Bootstrap.java revision 1245:c55ce3738888
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 26package jdk.nashorn.internal.runtime.linker; 27 28import static jdk.nashorn.internal.codegen.CompilerConstants.staticCallNoLookup; 29import static jdk.nashorn.internal.runtime.ECMAErrors.typeError; 30 31import java.lang.invoke.CallSite; 32import java.lang.invoke.ConstantCallSite; 33import java.lang.invoke.MethodHandle; 34import java.lang.invoke.MethodHandles; 35import java.lang.invoke.MethodHandles.Lookup; 36import java.lang.invoke.MethodType; 37import jdk.internal.dynalink.CallSiteDescriptor; 38import jdk.internal.dynalink.DynamicLinker; 39import jdk.internal.dynalink.DynamicLinkerFactory; 40import jdk.internal.dynalink.GuardedInvocationFilter; 41import jdk.internal.dynalink.beans.BeansLinker; 42import jdk.internal.dynalink.beans.StaticClass; 43import jdk.internal.dynalink.linker.GuardedInvocation; 44import jdk.internal.dynalink.linker.LinkRequest; 45import jdk.internal.dynalink.linker.LinkerServices; 46import jdk.internal.dynalink.linker.MethodTypeConversionStrategy; 47import jdk.internal.dynalink.support.TypeUtilities; 48import jdk.nashorn.api.scripting.JSObject; 49import jdk.nashorn.internal.codegen.CompilerConstants.Call; 50import jdk.nashorn.internal.codegen.ObjectClassGenerator; 51import jdk.nashorn.internal.lookup.MethodHandleFactory; 52import jdk.nashorn.internal.lookup.MethodHandleFunctionality; 53import jdk.nashorn.internal.objects.ScriptFunctionImpl; 54import jdk.nashorn.internal.runtime.ECMAException; 55import jdk.nashorn.internal.runtime.JSType; 56import jdk.nashorn.internal.runtime.OptimisticReturnFilters; 57import jdk.nashorn.internal.runtime.ScriptFunction; 58import jdk.nashorn.internal.runtime.ScriptRuntime; 59import jdk.nashorn.internal.runtime.options.Options; 60 61/** 62 * This class houses bootstrap method for invokedynamic instructions generated by compiler. 63 */ 64public final class Bootstrap { 65 /** Reference to the seed boostrap function */ 66 public static final Call BOOTSTRAP = staticCallNoLookup(Bootstrap.class, "bootstrap", CallSite.class, Lookup.class, String.class, MethodType.class, int.class); 67 68 private static final MethodHandleFunctionality MH = MethodHandleFactory.getFunctionality(); 69 70 private static final MethodHandle VOID_TO_OBJECT = MH.constant(Object.class, ScriptRuntime.UNDEFINED); 71 72 /** 73 * The default dynalink relink threshold for megamorphisism is 8. In the case 74 * of object fields only, it is fine. However, with dual fields, in order to get 75 * performance on benchmarks with a lot of object instantiation and then field 76 * reassignment, it can take slightly more relinks to become stable with type 77 * changes swapping out an entire property map and making a map guard fail. 78 * Since we need to set this value statically it must work with possibly changing 79 * optimistic types and dual fields settings. A higher value does not seem to have 80 * any other negative performance implication when running with object-only fields, 81 * so we choose a higher value here. 82 * 83 * See for example octane.gbemu, run with --log=fields:warning to study 84 * megamorphic behavior 85 */ 86 private static final int NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD = 16; 87 88 // do not create me!! 89 private Bootstrap() { 90 } 91 92 private static final DynamicLinker dynamicLinker; 93 static { 94 final DynamicLinkerFactory factory = new DynamicLinkerFactory(); 95 final NashornBeansLinker nashornBeansLinker = new NashornBeansLinker(); 96 factory.setPrioritizedLinkers( 97 new NashornLinker(), 98 new NashornPrimitiveLinker(), 99 new NashornStaticClassLinker(), 100 new BoundCallableLinker(), 101 new JavaSuperAdapterLinker(), 102 new JSObjectLinker(nashornBeansLinker), 103 new BrowserJSObjectLinker(nashornBeansLinker), 104 new ReflectionCheckLinker()); 105 factory.setFallbackLinkers(nashornBeansLinker, new NashornBottomLinker()); 106 factory.setSyncOnRelink(true); 107 factory.setPrelinkFilter(new GuardedInvocationFilter() { 108 @Override 109 public GuardedInvocation filter(final GuardedInvocation inv, final LinkRequest request, final LinkerServices linkerServices) { 110 final CallSiteDescriptor desc = request.getCallSiteDescriptor(); 111 return OptimisticReturnFilters.filterOptimisticReturnValue(inv, desc).asType(linkerServices, desc.getMethodType()); 112 } 113 }); 114 factory.setAutoConversionStrategy(new MethodTypeConversionStrategy() { 115 @Override 116 public MethodHandle asType(final MethodHandle target, final MethodType newType) { 117 return unboxReturnType(target, newType); 118 } 119 }); 120 factory.setInternalObjectsFilter(NashornBeansLinker.createHiddenObjectFilter()); 121 final int relinkThreshold = Options.getIntProperty("nashorn.unstable.relink.threshold", NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD); 122 if (relinkThreshold > -1) { 123 factory.setUnstableRelinkThreshold(relinkThreshold); 124 } 125 126 // Linkers for any additional language runtimes deployed alongside Nashorn will be picked up by the factory. 127 factory.setClassLoader(Bootstrap.class.getClassLoader()); 128 129 dynamicLinker = factory.createLinker(); 130 } 131 132 /** 133 * Returns if the given object is a "callable" 134 * @param obj object to be checked for callability 135 * @return true if the obj is callable 136 */ 137 public static boolean isCallable(final Object obj) { 138 if (obj == ScriptRuntime.UNDEFINED || obj == null) { 139 return false; 140 } 141 142 return obj instanceof ScriptFunction || 143 isJSObjectFunction(obj) || 144 BeansLinker.isDynamicMethod(obj) || 145 obj instanceof BoundCallable || 146 isFunctionalInterfaceObject(obj) || 147 obj instanceof StaticClass; 148 } 149 150 /** 151 * Returns true if the given object is a strict callable 152 * @param callable the callable object to be checked for strictness 153 * @return true if the obj is a strict callable, false if it is a non-strict callable. 154 * @throws ECMAException with {@code TypeError} if the object is not a callable. 155 */ 156 public static boolean isStrictCallable(final Object callable) { 157 if (callable instanceof ScriptFunction) { 158 return ((ScriptFunction)callable).isStrict(); 159 } else if (isJSObjectFunction(callable)) { 160 return ((JSObject)callable).isStrictFunction(); 161 } else if (callable instanceof BoundCallable) { 162 return isStrictCallable(((BoundCallable)callable).getCallable()); 163 } else if (BeansLinker.isDynamicMethod(callable) || callable instanceof StaticClass) { 164 return false; 165 } 166 throw notFunction(callable); 167 } 168 169 private static ECMAException notFunction(final Object obj) { 170 return typeError("not.a.function", ScriptRuntime.safeToString(obj)); 171 } 172 173 private static boolean isJSObjectFunction(final Object obj) { 174 return obj instanceof JSObject && ((JSObject)obj).isFunction(); 175 } 176 177 /** 178 * Returns if the given object is a dynalink Dynamic method 179 * @param obj object to be checked 180 * @return true if the obj is a dynamic method 181 */ 182 public static boolean isDynamicMethod(final Object obj) { 183 return BeansLinker.isDynamicMethod(obj instanceof BoundCallable ? ((BoundCallable)obj).getCallable() : obj); 184 } 185 186 /** 187 * Returns if the given object is an instance of an interface annotated with 188 * java.lang.FunctionalInterface 189 * @param obj object to be checked 190 * @return true if the obj is an instance of @FunctionalInterface interface 191 */ 192 public static boolean isFunctionalInterfaceObject(final Object obj) { 193 return !JSType.isPrimitive(obj) && (NashornBeansLinker.getFunctionalInterfaceMethod(obj.getClass()) != null); 194 } 195 196 /** 197 * Create a call site and link it for Nashorn. This version of the method conforms to the invokedynamic bootstrap 198 * method expected signature and is referenced from Nashorn generated bytecode as the bootstrap method for all 199 * invokedynamic instructions. 200 * @param lookup MethodHandle lookup. Ignored as Nashorn only uses public lookup. 201 * @param opDesc Dynalink dynamic operation descriptor. 202 * @param type Method type. 203 * @param flags flags for call type, trace/profile etc. 204 * @return CallSite with MethodHandle to appropriate method or null if not found. 205 */ 206 public static CallSite bootstrap(final Lookup lookup, final String opDesc, final MethodType type, final int flags) { 207 return dynamicLinker.link(LinkerCallSite.newLinkerCallSite(lookup, opDesc, type, flags)); 208 } 209 210 /** 211 * Boostrapper for math calls that may overflow 212 * @param lookup lookup 213 * @param name name of operation 214 * @param type method type 215 * @param programPoint program point to bind to callsite 216 * 217 * @return callsite for a math instrinic node 218 */ 219 public static CallSite mathBootstrap(final MethodHandles.Lookup lookup, final String name, final MethodType type, final int programPoint) { 220 final MethodHandle mh; 221 switch (name) { 222 case "iadd": 223 mh = JSType.ADD_EXACT.methodHandle(); 224 break; 225 case "isub": 226 mh = JSType.SUB_EXACT.methodHandle(); 227 break; 228 case "imul": 229 mh = JSType.MUL_EXACT.methodHandle(); 230 break; 231 case "idiv": 232 mh = JSType.DIV_EXACT.methodHandle(); 233 break; 234 case "irem": 235 mh = JSType.REM_EXACT.methodHandle(); 236 break; 237 case "ineg": 238 mh = JSType.NEGATE_EXACT.methodHandle(); 239 break; 240 case "ladd": 241 mh = JSType.ADD_EXACT_LONG.methodHandle(); 242 break; 243 case "lsub": 244 mh = JSType.SUB_EXACT_LONG.methodHandle(); 245 break; 246 case "lmul": 247 mh = JSType.MUL_EXACT_LONG.methodHandle(); 248 break; 249 case "ldiv": 250 mh = JSType.DIV_EXACT_LONG.methodHandle(); 251 break; 252 case "lrem": 253 mh = JSType.REM_EXACT_LONG.methodHandle(); 254 break; 255 case "lneg": 256 mh = JSType.NEGATE_EXACT_LONG.methodHandle(); 257 break; 258 default: 259 throw new AssertionError("unsupported math intrinsic"); 260 } 261 return new ConstantCallSite(MH.insertArguments(mh, mh.type().parameterCount() - 1, programPoint)); 262 } 263 264 /** 265 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. You can use this method to 266 * create a method handle that when invoked acts completely as if it were a Nashorn-linked call site. An overview of 267 * available dynamic operations can be found in the 268 * <a href="https://github.com/szegedi/dynalink/wiki/User-Guide-0.6">Dynalink User Guide</a>, but we'll show few 269 * examples here: 270 * <ul> 271 * <li>Get a named property with fixed name: 272 * <pre> 273 * MethodHandle getColor = Boostrap.createDynamicInvoker("dyn:getProp:color", Object.class, Object.class); 274 * Object obj = ...; // somehow obtain the object 275 * Object color = getColor.invokeExact(obj); 276 * </pre> 277 * </li> 278 * <li>Get a named property with variable name: 279 * <pre> 280 * MethodHandle getProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, String.class); 281 * Object obj = ...; // somehow obtain the object 282 * Object color = getProperty.invokeExact(obj, "color"); 283 * Object shape = getProperty.invokeExact(obj, "shape"); 284 * MethodHandle getNumProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, int.class); 285 * Object elem42 = getNumProperty.invokeExact(obj, 42); 286 * </pre> 287 * </li> 288 * <li>Set a named property with fixed name: 289 * <pre> 290 * MethodHandle setColor = Boostrap.createDynamicInvoker("dyn:setProp:color", void.class, Object.class, Object.class); 291 * Object obj = ...; // somehow obtain the object 292 * setColor.invokeExact(obj, Color.BLUE); 293 * </pre> 294 * </li> 295 * <li>Set a property with variable name: 296 * <pre> 297 * MethodHandle setProperty = Boostrap.createDynamicInvoker("dyn:setElem", void.class, Object.class, String.class, Object.class); 298 * Object obj = ...; // somehow obtain the object 299 * setProperty.invokeExact(obj, "color", Color.BLUE); 300 * setProperty.invokeExact(obj, "shape", Shape.CIRCLE); 301 * </pre> 302 * </li> 303 * <li>Call a function on an object; two-step variant. This is the actual variant used by Nashorn-generated code: 304 * <pre> 305 * MethodHandle findFooFunction = Boostrap.createDynamicInvoker("dyn:getMethod:foo", Object.class, Object.class); 306 * Object obj = ...; // somehow obtain the object 307 * Object foo_fn = findFooFunction.invokeExact(obj); 308 * MethodHandle callFunctionWithTwoArgs = Boostrap.createDynamicInvoker("dyn:call", Object.class, Object.class, Object.class, Object.class, Object.class); 309 * // Note: "call" operation takes a function, then a "this" value, then the arguments: 310 * Object foo_retval = callFunctionWithTwoArgs.invokeExact(foo_fn, obj, arg1, arg2); 311 * </pre> 312 * </li> 313 * <li>Call a function on an object; single-step variant. Although Nashorn doesn't use this variant and never 314 * emits any INVOKEDYNAMIC instructions with {@code dyn:getMethod}, it still supports this standard Dynalink 315 * operation: 316 * <pre> 317 * MethodHandle callFunctionFooWithTwoArgs = Boostrap.createDynamicInvoker("dyn:callMethod:foo", Object.class, Object.class, Object.class, Object.class); 318 * Object obj = ...; // somehow obtain the object 319 * Object foo_retval = callFunctionFooWithTwoArgs.invokeExact(obj, arg1, arg2); 320 * </pre> 321 * </li> 322 * </ul> 323 * Few additional remarks: 324 * <ul> 325 * <li>Just as Nashorn works with any Java object, the invokers returned from this method can also be applied to 326 * arbitrary Java objects in addition to Nashorn JavaScript objects.</li> 327 * <li>For invoking a named function on an object, you can also use the {@link InvokeByName} convenience class.</li> 328 * <li>For Nashorn objects {@code getElem}, {@code getProp}, and {@code getMethod} are handled almost identically, 329 * since JavaScript doesn't distinguish between different kinds of properties on an object. Either can be used with 330 * fixed property name or a variable property name. The only significant difference is handling of missing 331 * properties: {@code getMethod} for a missing member will link to a potential invocation of 332 * {@code __noSuchMethod__} on the object, {@code getProp} for a missing member will link to a potential invocation 333 * of {@code __noSuchProperty__}, while {@code getElem} for a missing member will link to an empty getter.</li> 334 * <li>In similar vein, {@code setElem} and {@code setProp} are handled identically on Nashorn objects.</li> 335 * <li>There's no rule that the variable property identifier has to be a {@code String} for {@code getProp/setProp} 336 * and {@code int} for {@code getElem/setElem}. You can declare their type to be {@code int}, {@code double}, 337 * {@code Object}, and so on regardless of the kind of the operation.</li> 338 * <li>You can be as specific in parameter types as you want. E.g. if you know that the receiver of the operation 339 * will always be {@code ScriptObject}, you can pass {@code ScriptObject.class} as its parameter type. If you happen 340 * to link to a method that expects different types, (you can use these invokers on POJOs too, after all, and end up 341 * linking with their methods that have strongly-typed signatures), all necessary conversions allowed by either Java 342 * or JavaScript will be applied: if invoked methods specify either primitive or wrapped Java numeric types, or 343 * {@code String} or {@code boolean/Boolean}, then the parameters might be subjected to standard ECMAScript 344 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the 345 * expected parameter type is a SAM type, and you pass a JavaScript function, a proxy object implementing the SAM 346 * type and delegating to the function will be passed. Linkage can often be optimized when linkers have more 347 * specific type information than "everything can be an object".</li> 348 * <li>You can also be as specific in return types as you want. For return types any necessary type conversion 349 * available in either Java or JavaScript will be automatically applied, similar to the process described for 350 * parameters, only in reverse direction: if you specify any either primitive or wrapped Java numeric type, or 351 * {@code String} or {@code boolean/Boolean}, then the return values will be subjected to standard ECMAScript 352 * {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the return 353 * type is a SAM type, and the return value is a JavaScript function, a proxy object implementing the SAM type and 354 * delegating to the function will be returned.</li> 355 * </ul> 356 * @param opDesc Dynalink dynamic operation descriptor. 357 * @param rtype the return type for the operation 358 * @param ptypes the parameter types for the operation 359 * @return MethodHandle for invoking the operation. 360 */ 361 public static MethodHandle createDynamicInvoker(final String opDesc, final Class<?> rtype, final Class<?>... ptypes) { 362 return createDynamicInvoker(opDesc, MethodType.methodType(rtype, ptypes)); 363 } 364 365 /** 366 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to 367 * {@link #createDynamicInvoker(String, Class, Class...)} but with an additional parameter to 368 * set the call site flags of the dynamic invoker. 369 * @param opDesc Dynalink dynamic operation descriptor. 370 * @param flags the call site flags for the operation 371 * @param rtype the return type for the operation 372 * @param ptypes the parameter types for the operation 373 * @return MethodHandle for invoking the operation. 374 */ 375 public static MethodHandle createDynamicInvoker(final String opDesc, final int flags, final Class<?> rtype, final Class<?>... ptypes) { 376 return bootstrap(MethodHandles.publicLookup(), opDesc, MethodType.methodType(rtype, ptypes), flags).dynamicInvoker(); 377 } 378 379 /** 380 * Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to 381 * {@link #createDynamicInvoker(String, Class, Class...)} but with return and parameter types composed into a 382 * method type in the signature. See the discussion of that method for details. 383 * @param opDesc Dynalink dynamic operation descriptor. 384 * @param type the method type for the operation 385 * @return MethodHandle for invoking the operation. 386 */ 387 public static MethodHandle createDynamicInvoker(final String opDesc, final MethodType type) { 388 return bootstrap(MethodHandles.publicLookup(), opDesc, type, 0).dynamicInvoker(); 389 } 390 391 /** 392 * Binds any object Nashorn can use as a [[Callable]] to a receiver and optionally arguments. 393 * @param callable the callable to bind 394 * @param boundThis the bound "this" value. 395 * @param boundArgs the bound arguments. Can be either null or empty array to signify no arguments are bound. 396 * @return a bound callable. 397 * @throws ECMAException with {@code TypeError} if the object is not a callable. 398 */ 399 public static Object bindCallable(final Object callable, final Object boundThis, final Object[] boundArgs) { 400 if (callable instanceof ScriptFunctionImpl) { 401 return ((ScriptFunctionImpl)callable).makeBoundFunction(boundThis, boundArgs); 402 } else if (callable instanceof BoundCallable) { 403 return ((BoundCallable)callable).bind(boundArgs); 404 } else if (isCallable(callable)) { 405 return new BoundCallable(callable, boundThis, boundArgs); 406 } 407 throw notFunction(callable); 408 } 409 410 /** 411 * Creates a super-adapter for an adapter, that is, an adapter to the adapter that allows invocation of superclass 412 * methods on it. 413 * @param adapter the original adapter 414 * @return a new adapter that can be used to invoke super methods on the original adapter. 415 */ 416 public static Object createSuperAdapter(final Object adapter) { 417 return new JavaSuperAdapter(adapter); 418 } 419 420 /** 421 * If the given class is a reflection-specific class (anything in {@code java.lang.reflect} and 422 * {@code java.lang.invoke} package, as well a {@link Class} and any subclass of {@link ClassLoader}) and there is 423 * a security manager in the system, then it checks the {@code nashorn.JavaReflection} {@code RuntimePermission}. 424 * @param clazz the class being tested 425 * @param isStatic is access checked for static members (or instance members) 426 */ 427 public static void checkReflectionAccess(final Class<?> clazz, final boolean isStatic) { 428 ReflectionCheckLinker.checkReflectionAccess(clazz, isStatic); 429 } 430 431 /** 432 * Returns the Nashorn's internally used dynamic linker's services object. Note that in code that is processing a 433 * linking request, you will normally use the {@code LinkerServices} object passed by whatever top-level linker 434 * invoked the linking (if the call site is in Nashorn-generated code, you'll get this object anyway). You should 435 * only resort to retrieving a linker services object using this method when you need some linker services (e.g. 436 * type converter method handles) outside of a code path that is linking a call site. 437 * @return Nashorn's internal dynamic linker's services object. 438 */ 439 public static LinkerServices getLinkerServices() { 440 return dynamicLinker.getLinkerServices(); 441 } 442 443 /** 444 * Takes a guarded invocation, and ensures its method and guard conform to the type of the call descriptor, using 445 * all type conversions allowed by the linker's services. This method is used by Nashorn's linkers as a last step 446 * before returning guarded invocations. Most of the code used to produce the guarded invocations does not make an 447 * effort to coordinate types of the methods, and so a final type adjustment before a guarded invocation is returned 448 * to the aggregating linker is the responsibility of the linkers themselves. 449 * @param inv the guarded invocation that needs to be type-converted. Can be null. 450 * @param linkerServices the linker services object providing the type conversions. 451 * @param desc the call site descriptor to whose method type the invocation needs to conform. 452 * @return the type-converted guarded invocation. If input is null, null is returned. If the input invocation 453 * already conforms to the requested type, it is returned unchanged. 454 */ 455 static GuardedInvocation asTypeSafeReturn(final GuardedInvocation inv, final LinkerServices linkerServices, final CallSiteDescriptor desc) { 456 return inv == null ? null : inv.asTypeSafeReturn(linkerServices, desc.getMethodType()); 457 } 458 459 /** 460 * Adapts the return type of the method handle with {@code explicitCastArguments} when it is an unboxing 461 * conversion. This will ensure that nulls are unwrapped to false or 0. 462 * @param target the target method handle 463 * @param newType the desired new type. Note that this method does not adapt the method handle completely to the 464 * new type, it only adapts the return type; this is allowed as per 465 * {@link DynamicLinkerFactory#setAutoConversionStrategy(MethodTypeConversionStrategy)}, which is what this method 466 * is used for. 467 * @return the method handle with adapted return type, if it required an unboxing conversion. 468 */ 469 private static MethodHandle unboxReturnType(final MethodHandle target, final MethodType newType) { 470 final MethodType targetType = target.type(); 471 final Class<?> oldReturnType = targetType.returnType(); 472 final Class<?> newReturnType = newType.returnType(); 473 if (TypeUtilities.isWrapperType(oldReturnType)) { 474 if (newReturnType.isPrimitive()) { 475 // The contract of setAutoConversionStrategy is such that the difference between newType and targetType 476 // can only be JLS method invocation conversions. 477 assert TypeUtilities.isMethodInvocationConvertible(oldReturnType, newReturnType); 478 return MethodHandles.explicitCastArguments(target, targetType.changeReturnType(newReturnType)); 479 } 480 } else if (oldReturnType == void.class && newReturnType == Object.class) { 481 return MethodHandles.filterReturnValue(target, VOID_TO_OBJECT); 482 } 483 return target; 484 } 485} 486