1 /*
2 * Copyright (c) 2017, 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 package java.lang.invoke;
26
27 import sun.invoke.util.Wrapper;
28
29 import java.lang.invoke.AbstractConstantGroup.BSCIWithCache;
30 import java.util.Arrays;
31
32 import static java.lang.invoke.BootstrapCallInfo.makeBootstrapCallInfo;
33 import static java.lang.invoke.ConstantGroup.makeConstantGroup;
34 import static java.lang.invoke.MethodHandleNatives.*;
35 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE;
36 import static java.lang.invoke.MethodHandles.Lookup;
37 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
38
39 final class BootstrapMethodInvoker {
40
41 /**
42 * Factored code for invoking a bootstrap method for invokedynamic
43 * or a dynamic constant.
44 * @param resultType the expected return type (either CallSite or a constant type)
45 * @param bootstrapMethod the BSM to call
46 * @param name the method name or constant name
47 * @param type the method type or constant type
48 * @param info information passed up from the JVM, to derive static arguments
49 * @param callerClass the class containing the resolved method call or constant load
50 * @param <T> the expected return type
51 * @return the expected value, either a CallSite or a constant value
52 */
53 static <T> T invoke(Class<T> resultType,
54 MethodHandle bootstrapMethod,
55 // Callee information:
56 String name, Object type,
57 // Extra arguments for BSM, if any:
58 Object info,
59 // Caller information:
60 Class<?> callerClass) {
61 MethodHandles.Lookup caller = IMPL_LOOKUP.in(callerClass);
62 Object result;
63 boolean pullMode = isPullModeBSM(bootstrapMethod); // default value is false
64 boolean vmIsPushing = !staticArgumentsPulled(info); // default value is true
65 MethodHandle pullModeBSM;
66 // match the VM with the BSM
67 if (vmIsPushing) {
68 // VM is pushing arguments at us
69 pullModeBSM = null;
70 if (pullMode) {
71 bootstrapMethod = pushMePullYou(bootstrapMethod, true);
72 }
73 } else {
74 // VM wants us to pull args from it
75 pullModeBSM = pullMode ? bootstrapMethod :
76 pushMePullYou(bootstrapMethod, false);
77 bootstrapMethod = null;
78 }
79 try {
80 // As an optimization we special case various known BSMs,
81 // such as LambdaMetafactory::metafactory and
82 // StringConcatFactory::makeConcatWithConstants.
83 //
84 // By providing static type information or even invoking
85 // exactly, we avoid emitting code to perform runtime
86 // checking.
87 info = maybeReBox(info);
88 if (info == null) {
89 // VM is allowed to pass up a null meaning no BSM args
90 result = invoke(bootstrapMethod, caller, name, type);
91 }
92 else if (!info.getClass().isArray()) {
93 // VM is allowed to pass up a single BSM arg directly
94
95 // Call to StringConcatFactory::makeConcatWithConstants
96 // with empty constant arguments?
97 if (isStringConcatFactoryBSM(bootstrapMethod.type())) {
98 result = (CallSite)bootstrapMethod
99 .invokeExact(caller, name, (MethodType)type,
100 (String)info, new Object[0]);
101 } else {
102 result = invoke(bootstrapMethod, caller, name, type, info);
103 }
104 }
105 else if (info.getClass() == int[].class) {
106 // VM is allowed to pass up a pair {argc, index}
107 // referring to 'argc' BSM args at some place 'index'
108 // in the guts of the VM (associated with callerClass).
109 // The format of this index pair is private to the
110 // handshake between the VM and this class only.
111 // This supports "pulling" of arguments.
112 // The VM is allowed to do this for any reason.
113 // The code in this method makes up for any mismatches.
114 BootstrapCallInfo<Object> bsci
115 = new VM_BSCI<>(bootstrapMethod, name, type, caller, (int[])info);
116 // Pull-mode API is (Lookup, BootstrapCallInfo) -> Object
117 result = pullModeBSM.invoke(caller, bsci);
118 }
119 else {
120 // VM is allowed to pass up a full array of resolved BSM args
121 Object[] argv = (Object[]) info;
122 maybeReBoxElements(argv);
123
124 MethodType bsmType = bootstrapMethod.type();
125 if (isLambdaMetafactoryIndyBSM(bsmType) && argv.length == 3) {
126 result = (CallSite)bootstrapMethod
127 .invokeExact(caller, name, (MethodType)type, (MethodType)argv[0],
128 (MethodHandle)argv[1], (MethodType)argv[2]);
129 } else if (isLambdaMetafactoryCondyBSM(bsmType) && argv.length == 3) {
130 result = bootstrapMethod
131 .invokeExact(caller, name, (Class<?>)type, (MethodType)argv[0],
132 (MethodHandle)argv[1], (MethodType)argv[2]);
133 } else if (isStringConcatFactoryBSM(bsmType) && argv.length >= 1) {
134 String recipe = (String)argv[0];
135 Object[] shiftedArgs = Arrays.copyOfRange(argv, 1, argv.length);
136 result = (CallSite)bootstrapMethod.invokeExact(caller, name, (MethodType)type, recipe, shiftedArgs);
137 } else if (isLambdaMetafactoryAltMetafactoryBSM(bsmType)) {
138 result = (CallSite)bootstrapMethod.invokeExact(caller, name, (MethodType)type, argv);
139 } else {
140 switch (argv.length) {
141 case 0:
142 result = invoke(bootstrapMethod, caller, name, type);
143 break;
144 case 1:
145 result = invoke(bootstrapMethod, caller, name, type,
146 argv[0]);
147 break;
148 case 2:
149 result = invoke(bootstrapMethod, caller, name, type,
150 argv[0], argv[1]);
151 break;
152 case 3:
153 result = invoke(bootstrapMethod, caller, name, type,
154 argv[0], argv[1], argv[2]);
155 break;
156 case 4:
157 result = invoke(bootstrapMethod, caller, name, type,
158 argv[0], argv[1], argv[2], argv[3]);
159 break;
160 case 5:
161 result = invoke(bootstrapMethod, caller, name, type,
162 argv[0], argv[1], argv[2], argv[3], argv[4]);
163 break;
164 case 6:
165 result = invoke(bootstrapMethod, caller, name, type,
166 argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
167 break;
168 default:
169 result = invokeWithManyArguments(bootstrapMethod, caller, name, type, argv);
170 }
171 }
172 }
173 if (resultType.isPrimitive()) {
174 // Non-reference conversions are more than just plain casts.
175 // By pushing the value through a funnel of the form (T x)->x,
176 // the boxed result can be widened as needed. See MH::asType.
177 MethodHandle funnel = MethodHandles.identity(resultType);
178 result = funnel.invoke(result);
179 // Now it is the wrapper type for resultType.
180 resultType = Wrapper.asWrapperType(resultType);
181 }
182 return resultType.cast(result);
183 }
184 catch (Error e) {
185 // Pass through an Error, including BootstrapMethodError, any other
186 // form of linkage error, such as IllegalAccessError if the bootstrap
187 // method is inaccessible, or say ThreadDeath/OutOfMemoryError
188 // See the "Linking Exceptions" section for the invokedynamic
189 // instruction in JVMS 6.5.
190 throw e;
191 }
192 catch (Throwable ex) {
193 // Wrap anything else in BootstrapMethodError
194 throw new BootstrapMethodError("bootstrap method initialization exception", ex);
195 }
196 }
197
198 // If we don't provide static type information for type, we'll generate runtime
199 // checks. Let's try not to...
200
201 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller,
202 String name, Object type) throws Throwable {
203 if (type instanceof Class) {
204 return bootstrapMethod.invoke(caller, name, (Class<?>)type);
205 } else {
206 return bootstrapMethod.invoke(caller, name, (MethodType)type);
207 }
208 }
209
210 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller,
211 String name, Object type, Object arg0) throws Throwable {
212 if (type instanceof Class) {
213 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0);
214 } else {
215 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0);
216 }
217 }
218
219 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name,
220 Object type, Object arg0, Object arg1) throws Throwable {
221 if (type instanceof Class) {
222 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0, arg1);
223 } else {
224 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1);
225 }
226 }
227
228 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name,
229 Object type, Object arg0, Object arg1,
230 Object arg2) throws Throwable {
231 if (type instanceof Class) {
232 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0, arg1, arg2);
233 } else {
234 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2);
235 }
236 }
237
238 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller, String name,
239 Object type, Object arg0, Object arg1,
240 Object arg2, Object arg3) throws Throwable {
241 if (type instanceof Class) {
242 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0, arg1, arg2, arg3);
243 } else {
244 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3);
245 }
246 }
247
248 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller,
249 String name, Object type, Object arg0, Object arg1,
250 Object arg2, Object arg3, Object arg4) throws Throwable {
251 if (type instanceof Class) {
252 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0, arg1, arg2, arg3, arg4);
253 } else {
254 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3, arg4);
255 }
256 }
257
258 private static Object invoke(MethodHandle bootstrapMethod, Lookup caller,
259 String name, Object type, Object arg0, Object arg1,
260 Object arg2, Object arg3, Object arg4, Object arg5) throws Throwable {
261 if (type instanceof Class) {
262 return bootstrapMethod.invoke(caller, name, (Class<?>)type, arg0, arg1, arg2, arg3, arg4, arg5);
263 } else {
264 return bootstrapMethod.invoke(caller, name, (MethodType)type, arg0, arg1, arg2, arg3, arg4, arg5);
265 }
266 }
267
268 private static Object invokeWithManyArguments(MethodHandle bootstrapMethod, Lookup caller,
269 String name, Object type, Object[] argv) throws Throwable {
270 final int NON_SPREAD_ARG_COUNT = 3; // (caller, name, type)
271 final int MAX_SAFE_SIZE = MethodType.MAX_MH_ARITY / 2 - NON_SPREAD_ARG_COUNT;
272 if (argv.length >= MAX_SAFE_SIZE) {
273 // to be on the safe side, use invokeWithArguments which handles jumbo lists
274 Object[] newargv = new Object[NON_SPREAD_ARG_COUNT + argv.length];
275 newargv[0] = caller;
276 newargv[1] = name;
277 newargv[2] = type;
278 System.arraycopy(argv, 0, newargv, NON_SPREAD_ARG_COUNT, argv.length);
279 return bootstrapMethod.invokeWithArguments(newargv);
280 } else {
281 MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argv.length);
282 MethodHandle typedBSM = bootstrapMethod.asType(invocationType);
283 MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT);
284 return spreader.invokeExact(typedBSM, (Object) caller, (Object) name, type, argv);
285 }
286 }
287
288 private static final MethodType LMF_INDY_MT = MethodType.methodType(CallSite.class,
289 Lookup.class, String.class, MethodType.class, MethodType.class, MethodHandle.class, MethodType.class);
290
291 private static final MethodType LMF_ALT_MT = MethodType.methodType(CallSite.class,
292 Lookup.class, String.class, MethodType.class, Object[].class);
293
294 private static final MethodType LMF_CONDY_MT = MethodType.methodType(Object.class,
295 Lookup.class, String.class, Class.class, MethodType.class, MethodHandle.class, MethodType.class);
296
297 private static final MethodType SCF_MT = MethodType.methodType(CallSite.class,
298 Lookup.class, String.class, MethodType.class, String.class, Object[].class);
299
300 /**
301 * @return true iff the BSM method type exactly matches
302 * {@see java.lang.invoke.StringConcatFactory#makeConcatWithConstants(MethodHandles.Lookup,
303 * String,MethodType,String,Object...))}
304 */
305 private static boolean isStringConcatFactoryBSM(MethodType bsmType) {
306 return bsmType == SCF_MT;
307 }
308
309 /**
310 * @return true iff the BSM method type exactly matches
311 * {@see java.lang.invoke.LambdaMetafactory#metafactory(
312 * MethodHandles.Lookup,String,Class,MethodType,MethodHandle,MethodType)}
313 */
314 private static boolean isLambdaMetafactoryCondyBSM(MethodType bsmType) {
315 return bsmType == LMF_CONDY_MT;
316 }
317
318 /**
319 * @return true iff the BSM method type exactly matches
320 * {@see java.lang.invoke.LambdaMetafactory#metafactory(
321 * MethodHandles.Lookup,String,MethodType,MethodType,MethodHandle,MethodType)}
322 */
323 private static boolean isLambdaMetafactoryIndyBSM(MethodType bsmType) {
324 return bsmType == LMF_INDY_MT;
325 }
326
327 /**
328 * @return true iff the BSM method type exactly matches
329 * {@see java.lang.invoke.LambdaMetafactory#altMetafactory(
330 * MethodHandles.Lookup,String,MethodType,Object[])}
331 */
332 private static boolean isLambdaMetafactoryAltMetafactoryBSM(MethodType bsmType) {
333 return bsmType == LMF_ALT_MT;
334 }
335
336 /** The JVM produces java.lang.Integer values to box
337 * CONSTANT_Integer boxes but does not intern them.
338 * Let's intern them. This is slightly wrong for
339 * a {@code CONSTANT_Dynamic} which produces an
340 * un-interned integer (e.g., {@code new Integer(0)}).
341 */
342 private static Object maybeReBox(Object x) {
343 if (x instanceof Integer) {
344 int xi = (int) x;
345 if (xi == (byte) xi)
346 x = xi; // must rebox; see JLS 5.1.7
347 }
348 return x;
349 }
350
351 private static void maybeReBoxElements(Object[] xa) {
352 for (int i = 0; i < xa.length; i++) {
353 xa[i] = maybeReBox(xa[i]);
354 }
355 }
356
357 /** Canonical VM-aware implementation of BootstrapCallInfo.
358 * Knows how to dig into the JVM for lazily resolved (pull-mode) constants.
359 */
360 private static final class VM_BSCI<T> extends BSCIWithCache<T> {
361 private final int[] indexInfo;
362 private final Class<?> caller; // for index resolution only
363
364 VM_BSCI(MethodHandle bsm, String name, T type,
365 Lookup lookup, int[] indexInfo) {
366 super(bsm, name, type, indexInfo[0]);
367 if (!lookup.hasPrivateAccess()) //D.I.D.
368 throw new AssertionError("bad Lookup object");
369 this.caller = lookup.lookupClass();
370 this.indexInfo = indexInfo;
371 // scoop up all the easy stuff right away:
372 prefetchIntoCache(0, size());
373 }
374
375 @Override Object fillCache(int i) {
376 Object[] buf = { null };
377 copyConstants(i, i+1, buf, 0);
378 Object res = wrapNull(buf[0]);
379 cache[i] = res;
380 int next = i + 1;
381 if (next < cache.length && cache[next] == null)
382 maybePrefetchIntoCache(next, false); // try to prefetch
383 return res;
384 }
385
386 @Override public int copyConstants(int start, int end,
387 Object[] buf, int pos) {
388 int i = start, bufi = pos;
389 while (i < end) {
390 Object x = cache[i];
391 if (x == null) break;
392 buf[bufi++] = unwrapNull(x);
393 i++;
394 }
395 // give up at first null and grab the rest in one big block
396 if (i >= end) return i;
397 Object[] temp = new Object[end - i];
398 if (TRACE_METHOD_LINKAGE) {
399 System.out.println("resolving more BSM arguments: " +
400 Arrays.asList(caller.getSimpleName(), Arrays.toString(indexInfo), i, end));
401 }
402 copyOutBootstrapArguments(caller, indexInfo,
403 i, end, temp, 0,
404 true, null);
405 for (Object x : temp) {
406 x = maybeReBox(x);
407 buf[bufi++] = x;
408 cache[i++] = wrapNull(x);
409 }
410 if (end < cache.length && cache[end] == null)
411 maybePrefetchIntoCache(end, true); // try to prefetch
412 return i;
413 }
414
415 private static final int MIN_PF = 4;
416 private void maybePrefetchIntoCache(int i, boolean bulk) {
417 int len = cache.length;
418 assert(0 <= i && i <= len);
419 int pfLimit = i;
420 if (bulk) pfLimit += i; // exponential prefetch expansion
421 // try to prefetch at least MIN_PF elements
422 if (pfLimit < i + MIN_PF) pfLimit = i + MIN_PF;
423 if (pfLimit > len || pfLimit < 0) pfLimit = len;
424 // stop prefetching where cache is more full than empty
425 int empty = 0, nonEmpty = 0, lastEmpty = i;
426 for (int j = i; j < pfLimit; j++) {
427 if (cache[j] == null) {
428 empty++;
429 lastEmpty = j;
430 } else {
431 nonEmpty++;
432 if (nonEmpty > empty) {
433 pfLimit = lastEmpty + 1;
434 break;
435 }
436 if (pfLimit < len) pfLimit++;
437 }
438 }
439 if (bulk && empty < MIN_PF && pfLimit < len)
440 return; // not worth the effort
441 prefetchIntoCache(i, pfLimit);
442 }
443
444 private void prefetchIntoCache(int i, int pfLimit) {
445 if (pfLimit <= i) return; // corner case
446 Object[] temp = new Object[pfLimit - i];
447 if (TRACE_METHOD_LINKAGE) {
448 System.out.println("prefetching BSM arguments: " +
449 Arrays.asList(caller.getSimpleName(), Arrays.toString(indexInfo), i, pfLimit));
450 }
451 copyOutBootstrapArguments(caller, indexInfo,
452 i, pfLimit, temp, 0,
453 false, NOT_PRESENT);
454 for (Object x : temp) {
455 if (x != NOT_PRESENT && cache[i] == null) {
456 cache[i] = wrapNull(maybeReBox(x));
457 }
458 i++;
459 }
460 }
461 }
462
463 /*non-public*/ static final
464 class PushAdapter {
465 // skeleton for push-mode BSM which wraps a pull-mode BSM:
466 static Object pushToBootstrapMethod(MethodHandle pullModeBSM,
467 MethodHandles.Lookup lookup, String name, Object type,
468 Object... arguments) throws Throwable {
469 ConstantGroup cons = makeConstantGroup(Arrays.asList(arguments));
470 BootstrapCallInfo<?> bsci = makeBootstrapCallInfo(pullModeBSM, name, type, cons);
471 if (TRACE_METHOD_LINKAGE)
472 System.out.println("pull-mode BSM gets pushed arguments from fake BSCI");
473 return pullModeBSM.invoke(lookup, bsci);
474 }
475
476 static final MethodHandle MH_pushToBootstrapMethod;
477 static {
478 final Class<?> THIS_CLASS = PushAdapter.class;
479 try {
480 MH_pushToBootstrapMethod = IMPL_LOOKUP
481 .findStatic(THIS_CLASS, "pushToBootstrapMethod",
482 MethodType.methodType(Object.class, MethodHandle.class,
483 Lookup.class, String.class, Object.class, Object[].class));
484 } catch (Throwable ex) {
485 throw new InternalError(ex);
486 }
487 }
488 }
489
490 /*non-public*/ static final
491 class PullAdapter {
492 // skeleton for pull-mode BSM which wraps a push-mode BSM:
493 static Object pullFromBootstrapMethod(MethodHandle pushModeBSM,
494 MethodHandles.Lookup lookup,
495 BootstrapCallInfo<?> bsci)
496 throws Throwable {
497 int argc = bsci.size();
498 switch (argc) {
499 case 0:
500 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType());
501 case 1:
502 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
503 bsci.get(0));
504 case 2:
505 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
506 bsci.get(0), bsci.get(1));
507 case 3:
508 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
509 bsci.get(0), bsci.get(1), bsci.get(2));
510 case 4:
511 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
512 bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3));
513 case 5:
514 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
515 bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3), bsci.get(4));
516 case 6:
517 return pushModeBSM.invoke(lookup, bsci.invocationName(), bsci.invocationType(),
518 bsci.get(0), bsci.get(1), bsci.get(2), bsci.get(3), bsci.get(4), bsci.get(5));
519 default:
520 final int NON_SPREAD_ARG_COUNT = 3; // (lookup, name, type)
521 final int MAX_SAFE_SIZE = MethodType.MAX_MH_ARITY / 2 - NON_SPREAD_ARG_COUNT;
522 if (argc >= MAX_SAFE_SIZE) {
523 // to be on the safe side, use invokeWithArguments which handles jumbo lists
524 Object[] newargv = new Object[NON_SPREAD_ARG_COUNT + argc];
525 newargv[0] = lookup;
526 newargv[1] = bsci.invocationName();
527 newargv[2] = bsci.invocationType();
528 bsci.copyConstants(0, argc, newargv, NON_SPREAD_ARG_COUNT);
529 return pushModeBSM.invokeWithArguments(newargv);
530 }
531 MethodType invocationType = MethodType.genericMethodType(NON_SPREAD_ARG_COUNT + argc);
532 MethodHandle typedBSM = pushModeBSM.asType(invocationType);
533 MethodHandle spreader = invocationType.invokers().spreadInvoker(NON_SPREAD_ARG_COUNT);
534 Object[] argv = new Object[argc];
535 bsci.copyConstants(0, argc, argv, 0);
536 return spreader.invokeExact(typedBSM, (Object) lookup, (Object) bsci.invocationName(), bsci.invocationType(), argv);
537 }
538 }
539
540 static final MethodHandle MH_pullFromBootstrapMethod;
541
542 static {
543 final Class<?> THIS_CLASS = PullAdapter.class;
544 try {
545 MH_pullFromBootstrapMethod = IMPL_LOOKUP
546 .findStatic(THIS_CLASS, "pullFromBootstrapMethod",
547 MethodType.methodType(Object.class, MethodHandle.class,
548 Lookup.class, BootstrapCallInfo.class));
549 } catch (Throwable ex) {
550 throw new InternalError(ex);
551 }
552 }
553 }
554
555 /** Given a push-mode BSM (taking one argument) convert it to a
556 * pull-mode BSM (taking N pre-resolved arguments).
557 * This method is used when, in fact, the JVM is passing up
558 * pre-resolved arguments, but the BSM is expecting lazy stuff.
559 * Or, when goToPushMode is true, do the reverse transform.
560 * (The two transforms are exactly inverse.)
561 */
562 static MethodHandle pushMePullYou(MethodHandle bsm, boolean goToPushMode) {
563 if (TRACE_METHOD_LINKAGE) {
564 System.out.println("converting BSM of type " + bsm.type() + " to "
565 + (goToPushMode ? "push mode" : "pull mode"));
566 }
567 assert(isPullModeBSM(bsm) == goToPushMode); // there must be a change
568 if (goToPushMode) {
569 return PushAdapter.MH_pushToBootstrapMethod.bindTo(bsm).withVarargs(true);
570 } else {
571 return PullAdapter.MH_pullFromBootstrapMethod.bindTo(bsm).withVarargs(false);
572 }
573 }
574 }