1 /*
2 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 import java.util.ArrayList;
31 import java.util.Arrays;
32 import java.util.Collections;
33 import java.util.function.Function;
34
35 import sun.invoke.empty.Empty;
36 import sun.invoke.util.ValueConversions;
37 import sun.invoke.util.VerifyType;
38 import sun.invoke.util.Wrapper;
39 import sun.reflect.CallerSensitive;
40 import sun.reflect.Reflection;
41 import static java.lang.invoke.LambdaForm.*;
42 import static java.lang.invoke.MethodHandleStatics.*;
43 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
44
45 /**
46 * Trusted implementation code for MethodHandle.
47 * @author jrose
48 */
49 /*non-public*/ abstract class MethodHandleImpl {
50 // Do not adjust this except for special platforms:
51 private static final int MAX_ARITY;
52 static {
53 final Object[] values = { 255 };
54 AccessController.doPrivileged(new PrivilegedAction<Void>() {
55 @Override
56 public Void run() {
57 values[0] = Integer.getInteger(MethodHandleImpl.class.getName()+".MAX_ARITY", 255);
58 return null;
59 }
60 });
61 MAX_ARITY = (Integer) values[0];
62 }
63
64 /// Factory methods to create method handles:
65
66 static void initStatics() {
67 // Trigger selected static initializations.
68 MemberName.Factory.INSTANCE.getClass();
69 }
70
71 static MethodHandle makeArrayElementAccessor(Class<?> arrayClass, boolean isSetter) {
72 if (arrayClass == Object[].class)
73 return (isSetter ? ArrayAccessor.OBJECT_ARRAY_SETTER : ArrayAccessor.OBJECT_ARRAY_GETTER);
74 if (!arrayClass.isArray())
75 throw newIllegalArgumentException("not an array: "+arrayClass);
76 MethodHandle[] cache = ArrayAccessor.TYPED_ACCESSORS.get(arrayClass);
77 int cacheIndex = (isSetter ? ArrayAccessor.SETTER_INDEX : ArrayAccessor.GETTER_INDEX);
78 MethodHandle mh = cache[cacheIndex];
79 if (mh != null) return mh;
80 mh = ArrayAccessor.getAccessor(arrayClass, isSetter);
81 MethodType correctType = ArrayAccessor.correctType(arrayClass, isSetter);
82 if (mh.type() != correctType) {
83 assert(mh.type().parameterType(0) == Object[].class);
84 assert((isSetter ? mh.type().parameterType(2) : mh.type().returnType()) == Object.class);
85 assert(isSetter || correctType.parameterType(0).getComponentType() == correctType.returnType());
86 // safe to view non-strictly, because element type follows from array type
87 mh = mh.viewAsType(correctType, false);
88 }
89 mh = makeIntrinsic(mh, (isSetter ? Intrinsic.ARRAY_STORE : Intrinsic.ARRAY_LOAD));
90 // Atomically update accessor cache.
91 synchronized(cache) {
92 if (cache[cacheIndex] == null) {
93 cache[cacheIndex] = mh;
94 } else {
95 // Throw away newly constructed accessor and use cached version.
96 mh = cache[cacheIndex];
97 }
98 }
99 return mh;
100 }
101
102 static final class ArrayAccessor {
103 /// Support for array element access
104 static final int GETTER_INDEX = 0, SETTER_INDEX = 1, INDEX_LIMIT = 2;
105 static final ClassValue<MethodHandle[]> TYPED_ACCESSORS
106 = new ClassValue<MethodHandle[]>() {
107 @Override
108 protected MethodHandle[] computeValue(Class<?> type) {
109 return new MethodHandle[INDEX_LIMIT];
110 }
111 };
112 static final MethodHandle OBJECT_ARRAY_GETTER, OBJECT_ARRAY_SETTER;
113 static {
114 MethodHandle[] cache = TYPED_ACCESSORS.get(Object[].class);
115 cache[GETTER_INDEX] = OBJECT_ARRAY_GETTER = makeIntrinsic(getAccessor(Object[].class, false), Intrinsic.ARRAY_LOAD);
116 cache[SETTER_INDEX] = OBJECT_ARRAY_SETTER = makeIntrinsic(getAccessor(Object[].class, true), Intrinsic.ARRAY_STORE);
117
118 assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_GETTER.internalMemberName()));
119 assert(InvokerBytecodeGenerator.isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_SETTER.internalMemberName()));
120 }
121
122 static int getElementI(int[] a, int i) { return a[i]; }
123 static long getElementJ(long[] a, int i) { return a[i]; }
124 static float getElementF(float[] a, int i) { return a[i]; }
125 static double getElementD(double[] a, int i) { return a[i]; }
126 static boolean getElementZ(boolean[] a, int i) { return a[i]; }
127 static byte getElementB(byte[] a, int i) { return a[i]; }
128 static short getElementS(short[] a, int i) { return a[i]; }
129 static char getElementC(char[] a, int i) { return a[i]; }
130 static Object getElementL(Object[] a, int i) { return a[i]; }
131
132 static void setElementI(int[] a, int i, int x) { a[i] = x; }
133 static void setElementJ(long[] a, int i, long x) { a[i] = x; }
134 static void setElementF(float[] a, int i, float x) { a[i] = x; }
135 static void setElementD(double[] a, int i, double x) { a[i] = x; }
136 static void setElementZ(boolean[] a, int i, boolean x) { a[i] = x; }
137 static void setElementB(byte[] a, int i, byte x) { a[i] = x; }
138 static void setElementS(short[] a, int i, short x) { a[i] = x; }
139 static void setElementC(char[] a, int i, char x) { a[i] = x; }
140 static void setElementL(Object[] a, int i, Object x) { a[i] = x; }
141
142 static String name(Class<?> arrayClass, boolean isSetter) {
143 Class<?> elemClass = arrayClass.getComponentType();
144 if (elemClass == null) throw newIllegalArgumentException("not an array", arrayClass);
145 return (!isSetter ? "getElement" : "setElement") + Wrapper.basicTypeChar(elemClass);
146 }
147 static MethodType type(Class<?> arrayClass, boolean isSetter) {
148 Class<?> elemClass = arrayClass.getComponentType();
149 Class<?> arrayArgClass = arrayClass;
150 if (!elemClass.isPrimitive()) {
151 arrayArgClass = Object[].class;
152 elemClass = Object.class;
153 }
154 return !isSetter ?
155 MethodType.methodType(elemClass, arrayArgClass, int.class) :
156 MethodType.methodType(void.class, arrayArgClass, int.class, elemClass);
157 }
158 static MethodType correctType(Class<?> arrayClass, boolean isSetter) {
159 Class<?> elemClass = arrayClass.getComponentType();
160 return !isSetter ?
161 MethodType.methodType(elemClass, arrayClass, int.class) :
162 MethodType.methodType(void.class, arrayClass, int.class, elemClass);
163 }
164 static MethodHandle getAccessor(Class<?> arrayClass, boolean isSetter) {
165 String name = name(arrayClass, isSetter);
166 MethodType type = type(arrayClass, isSetter);
167 try {
168 return IMPL_LOOKUP.findStatic(ArrayAccessor.class, name, type);
169 } catch (ReflectiveOperationException ex) {
170 throw uncaughtException(ex);
171 }
172 }
173 }
174
175 /**
176 * Create a JVM-level adapter method handle to conform the given method
177 * handle to the similar newType, using only pairwise argument conversions.
178 * For each argument, convert incoming argument to the exact type needed.
179 * The argument conversions allowed are casting, boxing and unboxing,
180 * integral widening or narrowing, and floating point widening or narrowing.
181 * @param srcType required call type
182 * @param target original method handle
183 * @param strict if true, only asType conversions are allowed; if false, explicitCastArguments conversions allowed
184 * @param monobox if true, unboxing conversions are assumed to be exactly typed (Integer to int only, not long or double)
185 * @return an adapter to the original handle with the desired new type,
186 * or the original target if the types are already identical
187 * or null if the adaptation cannot be made
188 */
189 static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
190 boolean strict, boolean monobox) {
191 MethodType dstType = target.type();
192 if (srcType == dstType)
193 return target;
194 return makePairwiseConvertByEditor(target, srcType, strict, monobox);
195 }
196
197 private static int countNonNull(Object[] array) {
198 int count = 0;
199 for (Object x : array) {
200 if (x != null) ++count;
201 }
202 return count;
203 }
204
205 static MethodHandle makePairwiseConvertByEditor(MethodHandle target, MethodType srcType,
206 boolean strict, boolean monobox) {
207 Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
208 int convCount = countNonNull(convSpecs);
209 if (convCount == 0)
210 return target.viewAsType(srcType, strict);
211 MethodType basicSrcType = srcType.basicType();
212 MethodType midType = target.type().basicType();
213 BoundMethodHandle mh = target.rebind();
214 // FIXME: Reduce number of bindings when there is more than one Class conversion.
215 // FIXME: Reduce number of bindings when there are repeated conversions.
216 for (int i = 0; i < convSpecs.length-1; i++) {
217 Object convSpec = convSpecs[i];
218 if (convSpec == null) continue;
219 MethodHandle fn;
220 if (convSpec instanceof Class) {
221 fn = Lazy.MH_castReference.bindTo(convSpec);
222 } else {
223 fn = (MethodHandle) convSpec;
224 }
225 Class<?> newType = basicSrcType.parameterType(i);
226 if (--convCount == 0)
227 midType = srcType;
228 else
229 midType = midType.changeParameterType(i, newType);
230 LambdaForm form2 = mh.editor().filterArgumentForm(1+i, BasicType.basicType(newType));
231 mh = mh.copyWithExtendL(midType, form2, fn);
232 mh = mh.rebind();
233 }
234 Object convSpec = convSpecs[convSpecs.length-1];
235 if (convSpec != null) {
236 MethodHandle fn;
237 if (convSpec instanceof Class) {
238 if (convSpec == void.class)
239 fn = null;
240 else
241 fn = Lazy.MH_castReference.bindTo(convSpec);
242 } else {
243 fn = (MethodHandle) convSpec;
244 }
245 Class<?> newType = basicSrcType.returnType();
246 assert(--convCount == 0);
247 midType = srcType;
248 if (fn != null) {
249 mh = mh.rebind(); // rebind if too complex
250 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), false);
251 mh = mh.copyWithExtendL(midType, form2, fn);
252 } else {
253 LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), true);
254 mh = mh.copyWith(midType, form2);
255 }
256 }
257 assert(convCount == 0);
258 assert(mh.type().equals(srcType));
259 return mh;
260 }
261
262 static MethodHandle makePairwiseConvertIndirect(MethodHandle target, MethodType srcType,
263 boolean strict, boolean monobox) {
264 assert(target.type().parameterCount() == srcType.parameterCount());
265 // Calculate extra arguments (temporaries) required in the names array.
266 Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
267 final int INARG_COUNT = srcType.parameterCount();
268 int convCount = countNonNull(convSpecs);
269 boolean retConv = (convSpecs[INARG_COUNT] != null);
270 boolean retVoid = srcType.returnType() == void.class;
271 if (retConv && retVoid) {
272 convCount -= 1;
273 retConv = false;
274 }
275
276 final int IN_MH = 0;
277 final int INARG_BASE = 1;
278 final int INARG_LIMIT = INARG_BASE + INARG_COUNT;
279 final int NAME_LIMIT = INARG_LIMIT + convCount + 1;
280 final int RETURN_CONV = (!retConv ? -1 : NAME_LIMIT - 1);
281 final int OUT_CALL = (!retConv ? NAME_LIMIT : RETURN_CONV) - 1;
282 final int RESULT = (retVoid ? -1 : NAME_LIMIT - 1);
283
284 // Now build a LambdaForm.
285 MethodType lambdaType = srcType.basicType().invokerType();
286 Name[] names = arguments(NAME_LIMIT - INARG_LIMIT, lambdaType);
287
288 // Collect the arguments to the outgoing call, maybe with conversions:
289 final int OUTARG_BASE = 0; // target MH is Name.function, name Name.arguments[0]
290 Object[] outArgs = new Object[OUTARG_BASE + INARG_COUNT];
291
292 int nameCursor = INARG_LIMIT;
293 for (int i = 0; i < INARG_COUNT; i++) {
294 Object convSpec = convSpecs[i];
295 if (convSpec == null) {
296 // do nothing: difference is trivial
297 outArgs[OUTARG_BASE + i] = names[INARG_BASE + i];
298 continue;
299 }
300
301 Name conv;
302 if (convSpec instanceof Class) {
303 Class<?> convClass = (Class<?>) convSpec;
304 conv = new Name(Lazy.MH_castReference, convClass, names[INARG_BASE + i]);
305 } else {
306 MethodHandle fn = (MethodHandle) convSpec;
307 conv = new Name(fn, names[INARG_BASE + i]);
308 }
309 assert(names[nameCursor] == null);
310 names[nameCursor++] = conv;
311 assert(outArgs[OUTARG_BASE + i] == null);
312 outArgs[OUTARG_BASE + i] = conv;
313 }
314
315 // Build argument array for the call.
316 assert(nameCursor == OUT_CALL);
317 names[OUT_CALL] = new Name(target, outArgs);
318
319 Object convSpec = convSpecs[INARG_COUNT];
320 if (!retConv) {
321 assert(OUT_CALL == names.length-1);
322 } else {
323 Name conv;
324 if (convSpec == void.class) {
325 conv = new Name(LambdaForm.constantZero(BasicType.basicType(srcType.returnType())));
326 } else if (convSpec instanceof Class) {
327 Class<?> convClass = (Class<?>) convSpec;
328 conv = new Name(Lazy.MH_castReference, convClass, names[OUT_CALL]);
329 } else {
330 MethodHandle fn = (MethodHandle) convSpec;
331 if (fn.type().parameterCount() == 0)
332 conv = new Name(fn); // don't pass retval to void conversion
333 else
334 conv = new Name(fn, names[OUT_CALL]);
335 }
336 assert(names[RETURN_CONV] == null);
337 names[RETURN_CONV] = conv;
338 assert(RETURN_CONV == names.length-1);
339 }
340
341 LambdaForm form = new LambdaForm("convert", lambdaType.parameterCount(), names, RESULT);
342 return SimpleMethodHandle.make(srcType, form);
343 }
344
345 /**
346 * Identity function, with reference cast.
347 * @param t an arbitrary reference type
348 * @param x an arbitrary reference value
349 * @return the same value x
350 */
351 @ForceInline
352 @SuppressWarnings("unchecked")
353 static <T,U> T castReference(Class<? extends T> t, U x) {
354 // inlined Class.cast because we can't ForceInline it
355 if (x != null && !t.isInstance(x))
356 throw newClassCastException(t, x);
357 return (T) x;
358 }
359
360 private static ClassCastException newClassCastException(Class<?> t, Object obj) {
361 return new ClassCastException("Cannot cast " + obj.getClass().getName() + " to " + t.getName());
362 }
363
364 static Object[] computeValueConversions(MethodType srcType, MethodType dstType,
365 boolean strict, boolean monobox) {
366 final int INARG_COUNT = srcType.parameterCount();
367 Object[] convSpecs = new Object[INARG_COUNT+1];
368 for (int i = 0; i <= INARG_COUNT; i++) {
369 boolean isRet = (i == INARG_COUNT);
370 Class<?> src = isRet ? dstType.returnType() : srcType.parameterType(i);
371 Class<?> dst = isRet ? srcType.returnType() : dstType.parameterType(i);
372 if (!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)) {
373 convSpecs[i] = valueConversion(src, dst, strict, monobox);
374 }
375 }
376 return convSpecs;
377 }
378 static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
379 boolean strict) {
380 return makePairwiseConvert(target, srcType, strict, /*monobox=*/ false);
381 }
382
383 /**
384 * Find a conversion function from the given source to the given destination.
385 * This conversion function will be used as a LF NamedFunction.
386 * Return a Class object if a simple cast is needed.
387 * Return void.class if void is involved.
388 */
389 static Object valueConversion(Class<?> src, Class<?> dst, boolean strict, boolean monobox) {
390 assert(!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)); // caller responsibility
391 if (dst == void.class)
392 return dst;
393 MethodHandle fn;
394 if (src.isPrimitive()) {
395 if (src == void.class) {
396 return void.class; // caller must recognize this specially
397 } else if (dst.isPrimitive()) {
398 // Examples: int->byte, byte->int, boolean->int (!strict)
399 fn = ValueConversions.convertPrimitive(src, dst);
400 } else {
401 // Examples: int->Integer, boolean->Object, float->Number
402 Wrapper wsrc = Wrapper.forPrimitiveType(src);
403 fn = ValueConversions.boxExact(wsrc);
404 assert(fn.type().parameterType(0) == wsrc.primitiveType());
405 assert(fn.type().returnType() == wsrc.wrapperType());
406 if (!VerifyType.isNullConversion(wsrc.wrapperType(), dst, strict)) {
407 // Corner case, such as int->Long, which will probably fail.
408 MethodType mt = MethodType.methodType(dst, src);
409 if (strict)
410 fn = fn.asType(mt);
411 else
412 fn = MethodHandleImpl.makePairwiseConvert(fn, mt, /*strict=*/ false);
413 }
414 }
415 } else if (dst.isPrimitive()) {
416 Wrapper wdst = Wrapper.forPrimitiveType(dst);
417 if (monobox || src == wdst.wrapperType()) {
418 // Use a strongly-typed unboxer, if possible.
419 fn = ValueConversions.unboxExact(wdst, strict);
420 } else {
421 // Examples: Object->int, Number->int, Comparable->int, Byte->int
422 // must include additional conversions
423 // src must be examined at runtime, to detect Byte, Character, etc.
424 fn = (strict
425 ? ValueConversions.unboxWiden(wdst)
426 : ValueConversions.unboxCast(wdst));
427 }
428 } else {
429 // Simple reference conversion.
430 // Note: Do not check for a class hierarchy relation
431 // between src and dst. In all cases a 'null' argument
432 // will pass the cast conversion.
433 return dst;
434 }
435 assert(fn.type().parameterCount() <= 1) : "pc"+Arrays.asList(src.getSimpleName(), dst.getSimpleName(), fn);
436 return fn;
437 }
438
439 static MethodHandle makeVarargsCollector(MethodHandle target, Class<?> arrayType) {
440 MethodType type = target.type();
441 int last = type.parameterCount() - 1;
442 if (type.parameterType(last) != arrayType)
443 target = target.asType(type.changeParameterType(last, arrayType));
444 target = target.asFixedArity(); // make sure this attribute is turned off
445 return new AsVarargsCollector(target, arrayType);
446 }
447
448 private static final class AsVarargsCollector extends DelegatingMethodHandle {
449 private final MethodHandle target;
450 private final Class<?> arrayType;
451 private @Stable MethodHandle asCollectorCache;
452
453 AsVarargsCollector(MethodHandle target, Class<?> arrayType) {
454 this(target.type(), target, arrayType);
455 }
456 AsVarargsCollector(MethodType type, MethodHandle target, Class<?> arrayType) {
457 super(type, target);
458 this.target = target;
459 this.arrayType = arrayType;
460 this.asCollectorCache = target.asCollector(arrayType, 0);
461 }
462
463 @Override
464 public boolean isVarargsCollector() {
465 return true;
466 }
467
468 @Override
469 protected MethodHandle getTarget() {
470 return target;
471 }
472
473 @Override
474 public MethodHandle asFixedArity() {
475 return target;
476 }
477
478 @Override
479 MethodHandle setVarargs(MemberName member) {
480 if (member.isVarargs()) return this;
481 return asFixedArity();
482 }
483
484 @Override
485 public MethodHandle asTypeUncached(MethodType newType) {
486 MethodType type = this.type();
487 int collectArg = type.parameterCount() - 1;
488 int newArity = newType.parameterCount();
489 if (newArity == collectArg+1 &&
490 type.parameterType(collectArg).isAssignableFrom(newType.parameterType(collectArg))) {
491 // if arity and trailing parameter are compatible, do normal thing
492 return asTypeCache = asFixedArity().asType(newType);
493 }
494 // check cache
495 MethodHandle acc = asCollectorCache;
496 if (acc != null && acc.type().parameterCount() == newArity)
497 return asTypeCache = acc.asType(newType);
498 // build and cache a collector
499 int arrayLength = newArity - collectArg;
500 MethodHandle collector;
501 try {
502 collector = asFixedArity().asCollector(arrayType, arrayLength);
503 assert(collector.type().parameterCount() == newArity) : "newArity="+newArity+" but collector="+collector;
504 } catch (IllegalArgumentException ex) {
505 throw new WrongMethodTypeException("cannot build collector", ex);
506 }
507 asCollectorCache = collector;
508 return asTypeCache = collector.asType(newType);
509 }
510
511 @Override
512 boolean viewAsTypeChecks(MethodType newType, boolean strict) {
513 super.viewAsTypeChecks(newType, true);
514 if (strict) return true;
515 // extra assertion for non-strict checks:
516 assert (type().lastParameterType().getComponentType()
517 .isAssignableFrom(
518 newType.lastParameterType().getComponentType()))
519 : Arrays.asList(this, newType);
520 return true;
521 }
522 }
523
524 /** Factory method: Spread selected argument. */
525 static MethodHandle makeSpreadArguments(MethodHandle target,
526 Class<?> spreadArgType, int spreadArgPos, int spreadArgCount) {
527 MethodType targetType = target.type();
528
529 for (int i = 0; i < spreadArgCount; i++) {
530 Class<?> arg = VerifyType.spreadArgElementType(spreadArgType, i);
531 if (arg == null) arg = Object.class;
532 targetType = targetType.changeParameterType(spreadArgPos + i, arg);
533 }
534 target = target.asType(targetType);
535
536 MethodType srcType = targetType
537 .replaceParameterTypes(spreadArgPos, spreadArgPos + spreadArgCount, spreadArgType);
538 // Now build a LambdaForm.
539 MethodType lambdaType = srcType.invokerType();
540 Name[] names = arguments(spreadArgCount + 2, lambdaType);
541 int nameCursor = lambdaType.parameterCount();
542 int[] indexes = new int[targetType.parameterCount()];
543
544 for (int i = 0, argIndex = 1; i < targetType.parameterCount() + 1; i++, argIndex++) {
545 Class<?> src = lambdaType.parameterType(i);
546 if (i == spreadArgPos) {
547 // Spread the array.
548 MethodHandle aload = MethodHandles.arrayElementGetter(spreadArgType);
549 Name array = names[argIndex];
550 names[nameCursor++] = new Name(Lazy.NF_checkSpreadArgument, array, spreadArgCount);
551 for (int j = 0; j < spreadArgCount; i++, j++) {
552 indexes[i] = nameCursor;
553 names[nameCursor++] = new Name(aload, array, j);
554 }
555 } else if (i < indexes.length) {
556 indexes[i] = argIndex;
557 }
558 }
559 assert(nameCursor == names.length-1); // leave room for the final call
560
561 // Build argument array for the call.
562 Name[] targetArgs = new Name[targetType.parameterCount()];
563 for (int i = 0; i < targetType.parameterCount(); i++) {
564 int idx = indexes[i];
565 targetArgs[i] = names[idx];
566 }
567 names[names.length - 1] = new Name(target, (Object[]) targetArgs);
568
569 LambdaForm form = new LambdaForm("spread", lambdaType.parameterCount(), names);
570 return SimpleMethodHandle.make(srcType, form);
571 }
572
573 static void checkSpreadArgument(Object av, int n) {
574 if (av == null) {
575 if (n == 0) return;
576 } else if (av instanceof Object[]) {
577 int len = ((Object[])av).length;
578 if (len == n) return;
579 } else {
580 int len = java.lang.reflect.Array.getLength(av);
581 if (len == n) return;
582 }
583 // fall through to error:
584 throw newIllegalArgumentException("array is not of length "+n);
585 }
586
587 /**
588 * Pre-initialized NamedFunctions for bootstrapping purposes.
589 * Factored in an inner class to delay initialization until first usage.
590 */
591 static class Lazy {
592 private static final Class<?> MHI = MethodHandleImpl.class;
593
594 private static final MethodHandle[] ARRAYS;
595 private static final MethodHandle[] FILL_ARRAYS;
596
597 static final NamedFunction NF_checkSpreadArgument;
598 static final NamedFunction NF_guardWithCatch;
599 static final NamedFunction NF_throwException;
600
601 static final MethodHandle MH_castReference;
602 static final MethodHandle MH_selectAlternative;
603 static final MethodHandle MH_copyAsPrimitiveArray;
604 static final MethodHandle MH_fillNewTypedArray;
605 static final MethodHandle MH_fillNewArray;
606 static final MethodHandle MH_arrayIdentity;
607
608 static {
609 ARRAYS = makeArrays();
610 FILL_ARRAYS = makeFillArrays();
611
612 try {
613 NF_checkSpreadArgument = new NamedFunction(MHI.getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
614 NF_guardWithCatch = new NamedFunction(MHI.getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
615 MethodHandle.class, Object[].class));
616 NF_throwException = new NamedFunction(MHI.getDeclaredMethod("throwException", Throwable.class));
617
618 NF_checkSpreadArgument.resolve();
619 NF_guardWithCatch.resolve();
620 NF_throwException.resolve();
621
622 MH_castReference = IMPL_LOOKUP.findStatic(MHI, "castReference",
623 MethodType.methodType(Object.class, Class.class, Object.class));
624 MH_copyAsPrimitiveArray = IMPL_LOOKUP.findStatic(MHI, "copyAsPrimitiveArray",
625 MethodType.methodType(Object.class, Wrapper.class, Object[].class));
626 MH_arrayIdentity = IMPL_LOOKUP.findStatic(MHI, "identity",
627 MethodType.methodType(Object[].class, Object[].class));
628 MH_fillNewArray = IMPL_LOOKUP.findStatic(MHI, "fillNewArray",
629 MethodType.methodType(Object[].class, Integer.class, Object[].class));
630 MH_fillNewTypedArray = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
631 MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
632
633 MH_selectAlternative = makeIntrinsic(
634 IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
635 MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class, int[].class)),
636 Intrinsic.SELECT_ALTERNATIVE);
637 } catch (ReflectiveOperationException ex) {
638 throw newInternalError(ex);
639 }
640 }
641 }
642
643 /** Factory method: Collect or filter selected argument(s). */
644 static MethodHandle makeCollectArguments(MethodHandle target,
645 MethodHandle collector, int collectArgPos, boolean retainOriginalArgs) {
646 MethodType targetType = target.type(); // (a..., c, [b...])=>r
647 MethodType collectorType = collector.type(); // (b...)=>c
648 int collectArgCount = collectorType.parameterCount();
649 Class<?> collectValType = collectorType.returnType();
650 int collectValCount = (collectValType == void.class ? 0 : 1);
651 MethodType srcType = targetType // (a..., [b...])=>r
652 .dropParameterTypes(collectArgPos, collectArgPos+collectValCount);
653 if (!retainOriginalArgs) { // (a..., b...)=>r
654 srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterList());
655 }
656 // in arglist: [0: ...keep1 | cpos: collect... | cpos+cacount: keep2... ]
657 // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
658 // out(retain): [0: ...keep1 | cpos: cV? coll... | cpos+cvc+cac: keep2... ]
659
660 // Now build a LambdaForm.
661 MethodType lambdaType = srcType.invokerType();
662 Name[] names = arguments(2, lambdaType);
663 final int collectNamePos = names.length - 2;
664 final int targetNamePos = names.length - 1;
665
666 Name[] collectorArgs = Arrays.copyOfRange(names, 1 + collectArgPos, 1 + collectArgPos + collectArgCount);
667 names[collectNamePos] = new Name(collector, (Object[]) collectorArgs);
668
669 // Build argument array for the target.
670 // Incoming LF args to copy are: [ (mh) headArgs collectArgs tailArgs ].
671 // Output argument array is [ headArgs (collectVal)? (collectArgs)? tailArgs ].
672 Name[] targetArgs = new Name[targetType.parameterCount()];
673 int inputArgPos = 1; // incoming LF args to copy to target
674 int targetArgPos = 0; // fill pointer for targetArgs
675 int chunk = collectArgPos; // |headArgs|
676 System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
677 inputArgPos += chunk;
678 targetArgPos += chunk;
679 if (collectValType != void.class) {
680 targetArgs[targetArgPos++] = names[collectNamePos];
681 }
682 chunk = collectArgCount;
683 if (retainOriginalArgs) {
684 System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
685 targetArgPos += chunk; // optionally pass on the collected chunk
686 }
687 inputArgPos += chunk;
688 chunk = targetArgs.length - targetArgPos; // all the rest
689 System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
690 assert(inputArgPos + chunk == collectNamePos); // use of rest of input args also
691 names[targetNamePos] = new Name(target, (Object[]) targetArgs);
692
693 LambdaForm form = new LambdaForm("collect", lambdaType.parameterCount(), names);
694 return SimpleMethodHandle.make(srcType, form);
695 }
696
697 @LambdaForm.Hidden
698 static
699 MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback, int[] counters) {
700 if (counters != null) {
701 updateCounters(counters, testResult);
702 }
703 if (testResult) {
704 return target;
705 } else {
706 return fallback;
707 }
708 }
709
710 // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
711 @LambdaForm.Hidden
712 static
713 boolean profileBranch(boolean result, int[] counters) {
714 updateCounters(counters, result);
715 return result;
716 }
717
718 @LambdaForm.Hidden
719 @ForceInline
720 static
721 void updateCounters(int[] counters, boolean result) {
722 int idx = result ? 0 : 1;
723 try {
724 counters[idx] = Math.addExact(counters[idx], 1);
725 } catch (ArithmeticException e) {
726 // Avoid continuous overflow by halving the problematic count.
727 counters[idx] = counters[idx] / 2;
728 }
729 }
730
731 static
732 MethodHandle makeGuardWithTest(MethodHandle test,
733 MethodHandle target,
734 MethodHandle fallback) {
735 MethodType type = target.type();
736 assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
737 MethodType basicType = type.basicType();
738 int[] counters = PROFILE_GWT ? new int[2] : null;
739 LambdaForm form = makeGuardWithTestForm(basicType);
740 BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLL();
741 BoundMethodHandle mh;
742
743 try {
744 mh = (BoundMethodHandle)
745 data.constructor().invokeBasic(type, form,
746 (Object) test, (Object) profile(target), (Object) profile(fallback), counters);
747 } catch (Throwable ex) {
748 throw uncaughtException(ex);
749 }
750 assert(mh.type() == type);
751 return mh;
752 }
753
754
755 static
756 MethodHandle profile(MethodHandle target) {
757 if (DONT_INLINE_THRESHOLD >= 0) {
758 return makeBlockInlningWrapper(target);
759 } else {
760 return target;
761 }
762 }
763
764 /**
765 * Block inlining during JIT-compilation of a target method handle if it hasn't been invoked enough times.
766 * Corresponding LambdaForm has @DontInline when compiled into bytecode.
767 */
768 static
769 MethodHandle makeBlockInlningWrapper(MethodHandle target) {
770 LambdaForm lform = PRODUCE_BLOCK_INLINING_FORM.apply(target);
771 return new CountingWrapper(target, lform,
772 PRODUCE_BLOCK_INLINING_FORM, PRODUCE_REINVOKER_FORM,
773 DONT_INLINE_THRESHOLD);
774 }
775
776 /** Constructs reinvoker lambda form which block inlining during JIT-compilation for a particular method handle */
777 private static final Function<MethodHandle, LambdaForm> PRODUCE_BLOCK_INLINING_FORM = new Function<MethodHandle, LambdaForm>() {
778 @Override
779 public LambdaForm apply(MethodHandle target) {
780 return DelegatingMethodHandle.makeReinvokerForm(target,
781 MethodTypeForm.LF_DELEGATE_BLOCK_INLINING, CountingWrapper.class, "reinvoker.dontInline", false,
782 DelegatingMethodHandle.NF_getTarget, CountingWrapper.NF_maybeStopCounting);
783 }
784 };
785
786 /** Constructs simple reinvoker lambda form for a particular method handle */
787 private static final Function<MethodHandle, LambdaForm> PRODUCE_REINVOKER_FORM = new Function<MethodHandle, LambdaForm>() {
788 @Override
789 public LambdaForm apply(MethodHandle target) {
790 return DelegatingMethodHandle.makeReinvokerForm(target,
791 MethodTypeForm.LF_DELEGATE, DelegatingMethodHandle.class, DelegatingMethodHandle.NF_getTarget);
792 }
793 };
794
795 /**
796 * Counting method handle. It has 2 states: counting and non-counting.
797 * It is in counting state for the first n invocations and then transitions to non-counting state.
798 * Behavior in counting and non-counting states is determined by lambda forms produced by
799 * countingFormProducer & nonCountingFormProducer respectively.
800 */
801 static class CountingWrapper extends DelegatingMethodHandle {
802 private final MethodHandle target;
803 private int count;
804 private Function<MethodHandle, LambdaForm> countingFormProducer;
805 private Function<MethodHandle, LambdaForm> nonCountingFormProducer;
806 private volatile boolean isCounting;
807
808 private CountingWrapper(MethodHandle target, LambdaForm lform,
809 Function<MethodHandle, LambdaForm> countingFromProducer,
810 Function<MethodHandle, LambdaForm> nonCountingFormProducer,
811 int count) {
812 super(target.type(), lform);
813 this.target = target;
814 this.count = count;
815 this.countingFormProducer = countingFromProducer;
816 this.nonCountingFormProducer = nonCountingFormProducer;
817 this.isCounting = (count > 0);
818 }
819
820 @Hidden
821 @Override
822 protected MethodHandle getTarget() {
823 return target;
824 }
825
826 @Override
827 public MethodHandle asTypeUncached(MethodType newType) {
828 MethodHandle newTarget = target.asType(newType);
829 MethodHandle wrapper;
830 if (isCounting) {
831 LambdaForm lform;
832 lform = countingFormProducer.apply(target);
833 wrapper = new CountingWrapper(newTarget, lform, countingFormProducer, nonCountingFormProducer, DONT_INLINE_THRESHOLD);
834 } else {
835 wrapper = newTarget; // no need for a counting wrapper anymore
836 }
837 return (asTypeCache = wrapper);
838 }
839
840 boolean countDown() {
841 if (count <= 0) {
842 // Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
843 if (isCounting) {
844 isCounting = false;
845 return true;
846 } else {
847 return false;
848 }
849 } else {
850 --count;
851 return false;
852 }
853 }
854
855 @Hidden
856 static void maybeStopCounting(Object o1) {
857 CountingWrapper wrapper = (CountingWrapper) o1;
858 if (wrapper.countDown()) {
859 // Reached invocation threshold. Replace counting behavior with a non-counting one.
860 LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
861 lform.compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
862 wrapper.updateForm(lform);
863 }
864 }
865
866 static final NamedFunction NF_maybeStopCounting;
867 static {
868 Class<?> THIS_CLASS = CountingWrapper.class;
869 try {
870 NF_maybeStopCounting = new NamedFunction(THIS_CLASS.getDeclaredMethod("maybeStopCounting", Object.class));
871 } catch (ReflectiveOperationException ex) {
872 throw newInternalError(ex);
873 }
874 }
875 }
876
877 static
878 LambdaForm makeGuardWithTestForm(MethodType basicType) {
879 LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWT);
880 if (lform != null) return lform;
881 final int THIS_MH = 0; // the BMH_LLL
882 final int ARG_BASE = 1; // start of incoming arguments
883 final int ARG_LIMIT = ARG_BASE + basicType.parameterCount();
884 int nameCursor = ARG_LIMIT;
885 final int GET_TEST = nameCursor++;
886 final int GET_TARGET = nameCursor++;
887 final int GET_FALLBACK = nameCursor++;
888 final int GET_COUNTERS = nameCursor++;
889 final int CALL_TEST = nameCursor++;
890 final int SELECT_ALT = nameCursor++;
891 final int CALL_TARGET = nameCursor++;
892 assert(CALL_TARGET == SELECT_ALT+1); // must be true to trigger IBG.emitSelectAlternative
893
894 MethodType lambdaType = basicType.invokerType();
895 Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
896
897 BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLL();
898 names[THIS_MH] = names[THIS_MH].withConstraint(data);
899 names[GET_TEST] = new Name(data.getterFunction(0), names[THIS_MH]);
900 names[GET_TARGET] = new Name(data.getterFunction(1), names[THIS_MH]);
901 names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
902 names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
903 Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
904
905 // call test
906 MethodType testType = basicType.changeReturnType(boolean.class).basicType();
907 invokeArgs[0] = names[GET_TEST];
908 names[CALL_TEST] = new Name(testType, invokeArgs);
909
910 // call selectAlternative
911 names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[CALL_TEST],
912 names[GET_TARGET], names[GET_FALLBACK], names[GET_COUNTERS]);
913
914 // call target or fallback
915 invokeArgs[0] = names[SELECT_ALT];
916 names[CALL_TARGET] = new Name(basicType, invokeArgs);
917
918 lform = new LambdaForm("guard", lambdaType.parameterCount(), names, /*forceInline=*/true);
919
920 return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
921 }
922
923 /**
924 * The LambdaForm shape for catchException combinator is the following:
925 * <blockquote><pre>{@code
926 * guardWithCatch=Lambda(a0:L,a1:L,a2:L)=>{
927 * t3:L=BoundMethodHandle$Species_LLLLL.argL0(a0:L);
928 * t4:L=BoundMethodHandle$Species_LLLLL.argL1(a0:L);
929 * t5:L=BoundMethodHandle$Species_LLLLL.argL2(a0:L);
930 * t6:L=BoundMethodHandle$Species_LLLLL.argL3(a0:L);
931 * t7:L=BoundMethodHandle$Species_LLLLL.argL4(a0:L);
932 * t8:L=MethodHandle.invokeBasic(t6:L,a1:L,a2:L);
933 * t9:L=MethodHandleImpl.guardWithCatch(t3:L,t4:L,t5:L,t8:L);
934 * t10:I=MethodHandle.invokeBasic(t7:L,t9:L);t10:I}
935 * }</pre></blockquote>
936 *
937 * argL0 and argL2 are target and catcher method handles. argL1 is exception class.
938 * argL3 and argL4 are auxiliary method handles: argL3 boxes arguments and wraps them into Object[]
939 * (ValueConversions.array()) and argL4 unboxes result if necessary (ValueConversions.unbox()).
940 *
941 * Having t8 and t10 passed outside and not hardcoded into a lambda form allows to share lambda forms
942 * among catchException combinators with the same basic type.
943 */
944 private static LambdaForm makeGuardWithCatchForm(MethodType basicType) {
945 MethodType lambdaType = basicType.invokerType();
946
947 LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWC);
948 if (lform != null) {
949 return lform;
950 }
951 final int THIS_MH = 0; // the BMH_LLLLL
952 final int ARG_BASE = 1; // start of incoming arguments
953 final int ARG_LIMIT = ARG_BASE + basicType.parameterCount();
954
955 int nameCursor = ARG_LIMIT;
956 final int GET_TARGET = nameCursor++;
957 final int GET_CLASS = nameCursor++;
958 final int GET_CATCHER = nameCursor++;
959 final int GET_COLLECT_ARGS = nameCursor++;
960 final int GET_UNBOX_RESULT = nameCursor++;
961 final int BOXED_ARGS = nameCursor++;
962 final int TRY_CATCH = nameCursor++;
963 final int UNBOX_RESULT = nameCursor++;
964
965 Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
966
967 BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
968 names[THIS_MH] = names[THIS_MH].withConstraint(data);
969 names[GET_TARGET] = new Name(data.getterFunction(0), names[THIS_MH]);
970 names[GET_CLASS] = new Name(data.getterFunction(1), names[THIS_MH]);
971 names[GET_CATCHER] = new Name(data.getterFunction(2), names[THIS_MH]);
972 names[GET_COLLECT_ARGS] = new Name(data.getterFunction(3), names[THIS_MH]);
973 names[GET_UNBOX_RESULT] = new Name(data.getterFunction(4), names[THIS_MH]);
974
975 // FIXME: rework argument boxing/result unboxing logic for LF interpretation
976
977 // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
978 MethodType collectArgsType = basicType.changeReturnType(Object.class);
979 MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
980 Object[] args = new Object[invokeBasic.type().parameterCount()];
981 args[0] = names[GET_COLLECT_ARGS];
982 System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT-ARG_BASE);
983 names[BOXED_ARGS] = new Name(makeIntrinsic(invokeBasic, Intrinsic.GUARD_WITH_CATCH), args);
984
985 // t_{i+1}:L=MethodHandleImpl.guardWithCatch(target:L,exType:L,catcher:L,t_{i}:L);
986 Object[] gwcArgs = new Object[] {names[GET_TARGET], names[GET_CLASS], names[GET_CATCHER], names[BOXED_ARGS]};
987 names[TRY_CATCH] = new Name(Lazy.NF_guardWithCatch, gwcArgs);
988
989 // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
990 MethodHandle invokeBasicUnbox = MethodHandles.basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
991 Object[] unboxArgs = new Object[] {names[GET_UNBOX_RESULT], names[TRY_CATCH]};
992 names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);
993
994 lform = new LambdaForm("guardWithCatch", lambdaType.parameterCount(), names);
995
996 return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWC, lform);
997 }
998
999 static
1000 MethodHandle makeGuardWithCatch(MethodHandle target,
1001 Class<? extends Throwable> exType,
1002 MethodHandle catcher) {
1003 MethodType type = target.type();
1004 LambdaForm form = makeGuardWithCatchForm(type.basicType());
1005
1006 // Prepare auxiliary method handles used during LambdaForm interpretation.
1007 // Box arguments and wrap them into Object[]: ValueConversions.array().
1008 MethodType varargsType = type.changeReturnType(Object[].class);
1009 MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
1010 // Result unboxing: ValueConversions.unbox() OR ValueConversions.identity() OR ValueConversions.ignore().
1011 MethodHandle unboxResult;
1012 Class<?> rtype = type.returnType();
1013 if (rtype.isPrimitive()) {
1014 if (rtype == void.class) {
1015 unboxResult = ValueConversions.ignore();
1016 } else {
1017 Wrapper w = Wrapper.forPrimitiveType(type.returnType());
1018 unboxResult = ValueConversions.unboxExact(w);
1019 }
1020 } else {
1021 unboxResult = MethodHandles.identity(Object.class);
1022 }
1023
1024 BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
1025 BoundMethodHandle mh;
1026 try {
1027 mh = (BoundMethodHandle)
1028 data.constructor().invokeBasic(type, form, (Object) target, (Object) exType, (Object) catcher,
1029 (Object) collectArgs, (Object) unboxResult);
1030 } catch (Throwable ex) {
1031 throw uncaughtException(ex);
1032 }
1033 assert(mh.type() == type);
1034 return mh;
1035 }
1036
1037 /**
1038 * Intrinsified during LambdaForm compilation
1039 * (see {@link InvokerBytecodeGenerator#emitGuardWithCatch emitGuardWithCatch}).
1040 */
1041 @LambdaForm.Hidden
1042 static Object guardWithCatch(MethodHandle target, Class<? extends Throwable> exType, MethodHandle catcher,
1043 Object... av) throws Throwable {
1044 // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case.
1045 try {
1046 return target.asFixedArity().invokeWithArguments(av);
1047 } catch (Throwable t) {
1048 if (!exType.isInstance(t)) throw t;
1049 return catcher.asFixedArity().invokeWithArguments(prepend(t, av));
1050 }
1051 }
1052
1053 /** Prepend an element {@code elem} to an {@code array}. */
1054 @LambdaForm.Hidden
1055 private static Object[] prepend(Object elem, Object[] array) {
1056 Object[] newArray = new Object[array.length+1];
1057 newArray[0] = elem;
1058 System.arraycopy(array, 0, newArray, 1, array.length);
1059 return newArray;
1060 }
1061
1062 static
1063 MethodHandle throwException(MethodType type) {
1064 assert(Throwable.class.isAssignableFrom(type.parameterType(0)));
1065 int arity = type.parameterCount();
1066 if (arity > 1) {
1067 MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
1068 mh = MethodHandles.dropArguments(mh, 1, type.parameterList().subList(1, arity));
1069 return mh;
1070 }
1071 return makePairwiseConvert(Lazy.NF_throwException.resolvedHandle(), type, false, true);
1072 }
1073
1074 static <T extends Throwable> Empty throwException(T t) throws T { throw t; }
1075
1076 static MethodHandle[] FAKE_METHOD_HANDLE_INVOKE = new MethodHandle[2];
1077 static MethodHandle fakeMethodHandleInvoke(MemberName method) {
1078 int idx;
1079 assert(method.isMethodHandleInvoke());
1080 switch (method.getName()) {
1081 case "invoke": idx = 0; break;
1082 case "invokeExact": idx = 1; break;
1083 default: throw new InternalError(method.getName());
1084 }
1085 MethodHandle mh = FAKE_METHOD_HANDLE_INVOKE[idx];
1086 if (mh != null) return mh;
1087 MethodType type = MethodType.methodType(Object.class, UnsupportedOperationException.class,
1088 MethodHandle.class, Object[].class);
1089 mh = throwException(type);
1090 mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke MethodHandle"));
1091 if (!method.getInvocationType().equals(mh.type()))
1092 throw new InternalError(method.toString());
1093 mh = mh.withInternalMemberName(method, false);
1094 mh = mh.asVarargsCollector(Object[].class);
1095 assert(method.isVarargs());
1096 FAKE_METHOD_HANDLE_INVOKE[idx] = mh;
1097 return mh;
1098 }
1099
1100 /**
1101 * Create an alias for the method handle which, when called,
1102 * appears to be called from the same class loader and protection domain
1103 * as hostClass.
1104 * This is an expensive no-op unless the method which is called
1105 * is sensitive to its caller. A small number of system methods
1106 * are in this category, including Class.forName and Method.invoke.
1107 */
1108 static
1109 MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1110 return BindCaller.bindCaller(mh, hostClass);
1111 }
1112
1113 // Put the whole mess into its own nested class.
1114 // That way we can lazily load the code and set up the constants.
1115 private static class BindCaller {
1116 static
1117 MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
1118 // Do not use this function to inject calls into system classes.
1119 if (hostClass == null
1120 || (hostClass.isArray() ||
1121 hostClass.isPrimitive() ||
1122 hostClass.getName().startsWith("java.") ||
1123 hostClass.getName().startsWith("sun."))) {
1124 throw new InternalError(); // does not happen, and should not anyway
1125 }
1126 // For simplicity, convert mh to a varargs-like method.
1127 MethodHandle vamh = prepareForInvoker(mh);
1128 // Cache the result of makeInjectedInvoker once per argument class.
1129 MethodHandle bccInvoker = CV_makeInjectedInvoker.get(hostClass);
1130 return restoreToType(bccInvoker.bindTo(vamh), mh, hostClass);
1131 }
1132
1133 private static MethodHandle makeInjectedInvoker(Class<?> hostClass) {
1134 Class<?> bcc = UNSAFE.defineAnonymousClass(hostClass, T_BYTES, null);
1135 if (hostClass.getClassLoader() != bcc.getClassLoader())
1136 throw new InternalError(hostClass.getName()+" (CL)");
1137 try {
1138 if (hostClass.getProtectionDomain() != bcc.getProtectionDomain())
1139 throw new InternalError(hostClass.getName()+" (PD)");
1140 } catch (SecurityException ex) {
1141 // Self-check was blocked by security manager. This is OK.
1142 // In fact the whole try body could be turned into an assertion.
1143 }
1144 try {
1145 MethodHandle init = IMPL_LOOKUP.findStatic(bcc, "init", MethodType.methodType(void.class));
1146 init.invokeExact(); // force initialization of the class
1147 } catch (Throwable ex) {
1148 throw uncaughtException(ex);
1149 }
1150 MethodHandle bccInvoker;
1151 try {
1152 MethodType invokerMT = MethodType.methodType(Object.class, MethodHandle.class, Object[].class);
1153 bccInvoker = IMPL_LOOKUP.findStatic(bcc, "invoke_V", invokerMT);
1154 } catch (ReflectiveOperationException ex) {
1155 throw uncaughtException(ex);
1156 }
1157 // Test the invoker, to ensure that it really injects into the right place.
1158 try {
1159 MethodHandle vamh = prepareForInvoker(MH_checkCallerClass);
1160 Object ok = bccInvoker.invokeExact(vamh, new Object[]{hostClass, bcc});
1161 } catch (Throwable ex) {
1162 throw new InternalError(ex);
1163 }
1164 return bccInvoker;
1165 }
1166 private static ClassValue<MethodHandle> CV_makeInjectedInvoker = new ClassValue<MethodHandle>() {
1167 @Override protected MethodHandle computeValue(Class<?> hostClass) {
1168 return makeInjectedInvoker(hostClass);
1169 }
1170 };
1171
1172 // Adapt mh so that it can be called directly from an injected invoker:
1173 private static MethodHandle prepareForInvoker(MethodHandle mh) {
1174 mh = mh.asFixedArity();
1175 MethodType mt = mh.type();
1176 int arity = mt.parameterCount();
1177 MethodHandle vamh = mh.asType(mt.generic());
1178 vamh.internalForm().compileToBytecode(); // eliminate LFI stack frames
1179 vamh = vamh.asSpreader(Object[].class, arity);
1180 vamh.internalForm().compileToBytecode(); // eliminate LFI stack frames
1181 return vamh;
1182 }
1183
1184 // Undo the adapter effect of prepareForInvoker:
1185 private static MethodHandle restoreToType(MethodHandle vamh,
1186 MethodHandle original,
1187 Class<?> hostClass) {
1188 MethodType type = original.type();
1189 MethodHandle mh = vamh.asCollector(Object[].class, type.parameterCount());
1190 MemberName member = original.internalMemberName();
1191 mh = mh.asType(type);
1192 mh = new WrappedMember(mh, type, member, original.isInvokeSpecial(), hostClass);
1193 return mh;
1194 }
1195
1196 private static final MethodHandle MH_checkCallerClass;
1197 static {
1198 final Class<?> THIS_CLASS = BindCaller.class;
1199 assert(checkCallerClass(THIS_CLASS, THIS_CLASS));
1200 try {
1201 MH_checkCallerClass = IMPL_LOOKUP
1202 .findStatic(THIS_CLASS, "checkCallerClass",
1203 MethodType.methodType(boolean.class, Class.class, Class.class));
1204 assert((boolean) MH_checkCallerClass.invokeExact(THIS_CLASS, THIS_CLASS));
1205 } catch (Throwable ex) {
1206 throw new InternalError(ex);
1207 }
1208 }
1209
1210 @CallerSensitive
1211 private static boolean checkCallerClass(Class<?> expected, Class<?> expected2) {
1212 // This method is called via MH_checkCallerClass and so it's
1213 // correct to ask for the immediate caller here.
1214 Class<?> actual = Reflection.getCallerClass();
1215 if (actual != expected && actual != expected2)
1216 throw new InternalError("found "+actual.getName()+", expected "+expected.getName()
1217 +(expected == expected2 ? "" : ", or else "+expected2.getName()));
1218 return true;
1219 }
1220
1221 private static final byte[] T_BYTES;
1222 static {
1223 final Object[] values = {null};
1224 AccessController.doPrivileged(new PrivilegedAction<Void>() {
1225 public Void run() {
1226 try {
1227 Class<T> tClass = T.class;
1228 String tName = tClass.getName();
1229 String tResource = tName.substring(tName.lastIndexOf('.')+1)+".class";
1230 java.net.URLConnection uconn = tClass.getResource(tResource).openConnection();
1231 int len = uconn.getContentLength();
1232 byte[] bytes = new byte[len];
1233 try (java.io.InputStream str = uconn.getInputStream()) {
1234 int nr = str.read(bytes);
1235 if (nr != len) throw new java.io.IOException(tResource);
1236 }
1237 values[0] = bytes;
1238 } catch (java.io.IOException ex) {
1239 throw new InternalError(ex);
1240 }
1241 return null;
1242 }
1243 });
1244 T_BYTES = (byte[]) values[0];
1245 }
1246
1247 // The following class is used as a template for Unsafe.defineAnonymousClass:
1248 private static class T {
1249 static void init() { } // side effect: initializes this class
1250 static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
1251 return vamh.invokeExact(args);
1252 }
1253 }
1254 }
1255
1256
1257 /** This subclass allows a wrapped method handle to be re-associated with an arbitrary member name. */
1258 private static final class WrappedMember extends DelegatingMethodHandle {
1259 private final MethodHandle target;
1260 private final MemberName member;
1261 private final Class<?> callerClass;
1262 private final boolean isInvokeSpecial;
1263
1264 private WrappedMember(MethodHandle target, MethodType type,
1265 MemberName member, boolean isInvokeSpecial,
1266 Class<?> callerClass) {
1267 super(type, target);
1268 this.target = target;
1269 this.member = member;
1270 this.callerClass = callerClass;
1271 this.isInvokeSpecial = isInvokeSpecial;
1272 }
1273
1274 @Override
1275 MemberName internalMemberName() {
1276 return member;
1277 }
1278 @Override
1279 Class<?> internalCallerClass() {
1280 return callerClass;
1281 }
1282 @Override
1283 boolean isInvokeSpecial() {
1284 return isInvokeSpecial;
1285 }
1286 @Override
1287 protected MethodHandle getTarget() {
1288 return target;
1289 }
1290 @Override
1291 public MethodHandle asTypeUncached(MethodType newType) {
1292 // This MH is an alias for target, except for the MemberName
1293 // Drop the MemberName if there is any conversion.
1294 return asTypeCache = target.asType(newType);
1295 }
1296 }
1297
1298 static MethodHandle makeWrappedMember(MethodHandle target, MemberName member, boolean isInvokeSpecial) {
1299 if (member.equals(target.internalMemberName()) && isInvokeSpecial == target.isInvokeSpecial())
1300 return target;
1301 return new WrappedMember(target, target.type(), member, isInvokeSpecial, null);
1302 }
1303
1304 /** Intrinsic IDs */
1305 /*non-public*/
1306 enum Intrinsic {
1307 SELECT_ALTERNATIVE,
1308 GUARD_WITH_CATCH,
1309 NEW_ARRAY,
1310 ARRAY_LOAD,
1311 ARRAY_STORE,
1312 IDENTITY,
1313 ZERO,
1314 NONE // no intrinsic associated
1315 }
1316
1317 /** Mark arbitrary method handle as intrinsic.
1318 * InvokerBytecodeGenerator uses this info to produce more efficient bytecode shape. */
1319 private static final class IntrinsicMethodHandle extends DelegatingMethodHandle {
1320 private final MethodHandle target;
1321 private final Intrinsic intrinsicName;
1322
1323 IntrinsicMethodHandle(MethodHandle target, Intrinsic intrinsicName) {
1324 super(target.type(), target);
1325 this.target = target;
1326 this.intrinsicName = intrinsicName;
1327 }
1328
1329 @Override
1330 protected MethodHandle getTarget() {
1331 return target;
1332 }
1333
1334 @Override
1335 Intrinsic intrinsicName() {
1336 return intrinsicName;
1337 }
1338
1339 @Override
1340 public MethodHandle asTypeUncached(MethodType newType) {
1341 // This MH is an alias for target, except for the intrinsic name
1342 // Drop the name if there is any conversion.
1343 return asTypeCache = target.asType(newType);
1344 }
1345
1346 @Override
1347 String internalProperties() {
1348 return super.internalProperties() +
1349 "\n& Intrinsic="+intrinsicName;
1350 }
1351
1352 @Override
1353 public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
1354 if (intrinsicName == Intrinsic.IDENTITY) {
1355 MethodType resultType = type().asCollectorType(arrayType, arrayLength);
1356 MethodHandle newArray = MethodHandleImpl.varargsArray(arrayType, arrayLength);
1357 return newArray.asType(resultType);
1358 }
1359 return super.asCollector(arrayType, arrayLength);
1360 }
1361 }
1362
1363 static MethodHandle makeIntrinsic(MethodHandle target, Intrinsic intrinsicName) {
1364 if (intrinsicName == target.intrinsicName())
1365 return target;
1366 return new IntrinsicMethodHandle(target, intrinsicName);
1367 }
1368
1369 static MethodHandle makeIntrinsic(MethodType type, LambdaForm form, Intrinsic intrinsicName) {
1370 return new IntrinsicMethodHandle(SimpleMethodHandle.make(type, form), intrinsicName);
1371 }
1372
1373 /// Collection of multiple arguments.
1374
1375 private static MethodHandle findCollector(String name, int nargs, Class<?> rtype, Class<?>... ptypes) {
1376 MethodType type = MethodType.genericMethodType(nargs)
1377 .changeReturnType(rtype)
1378 .insertParameterTypes(0, ptypes);
1379 try {
1380 return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, name, type);
1381 } catch (ReflectiveOperationException ex) {
1382 return null;
1383 }
1384 }
1385
1386 private static final Object[] NO_ARGS_ARRAY = {};
1387 private static Object[] makeArray(Object... args) { return args; }
1388 private static Object[] array() { return NO_ARGS_ARRAY; }
1389 private static Object[] array(Object a0)
1390 { return makeArray(a0); }
1391 private static Object[] array(Object a0, Object a1)
1392 { return makeArray(a0, a1); }
1393 private static Object[] array(Object a0, Object a1, Object a2)
1394 { return makeArray(a0, a1, a2); }
1395 private static Object[] array(Object a0, Object a1, Object a2, Object a3)
1396 { return makeArray(a0, a1, a2, a3); }
1397 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1398 Object a4)
1399 { return makeArray(a0, a1, a2, a3, a4); }
1400 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1401 Object a4, Object a5)
1402 { return makeArray(a0, a1, a2, a3, a4, a5); }
1403 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1404 Object a4, Object a5, Object a6)
1405 { return makeArray(a0, a1, a2, a3, a4, a5, a6); }
1406 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1407 Object a4, Object a5, Object a6, Object a7)
1408 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7); }
1409 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1410 Object a4, Object a5, Object a6, Object a7,
1411 Object a8)
1412 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8); }
1413 private static Object[] array(Object a0, Object a1, Object a2, Object a3,
1414 Object a4, Object a5, Object a6, Object a7,
1415 Object a8, Object a9)
1416 { return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); }
1417
1418 private static final int ARRAYS_COUNT = 11;
1419
1420 private static MethodHandle[] makeArrays() {
1421 MethodHandle[] mhs = new MethodHandle[MAX_ARITY + 1];
1422 for (int i = 0; i < ARRAYS_COUNT; i++) {
1423 MethodHandle mh = findCollector("array", i, Object[].class);
1424 mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1425 mhs[i] = mh;
1426 }
1427 assert(assertArrayMethodCount(mhs));
1428 return mhs;
1429 }
1430
1431 private static boolean assertArrayMethodCount(MethodHandle[] mhs) {
1432 assert(findCollector("array", ARRAYS_COUNT, Object[].class) == null);
1433 for (int i = 0; i < ARRAYS_COUNT; i++) {
1434 assert(mhs[i] != null);
1435 }
1436 return true;
1437 }
1438
1439 // filling versions of the above:
1440 // using Integer len instead of int len and no varargs to avoid bootstrapping problems
1441 private static Object[] fillNewArray(Integer len, Object[] /*not ...*/ args) {
1442 Object[] a = new Object[len];
1443 fillWithArguments(a, 0, args);
1444 return a;
1445 }
1446 private static Object[] fillNewTypedArray(Object[] example, Integer len, Object[] /*not ...*/ args) {
1447 Object[] a = Arrays.copyOf(example, len);
1448 assert(a.getClass() != Object[].class);
1449 fillWithArguments(a, 0, args);
1450 return a;
1451 }
1452 private static void fillWithArguments(Object[] a, int pos, Object... args) {
1453 System.arraycopy(args, 0, a, pos, args.length);
1454 }
1455 // using Integer pos instead of int pos to avoid bootstrapping problems
1456 private static Object[] fillArray(Integer pos, Object[] a, Object a0)
1457 { fillWithArguments(a, pos, a0); return a; }
1458 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1)
1459 { fillWithArguments(a, pos, a0, a1); return a; }
1460 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2)
1461 { fillWithArguments(a, pos, a0, a1, a2); return a; }
1462 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3)
1463 { fillWithArguments(a, pos, a0, a1, a2, a3); return a; }
1464 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1465 Object a4)
1466 { fillWithArguments(a, pos, a0, a1, a2, a3, a4); return a; }
1467 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1468 Object a4, Object a5)
1469 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5); return a; }
1470 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1471 Object a4, Object a5, Object a6)
1472 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6); return a; }
1473 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1474 Object a4, Object a5, Object a6, Object a7)
1475 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7); return a; }
1476 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1477 Object a4, Object a5, Object a6, Object a7,
1478 Object a8)
1479 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8); return a; }
1480 private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2, Object a3,
1481 Object a4, Object a5, Object a6, Object a7,
1482 Object a8, Object a9)
1483 { fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); return a; }
1484
1485 private static final int FILL_ARRAYS_COUNT = 11; // current number of fillArray methods
1486
1487 private static MethodHandle[] makeFillArrays() {
1488 MethodHandle[] mhs = new MethodHandle[FILL_ARRAYS_COUNT];
1489 mhs[0] = null; // there is no empty fill; at least a0 is required
1490 for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1491 MethodHandle mh = findCollector("fillArray", i, Object[].class, Integer.class, Object[].class);
1492 mhs[i] = mh;
1493 }
1494 assert(assertFillArrayMethodCount(mhs));
1495 return mhs;
1496 }
1497
1498 private static boolean assertFillArrayMethodCount(MethodHandle[] mhs) {
1499 assert(findCollector("fillArray", FILL_ARRAYS_COUNT, Object[].class, Integer.class, Object[].class) == null);
1500 for (int i = 1; i < FILL_ARRAYS_COUNT; i++) {
1501 assert(mhs[i] != null);
1502 }
1503 return true;
1504 }
1505
1506 private static Object copyAsPrimitiveArray(Wrapper w, Object... boxes) {
1507 Object a = w.makeArray(boxes.length);
1508 w.copyArrayUnboxing(boxes, 0, a, 0, boxes.length);
1509 return a;
1510 }
1511
1512 /** Return a method handle that takes the indicated number of Object
1513 * arguments and returns an Object array of them, as if for varargs.
1514 */
1515 static MethodHandle varargsArray(int nargs) {
1516 MethodHandle mh = Lazy.ARRAYS[nargs];
1517 if (mh != null) return mh;
1518 mh = buildVarargsArray(Lazy.MH_fillNewArray, Lazy.MH_arrayIdentity, nargs);
1519 assert(assertCorrectArity(mh, nargs));
1520 mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1521 return Lazy.ARRAYS[nargs] = mh;
1522 }
1523
1524 private static boolean assertCorrectArity(MethodHandle mh, int arity) {
1525 assert(mh.type().parameterCount() == arity) : "arity != "+arity+": "+mh;
1526 return true;
1527 }
1528
1529 // Array identity function (used as Lazy.MH_arrayIdentity).
1530 static <T> T[] identity(T[] x) {
1531 return x;
1532 }
1533
1534 private static MethodHandle buildVarargsArray(MethodHandle newArray, MethodHandle finisher, int nargs) {
1535 // Build up the result mh as a sequence of fills like this:
1536 // finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
1537 // The various fill(_,10*I,___*[J]) are reusable.
1538 int leftLen = Math.min(nargs, LEFT_ARGS); // absorb some arguments immediately
1539 int rightLen = nargs - leftLen;
1540 MethodHandle leftCollector = newArray.bindTo(nargs);
1541 leftCollector = leftCollector.asCollector(Object[].class, leftLen);
1542 MethodHandle mh = finisher;
1543 if (rightLen > 0) {
1544 MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
1545 if (mh == Lazy.MH_arrayIdentity)
1546 mh = rightFiller;
1547 else
1548 mh = MethodHandles.collectArguments(mh, 0, rightFiller);
1549 }
1550 if (mh == Lazy.MH_arrayIdentity)
1551 mh = leftCollector;
1552 else
1553 mh = MethodHandles.collectArguments(mh, 0, leftCollector);
1554 return mh;
1555 }
1556
1557 private static final int LEFT_ARGS = FILL_ARRAYS_COUNT - 1;
1558 private static final MethodHandle[] FILL_ARRAY_TO_RIGHT = new MethodHandle[MAX_ARITY+1];
1559 /** fill_array_to_right(N).invoke(a, argL..arg[N-1])
1560 * fills a[L]..a[N-1] with corresponding arguments,
1561 * and then returns a. The value L is a global constant (LEFT_ARGS).
1562 */
1563 private static MethodHandle fillToRight(int nargs) {
1564 MethodHandle filler = FILL_ARRAY_TO_RIGHT[nargs];
1565 if (filler != null) return filler;
1566 filler = buildFiller(nargs);
1567 assert(assertCorrectArity(filler, nargs - LEFT_ARGS + 1));
1568 return FILL_ARRAY_TO_RIGHT[nargs] = filler;
1569 }
1570 private static MethodHandle buildFiller(int nargs) {
1571 if (nargs <= LEFT_ARGS)
1572 return Lazy.MH_arrayIdentity; // no args to fill; return the array unchanged
1573 // we need room for both mh and a in mh.invoke(a, arg*[nargs])
1574 final int CHUNK = LEFT_ARGS;
1575 int rightLen = nargs % CHUNK;
1576 int midLen = nargs - rightLen;
1577 if (rightLen == 0) {
1578 midLen = nargs - (rightLen = CHUNK);
1579 if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
1580 // build some precursors from left to right
1581 for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK)
1582 if (j > LEFT_ARGS) fillToRight(j);
1583 }
1584 }
1585 if (midLen < LEFT_ARGS) rightLen = nargs - (midLen = LEFT_ARGS);
1586 assert(rightLen > 0);
1587 MethodHandle midFill = fillToRight(midLen); // recursive fill
1588 MethodHandle rightFill = Lazy.FILL_ARRAYS[rightLen].bindTo(midLen); // [midLen..nargs-1]
1589 assert(midFill.type().parameterCount() == 1 + midLen - LEFT_ARGS);
1590 assert(rightFill.type().parameterCount() == 1 + rightLen);
1591
1592 // Combine the two fills:
1593 // right(mid(a, x10..x19), x20..x23)
1594 // The final product will look like this:
1595 // right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
1596 if (midLen == LEFT_ARGS)
1597 return rightFill;
1598 else
1599 return MethodHandles.collectArguments(rightFill, 0, midFill);
1600 }
1601
1602 // Type-polymorphic version of varargs maker.
1603 private static final ClassValue<MethodHandle[]> TYPED_COLLECTORS
1604 = new ClassValue<MethodHandle[]>() {
1605 @Override
1606 protected MethodHandle[] computeValue(Class<?> type) {
1607 return new MethodHandle[256];
1608 }
1609 };
1610
1611 static final int MAX_JVM_ARITY = 255; // limit imposed by the JVM
1612
1613 /** Return a method handle that takes the indicated number of
1614 * typed arguments and returns an array of them.
1615 * The type argument is the array type.
1616 */
1617 static MethodHandle varargsArray(Class<?> arrayType, int nargs) {
1618 Class<?> elemType = arrayType.getComponentType();
1619 if (elemType == null) throw new IllegalArgumentException("not an array: "+arrayType);
1620 // FIXME: Need more special casing and caching here.
1621 if (nargs >= MAX_JVM_ARITY/2 - 1) {
1622 int slots = nargs;
1623 final int MAX_ARRAY_SLOTS = MAX_JVM_ARITY - 1; // 1 for receiver MH
1624 if (slots <= MAX_ARRAY_SLOTS && elemType.isPrimitive())
1625 slots *= Wrapper.forPrimitiveType(elemType).stackSlots();
1626 if (slots > MAX_ARRAY_SLOTS)
1627 throw new IllegalArgumentException("too many arguments: "+arrayType.getSimpleName()+", length "+nargs);
1628 }
1629 if (elemType == Object.class)
1630 return varargsArray(nargs);
1631 // other cases: primitive arrays, subtypes of Object[]
1632 MethodHandle cache[] = TYPED_COLLECTORS.get(elemType);
1633 MethodHandle mh = nargs < cache.length ? cache[nargs] : null;
1634 if (mh != null) return mh;
1635 if (nargs == 0) {
1636 Object example = java.lang.reflect.Array.newInstance(arrayType.getComponentType(), 0);
1637 mh = MethodHandles.constant(arrayType, example);
1638 } else if (elemType.isPrimitive()) {
1639 MethodHandle builder = Lazy.MH_fillNewArray;
1640 MethodHandle producer = buildArrayProducer(arrayType);
1641 mh = buildVarargsArray(builder, producer, nargs);
1642 } else {
1643 Class<? extends Object[]> objArrayType = arrayType.asSubclass(Object[].class);
1644 Object[] example = Arrays.copyOf(NO_ARGS_ARRAY, 0, objArrayType);
1645 MethodHandle builder = Lazy.MH_fillNewTypedArray.bindTo(example);
1646 MethodHandle producer = Lazy.MH_arrayIdentity; // must be weakly typed
1647 mh = buildVarargsArray(builder, producer, nargs);
1648 }
1649 mh = mh.asType(MethodType.methodType(arrayType, Collections.<Class<?>>nCopies(nargs, elemType)));
1650 mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
1651 assert(assertCorrectArity(mh, nargs));
1652 if (nargs < cache.length)
1653 cache[nargs] = mh;
1654 return mh;
1655 }
1656
1657 private static MethodHandle buildArrayProducer(Class<?> arrayType) {
1658 Class<?> elemType = arrayType.getComponentType();
1659 assert(elemType.isPrimitive());
1660 return Lazy.MH_copyAsPrimitiveArray.bindTo(Wrapper.forPrimitiveType(elemType));
1661 }
1662 }