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