1 /* 2 * Copyright (c) 2008, 2022, 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.misc.VM; 29 import jdk.internal.ref.CleanerFactory; 30 import sun.invoke.util.Wrapper; 31 32 import java.lang.invoke.MethodHandles.Lookup; 33 import java.lang.reflect.Field; 34 35 import static java.lang.invoke.MethodHandleNatives.Constants.*; 36 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE; 37 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; 38 39 /** 40 * The JVM interface for the method handles package is all here. 41 * This is an interface internal and private to an implementation of JSR 292. 42 * <em>This class is not part of the JSR 292 standard.</em> 43 * @author jrose 44 */ 45 class MethodHandleNatives { 46 47 private MethodHandleNatives() { } // static only 48 49 /// MemberName support 50 51 static native void init(MemberName self, Object ref); 52 static native void expand(MemberName self); 53 static native MemberName resolve(MemberName self, Class<?> caller, int lookupMode, 54 boolean speculativeResolve) throws LinkageError, ClassNotFoundException; 55 static native int getMembers(Class<?> defc, String matchName, String matchSig, 56 int matchFlags, Class<?> caller, int skip, MemberName[] results); 57 58 /// Field layout queries parallel to jdk.internal.misc.Unsafe: 59 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex 60 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex 61 static native Object staticFieldBase(MemberName self); // e.g., returns clazz 62 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget} 63 64 /// CallSite support 65 66 /** Tell the JVM that we need to change the target of a CallSite. */ 67 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target); 68 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target); 69 70 static native void copyOutBootstrapArguments(Class<?> caller, int[] indexInfo, 71 int start, int end, 72 Object[] buf, int pos, 73 boolean resolve, 74 Object ifNotAvailable); 75 76 /** Represents a context to track nmethod dependencies on CallSite instance target. */ 77 static class CallSiteContext implements Runnable { 78 //@Injected JVM_nmethodBucket* vmdependencies; 79 //@Injected jlong last_cleanup; 80 81 static CallSiteContext make(CallSite cs) { 82 final CallSiteContext newContext = new CallSiteContext(); 83 // CallSite instance is tracked by a Cleanable which clears native 84 // structures allocated for CallSite context. Though the CallSite can 85 // become unreachable, its Context is retained by the Cleanable instance 86 // (which is referenced from Cleaner instance which is referenced from 87 // CleanerFactory class) until cleanup is performed. 88 CleanerFactory.cleaner().register(cs, newContext); 89 return newContext; 90 } 91 92 @Override 93 public void run() { 94 MethodHandleNatives.clearCallSiteContext(this); 95 } 96 } 97 98 /** Invalidate all recorded nmethods. */ 99 private static native void clearCallSiteContext(CallSiteContext context); 100 101 private static native void registerNatives(); 102 static { 103 registerNatives(); 104 } 105 106 /** 107 * Compile-time constants go here. This collection exists not only for 108 * reference from clients, but also for ensuring the VM and JDK agree on the 109 * values of these constants (see {@link #verifyConstants()}). 110 */ 111 static class Constants { 112 Constants() { } // static only 113 114 static final int 115 MN_IS_METHOD = 0x00010000, // method (not constructor) 116 MN_IS_CONSTRUCTOR = 0x00020000, // constructor 117 MN_IS_FIELD = 0x00040000, // field 118 MN_IS_TYPE = 0x00080000, // nested type 119 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected 120 MN_TRUSTED_FINAL = 0x00200000, // trusted final field 121 MN_REFERENCE_KIND_SHIFT = 24, // refKind 122 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT, 123 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers: 124 MN_SEARCH_SUPERCLASSES = 0x00100000, 125 MN_SEARCH_INTERFACES = 0x00200000; 126 127 /** 128 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries. 129 */ 130 static final byte 131 REF_NONE = 0, // null value 132 REF_getField = 1, 133 REF_getStatic = 2, 134 REF_putField = 3, 135 REF_putStatic = 4, 136 REF_invokeVirtual = 5, 137 REF_invokeStatic = 6, 138 REF_invokeSpecial = 7, 139 REF_newInvokeSpecial = 8, 140 REF_invokeInterface = 9, 141 REF_LIMIT = 10; 142 143 /** 144 * Flags for Lookup.ClassOptions 145 */ 146 static final int 147 NESTMATE_CLASS = 0x00000001, 148 HIDDEN_CLASS = 0x00000002, 149 STRONG_LOADER_LINK = 0x00000004, 150 ACCESS_VM_ANNOTATIONS = 0x00000008; 151 152 /** 153 * Lookup modes 154 */ 155 static final int 156 LM_MODULE = Lookup.MODULE, 157 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL, 158 LM_TRUSTED = -1; 159 160 } 161 162 static boolean refKindIsValid(int refKind) { 163 return (refKind > REF_NONE && refKind < REF_LIMIT); 164 } 165 static boolean refKindIsField(byte refKind) { 166 assert(refKindIsValid(refKind)); 167 return (refKind <= REF_putStatic); 168 } 169 static boolean refKindIsGetter(byte refKind) { 170 assert(refKindIsValid(refKind)); 171 return (refKind <= REF_getStatic); 172 } 173 static boolean refKindIsSetter(byte refKind) { 174 return refKindIsField(refKind) && !refKindIsGetter(refKind); 175 } 176 static boolean refKindIsMethod(byte refKind) { 177 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial); 178 } 179 static boolean refKindIsConstructor(byte refKind) { 180 return (refKind == REF_newInvokeSpecial); 181 } 182 static boolean refKindHasReceiver(byte refKind) { 183 assert(refKindIsValid(refKind)); 184 return (refKind & 1) != 0; 185 } 186 static boolean refKindIsStatic(byte refKind) { 187 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial); 188 } 189 static boolean refKindDoesDispatch(byte refKind) { 190 assert(refKindIsValid(refKind)); 191 return (refKind == REF_invokeVirtual || 192 refKind == REF_invokeInterface); 193 } 194 static { 195 final int HR_MASK = ((1 << REF_getField) | 196 (1 << REF_putField) | 197 (1 << REF_invokeVirtual) | 198 (1 << REF_invokeSpecial) | 199 (1 << REF_invokeInterface) 200 ); 201 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) { 202 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind; 203 } 204 } 205 static String refKindName(byte refKind) { 206 assert(refKindIsValid(refKind)); 207 return switch (refKind) { 208 case REF_getField -> "getField"; 209 case REF_getStatic -> "getStatic"; 210 case REF_putField -> "putField"; 211 case REF_putStatic -> "putStatic"; 212 case REF_invokeVirtual -> "invokeVirtual"; 213 case REF_invokeStatic -> "invokeStatic"; 214 case REF_invokeSpecial -> "invokeSpecial"; 215 case REF_newInvokeSpecial -> "newInvokeSpecial"; 216 case REF_invokeInterface -> "invokeInterface"; 217 default -> "REF_???"; 218 }; 219 } 220 221 private static native int getNamedCon(int which, Object[] name); 222 static boolean verifyConstants() { 223 Object[] box = { null }; 224 for (int i = 0; ; i++) { 225 box[0] = null; 226 int vmval = getNamedCon(i, box); 227 if (box[0] == null) break; 228 String name = (String) box[0]; 229 try { 230 Field con = Constants.class.getDeclaredField(name); 231 int jval = con.getInt(null); 232 if (jval == vmval) continue; 233 String err = (name+": JVM has "+vmval+" while Java has "+jval); 234 if (name.equals("CONV_OP_LIMIT")) { 235 System.err.println("warning: "+err); 236 continue; 237 } 238 throw new InternalError(err); 239 } catch (NoSuchFieldException | IllegalAccessException ex) { 240 String err = (name+": JVM has "+vmval+" which Java does not define"); 241 // ignore exotic ops the JVM cares about; we just won't issue them 242 //System.err.println("warning: "+err); 243 continue; 244 } 245 } 246 return true; 247 } 248 static { 249 VM.setJavaLangInvokeInited(); 250 assert(verifyConstants()); 251 } 252 253 // Up-calls from the JVM. 254 // These must NOT be public. 255 256 /** 257 * The JVM is linking an invokedynamic instruction. Create a reified call site for it. 258 */ 259 static MemberName linkCallSite(Object callerObj, 260 Object bootstrapMethodObj, 261 Object nameObj, Object typeObj, 262 Object staticArguments, 263 Object[] appendixResult) { 264 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 265 Class<?> caller = (Class<?>)callerObj; 266 String name = nameObj.toString().intern(); 267 MethodType type = (MethodType)typeObj; 268 if (!TRACE_METHOD_LINKAGE) 269 return linkCallSiteImpl(caller, bootstrapMethod, name, type, 270 staticArguments, appendixResult); 271 return linkCallSiteTracing(caller, bootstrapMethod, name, type, 272 staticArguments, appendixResult); 273 } 274 static MemberName linkCallSiteImpl(Class<?> caller, 275 MethodHandle bootstrapMethod, 276 String name, MethodType type, 277 Object staticArguments, 278 Object[] appendixResult) { 279 CallSite callSite = CallSite.makeSite(bootstrapMethod, 280 name, 281 type, 282 staticArguments, 283 caller); 284 if (TRACE_METHOD_LINKAGE) { 285 MethodHandle target = callSite.getTarget(); 286 System.out.println("linkCallSite target class => " + target.getClass().getName()); 287 System.out.println("linkCallSite target => " + target.debugString(0)); 288 } 289 290 if (callSite instanceof ConstantCallSite) { 291 appendixResult[0] = callSite.dynamicInvoker(); 292 return Invokers.linkToTargetMethod(type); 293 } else { 294 appendixResult[0] = callSite; 295 return Invokers.linkToCallSiteMethod(type); 296 } 297 } 298 // Tracing logic: 299 static MemberName linkCallSiteTracing(Class<?> caller, 300 MethodHandle bootstrapMethod, 301 String name, MethodType type, 302 Object staticArguments, 303 Object[] appendixResult) { 304 Object bsmReference = bootstrapMethod.internalMemberName(); 305 if (bsmReference == null) bsmReference = bootstrapMethod; 306 String staticArglist = staticArglistForTrace(staticArguments); 307 System.out.println("linkCallSite "+getCallerInfo(caller)+" "+ 308 bsmReference+" "+ 309 name+type+"/"+staticArglist); 310 try { 311 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type, 312 staticArguments, appendixResult); 313 System.out.println("linkCallSite linkage => "+res+" + "+appendixResult[0]); 314 return res; 315 } catch (Throwable ex) { 316 ex.printStackTrace(); // print now in case exception is swallowed 317 System.out.println("linkCallSite => throw "+ex); 318 throw ex; 319 } 320 } 321 322 /** 323 * Return a human-readable description of the caller. Something like 324 * "java.base/java.security.Security.<clinit>(Security.java:82)" 325 */ 326 private static String getCallerInfo(Class<?> caller) { 327 for (StackTraceElement e : Thread.currentThread().getStackTrace()) { 328 if (e.getClassName().equals(caller.getName())) { 329 return e.toString(); 330 } 331 } 332 // fallback if the caller is somehow missing from the stack. 333 return caller.getName(); 334 } 335 336 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant: 337 static Object linkDynamicConstant(Object callerObj, 338 Object bootstrapMethodObj, 339 Object nameObj, Object typeObj, 340 Object staticArguments) { 341 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 342 Class<?> caller = (Class<?>)callerObj; 343 String name = nameObj.toString().intern(); 344 Class<?> type = (Class<?>)typeObj; 345 if (!TRACE_METHOD_LINKAGE) 346 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments); 347 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments); 348 } 349 350 static Object linkDynamicConstantImpl(Class<?> caller, 351 MethodHandle bootstrapMethod, 352 String name, Class<?> type, 353 Object staticArguments) { 354 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller); 355 } 356 357 private static String staticArglistForTrace(Object staticArguments) { 358 if (staticArguments instanceof Object[]) 359 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments); 360 if (staticArguments instanceof int[]) 361 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments); 362 if (staticArguments == null) 363 return "BSA0=null"; 364 return "BSA1="+staticArguments; 365 } 366 367 // Tracing logic: 368 static Object linkDynamicConstantTracing(Class<?> caller, 369 MethodHandle bootstrapMethod, 370 String name, Class<?> type, 371 Object staticArguments) { 372 Object bsmReference = bootstrapMethod.internalMemberName(); 373 if (bsmReference == null) bsmReference = bootstrapMethod; 374 String staticArglist = staticArglistForTrace(staticArguments); 375 System.out.println("linkDynamicConstant "+caller.getName()+" "+ 376 bsmReference+" "+ 377 name+type+"/"+staticArglist); 378 try { 379 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments); 380 System.out.println("linkDynamicConstantImpl => "+res); 381 return res; 382 } catch (Throwable ex) { 383 ex.printStackTrace(); // print now in case exception is swallowed 384 System.out.println("linkDynamicConstant => throw "+ex); 385 throw ex; 386 } 387 } 388 389 /** The JVM is requesting pull-mode bootstrap when it provides 390 * a tuple of the form int[]{ argc, vmindex }. 391 * The BSM is expected to call back to the JVM using the caller 392 * class and vmindex to resolve the static arguments. 393 */ 394 static boolean staticArgumentsPulled(Object staticArguments) { 395 return staticArguments instanceof int[]; 396 } 397 398 /** A BSM runs in pull-mode if and only if its sole arguments 399 * are (Lookup, BootstrapCallInfo), or can be converted pairwise 400 * to those types, and it is not of variable arity. 401 * Excluding error cases, we can just test that the arity is a constant 2. 402 * 403 * NOTE: This method currently returns false, since pulling is not currently 404 * exposed to a BSM. When pull mode is supported the method block will be 405 * replaced with currently commented out code. 406 */ 407 static boolean isPullModeBSM(MethodHandle bsm) { 408 return false; 409 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector(); 410 } 411 412 /** 413 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one. 414 */ 415 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) { 416 return MethodType.methodType(rtype, ptypes, true); 417 } 418 419 /** 420 * The JVM wants to link a call site that requires a dynamic type check. 421 * Name is a type-checking invoker, invokeExact or invoke. 422 * Return a JVM method (MemberName) to handle the invoking. 423 * The method assumes the following arguments on the stack: 424 * 0: the method handle being invoked 425 * 1-N: the arguments to the method handle invocation 426 * N+1: an optional, implicitly added argument (typically the given MethodType) 427 * <p> 428 * The nominal method at such a call site is an instance of 429 * a signature-polymorphic method (see @PolymorphicSignature). 430 * Such method instances are user-visible entities which are 431 * "split" from the generic placeholder method in {@code MethodHandle}. 432 * (Note that the placeholder method is not identical with any of 433 * its instances. If invoked reflectively, is guaranteed to throw an 434 * {@code UnsupportedOperationException}.) 435 * If the signature-polymorphic method instance is ever reified, 436 * it appears as a "copy" of the original placeholder 437 * (a native final member of {@code MethodHandle}) except 438 * that its type descriptor has shape required by the instance, 439 * and the method instance is <em>not</em> varargs. 440 * The method instance is also marked synthetic, since the 441 * method (by definition) does not appear in Java source code. 442 * <p> 443 * The JVM is allowed to reify this method as instance metadata. 444 * For example, {@code invokeBasic} is always reified. 445 * But the JVM may instead call {@code linkMethod}. 446 * If the result is an * ordered pair of a {@code (method, appendix)}, 447 * the method gets all the arguments (0..N inclusive) 448 * plus the appendix (N+1), and uses the appendix to complete the call. 449 * In this way, one reusable method (called a "linker method") 450 * can perform the function of any number of polymorphic instance 451 * methods. 452 * <p> 453 * Linker methods are allowed to be weakly typed, with any or 454 * all references rewritten to {@code Object} and any primitives 455 * (except {@code long}/{@code float}/{@code double}) 456 * rewritten to {@code int}. 457 * A linker method is trusted to return a strongly typed result, 458 * according to the specific method type descriptor of the 459 * signature-polymorphic instance it is emulating. 460 * This can involve (as necessary) a dynamic check using 461 * data extracted from the appendix argument. 462 * <p> 463 * The JVM does not inspect the appendix, other than to pass 464 * it verbatim to the linker method at every call. 465 * This means that the JDK runtime has wide latitude 466 * for choosing the shape of each linker method and its 467 * corresponding appendix. 468 * Linker methods should be generated from {@code LambdaForm}s 469 * so that they do not become visible on stack traces. 470 * <p> 471 * The {@code linkMethod} call is free to omit the appendix 472 * (returning null) and instead emulate the required function 473 * completely in the linker method. 474 * As a corner case, if N==255, no appendix is possible. 475 * In this case, the method returned must be custom-generated to 476 * perform any needed type checking. 477 * <p> 478 * If the JVM does not reify a method at a call site, but instead 479 * calls {@code linkMethod}, the corresponding call represented 480 * in the bytecodes may mention a valid method which is not 481 * representable with a {@code MemberName}. 482 * Therefore, use cases for {@code linkMethod} tend to correspond to 483 * special cases in reflective code such as {@code findVirtual} 484 * or {@code revealDirect}. 485 */ 486 static MemberName linkMethod(Class<?> callerClass, int refKind, 487 Class<?> defc, String name, Object type, 488 Object[] appendixResult) { 489 if (!TRACE_METHOD_LINKAGE) 490 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 491 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult); 492 } 493 static MemberName linkMethodImpl(Class<?> callerClass, int refKind, 494 Class<?> defc, String name, Object type, 495 Object[] appendixResult) { 496 try { 497 if (refKind == REF_invokeVirtual) { 498 if (defc == MethodHandle.class) { 499 return Invokers.methodHandleInvokeLinkerMethod( 500 name, fixMethodType(callerClass, type), appendixResult); 501 } else if (defc == VarHandle.class) { 502 return varHandleOperationLinkerMethod( 503 name, fixMethodType(callerClass, type), appendixResult); 504 } 505 } 506 } catch (Error e) { 507 // Pass through an Error, including say StackOverflowError or 508 // OutOfMemoryError 509 throw e; 510 } catch (Throwable ex) { 511 // Wrap anything else in LinkageError 512 throw new LinkageError(ex.getMessage(), ex); 513 } 514 throw new LinkageError("no such method "+defc.getName()+"."+name+type); 515 } 516 private static MethodType fixMethodType(Class<?> callerClass, Object type) { 517 if (type instanceof MethodType) 518 return (MethodType) type; 519 else 520 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader()); 521 } 522 // Tracing logic: 523 static MemberName linkMethodTracing(Class<?> callerClass, int refKind, 524 Class<?> defc, String name, Object type, 525 Object[] appendixResult) { 526 System.out.println("linkMethod "+defc.getName()+"."+ 527 name+type+"/"+Integer.toHexString(refKind)); 528 try { 529 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 530 System.out.println("linkMethod => "+res+" + "+appendixResult[0]); 531 return res; 532 } catch (Throwable ex) { 533 System.out.println("linkMethod => throw "+ex); 534 throw ex; 535 } 536 } 537 538 /** 539 * Obtain the method to link to the VarHandle operation. 540 * This method is located here and not in Invokers to avoid 541 * initializing that and other classes early on in VM bootup. 542 */ 543 private static MemberName varHandleOperationLinkerMethod(String name, 544 MethodType mtype, 545 Object[] appendixResult) { 546 // Get the signature method type 547 final MethodType sigType = mtype.basicType(); 548 549 // Get the access kind from the method name 550 VarHandle.AccessMode ak; 551 try { 552 ak = VarHandle.AccessMode.valueFromMethodName(name); 553 } catch (IllegalArgumentException e) { 554 throw MethodHandleStatics.newInternalError(e); 555 } 556 557 // Create the appendix descriptor constant 558 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal()); 559 appendixResult[0] = ad; 560 561 if (MethodHandleStatics.VAR_HANDLE_GUARDS) { 562 // If not polymorphic in the return type, such as the compareAndSet 563 // methods that return boolean 564 Class<?> guardReturnType = sigType.returnType(); 565 if (ak.at.isMonomorphicInReturnType) { 566 if (ak.at.returnType != mtype.returnType()) { 567 // The caller contains a different return type than that 568 // defined by the method 569 throw newNoSuchMethodErrorOnVarHandle(name, mtype); 570 } 571 // Adjust the return type of the signature method type 572 guardReturnType = ak.at.returnType; 573 } 574 575 // Get the guard method type for linking 576 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2]; 577 // VarHandle at start 578 guardParams[0] = VarHandle.class; 579 for (int i = 0; i < sigType.parameterCount(); i++) { 580 guardParams[i + 1] = sigType.parameterType(i); 581 } 582 // Access descriptor at end 583 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class; 584 MethodType guardType = MethodType.methodType(guardReturnType, guardParams, true); 585 586 MemberName linker = new MemberName( 587 VarHandleGuards.class, getVarHandleGuardMethodName(guardType), 588 guardType, REF_invokeStatic); 589 590 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker, 591 VarHandleGuards.class, LM_TRUSTED); 592 if (linker != null) { 593 return linker; 594 } 595 // Fall back to lambda form linkage if guard method is not available 596 // TODO Optionally log fallback ? 597 } 598 return Invokers.varHandleInvokeLinkerMethod(mtype); 599 } 600 static String getVarHandleGuardMethodName(MethodType guardType) { 601 String prefix = "guard_"; 602 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount()); 603 604 sb.append(prefix); 605 for (int i = 1; i < guardType.parameterCount() - 1; i++) { 606 Class<?> pt = guardType.parameterType(i); 607 sb.append(getCharType(pt)); 608 } 609 sb.append('_').append(getCharType(guardType.returnType())); 610 return sb.toString(); 611 } 612 static char getCharType(Class<?> pt) { 613 return Wrapper.forBasicType(pt).basicTypeChar(); 614 } 615 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) { 616 return new NoSuchMethodError("VarHandle." + name + mtype); 617 } 618 619 /** 620 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help. 621 * It will make an up-call to this method. (Do not change the name or signature.) 622 * The type argument is a Class for field requests and a MethodType for non-fields. 623 * <p> 624 * Recent versions of the JVM may also pass a resolved MemberName for the type. 625 * In that case, the name is ignored and may be null. 626 */ 627 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind, 628 Class<?> defc, String name, Object type) { 629 try { 630 Lookup lookup = IMPL_LOOKUP.in(callerClass); 631 assert(refKindIsValid(refKind)); 632 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type); 633 } catch (ReflectiveOperationException ex) { 634 throw mapLookupExceptionToError(ex); 635 } 636 } 637 638 /** 639 * Map a reflective exception to a linkage error. 640 */ 641 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) { 642 LinkageError err; 643 if (ex instanceof IllegalAccessException) { 644 Throwable cause = ex.getCause(); 645 if (cause instanceof AbstractMethodError) { 646 return (AbstractMethodError) cause; 647 } else { 648 err = new IllegalAccessError(ex.getMessage()); 649 } 650 } else if (ex instanceof NoSuchMethodException) { 651 err = new NoSuchMethodError(ex.getMessage()); 652 } else if (ex instanceof NoSuchFieldException) { 653 err = new NoSuchFieldError(ex.getMessage()); 654 } else { 655 err = new IncompatibleClassChangeError(); 656 } 657 return initCauseFrom(err, ex); 658 } 659 660 /** 661 * Use best possible cause for err.initCause(), substituting the 662 * cause for err itself if the cause has the same (or better) type. 663 */ 664 static <E extends Error> E initCauseFrom(E err, Exception ex) { 665 Throwable th = ex.getCause(); 666 @SuppressWarnings("unchecked") 667 final Class<E> Eclass = (Class<E>) err.getClass(); 668 if (Eclass.isInstance(th)) 669 return Eclass.cast(th); 670 err.initCause(th == null ? ex : th); 671 return err; 672 } 673 674 /** 675 * Is this method a caller-sensitive method? 676 * I.e., does it call Reflection.getCallerClass or a similar method 677 * to ask about the identity of its caller? 678 */ 679 static boolean isCallerSensitive(MemberName mem) { 680 if (!mem.isInvocable()) return false; // fields are not caller sensitive 681 682 return mem.isCallerSensitive() || canBeCalledVirtual(mem); 683 } 684 685 static boolean canBeCalledVirtual(MemberName mem) { 686 assert(mem.isInvocable()); 687 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class); 688 } 689 690 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) { 691 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass(); 692 if (symbolicRefClass == definingClass) return true; 693 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false; 694 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef 695 symbolicRefClass.isInterface()); // Mdef implements Msym 696 } 697 }