1 /*
2 * Copyright (c) 2008, 2021, 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, // constructor117 MN_IS_FIELD = 0x00040000, // field118 MN_IS_TYPE = 0x00080000, // nested type119 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected120 MN_TRUSTED_FINAL = 0x00200000, // trusted final field121 MN_REFERENCE_KIND_SHIFT = 24, // refKind122 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 wont 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 (callSite instanceof ConstantCallSite) {
285 appendixResult[0] = callSite.dynamicInvoker();
286 return Invokers.linkToTargetMethod(type);
287 } else {
288 appendixResult[0] = callSite;
289 return Invokers.linkToCallSiteMethod(type);
290 }
291 }
292 // Tracing logic:
293 static MemberName linkCallSiteTracing(Class<?> caller,
294 MethodHandle bootstrapMethod,
295 String name, MethodType type,
296 Object staticArguments,
297 Object[] appendixResult) {
298 Object bsmReference = bootstrapMethod.internalMemberName();
299 if (bsmReference == null) bsmReference = bootstrapMethod;
300 String staticArglist = staticArglistForTrace(staticArguments);
301 System.out.println("linkCallSite "+caller.getName()+" "+
302 bsmReference+" "+
303 name+type+"/"+staticArglist);
304 try {
305 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
306 staticArguments, appendixResult);
307 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
308 return res;
309 } catch (Throwable ex) {
310 ex.printStackTrace(); // print now in case exception is swallowed
311 System.out.println("linkCallSite => throw "+ex);
312 throw ex;
313 }
314 }
315
316 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
317 static Object linkDynamicConstant(Object callerObj,
318 Object bootstrapMethodObj,
319 Object nameObj, Object typeObj,
320 Object staticArguments) {
321 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
322 Class<?> caller = (Class<?>)callerObj;
323 String name = nameObj.toString().intern();
324 Class<?> type = (Class<?>)typeObj;
325 if (!TRACE_METHOD_LINKAGE)
326 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
327 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
328 }
329
330 static Object linkDynamicConstantImpl(Class<?> caller,
331 MethodHandle bootstrapMethod,
332 String name, Class<?> type,
333 Object staticArguments) {
334 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
335 }
336
337 private static String staticArglistForTrace(Object staticArguments) {
338 if (staticArguments instanceof Object[])
339 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments);
340 if (staticArguments instanceof int[])
341 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments);
342 if (staticArguments == null)
343 return "BSA0=null";
344 return "BSA1="+staticArguments;
345 }
346
347 // Tracing logic:
348 static Object linkDynamicConstantTracing(Class<?> caller,
349 MethodHandle bootstrapMethod,
350 String name, Class<?> type,
351 Object staticArguments) {
352 Object bsmReference = bootstrapMethod.internalMemberName();
353 if (bsmReference == null) bsmReference = bootstrapMethod;
354 String staticArglist = staticArglistForTrace(staticArguments);
355 System.out.println("linkDynamicConstant "+caller.getName()+" "+
356 bsmReference+" "+
357 name+type+"/"+staticArglist);
358 try {
359 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
360 System.out.println("linkDynamicConstantImpl => "+res);
361 return res;
362 } catch (Throwable ex) {
363 ex.printStackTrace(); // print now in case exception is swallowed
364 System.out.println("linkDynamicConstant => throw "+ex);
365 throw ex;
366 }
367 }
368
369 /** The JVM is requesting pull-mode bootstrap when it provides
370 * a tuple of the form int[]{ argc, vmindex }.
371 * The BSM is expected to call back to the JVM using the caller
372 * class and vmindex to resolve the static arguments.
373 */
374 static boolean staticArgumentsPulled(Object staticArguments) {
375 return staticArguments instanceof int[];
376 }
377
378 /** A BSM runs in pull-mode if and only if its sole arguments
379 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
380 * to those types, and it is not of variable arity.
381 * Excluding error cases, we can just test that the arity is a constant 2.
382 *
383 * NOTE: This method currently returns false, since pulling is not currently
384 * exposed to a BSM. When pull mode is supported the method block will be
385 * replaced with currently commented out code.
386 */
387 static boolean isPullModeBSM(MethodHandle bsm) {
388 return false;
389 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
390 }
391
392 /**
393 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
394 */
395 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
396 return MethodType.makeImpl(rtype, ptypes, true);
397 }
398
399 /**
400 * The JVM wants to link a call site that requires a dynamic type check.
401 * Name is a type-checking invoker, invokeExact or invoke.
402 * Return a JVM method (MemberName) to handle the invoking.
403 * The method assumes the following arguments on the stack:
404 * 0: the method handle being invoked
405 * 1-N: the arguments to the method handle invocation
406 * N+1: an optional, implicitly added argument (typically the given MethodType)
407 * <p>
408 * The nominal method at such a call site is an instance of
409 * a signature-polymorphic method (see @PolymorphicSignature).
410 * Such method instances are user-visible entities which are
411 * "split" from the generic placeholder method in {@code MethodHandle}.
412 * (Note that the placeholder method is not identical with any of
413 * its instances. If invoked reflectively, is guaranteed to throw an
414 * {@code UnsupportedOperationException}.)
415 * If the signature-polymorphic method instance is ever reified,
416 * it appears as a "copy" of the original placeholder
417 * (a native final member of {@code MethodHandle}) except
418 * that its type descriptor has shape required by the instance,
419 * and the method instance is <em>not</em> varargs.
420 * The method instance is also marked synthetic, since the
421 * method (by definition) does not appear in Java source code.
422 * <p>
423 * The JVM is allowed to reify this method as instance metadata.
424 * For example, {@code invokeBasic} is always reified.
425 * But the JVM may instead call {@code linkMethod}.
426 * If the result is an * ordered pair of a {@code (method, appendix)},
427 * the method gets all the arguments (0..N inclusive)
428 * plus the appendix (N+1), and uses the appendix to complete the call.
429 * In this way, one reusable method (called a "linker method")
430 * can perform the function of any number of polymorphic instance
431 * methods.
432 * <p>
433 * Linker methods are allowed to be weakly typed, with any or
434 * all references rewritten to {@code Object} and any primitives
435 * (except {@code long}/{@code float}/{@code double})
436 * rewritten to {@code int}.
437 * A linker method is trusted to return a strongly typed result,
438 * according to the specific method type descriptor of the
439 * signature-polymorphic instance it is emulating.
440 * This can involve (as necessary) a dynamic check using
441 * data extracted from the appendix argument.
442 * <p>
443 * The JVM does not inspect the appendix, other than to pass
444 * it verbatim to the linker method at every call.
445 * This means that the JDK runtime has wide latitude
446 * for choosing the shape of each linker method and its
447 * corresponding appendix.
448 * Linker methods should be generated from {@code LambdaForm}s
449 * so that they do not become visible on stack traces.
450 * <p>
451 * The {@code linkMethod} call is free to omit the appendix
452 * (returning null) and instead emulate the required function
453 * completely in the linker method.
454 * As a corner case, if N==255, no appendix is possible.
455 * In this case, the method returned must be custom-generated to
456 * perform any needed type checking.
457 * <p>
458 * If the JVM does not reify a method at a call site, but instead
459 * calls {@code linkMethod}, the corresponding call represented
460 * in the bytecodes may mention a valid method which is not
461 * representable with a {@code MemberName}.
462 * Therefore, use cases for {@code linkMethod} tend to correspond to
463 * special cases in reflective code such as {@code findVirtual}
464 * or {@code revealDirect}.
465 */
466 static MemberName linkMethod(Class<?> callerClass, int refKind,
467 Class<?> defc, String name, Object type,
468 Object[] appendixResult) {
469 if (!TRACE_METHOD_LINKAGE)
470 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
471 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
472 }
473 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
474 Class<?> defc, String name, Object type,
475 Object[] appendixResult) {
476 try {
477 if (refKind == REF_invokeVirtual) {
478 if (defc == MethodHandle.class) {
479 return Invokers.methodHandleInvokeLinkerMethod(
480 name, fixMethodType(callerClass, type), appendixResult);
481 } else if (defc == VarHandle.class) {
482 return varHandleOperationLinkerMethod(
483 name, fixMethodType(callerClass, type), appendixResult);
484 }
485 }
486 } catch (Error e) {
487 // Pass through an Error, including say StackOverflowError or
488 // OutOfMemoryError
489 throw e;
490 } catch (Throwable ex) {
491 // Wrap anything else in LinkageError
492 throw new LinkageError(ex.getMessage(), ex);
493 }
494 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
495 }
496 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
497 if (type instanceof MethodType)
498 return (MethodType) type;
499 else
500 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
501 }
502 // Tracing logic:
503 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
504 Class<?> defc, String name, Object type,
505 Object[] appendixResult) {
506 System.out.println("linkMethod "+defc.getName()+"."+
507 name+type+"/"+Integer.toHexString(refKind));
508 try {
509 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
510 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
511 return res;
512 } catch (Throwable ex) {
513 System.out.println("linkMethod => throw "+ex);
514 throw ex;
515 }
516 }
517
518 /**
519 * Obtain the method to link to the VarHandle operation.
520 * This method is located here and not in Invokers to avoid
521 * initializing that and other classes early on in VM bootup.
522 */
523 private static MemberName varHandleOperationLinkerMethod(String name,
524 MethodType mtype,
525 Object[] appendixResult) {
526 // Get the signature method type
527 final MethodType sigType = mtype.basicType();
528
529 // Get the access kind from the method name
530 VarHandle.AccessMode ak;
531 try {
532 ak = VarHandle.AccessMode.valueFromMethodName(name);
533 } catch (IllegalArgumentException e) {
534 throw MethodHandleStatics.newInternalError(e);
535 }
536
537 // Create the appendix descriptor constant
538 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
539 appendixResult[0] = ad;
540
541 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
542 // If not polymorphic in the return type, such as the compareAndSet
543 // methods that return boolean
544 Class<?> guardReturnType = sigType.returnType();
545 if (ak.at.isMonomorphicInReturnType) {
546 if (ak.at.returnType != mtype.returnType()) {
547 // The caller contains a different return type than that
548 // defined by the method
549 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
550 }
551 // Adjust the return type of the signature method type
552 guardReturnType = ak.at.returnType;
553 }
554
555 // Get the guard method type for linking
556 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
557 // VarHandle at start
558 guardParams[0] = VarHandle.class;
559 for (int i = 0; i < sigType.parameterCount(); i++) {
560 guardParams[i + 1] = sigType.parameterType(i);
561 }
562 // Access descriptor at end
563 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
564 MethodType guardType = MethodType.makeImpl(guardReturnType, guardParams, true);
565
566 MemberName linker = new MemberName(
567 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
568 guardType, REF_invokeStatic);
569
570 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
571 VarHandleGuards.class, LM_TRUSTED);
572 if (linker != null) {
573 return linker;
574 }
575 // Fall back to lambda form linkage if guard method is not available
576 // TODO Optionally log fallback ?
577 }
578 return Invokers.varHandleInvokeLinkerMethod(mtype);
579 }
580 static String getVarHandleGuardMethodName(MethodType guardType) {
581 String prefix = "guard_";
582 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
583
584 sb.append(prefix);
585 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
586 Class<?> pt = guardType.parameterType(i);
587 sb.append(getCharType(pt));
588 }
589 sb.append('_').append(getCharType(guardType.returnType()));
590 return sb.toString();
591 }
592 static char getCharType(Class<?> pt) {
593 return Wrapper.forBasicType(pt).basicTypeChar();
594 }
595 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
596 return new NoSuchMethodError("VarHandle." + name + mtype);
597 }
598
599 /**
600 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
601 * It will make an up-call to this method. (Do not change the name or signature.)
602 * The type argument is a Class for field requests and a MethodType for non-fields.
603 * <p>
604 * Recent versions of the JVM may also pass a resolved MemberName for the type.
605 * In that case, the name is ignored and may be null.
606 */
607 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
608 Class<?> defc, String name, Object type) {
609 try {
610 Lookup lookup = IMPL_LOOKUP.in(callerClass);
611 assert(refKindIsValid(refKind));
612 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
613 } catch (ReflectiveOperationException ex) {
614 throw mapLookupExceptionToError(ex);
615 }
616 }
617
618 /**
619 * Map a reflective exception to a linkage error.
620 */
621 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
622 LinkageError err;
623 if (ex instanceof IllegalAccessException) {
624 Throwable cause = ex.getCause();
625 if (cause instanceof AbstractMethodError) {
626 return (AbstractMethodError) cause;
627 } else {
628 err = new IllegalAccessError(ex.getMessage());
629 }
630 } else if (ex instanceof NoSuchMethodException) {
631 err = new NoSuchMethodError(ex.getMessage());
632 } else if (ex instanceof NoSuchFieldException) {
633 err = new NoSuchFieldError(ex.getMessage());
634 } else {
635 err = new IncompatibleClassChangeError();
636 }
637 return initCauseFrom(err, ex);
638 }
639
640 /**
641 * Use best possible cause for err.initCause(), substituting the
642 * cause for err itself if the cause has the same (or better) type.
643 */
644 static <E extends Error> E initCauseFrom(E err, Exception ex) {
645 Throwable th = ex.getCause();
646 @SuppressWarnings("unchecked")
647 final Class<E> Eclass = (Class<E>) err.getClass();
648 if (Eclass.isInstance(th))
649 return Eclass.cast(th);
650 err.initCause(th == null ? ex : th);
651 return err;
652 }
653
654 /**
655 * Is this method a caller-sensitive method?
656 * I.e., does it call Reflection.getCallerClass or a similar method
657 * to ask about the identity of its caller?
658 */
659 static boolean isCallerSensitive(MemberName mem) {
660 if (!mem.isInvocable()) return false; // fields are not caller sensitive
661
662 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
663 }
664
665 static boolean canBeCalledVirtual(MemberName mem) {
666 assert(mem.isInvocable());
667 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class);
668 }
669
670 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
671 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
672 if (symbolicRefClass == definingClass) return true;
673 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
674 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
675 symbolicRefClass.isInterface()); // Mdef implements Msym
676 }
677 }
--- EOF ---