1573 count++;
1574 }
1575 }
1576 }
1577 return count;
1578 }
1579
1580 public boolean equals(Name that) {
1581 if (this == that) return true;
1582 if (isParam())
1583 // each parameter is a unique atom
1584 return false; // this != that
1585 return
1586 //this.index == that.index &&
1587 this.type == that.type &&
1588 this.function.equals(that.function) &&
1589 Arrays.equals(this.arguments, that.arguments);
1590 }
1591 @Override
1592 public boolean equals(Object x) {
1593 return x instanceof Name && equals((Name)x);
1594 }
1595 @Override
1596 public int hashCode() {
1597 if (isParam())
1598 return index | (type.ordinal() << 8);
1599 return function.hashCode() ^ Arrays.hashCode(arguments);
1600 }
1601 }
1602
1603 /** Return the index of the last name which contains n as an argument.
1604 * Return -1 if the name is not used. Return names.length if it is the return value.
1605 */
1606 int lastUseIndex(Name n) {
1607 int ni = n.index, nmax = names.length;
1608 assert(names[ni] == n);
1609 if (result == ni) return nmax; // live all the way beyond the end
1610 for (int i = nmax; --i > ni; ) {
1611 if (names[i].lastUseIndex(n) >= 0)
1612 return i;
1613 }
1614 return -1;
1615 }
1616
1617 /** Return the number of times n is used as an argument or return value. */
1618 int useCount(Name n) {
1619 int count = (result == n.index) ? 1 : 0;
1620 int i = Math.max(n.index + 1, arity);
1621 while (i < names.length) {
1622 count += names[i++].useCount(n);
1623 }
1624 return count;
1625 }
1626
1627 static Name argument(int which, BasicType type) {
1628 if (which >= INTERNED_ARGUMENT_LIMIT)
1629 return new Name(which, type);
1630 return INTERNED_ARGUMENTS[type.ordinal()][which];
1631 }
1632 static Name internArgument(Name n) {
1633 assert(n.isParam()) : "not param: " + n;
1634 assert(n.index < INTERNED_ARGUMENT_LIMIT);
1635 if (n.constraint != null) return n;
1636 return argument(n.index, n.type);
1637 }
1638 static Name[] arguments(int extra, MethodType types) {
1639 int length = types.parameterCount();
1640 Name[] names = new Name[length + extra];
1641 for (int i = 0; i < length; i++)
1642 names[i] = argument(i, basicType(types.parameterType(i)));
1643 return names;
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 = new LambdaForm(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 = new LambdaForm(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 = new LambdaForm(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 }