1 /* 2 * Copyright (c) 2008, 2019, 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 jdk.internal.ref.CleanerFactory; 29 import sun.invoke.util.Wrapper; 30 31 import java.lang.invoke.MethodHandles.Lookup; 32 import java.lang.reflect.Field; 33 34 import static java.lang.invoke.MethodHandleNatives.Constants.*; 35 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE; 36 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; 37 38 /** 39 * The JVM interface for the method handles package is all here. 40 * This is an interface internal and private to an implementation of JSR 292. 41 * <em>This class is not part of the JSR 292 standard.</em> 42 * @author jrose 43 */ 44 class MethodHandleNatives { 45 46 private MethodHandleNatives() { } // static only 47 48 /// MemberName support 49 50 static native void init(MemberName self, Object ref); 51 static native void expand(MemberName self); 52 static native MemberName resolve(MemberName self, Class<?> caller, 53 boolean speculativeResolve) throws LinkageError, ClassNotFoundException; 54 static native int getMembers(Class<?> defc, String matchName, String matchSig, 55 int matchFlags, Class<?> caller, int skip, MemberName[] results); 56 57 /// Field layout queries parallel to jdk.internal.misc.Unsafe: 58 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex 59 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex 60 static native Object staticFieldBase(MemberName self); // e.g., returns clazz 61 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget} 62 63 /// CallSite support 64 65 /** Tell the JVM that we need to change the target of a CallSite. */ 66 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target); 67 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target); 68 69 static native void copyOutBootstrapArguments(Class<?> caller, int[] indexInfo, 70 int start, int end, 71 Object[] buf, int pos, 72 boolean resolve, 73 Object ifNotAvailable); 74 75 /// ClassData support 76 static native Object classData(Class<?> lookupClass); 77 78 /** Represents a context to track nmethod dependencies on CallSite instance target. */ 79 static class CallSiteContext implements Runnable { 80 //@Injected JVM_nmethodBucket* vmdependencies; 81 //@Injected jlong last_cleanup; 82 83 static CallSiteContext make(CallSite cs) { 84 final CallSiteContext newContext = new CallSiteContext(); 85 // CallSite instance is tracked by a Cleanable which clears native 86 // structures allocated for CallSite context. Though the CallSite can 87 // become unreachable, its Context is retained by the Cleanable instance 88 // (which is referenced from Cleaner instance which is referenced from 89 // CleanerFactory class) until cleanup is performed. 90 CleanerFactory.cleaner().register(cs, newContext); 91 return newContext; 92 } 93 94 @Override 95 public void run() { 96 MethodHandleNatives.clearCallSiteContext(this); 97 } 98 } 99 100 /** Invalidate all recorded nmethods. */ 101 private static native void clearCallSiteContext(CallSiteContext context); 102 103 private static native void registerNatives(); 104 static { 105 registerNatives(); 106 } 107 108 /** 109 * Compile-time constants go here. This collection exists not only for 110 * reference from clients, but also for ensuring the VM and JDK agree on the 111 * values of these constants (see {@link #verifyConstants()}). 112 */ 113 static class Constants { 114 Constants() { } // static only 115 116 static final int 117 MN_IS_METHOD = 0x00010000, // method (not constructor) 118 MN_IS_CONSTRUCTOR = 0x00020000, // constructor 119 MN_IS_FIELD = 0x00040000, // field 120 MN_IS_TYPE = 0x00080000, // nested type 121 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected 122 MN_REFERENCE_KIND_SHIFT = 24, // refKind 123 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT, 124 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers: 125 MN_SEARCH_SUPERCLASSES = 0x00100000, 126 MN_SEARCH_INTERFACES = 0x00200000; 127 128 /** 129 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries. 130 */ 131 static final byte 132 REF_NONE = 0, // null value 133 REF_getField = 1, 134 REF_getStatic = 2, 135 REF_putField = 3, 136 REF_putStatic = 4, 137 REF_invokeVirtual = 5, 138 REF_invokeStatic = 6, 139 REF_invokeSpecial = 7, 140 REF_newInvokeSpecial = 8, 141 REF_invokeInterface = 9, 142 REF_LIMIT = 10; 143 144 /** 145 * Flags for Lookup.ClassOptions 146 */ 147 static final int 148 NESTMATE_CLASS = 0x00000001, 149 HIDDEN_CLASS = 0x00000002, 150 STRONG_LOADER_LINK = 0x00000004, 151 ACCESS_VM_ANNOTATIONS = 0x00100000; 152 } 153 154 static boolean refKindIsValid(int refKind) { 155 return (refKind > REF_NONE && refKind < REF_LIMIT); 156 } 157 static boolean refKindIsField(byte refKind) { 158 assert(refKindIsValid(refKind)); 159 return (refKind <= REF_putStatic); 160 } 161 static boolean refKindIsGetter(byte refKind) { 162 assert(refKindIsValid(refKind)); 163 return (refKind <= REF_getStatic); 164 } 165 static boolean refKindIsSetter(byte refKind) { 166 return refKindIsField(refKind) && !refKindIsGetter(refKind); 167 } 168 static boolean refKindIsMethod(byte refKind) { 169 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial); 170 } 171 static boolean refKindIsConstructor(byte refKind) { 172 return (refKind == REF_newInvokeSpecial); 173 } 174 static boolean refKindHasReceiver(byte refKind) { 175 assert(refKindIsValid(refKind)); 176 return (refKind & 1) != 0; 177 } 178 static boolean refKindIsStatic(byte refKind) { 179 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial); 180 } 181 static boolean refKindDoesDispatch(byte refKind) { 182 assert(refKindIsValid(refKind)); 183 return (refKind == REF_invokeVirtual || 184 refKind == REF_invokeInterface); 185 } 186 static { 187 final int HR_MASK = ((1 << REF_getField) | 188 (1 << REF_putField) | 189 (1 << REF_invokeVirtual) | 190 (1 << REF_invokeSpecial) | 191 (1 << REF_invokeInterface) 192 ); 193 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) { 194 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind; 195 } 196 } 197 static String refKindName(byte refKind) { 198 assert(refKindIsValid(refKind)); 199 switch (refKind) { 200 case REF_getField: return "getField"; 201 case REF_getStatic: return "getStatic"; 202 case REF_putField: return "putField"; 203 case REF_putStatic: return "putStatic"; 204 case REF_invokeVirtual: return "invokeVirtual"; 205 case REF_invokeStatic: return "invokeStatic"; 206 case REF_invokeSpecial: return "invokeSpecial"; 207 case REF_newInvokeSpecial: return "newInvokeSpecial"; 208 case REF_invokeInterface: return "invokeInterface"; 209 default: return "REF_???"; 210 } 211 } 212 213 private static native int getNamedCon(int which, Object[] name); 214 static boolean verifyConstants() { 215 Object[] box = { null }; 216 for (int i = 0; ; i++) { 217 box[0] = null; 218 int vmval = getNamedCon(i, box); 219 if (box[0] == null) break; 220 String name = (String) box[0]; 221 try { 222 Field con = Constants.class.getDeclaredField(name); 223 int jval = con.getInt(null); 224 if (jval == vmval) continue; 225 String err = (name+": JVM has "+vmval+" while Java has "+jval); 226 if (name.equals("CONV_OP_LIMIT")) { 227 System.err.println("warning: "+err); 228 continue; 229 } 230 throw new InternalError(err); 231 } catch (NoSuchFieldException | IllegalAccessException ex) { 232 String err = (name+": JVM has "+vmval+" which Java does not define"); 233 // ignore exotic ops the JVM cares about; we just wont issue them 234 //System.err.println("warning: "+err); 235 continue; 236 } 237 } 238 return true; 239 } 240 static { 241 assert(verifyConstants()); 242 } 243 244 // Up-calls from the JVM. 245 // These must NOT be public. 246 247 /** 248 * The JVM is linking an invokedynamic instruction. Create a reified call site for it. 249 */ 250 static MemberName linkCallSite(Object callerObj, 251 int indexInCP, 252 Object bootstrapMethodObj, 253 Object nameObj, Object typeObj, 254 Object staticArguments, 255 Object[] appendixResult) { 256 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 257 Class<?> caller = (Class<?>)callerObj; 258 String name = nameObj.toString().intern(); 259 MethodType type = (MethodType)typeObj; 260 if (!TRACE_METHOD_LINKAGE) 261 return linkCallSiteImpl(caller, bootstrapMethod, name, type, 262 staticArguments, appendixResult); 263 return linkCallSiteTracing(caller, bootstrapMethod, name, type, 264 staticArguments, appendixResult); 265 } 266 static MemberName linkCallSiteImpl(Class<?> caller, 267 MethodHandle bootstrapMethod, 268 String name, MethodType type, 269 Object staticArguments, 270 Object[] appendixResult) { 271 CallSite callSite = CallSite.makeSite(bootstrapMethod, 272 name, 273 type, 274 staticArguments, 275 caller); 276 if (callSite instanceof ConstantCallSite) { 277 appendixResult[0] = callSite.dynamicInvoker(); 278 return Invokers.linkToTargetMethod(type); 279 } else { 280 appendixResult[0] = callSite; 281 return Invokers.linkToCallSiteMethod(type); 282 } 283 } 284 // Tracing logic: 285 static MemberName linkCallSiteTracing(Class<?> caller, 286 MethodHandle bootstrapMethod, 287 String name, MethodType type, 288 Object staticArguments, 289 Object[] appendixResult) { 290 Object bsmReference = bootstrapMethod.internalMemberName(); 291 if (bsmReference == null) bsmReference = bootstrapMethod; 292 String staticArglist = staticArglistForTrace(staticArguments); 293 System.out.println("linkCallSite "+caller.getName()+" "+ 294 bsmReference+" "+ 295 name+type+"/"+staticArglist); 296 try { 297 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type, 298 staticArguments, appendixResult); 299 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]); 300 return res; 301 } catch (Throwable ex) { 302 ex.printStackTrace(); // print now in case exception is swallowed 303 System.out.println("linkCallSite => throw "+ex); 304 throw ex; 305 } 306 } 307 308 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant: 309 static Object linkDynamicConstant(Object callerObj, 310 int indexInCP, 311 Object bootstrapMethodObj, 312 Object nameObj, Object typeObj, 313 Object staticArguments) { 314 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 315 Class<?> caller = (Class<?>)callerObj; 316 String name = nameObj.toString().intern(); 317 Class<?> type = (Class<?>)typeObj; 318 if (!TRACE_METHOD_LINKAGE) 319 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments); 320 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments); 321 } 322 323 static Object linkDynamicConstantImpl(Class<?> caller, 324 MethodHandle bootstrapMethod, 325 String name, Class<?> type, 326 Object staticArguments) { 327 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller); 328 } 329 330 private static String staticArglistForTrace(Object staticArguments) { 331 if (staticArguments instanceof Object[]) 332 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments); 333 if (staticArguments instanceof int[]) 334 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments); 335 if (staticArguments == null) 336 return "BSA0=null"; 337 return "BSA1="+staticArguments; 338 } 339 340 // Tracing logic: 341 static Object linkDynamicConstantTracing(Class<?> caller, 342 MethodHandle bootstrapMethod, 343 String name, Class<?> type, 344 Object staticArguments) { 345 Object bsmReference = bootstrapMethod.internalMemberName(); 346 if (bsmReference == null) bsmReference = bootstrapMethod; 347 String staticArglist = staticArglistForTrace(staticArguments); 348 System.out.println("linkDynamicConstant "+caller.getName()+" "+ 349 bsmReference+" "+ 350 name+type+"/"+staticArglist); 351 try { 352 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments); 353 System.out.println("linkDynamicConstantImpl => "+res); 354 return res; 355 } catch (Throwable ex) { 356 ex.printStackTrace(); // print now in case exception is swallowed 357 System.out.println("linkDynamicConstant => throw "+ex); 358 throw ex; 359 } 360 } 361 362 /** The JVM is requesting pull-mode bootstrap when it provides 363 * a tuple of the form int[]{ argc, vmindex }. 364 * The BSM is expected to call back to the JVM using the caller 365 * class and vmindex to resolve the static arguments. 366 */ 367 static boolean staticArgumentsPulled(Object staticArguments) { 368 return staticArguments instanceof int[]; 369 } 370 371 /** A BSM runs in pull-mode if and only if its sole arguments 372 * are (Lookup, BootstrapCallInfo), or can be converted pairwise 373 * to those types, and it is not of variable arity. 374 * Excluding error cases, we can just test that the arity is a constant 2. 375 * 376 * NOTE: This method currently returns false, since pulling is not currently 377 * exposed to a BSM. When pull mode is supported the method block will be 378 * replaced with currently commented out code. 379 */ 380 static boolean isPullModeBSM(MethodHandle bsm) { 381 return false; 382 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector(); 383 } 384 385 /** 386 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one. 387 */ 388 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) { 389 return MethodType.makeImpl(rtype, ptypes, true); 390 } 391 392 /** 393 * The JVM wants to link a call site that requires a dynamic type check. 394 * Name is a type-checking invoker, invokeExact or invoke. 395 * Return a JVM method (MemberName) to handle the invoking. 396 * The method assumes the following arguments on the stack: 397 * 0: the method handle being invoked 398 * 1-N: the arguments to the method handle invocation 399 * N+1: an optional, implicitly added argument (typically the given MethodType) 400 * <p> 401 * The nominal method at such a call site is an instance of 402 * a signature-polymorphic method (see @PolymorphicSignature). 403 * Such method instances are user-visible entities which are 404 * "split" from the generic placeholder method in {@code MethodHandle}. 405 * (Note that the placeholder method is not identical with any of 406 * its instances. If invoked reflectively, is guaranteed to throw an 407 * {@code UnsupportedOperationException}.) 408 * If the signature-polymorphic method instance is ever reified, 409 * it appears as a "copy" of the original placeholder 410 * (a native final member of {@code MethodHandle}) except 411 * that its type descriptor has shape required by the instance, 412 * and the method instance is <em>not</em> varargs. 413 * The method instance is also marked synthetic, since the 414 * method (by definition) does not appear in Java source code. 415 * <p> 416 * The JVM is allowed to reify this method as instance metadata. 417 * For example, {@code invokeBasic} is always reified. 418 * But the JVM may instead call {@code linkMethod}. 419 * If the result is an * ordered pair of a {@code (method, appendix)}, 420 * the method gets all the arguments (0..N inclusive) 421 * plus the appendix (N+1), and uses the appendix to complete the call. 422 * In this way, one reusable method (called a "linker method") 423 * can perform the function of any number of polymorphic instance 424 * methods. 425 * <p> 426 * Linker methods are allowed to be weakly typed, with any or 427 * all references rewritten to {@code Object} and any primitives 428 * (except {@code long}/{@code float}/{@code double}) 429 * rewritten to {@code int}. 430 * A linker method is trusted to return a strongly typed result, 431 * according to the specific method type descriptor of the 432 * signature-polymorphic instance it is emulating. 433 * This can involve (as necessary) a dynamic check using 434 * data extracted from the appendix argument. 435 * <p> 436 * The JVM does not inspect the appendix, other than to pass 437 * it verbatim to the linker method at every call. 438 * This means that the JDK runtime has wide latitude 439 * for choosing the shape of each linker method and its 440 * corresponding appendix. 441 * Linker methods should be generated from {@code LambdaForm}s 442 * so that they do not become visible on stack traces. 443 * <p> 444 * The {@code linkMethod} call is free to omit the appendix 445 * (returning null) and instead emulate the required function 446 * completely in the linker method. 447 * As a corner case, if N==255, no appendix is possible. 448 * In this case, the method returned must be custom-generated to 449 * perform any needed type checking. 450 * <p> 451 * If the JVM does not reify a method at a call site, but instead 452 * calls {@code linkMethod}, the corresponding call represented 453 * in the bytecodes may mention a valid method which is not 454 * representable with a {@code MemberName}. 455 * Therefore, use cases for {@code linkMethod} tend to correspond to 456 * special cases in reflective code such as {@code findVirtual} 457 * or {@code revealDirect}. 458 */ 459 static MemberName linkMethod(Class<?> callerClass, int refKind, 460 Class<?> defc, String name, Object type, 461 Object[] appendixResult) { 462 if (!TRACE_METHOD_LINKAGE) 463 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 464 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult); 465 } 466 static MemberName linkMethodImpl(Class<?> callerClass, int refKind, 467 Class<?> defc, String name, Object type, 468 Object[] appendixResult) { 469 try { 470 if (refKind == REF_invokeVirtual) { 471 if (defc == MethodHandle.class) { 472 return Invokers.methodHandleInvokeLinkerMethod( 473 name, fixMethodType(callerClass, type), appendixResult); 474 } else if (defc == VarHandle.class) { 475 return varHandleOperationLinkerMethod( 476 name, fixMethodType(callerClass, type), appendixResult); 477 } 478 } 479 } catch (Error e) { 480 // Pass through an Error, including say StackOverflowError or 481 // OutOfMemoryError 482 throw e; 483 } catch (Throwable ex) { 484 // Wrap anything else in LinkageError 485 throw new LinkageError(ex.getMessage(), ex); 486 } 487 throw new LinkageError("no such method "+defc.getName()+"."+name+type); 488 } 489 private static MethodType fixMethodType(Class<?> callerClass, Object type) { 490 if (type instanceof MethodType) 491 return (MethodType) type; 492 else 493 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader()); 494 } 495 // Tracing logic: 496 static MemberName linkMethodTracing(Class<?> callerClass, int refKind, 497 Class<?> defc, String name, Object type, 498 Object[] appendixResult) { 499 System.out.println("linkMethod "+defc.getName()+"."+ 500 name+type+"/"+Integer.toHexString(refKind)); 501 try { 502 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 503 System.out.println("linkMethod => "+res+" + "+appendixResult[0]); 504 return res; 505 } catch (Throwable ex) { 506 System.out.println("linkMethod => throw "+ex); 507 throw ex; 508 } 509 } 510 511 /** 512 * Obtain the method to link to the VarHandle operation. 513 * This method is located here and not in Invokers to avoid 514 * intializing that and other classes early on in VM bootup. 515 */ 516 private static MemberName varHandleOperationLinkerMethod(String name, 517 MethodType mtype, 518 Object[] appendixResult) { 519 // Get the signature method type 520 final MethodType sigType = mtype.basicType(); 521 522 // Get the access kind from the method name 523 VarHandle.AccessMode ak; 524 try { 525 ak = VarHandle.AccessMode.valueFromMethodName(name); 526 } catch (IllegalArgumentException e) { 527 throw MethodHandleStatics.newInternalError(e); 528 } 529 530 // Create the appendix descriptor constant 531 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal()); 532 appendixResult[0] = ad; 533 534 if (MethodHandleStatics.VAR_HANDLE_GUARDS) { 535 // If not polymorphic in the return type, such as the compareAndSet 536 // methods that return boolean 537 Class<?> guardReturnType = sigType.returnType(); 538 if (ak.at.isMonomorphicInReturnType) { 539 if (ak.at.returnType != mtype.returnType()) { 540 // The caller contains a different return type than that 541 // defined by the method 542 throw newNoSuchMethodErrorOnVarHandle(name, mtype); 543 } 544 // Adjust the return type of the signature method type 545 guardReturnType = ak.at.returnType; 546 } 547 548 // Get the guard method type for linking 549 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2]; 550 // VarHandle at start 551 guardParams[0] = VarHandle.class; 552 for (int i = 0; i < sigType.parameterCount(); i++) { 553 guardParams[i + 1] = sigType.parameterType(i); 554 } 555 // Access descriptor at end 556 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class; 557 MethodType guardType = MethodType.makeImpl(guardReturnType, guardParams, true); 558 559 MemberName linker = new MemberName( 560 VarHandleGuards.class, getVarHandleGuardMethodName(guardType), 561 guardType, REF_invokeStatic); 562 563 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker, 564 VarHandleGuards.class); 565 if (linker != null) { 566 return linker; 567 } 568 // Fall back to lambda form linkage if guard method is not available 569 // TODO Optionally log fallback ? 570 } 571 return Invokers.varHandleInvokeLinkerMethod(ak, mtype); 572 } 573 static String getVarHandleGuardMethodName(MethodType guardType) { 574 String prefix = "guard_"; 575 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount()); 576 577 sb.append(prefix); 578 for (int i = 1; i < guardType.parameterCount() - 1; i++) { 579 Class<?> pt = guardType.parameterType(i); 580 sb.append(getCharType(pt)); 581 } 582 sb.append('_').append(getCharType(guardType.returnType())); 583 return sb.toString(); 584 } 585 static char getCharType(Class<?> pt) { 586 return Wrapper.forBasicType(pt).basicTypeChar(); 587 } 588 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) { 589 return new NoSuchMethodError("VarHandle." + name + mtype); 590 } 591 592 /** 593 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help. 594 * It will make an up-call to this method. (Do not change the name or signature.) 595 * The type argument is a Class for field requests and a MethodType for non-fields. 596 * <p> 597 * Recent versions of the JVM may also pass a resolved MemberName for the type. 598 * In that case, the name is ignored and may be null. 599 */ 600 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind, 601 Class<?> defc, String name, Object type) { 602 try { 603 Lookup lookup = IMPL_LOOKUP.in(callerClass); 604 assert(refKindIsValid(refKind)); 605 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type); 606 } catch (ReflectiveOperationException ex) { 607 throw mapLookupExceptionToError(ex); 608 } 609 } 610 611 /** 612 * Map a reflective exception to a linkage error. 613 */ 614 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) { 615 LinkageError err; 616 if (ex instanceof IllegalAccessException) { 617 Throwable cause = ex.getCause(); 618 if (cause instanceof AbstractMethodError) { 619 return (AbstractMethodError) cause; 620 } else { 621 err = new IllegalAccessError(ex.getMessage()); 622 } 623 } else if (ex instanceof NoSuchMethodException) { 624 err = new NoSuchMethodError(ex.getMessage()); 625 } else if (ex instanceof NoSuchFieldException) { 626 err = new NoSuchFieldError(ex.getMessage()); 627 } else { 628 err = new IncompatibleClassChangeError(); 629 } 630 return initCauseFrom(err, ex); 631 } 632 633 /** 634 * Use best possible cause for err.initCause(), substituting the 635 * cause for err itself if the cause has the same (or better) type. 636 */ 637 static <E extends Error> E initCauseFrom(E err, Exception ex) { 638 Throwable th = ex.getCause(); 639 @SuppressWarnings("unchecked") 640 final Class<E> Eclass = (Class<E>) err.getClass(); 641 if (Eclass.isInstance(th)) 642 return Eclass.cast(th); 643 err.initCause(th == null ? ex : th); 644 return err; 645 } 646 647 /** 648 * Is this method a caller-sensitive method? 649 * I.e., does it call Reflection.getCallerClass or a similar method 650 * to ask about the identity of its caller? 651 */ 652 static boolean isCallerSensitive(MemberName mem) { 653 if (!mem.isInvocable()) return false; // fields are not caller sensitive 654 655 return mem.isCallerSensitive() || canBeCalledVirtual(mem); 656 } 657 658 static boolean canBeCalledVirtual(MemberName mem) { 659 assert(mem.isInvocable()); 660 switch (mem.getName()) { 661 case "getContextClassLoader": 662 return canBeCalledVirtual(mem, java.lang.Thread.class); 663 } 664 return false; 665 } 666 667 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) { 668 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass(); 669 if (symbolicRefClass == definingClass) return true; 670 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false; 671 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef 672 symbolicRefClass.isInterface()); // Mdef implements Msym 673 } 674 }