1 /*
2 * Copyright (c) 2010, 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 jdk.nashorn.internal.runtime.linker;
27
28 import static jdk.nashorn.internal.codegen.CompilerConstants.staticCallNoLookup;
29 import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
30
31 import java.lang.invoke.CallSite;
32 import java.lang.invoke.ConstantCallSite;
33 import java.lang.invoke.MethodHandle;
34 import java.lang.invoke.MethodHandles;
35 import java.lang.invoke.MethodHandles.Lookup;
36 import java.lang.invoke.MethodType;
37 import jdk.internal.dynalink.CallSiteDescriptor;
38 import jdk.internal.dynalink.DynamicLinker;
39 import jdk.internal.dynalink.DynamicLinkerFactory;
40 import jdk.internal.dynalink.GuardedInvocationFilter;
41 import jdk.internal.dynalink.beans.BeansLinker;
42 import jdk.internal.dynalink.beans.StaticClass;
43 import jdk.internal.dynalink.linker.GuardedInvocation;
44 import jdk.internal.dynalink.linker.LinkRequest;
45 import jdk.internal.dynalink.linker.LinkerServices;
46 import jdk.internal.dynalink.linker.MethodTypeConversionStrategy;
47 import jdk.internal.dynalink.support.TypeUtilities;
48 import jdk.nashorn.api.scripting.JSObject;
49 import jdk.nashorn.internal.codegen.CompilerConstants.Call;
50 import jdk.nashorn.internal.codegen.ObjectClassGenerator;
51 import jdk.nashorn.internal.lookup.MethodHandleFactory;
52 import jdk.nashorn.internal.lookup.MethodHandleFunctionality;
53 import jdk.nashorn.internal.runtime.ECMAException;
54 import jdk.nashorn.internal.runtime.JSType;
55 import jdk.nashorn.internal.runtime.OptimisticReturnFilters;
56 import jdk.nashorn.internal.runtime.ScriptFunction;
57 import jdk.nashorn.internal.runtime.ScriptRuntime;
58 import jdk.nashorn.internal.runtime.options.Options;
59
60 /**
61 * This class houses bootstrap method for invokedynamic instructions generated by compiler.
62 */
63 public final class Bootstrap {
64 /** Reference to the seed boostrap function */
65 public static final Call BOOTSTRAP = staticCallNoLookup(Bootstrap.class, "bootstrap", CallSite.class, Lookup.class, String.class, MethodType.class, int.class);
66
67 private static final MethodHandleFunctionality MH = MethodHandleFactory.getFunctionality();
68
69 private static final MethodHandle VOID_TO_OBJECT = MH.constant(Object.class, ScriptRuntime.UNDEFINED);
70
71 /**
72 * The default dynalink relink threshold for megamorphism is 8. In the case
73 * of object fields only, it is fine. However, with dual fields, in order to get
74 * performance on benchmarks with a lot of object instantiation and then field
75 * reassignment, it can take slightly more relinks to become stable with type
76 * changes swapping out an entire property map and making a map guard fail.
77 * Since we need to set this value statically it must work with possibly changing
78 * optimistic types and dual fields settings. A higher value does not seem to have
79 * any other negative performance implication when running with object-only fields,
80 * so we choose a higher value here.
81 *
82 * See for example octane.gbemu, run with --log=fields:warning to study
83 * megamorphic behavior
84 */
85 private static final int NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD = 16;
86
87 // do not create me!!
88 private Bootstrap() {
89 }
90
91 private static final DynamicLinker dynamicLinker;
92 static {
93 final DynamicLinkerFactory factory = new DynamicLinkerFactory();
94 final NashornBeansLinker nashornBeansLinker = new NashornBeansLinker();
95 factory.setPrioritizedLinkers(
96 new NashornLinker(),
97 new NashornPrimitiveLinker(),
98 new NashornStaticClassLinker(),
99 new BoundCallableLinker(),
100 new JavaSuperAdapterLinker(),
101 new JSObjectLinker(nashornBeansLinker),
102 new BrowserJSObjectLinker(nashornBeansLinker),
103 new ReflectionCheckLinker());
104 factory.setFallbackLinkers(nashornBeansLinker, new NashornBottomLinker());
105 factory.setSyncOnRelink(true);
106 factory.setPrelinkFilter(new GuardedInvocationFilter() {
107 @Override
108 public GuardedInvocation filter(final GuardedInvocation inv, final LinkRequest request, final LinkerServices linkerServices) {
109 final CallSiteDescriptor desc = request.getCallSiteDescriptor();
110 return OptimisticReturnFilters.filterOptimisticReturnValue(inv, desc).asType(linkerServices, desc.getMethodType());
111 }
112 });
113 factory.setAutoConversionStrategy(new MethodTypeConversionStrategy() {
114 @Override
115 public MethodHandle asType(final MethodHandle target, final MethodType newType) {
116 return unboxReturnType(target, newType);
117 }
118 });
119 factory.setInternalObjectsFilter(NashornBeansLinker.createHiddenObjectFilter());
120 final int relinkThreshold = Options.getIntProperty("nashorn.unstable.relink.threshold", NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD);
121 if (relinkThreshold > -1) {
122 factory.setUnstableRelinkThreshold(relinkThreshold);
123 }
124
125 // Linkers for any additional language runtimes deployed alongside Nashorn will be picked up by the factory.
126 factory.setClassLoader(Bootstrap.class.getClassLoader());
127
128 dynamicLinker = factory.createLinker();
129 }
130
131 /**
132 * Returns if the given object is a "callable"
133 * @param obj object to be checked for callability
134 * @return true if the obj is callable
135 */
136 public static boolean isCallable(final Object obj) {
137 if (obj == ScriptRuntime.UNDEFINED || obj == null) {
138 return false;
139 }
140
141 return obj instanceof ScriptFunction ||
142 isJSObjectFunction(obj) ||
143 BeansLinker.isDynamicMethod(obj) ||
144 obj instanceof BoundCallable ||
145 isFunctionalInterfaceObject(obj) ||
146 obj instanceof StaticClass;
147 }
148
149 /**
150 * Returns true if the given object is a strict callable
151 * @param callable the callable object to be checked for strictness
152 * @return true if the obj is a strict callable, false if it is a non-strict callable.
153 * @throws ECMAException with {@code TypeError} if the object is not a callable.
154 */
155 public static boolean isStrictCallable(final Object callable) {
156 if (callable instanceof ScriptFunction) {
157 return ((ScriptFunction)callable).isStrict();
158 } else if (isJSObjectFunction(callable)) {
159 return ((JSObject)callable).isStrictFunction();
160 } else if (callable instanceof BoundCallable) {
161 return isStrictCallable(((BoundCallable)callable).getCallable());
162 } else if (BeansLinker.isDynamicMethod(callable) || callable instanceof StaticClass) {
163 return false;
164 }
165 throw notFunction(callable);
166 }
167
168 private static ECMAException notFunction(final Object obj) {
169 return typeError("not.a.function", ScriptRuntime.safeToString(obj));
170 }
171
172 private static boolean isJSObjectFunction(final Object obj) {
173 return obj instanceof JSObject && ((JSObject)obj).isFunction();
174 }
175
176 /**
177 * Returns if the given object is a dynalink Dynamic method
178 * @param obj object to be checked
179 * @return true if the obj is a dynamic method
180 */
181 public static boolean isDynamicMethod(final Object obj) {
182 return BeansLinker.isDynamicMethod(obj instanceof BoundCallable ? ((BoundCallable)obj).getCallable() : obj);
183 }
184
185 /**
186 * Returns if the given object is an instance of an interface annotated with
187 * java.lang.FunctionalInterface
188 * @param obj object to be checked
189 * @return true if the obj is an instance of @FunctionalInterface interface
190 */
191 public static boolean isFunctionalInterfaceObject(final Object obj) {
192 return !JSType.isPrimitive(obj) && (NashornBeansLinker.getFunctionalInterfaceMethodName(obj.getClass()) != null);
193 }
194
195 /**
196 * Create a call site and link it for Nashorn. This version of the method conforms to the invokedynamic bootstrap
197 * method expected signature and is referenced from Nashorn generated bytecode as the bootstrap method for all
198 * invokedynamic instructions.
199 * @param lookup MethodHandle lookup. Ignored as Nashorn only uses public lookup.
200 * @param opDesc Dynalink dynamic operation descriptor.
201 * @param type Method type.
202 * @param flags flags for call type, trace/profile etc.
203 * @return CallSite with MethodHandle to appropriate method or null if not found.
204 */
205 public static CallSite bootstrap(final Lookup lookup, final String opDesc, final MethodType type, final int flags) {
206 return dynamicLinker.link(LinkerCallSite.newLinkerCallSite(lookup, opDesc, type, flags));
207 }
208
209 /**
210 * Boostrapper for math calls that may overflow
211 * @param lookup lookup
212 * @param name name of operation
213 * @param type method type
214 * @param programPoint program point to bind to callsite
215 *
216 * @return callsite for a math intrinsic node
217 */
218 public static CallSite mathBootstrap(final MethodHandles.Lookup lookup, final String name, final MethodType type, final int programPoint) {
219 final MethodHandle mh;
220 switch (name) {
221 case "iadd":
222 mh = JSType.ADD_EXACT.methodHandle();
223 break;
224 case "isub":
225 mh = JSType.SUB_EXACT.methodHandle();
226 break;
227 case "imul":
228 mh = JSType.MUL_EXACT.methodHandle();
229 break;
230 case "idiv":
231 mh = JSType.DIV_EXACT.methodHandle();
232 break;
233 case "irem":
234 mh = JSType.REM_EXACT.methodHandle();
235 break;
236 case "ineg":
237 mh = JSType.NEGATE_EXACT.methodHandle();
238 break;
239 case "ladd":
240 mh = JSType.ADD_EXACT_LONG.methodHandle();
241 break;
242 case "lsub":
243 mh = JSType.SUB_EXACT_LONG.methodHandle();
244 break;
245 case "lmul":
246 mh = JSType.MUL_EXACT_LONG.methodHandle();
247 break;
248 case "ldiv":
249 mh = JSType.DIV_EXACT_LONG.methodHandle();
250 break;
251 case "lrem":
252 mh = JSType.REM_EXACT_LONG.methodHandle();
253 break;
254 case "lneg":
255 mh = JSType.NEGATE_EXACT_LONG.methodHandle();
256 break;
257 default:
258 throw new AssertionError("unsupported math intrinsic");
259 }
260 return new ConstantCallSite(MH.insertArguments(mh, mh.type().parameterCount() - 1, programPoint));
261 }
262
263 /**
264 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. You can use this method to
265 * create a method handle that when invoked acts completely as if it were a Nashorn-linked call site. An overview of
266 * available dynamic operations can be found in the
267 * <a href="https://github.com/szegedi/dynalink/wiki/User-Guide-0.6">Dynalink User Guide</a>, but we'll show few
268 * examples here:
269 * <ul>
270 * <li>Get a named property with fixed name:
271 * <pre>
272 * MethodHandle getColor = Boostrap.createDynamicInvoker("dyn:getProp:color", Object.class, Object.class);
273 * Object obj = ...; // somehow obtain the object
274 * Object color = getColor.invokeExact(obj);
275 * </pre>
276 * </li>
277 * <li>Get a named property with variable name:
278 * <pre>
279 * MethodHandle getProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, String.class);
280 * Object obj = ...; // somehow obtain the object
281 * Object color = getProperty.invokeExact(obj, "color");
282 * Object shape = getProperty.invokeExact(obj, "shape");
283 * MethodHandle getNumProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, int.class);
284 * Object elem42 = getNumProperty.invokeExact(obj, 42);
285 * </pre>
286 * </li>
287 * <li>Set a named property with fixed name:
288 * <pre>
289 * MethodHandle setColor = Boostrap.createDynamicInvoker("dyn:setProp:color", void.class, Object.class, Object.class);
290 * Object obj = ...; // somehow obtain the object
291 * setColor.invokeExact(obj, Color.BLUE);
292 * </pre>
293 * </li>
294 * <li>Set a property with variable name:
295 * <pre>
296 * MethodHandle setProperty = Boostrap.createDynamicInvoker("dyn:setElem", void.class, Object.class, String.class, Object.class);
297 * Object obj = ...; // somehow obtain the object
298 * setProperty.invokeExact(obj, "color", Color.BLUE);
299 * setProperty.invokeExact(obj, "shape", Shape.CIRCLE);
300 * </pre>
301 * </li>
302 * <li>Call a function on an object; two-step variant. This is the actual variant used by Nashorn-generated code:
303 * <pre>
304 * MethodHandle findFooFunction = Boostrap.createDynamicInvoker("dyn:getMethod:foo", Object.class, Object.class);
305 * Object obj = ...; // somehow obtain the object
306 * Object foo_fn = findFooFunction.invokeExact(obj);
307 * MethodHandle callFunctionWithTwoArgs = Boostrap.createDynamicInvoker("dyn:call", Object.class, Object.class, Object.class, Object.class, Object.class);
308 * // Note: "call" operation takes a function, then a "this" value, then the arguments:
309 * Object foo_retval = callFunctionWithTwoArgs.invokeExact(foo_fn, obj, arg1, arg2);
310 * </pre>
311 * </li>
312 * <li>Call a function on an object; single-step variant. Although Nashorn doesn't use this variant and never
313 * emits any INVOKEDYNAMIC instructions with {@code dyn:getMethod}, it still supports this standard Dynalink
314 * operation:
315 * <pre>
316 * MethodHandle callFunctionFooWithTwoArgs = Boostrap.createDynamicInvoker("dyn:callMethod:foo", Object.class, Object.class, Object.class, Object.class);
317 * Object obj = ...; // somehow obtain the object
318 * Object foo_retval = callFunctionFooWithTwoArgs.invokeExact(obj, arg1, arg2);
319 * </pre>
320 * </li>
321 * </ul>
322 * Few additional remarks:
323 * <ul>
324 * <li>Just as Nashorn works with any Java object, the invokers returned from this method can also be applied to
325 * arbitrary Java objects in addition to Nashorn JavaScript objects.</li>
326 * <li>For invoking a named function on an object, you can also use the {@link InvokeByName} convenience class.</li>
327 * <li>For Nashorn objects {@code getElem}, {@code getProp}, and {@code getMethod} are handled almost identically,
328 * since JavaScript doesn't distinguish between different kinds of properties on an object. Either can be used with
329 * fixed property name or a variable property name. The only significant difference is handling of missing
330 * properties: {@code getMethod} for a missing member will link to a potential invocation of
331 * {@code __noSuchMethod__} on the object, {@code getProp} for a missing member will link to a potential invocation
332 * of {@code __noSuchProperty__}, while {@code getElem} for a missing member will link to an empty getter.</li>
333 * <li>In similar vein, {@code setElem} and {@code setProp} are handled identically on Nashorn objects.</li>
334 * <li>There's no rule that the variable property identifier has to be a {@code String} for {@code getProp/setProp}
335 * and {@code int} for {@code getElem/setElem}. You can declare their type to be {@code int}, {@code double},
336 * {@code Object}, and so on regardless of the kind of the operation.</li>
337 * <li>You can be as specific in parameter types as you want. E.g. if you know that the receiver of the operation
338 * will always be {@code ScriptObject}, you can pass {@code ScriptObject.class} as its parameter type. If you happen
339 * to link to a method that expects different types, (you can use these invokers on POJOs too, after all, and end up
340 * linking with their methods that have strongly-typed signatures), all necessary conversions allowed by either Java
341 * or JavaScript will be applied: if invoked methods specify either primitive or wrapped Java numeric types, or
342 * {@code String} or {@code boolean/Boolean}, then the parameters might be subjected to standard ECMAScript
343 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the
344 * expected parameter type is a SAM type, and you pass a JavaScript function, a proxy object implementing the SAM
345 * type and delegating to the function will be passed. Linkage can often be optimized when linkers have more
346 * specific type information than "everything can be an object".</li>
347 * <li>You can also be as specific in return types as you want. For return types any necessary type conversion
348 * available in either Java or JavaScript will be automatically applied, similar to the process described for
349 * parameters, only in reverse direction: if you specify any either primitive or wrapped Java numeric type, or
350 * {@code String} or {@code boolean/Boolean}, then the return values will be subjected to standard ECMAScript
351 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the return
352 * type is a SAM type, and the return value is a JavaScript function, a proxy object implementing the SAM type and
353 * delegating to the function will be returned.</li>
354 * </ul>
355 * @param opDesc Dynalink dynamic operation descriptor.
356 * @param rtype the return type for the operation
357 * @param ptypes the parameter types for the operation
358 * @return MethodHandle for invoking the operation.
359 */
360 public static MethodHandle createDynamicInvoker(final String opDesc, final Class<?> rtype, final Class<?>... ptypes) {
361 return createDynamicInvoker(opDesc, MethodType.methodType(rtype, ptypes));
362 }
363
364 /**
365 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to
366 * {@link #createDynamicInvoker(String, Class, Class...)} but with an additional parameter to
367 * set the call site flags of the dynamic invoker.
368 * @param opDesc Dynalink dynamic operation descriptor.
369 * @param flags the call site flags for the operation
370 * @param rtype the return type for the operation
371 * @param ptypes the parameter types for the operation
372 * @return MethodHandle for invoking the operation.
373 */
374 public static MethodHandle createDynamicInvoker(final String opDesc, final int flags, final Class<?> rtype, final Class<?>... ptypes) {
375 return bootstrap(MethodHandles.publicLookup(), opDesc, MethodType.methodType(rtype, ptypes), flags).dynamicInvoker();
376 }
377
378 /**
379 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to
380 * {@link #createDynamicInvoker(String, Class, Class...)} but with return and parameter types composed into a
381 * method type in the signature. See the discussion of that method for details.
382 * @param opDesc Dynalink dynamic operation descriptor.
383 * @param type the method type for the operation
384 * @return MethodHandle for invoking the operation.
385 */
386 public static MethodHandle createDynamicInvoker(final String opDesc, final MethodType type) {
387 return bootstrap(MethodHandles.publicLookup(), opDesc, type, 0).dynamicInvoker();
388 }
389
390 /**
391 * Binds any object Nashorn can use as a [[Callable]] to a receiver and optionally arguments.
392 * @param callable the callable to bind
393 * @param boundThis the bound "this" value.
394 * @param boundArgs the bound arguments. Can be either null or empty array to signify no arguments are bound.
395 * @return a bound callable.
396 * @throws ECMAException with {@code TypeError} if the object is not a callable.
397 */
398 public static Object bindCallable(final Object callable, final Object boundThis, final Object[] boundArgs) {
399 if (callable instanceof ScriptFunction) {
400 return ((ScriptFunction)callable).createBound(boundThis, boundArgs);
401 } else if (callable instanceof BoundCallable) {
402 return ((BoundCallable)callable).bind(boundArgs);
403 } else if (isCallable(callable)) {
404 return new BoundCallable(callable, boundThis, boundArgs);
405 }
406 throw notFunction(callable);
407 }
408
409 /**
410 * Creates a super-adapter for an adapter, that is, an adapter to the adapter that allows invocation of superclass
411 * methods on it.
412 * @param adapter the original adapter
413 * @return a new adapter that can be used to invoke super methods on the original adapter.
414 */
415 public static Object createSuperAdapter(final Object adapter) {
416 return new JavaSuperAdapter(adapter);
417 }
418
419 /**
420 * If the given class is a reflection-specific class (anything in {@code java.lang.reflect} and
421 * {@code java.lang.invoke} package, as well a {@link Class} and any subclass of {@link ClassLoader}) and there is
422 * a security manager in the system, then it checks the {@code nashorn.JavaReflection} {@code RuntimePermission}.
423 * @param clazz the class being tested
424 * @param isStatic is access checked for static members (or instance members)
425 */
426 public static void checkReflectionAccess(final Class<?> clazz, final boolean isStatic) {
427 ReflectionCheckLinker.checkReflectionAccess(clazz, isStatic);
428 }
429
430 /**
431 * Returns the Nashorn's internally used dynamic linker's services object. Note that in code that is processing a
432 * linking request, you will normally use the {@code LinkerServices} object passed by whatever top-level linker
433 * invoked the linking (if the call site is in Nashorn-generated code, you'll get this object anyway). You should
434 * only resort to retrieving a linker services object using this method when you need some linker services (e.g.
435 * type converter method handles) outside of a code path that is linking a call site.
436 * @return Nashorn's internal dynamic linker's services object.
437 */
438 public static LinkerServices getLinkerServices() {
439 return dynamicLinker.getLinkerServices();
440 }
441
442 /**
443 * Takes a guarded invocation, and ensures its method and guard conform to the type of the call descriptor, using
444 * all type conversions allowed by the linker's services. This method is used by Nashorn's linkers as a last step
445 * before returning guarded invocations. Most of the code used to produce the guarded invocations does not make an
446 * effort to coordinate types of the methods, and so a final type adjustment before a guarded invocation is returned
447 * to the aggregating linker is the responsibility of the linkers themselves.
448 * @param inv the guarded invocation that needs to be type-converted. Can be null.
449 * @param linkerServices the linker services object providing the type conversions.
450 * @param desc the call site descriptor to whose method type the invocation needs to conform.
451 * @return the type-converted guarded invocation. If input is null, null is returned. If the input invocation
452 * already conforms to the requested type, it is returned unchanged.
453 */
454 static GuardedInvocation asTypeSafeReturn(final GuardedInvocation inv, final LinkerServices linkerServices, final CallSiteDescriptor desc) {
455 return inv == null ? null : inv.asTypeSafeReturn(linkerServices, desc.getMethodType());
456 }
457
458 /**
459 * Adapts the return type of the method handle with {@code explicitCastArguments} when it is an unboxing
460 * conversion. This will ensure that nulls are unwrapped to false or 0.
461 * @param target the target method handle
462 * @param newType the desired new type. Note that this method does not adapt the method handle completely to the
463 * new type, it only adapts the return type; this is allowed as per
464 * {@link DynamicLinkerFactory#setAutoConversionStrategy(MethodTypeConversionStrategy)}, which is what this method
465 * is used for.
466 * @return the method handle with adapted return type, if it required an unboxing conversion.
467 */
468 private static MethodHandle unboxReturnType(final MethodHandle target, final MethodType newType) {
469 final MethodType targetType = target.type();
470 final Class<?> oldReturnType = targetType.returnType();
471 final Class<?> newReturnType = newType.returnType();
472 if (TypeUtilities.isWrapperType(oldReturnType)) {
473 if (newReturnType.isPrimitive()) {
474 // The contract of setAutoConversionStrategy is such that the difference between newType and targetType
475 // can only be JLS method invocation conversions.
476 assert TypeUtilities.isMethodInvocationConvertible(oldReturnType, newReturnType);
477 return MethodHandles.explicitCastArguments(target, targetType.changeReturnType(newReturnType));
478 }
479 } else if (oldReturnType == void.class && newReturnType == Object.class) {
480 return MethodHandles.filterReturnValue(target, VOID_TO_OBJECT);
481 }
482 return target;
483 }
484 }