1 /*
2 * Copyright (c) 2008, 2018, 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 jdk.internal.reflect.ConstantPool;
30 import sun.invoke.util.Wrapper;
31
32 import java.lang.constant.ClassDesc;
33 import java.lang.constant.MethodTypeDesc;
34 import java.lang.invoke.AbstractBootstrapCallInfo.TypeView;
35 import java.lang.invoke.BootstrapMethodInvoker.VM_BSCI;
36 import java.lang.invoke.MethodHandles.Lookup;
37 import java.lang.reflect.Field;
38 import java.util.Arrays;
39
40 import static java.lang.invoke.MethodHandleNatives.Constants.*;
41 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE;
42 import static java.lang.invoke.MethodHandleStatics.TRACE_RESOLVE;
43 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
44
45 /**
46 * The JVM interface for the method handles package is all here.
47 * This is an interface internal and private to an implementation of JSR 292.
48 * <em>This class is not part of the JSR 292 standard.</em>
49 * @author jrose
50 */
51 class MethodHandleNatives {
52
53 private MethodHandleNatives() { } // static only
54
55 /// MemberName support
56
57 static native void init(MemberName self, Object ref);
58 static native void expand(MemberName self);
59 static native MemberName resolve(MemberName self, Class<?> caller,
60 boolean speculativeResolve) throws LinkageError, ClassNotFoundException;
61 static native int getMembers(Class<?> defc, String matchName, String matchSig,
62 int matchFlags, Class<?> caller, int skip, MemberName[] results);
63
64 /// Field layout queries parallel to jdk.internal.misc.Unsafe:
65 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
66 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
67 static native Object staticFieldBase(MemberName self); // e.g., returns clazz
68 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
69
70 /// CallSite support
71
72 /** Tell the JVM that we need to change the target of a CallSite. */
73 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
74 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
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
80 static CallSiteContext make(CallSite cs) {
81 final CallSiteContext newContext = new CallSiteContext();
82 // CallSite instance is tracked by a Cleanable which clears native
83 // structures allocated for CallSite context. Though the CallSite can
84 // become unreachable, its Context is retained by the Cleanable instance
85 // (which is referenced from Cleaner instance which is referenced from
86 // CleanerFactory class) until cleanup is performed.
87 CleanerFactory.cleaner().register(cs, newContext);
88 return newContext;
89 }
90
91 @Override
92 public void run() {
93 MethodHandleNatives.clearCallSiteContext(this);
94 }
95 }
96
97 /** Invalidate all recorded nmethods. */
98 private static native void clearCallSiteContext(CallSiteContext context);
99
100 private static native void registerNatives();
101 static {
102 registerNatives();
103 }
104
105 /**
106 * Compile-time constants go here. This collection exists not only for
107 * reference from clients, but also for ensuring the VM and JDK agree on the
108 * values of these constants (see {@link #verifyConstants()}).
109 */
110 static class Constants {
111 Constants() { } // static only
112
113 static final int
114 MN_IS_METHOD = 0x00010000, // method (not constructor)
115 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
116 MN_IS_FIELD = 0x00040000, // field
117 MN_IS_TYPE = 0x00080000, // nested type
118 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
119 MN_REFERENCE_KIND_SHIFT = 24, // refKind
120 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
121 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
122 MN_SEARCH_SUPERCLASSES = 0x00100000,
123 MN_SEARCH_INTERFACES = 0x00200000;
124
125 /**
126 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
127 */
128 static final byte
129 REF_NONE = 0, // null value
130 REF_getField = 1,
131 REF_getStatic = 2,
132 REF_putField = 3,
133 REF_putStatic = 4,
134 REF_invokeVirtual = 5,
135 REF_invokeStatic = 6,
136 REF_invokeSpecial = 7,
137 REF_newInvokeSpecial = 8,
138 REF_invokeInterface = 9,
139 REF_LIMIT = 10;
140
141 /**
142 * Flag values which affect the copying of bootstrap static arguments.
143 */
144 static final byte BAR_IFPRESENT = 0, BAR_FORCE = 1, BAR_SYMREF = 2;
145 }
146
147 static boolean refKindIsValid(int refKind) {
148 return (refKind > REF_NONE && refKind < REF_LIMIT);
149 }
150 static boolean refKindIsField(byte refKind) {
151 assert(refKindIsValid(refKind));
152 return (refKind <= REF_putStatic);
153 }
154 static boolean refKindIsGetter(byte refKind) {
155 assert(refKindIsValid(refKind));
156 return (refKind <= REF_getStatic);
157 }
158 static boolean refKindIsSetter(byte refKind) {
159 return refKindIsField(refKind) && !refKindIsGetter(refKind);
160 }
161 static boolean refKindIsMethod(byte refKind) {
162 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
163 }
164 static boolean refKindIsConstructor(byte refKind) {
165 return (refKind == REF_newInvokeSpecial);
166 }
167 static boolean refKindHasReceiver(byte refKind) {
168 assert(refKindIsValid(refKind));
169 return (refKind & 1) != 0;
170 }
171 static boolean refKindIsStatic(byte refKind) {
172 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
173 }
174 static boolean refKindDoesDispatch(byte refKind) {
175 assert(refKindIsValid(refKind));
176 return (refKind == REF_invokeVirtual ||
177 refKind == REF_invokeInterface);
178 }
179 static {
180 final int HR_MASK = ((1 << REF_getField) |
181 (1 << REF_putField) |
182 (1 << REF_invokeVirtual) |
183 (1 << REF_invokeSpecial) |
184 (1 << REF_invokeInterface)
185 );
186 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
187 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
188 }
189 }
190 static String refKindName(byte refKind) {
191 assert(refKindIsValid(refKind));
192 switch (refKind) {
193 case REF_getField: return "getField";
194 case REF_getStatic: return "getStatic";
195 case REF_putField: return "putField";
196 case REF_putStatic: return "putStatic";
197 case REF_invokeVirtual: return "invokeVirtual";
198 case REF_invokeStatic: return "invokeStatic";
199 case REF_invokeSpecial: return "invokeSpecial";
200 case REF_newInvokeSpecial: return "newInvokeSpecial";
201 case REF_invokeInterface: return "invokeInterface";
202 default: return "REF_???";
203 }
204 }
205
206 private static native int getNamedCon(int which, Object[] name);
207 static boolean verifyConstants() {
208 // This code requires ADVERTISE_CON_VALUES to be turned on
209 // in methodHandles.cpp, which is usually only true in debug builds.
210 // If that is not the case, then getNamedCon returns nothing and
211 // the loop body never runs.
212 Object[] box = { null };
213 for (int i = 0; ; i++) {
214 box[0] = null;
215 int vmval = getNamedCon(i, box);
216 if (box[0] == null) break;
217 String name = (String) box[0];
218 try {
219 Field con = Constants.class.getDeclaredField(name);
220 int jval = con.getInt(null);
221 if (TRACE_RESOLVE) {
222 System.out.println("[CON_RESOLVE] " + name + " = " + vmval);
223 }
224 if (jval == vmval) continue;
225 String err = (name+": JVM has "+vmval+" while Java has "+jval);
226 throw new InternalError(err);
227 } catch (NoSuchFieldException | IllegalAccessException ex) {
228 String err = (name+": JVM has "+vmval+" which Java does not define");
229 // ignore exotic ops the JVM cares about; we just wont issue them
230 //System.err.println("warning: "+err);
231 continue;
232 }
233 }
234 return true;
235 }
236 static {
237 if (TRACE_RESOLVE) {
238 boolean ok = verifyConstants();
239 assert(ok);
240 } else {
241 assert(verifyConstants());
242 }
243 }
244
245 // Up-calls from the JVM.
246 // These must NOT be public.
247
248 /**
249 * All bootstrap method invocations funnel through this single method.
250 * A large subset of the values of the JVM's BootstrapInfo structure is
251 * made available here, basically everything that can be easily computed
252 * without a detectable side effect or exception. The callee is
253 * invited to call back the JVM for more information.
254 */
255 static Object bootstrapMethodHelper(ConstantPool pool,
256 int bssIndex,
257 int indyIndex,
258 int argc,
259 MethodHandle bsm,
260 String name,
261 Object type, // Class or MethodType or String
262 int[] argIndexes,
263 Object[] argValues,
264 Object request,
265 Object[] appendixResult) {
266 assert((appendixResult != null) == (indyIndex != 0));
267 assert(request == (indyIndex == 0 ? null : CallSite.class));
268 // Special case: If the bsm does not begin with Lookup, *and*
269 // it is a CallSite request (i.e., legacy from Java 7), then
270 // forcibly convert the leading type to Lookup.
271 if (request == CallSite.class && BootstrapMethodInvoker.isExpressionBSM(bsm)) {
272 bsm = BootstrapMethodInvoker.forceLookupParameter(bsm);
273 assert(!BootstrapMethodInvoker.isExpressionBSM(bsm)); // properly wrapped
274 }
275 // Make a full-power lookup into the CP (a privileged operation).
276 Lookup lookup = IMPL_LOOKUP.in(pool.getHolder());
277 // Process the type: { field, method } x { resolved, string }
278 TypeView<Class<?>> ftype = null;
279 TypeView<MethodType> mtype = null;
280 if (type instanceof MethodType) {
281 mtype = new TypeView<>((MethodType)type);
282 } else if (type instanceof Class<?>) {
283 ftype = new TypeView<>((Class<?>)type);
284 } else {
285 // JVM was not able to resolve the type. Keep the ball rolling.
286 String desc = (String) type;
287 if (desc.startsWith("("))
288 mtype = new TypeView<>(MethodTypeDesc.ofDescriptor(desc), lookup);
289 else
290 ftype = new TypeView<>(ClassDesc.ofDescriptor(desc), lookup);
291 }
292 // If VM is pushing up argument values, use them. Otherwise make a fresh buffer.
293 if (argValues == null) {
294 argValues = new Object[argc];
295 } else {
296 assert(argValues.length == argc);
297 // The JVM resolves CONSTANT_Integer CP items without calling Integer.valueOf.
298 BootstrapMethodInvoker.maybeReBoxElements(argValues);
299 }
300 // Make a BSCI wrapper for all of this state.
301 VM_BSCI<?> bsci;
302 // (The following if/then/else is required to make the generic types match up.)
303 if (ftype != null)
304 bsci = new VM_BSCI<>(pool, bssIndex, indyIndex, bsm, name, ftype, argValues);
305 else
306 bsci = new VM_BSCI<>(pool, bssIndex, indyIndex, bsm, name, mtype, argValues);
307 // If VM is passing up argument indexes, accept that also.
308 if (argIndexes != null) bsci.setArgIndexes(argIndexes);
309 // Finish the job by invoking the fresh BSCI under the Lookup:
310 if (!TRACE_METHOD_LINKAGE) {
311 Object res = BootstrapMethodInvoker.invoke(lookup, bsci);
312 if (appendixResult == null) {
313 return res;
314 }
315 return encodeBindingViaAppendix(bsci, res, appendixResult);
316 }
317
318 // Tracing logic follows:
319 String linkWhat = "[TRACE_METHOD_LINKAGE] link"
320 + ((request == null) ? "DynamicConstant"
321 : request instanceof Class ? ((Class<?>)request).getSimpleName()
322 : request);
323 System.out.println(linkWhat+" "+bsci.toString());
324 try {
325 Object res = BootstrapMethodInvoker.invoke(lookup, bsci);
326 if (appendixResult == null) {
327 System.out.println(linkWhat+" => "+res); return res;
328 }
329 MemberName mem = encodeBindingViaAppendix(bsci, res, appendixResult);
330 System.out.println(linkWhat+" => "+res+" => "+mem+" + "+appendixResult[0]);
331 return mem;
332 } catch (Throwable ex) {
333 ex.printStackTrace(); // print now in case exception is swallowed
334 System.out.println(linkWhat+" => throw "+ex);
335 throw ex;
336 }
337 }
338
339 // Follow-up step to bootstrapMethodHelper, when an appendix was provided.
340 // The basic result was a specific behavior; factor it (for the VM's sake)
341 // into a generic chunk of argument shuffling plus a datum.
342 static MemberName encodeBindingViaAppendix(BootstrapCallInfo<?> bsci, Object binding, Object[] appendixResult) {
343 MethodType type = (MethodType) bsci.invocationType();
344 MemberName result;
345 MethodType resultType;
346 Object appendix;
347 if (binding instanceof ConstantCallSite) {
348 ConstantCallSite ccs = (ConstantCallSite) binding;
349 result = Invokers.linkToTargetMethod(type);
350 appendix = ccs.getTarget();
351 resultType = ((MethodHandle) appendix).type();
352 } else if (binding instanceof CallSite) {
353 result = Invokers.linkToCallSiteMethod(type);
354 appendix = binding;
355 resultType = ((CallSite) appendix).type();
356 } else if (binding instanceof MethodHandle) {
357 result = Invokers.linkToTargetMethod(type);
358 appendix = binding;
359 resultType = ((MethodHandle) appendix).type();
360 } else {
361 throw new InternalError("should not get here: "+binding+":"+binding.getClass().getName());
362 }
363 // Double-check the function type also.
364 if (!resultType.equals(type)) {
365 throw new InternalError("should not get here: "+binding+type);
366 }
367 // After type checking, give the JVM the two bits it needs
368 // to implement the call site: A behavior method, and a cookie.
369 appendixResult[0] = appendix;
370 return result;
371 }
372
373 /**
374 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
375 */
376 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
377 return MethodType.makeImpl(rtype, ptypes, true);
378 }
379
380 /**
381 * The JVM wants to link a call site that requires a dynamic type check.
382 * Name is a type-checking invoker, invokeExact or invoke.
383 * Return a JVM method (MemberName) to handle the invoking.
384 * The method assumes the following arguments on the stack:
385 * 0: the method handle being invoked
386 * 1-N: the arguments to the method handle invocation
387 * N+1: an optional, implicitly added argument (typically the given MethodType)
388 * <p>
389 * The nominal method at such a call site is an instance of
390 * a signature-polymorphic method (see @PolymorphicSignature).
391 * Such method instances are user-visible entities which are
392 * "split" from the generic placeholder method in {@code MethodHandle}.
393 * (Note that the placeholder method is not identical with any of
394 * its instances. If invoked reflectively, is guaranteed to throw an
395 * {@code UnsupportedOperationException}.)
396 * If the signature-polymorphic method instance is ever reified,
397 * it appears as a "copy" of the original placeholder
398 * (a native final member of {@code MethodHandle}) except
399 * that its type descriptor has shape required by the instance,
400 * and the method instance is <em>not</em> varargs.
401 * The method instance is also marked synthetic, since the
402 * method (by definition) does not appear in Java source code.
403 * <p>
404 * The JVM is allowed to reify this method as instance metadata.
405 * For example, {@code invokeBasic} is always reified.
406 * But the JVM may instead call {@code linkMethod}.
407 * If the result is an * ordered pair of a {@code (method, appendix)},
408 * the method gets all the arguments (0..N inclusive)
409 * plus the appendix (N+1), and uses the appendix to complete the call.
410 * In this way, one reusable method (called a "linker method")
411 * can perform the function of any number of polymorphic instance
412 * methods.
413 * <p>
414 * Linker methods are allowed to be weakly typed, with any or
415 * all references rewritten to {@code Object} and any primitives
416 * (except {@code long}/{@code float}/{@code double})
417 * rewritten to {@code int}.
418 * A linker method is trusted to return a strongly typed result,
419 * according to the specific method type descriptor of the
420 * signature-polymorphic instance it is emulating.
421 * This can involve (as necessary) a dynamic check using
422 * data extracted from the appendix argument.
423 * <p>
424 * The JVM does not inspect the appendix, other than to pass
425 * it verbatim to the linker method at every call.
426 * This means that the JDK runtime has wide latitude
427 * for choosing the shape of each linker method and its
428 * corresponding appendix.
429 * Linker methods should be generated from {@code LambdaForm}s
430 * so that they do not become visible on stack traces.
431 * <p>
432 * The {@code linkMethod} call is free to omit the appendix
433 * (returning null) and instead emulate the required function
434 * completely in the linker method.
435 * As a corner case, if N==255, no appendix is possible.
436 * In this case, the method returned must be custom-generated to
437 * to perform any needed type checking.
438 * <p>
439 * If the JVM does not reify a method at a call site, but instead
440 * calls {@code linkMethod}, the corresponding call represented
441 * in the bytecodes may mention a valid method which is not
442 * representable with a {@code MemberName}.
443 * Therefore, use cases for {@code linkMethod} tend to correspond to
444 * special cases in reflective code such as {@code findVirtual}
445 * or {@code revealDirect}.
446 */
447 static MemberName linkMethod(Class<?> callerClass, int refKind,
448 Class<?> defc, String name, Object type,
449 Object[] appendixResult) {
450 if (!TRACE_METHOD_LINKAGE)
451 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
452 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
453 }
454 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
455 Class<?> defc, String name, Object type,
456 Object[] appendixResult) {
457 try {
458 if (refKind == REF_invokeVirtual) {
459 if (defc == MethodHandle.class) {
460 return Invokers.methodHandleInvokeLinkerMethod(
461 name, fixMethodType(callerClass, type), appendixResult);
462 } else if (defc == VarHandle.class) {
463 return varHandleOperationLinkerMethod(
464 name, fixMethodType(callerClass, type), appendixResult);
465 }
466 }
467 } catch (Error e) {
468 // Pass through an Error, including say StackOverflowError or
469 // OutOfMemoryError
470 throw e;
471 } catch (Throwable ex) {
472 // Wrap anything else in LinkageError
473 throw new LinkageError(ex.getMessage(), ex);
474 }
475 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
476 }
477
478 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
479 if (type instanceof MethodType)
480 return (MethodType) type;
481 else
482 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
483 }
484 // Tracing logic:
485 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
486 Class<?> defc, String name, Object type,
487 Object[] appendixResult) {
488 System.out.println("linkMethod "+defc.getName()+"."+
489 name+type+"/"+Integer.toHexString(refKind));
490 try {
491 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
492 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
493 return res;
494 } catch (Throwable ex) {
495 System.out.println("linkMethod => throw "+ex);
496 throw ex;
497 }
498 }
499
500 /**
501 * Obtain the method to link to the VarHandle operation.
502 * This method is located here and not in Invokers to avoid
503 * intializing that and other classes early on in VM bootup.
504 */
505 private static MemberName varHandleOperationLinkerMethod(String name,
506 MethodType mtype,
507 Object[] appendixResult) {
508 // Get the signature method type
509 final MethodType sigType = mtype.basicType();
510
511 // Get the access kind from the method name
512 VarHandle.AccessMode ak;
513 try {
514 ak = VarHandle.AccessMode.valueFromMethodName(name);
515 } catch (IllegalArgumentException e) {
516 throw MethodHandleStatics.newInternalError(e);
517 }
518
519 // Create the appendix descriptor constant
520 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
521 appendixResult[0] = ad;
522
523 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
524 // If not polymorphic in the return type, such as the compareAndSet
525 // methods that return boolean
526 Class<?> guardReturnType = sigType.returnType();
527 if (ak.at.isMonomorphicInReturnType) {
528 if (ak.at.returnType != mtype.returnType()) {
529 // The caller contains a different return type than that
530 // defined by the method
531 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
532 }
533 // Adjust the return type of the signature method type
534 guardReturnType = ak.at.returnType;
535 }
536
537 // Get the guard method type for linking
538 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
539 // VarHandle at start
540 guardParams[0] = VarHandle.class;
541 for (int i = 0; i < sigType.parameterCount(); i++) {
542 guardParams[i + 1] = sigType.parameterType(i);
543 }
544 // Access descriptor at end
545 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
546 MethodType guardType = MethodType.makeImpl(guardReturnType, guardParams, true);
547
548 MemberName linker = new MemberName(
549 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
550 guardType, REF_invokeStatic);
551
552 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
553 VarHandleGuards.class);
554 if (linker != null) {
555 return linker;
556 }
557 // Fall back to lambda form linkage if guard method is not available
558 // TODO Optionally log fallback ?
559 }
560 return Invokers.varHandleInvokeLinkerMethod(ak, mtype);
561 }
562 static String getVarHandleGuardMethodName(MethodType guardType) {
563 String prefix = "guard_";
564 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
565
566 sb.append(prefix);
567 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
568 Class<?> pt = guardType.parameterType(i);
569 sb.append(getCharType(pt));
570 }
571 sb.append('_').append(getCharType(guardType.returnType()));
572 return sb.toString();
573 }
574 static char getCharType(Class<?> pt) {
575 return Wrapper.forBasicType(pt).basicTypeChar();
576 }
577 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
578 return new NoSuchMethodError("VarHandle." + name + mtype);
579 }
580
581 /**
582 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
583 * It will make an up-call to this method. (Do not change the name or signature.)
584 * The type argument is a Class for field requests and a MethodType for non-fields.
585 * <p>
586 * Recent versions of the JVM may also pass a resolved MemberName for the type.
587 * In that case, the name is ignored and may be null.
588 */
589 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
590 Class<?> defc, String name, Object type) {
591 try {
592 Lookup lookup = IMPL_LOOKUP.in(callerClass);
593 assert(refKindIsValid(refKind));
594 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
595 } catch (ReflectiveOperationException ex) {
596 throw mapLookupExceptionToError(ex);
597 }
598 }
599
600 /**
601 * Map a reflective exception to a linkage error.
602 */
603 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
604 LinkageError err;
605 if (ex instanceof IllegalAccessException) {
606 Throwable cause = ex.getCause();
607 if (cause instanceof AbstractMethodError) {
608 return (AbstractMethodError) cause;
609 } else {
610 err = new IllegalAccessError(ex.getMessage());
611 }
612 } else if (ex instanceof NoSuchMethodException) {
613 err = new NoSuchMethodError(ex.getMessage());
614 } else if (ex instanceof NoSuchFieldException) {
615 err = new NoSuchFieldError(ex.getMessage());
616 } else {
617 err = new IncompatibleClassChangeError();
618 }
619 return initCauseFrom(err, ex);
620 }
621
622 /**
623 * Use best possible cause for err.initCause(), substituting the
624 * cause for err itself if the cause has the same (or better) type.
625 */
626 static <E extends Error> E initCauseFrom(E err, Exception ex) {
627 Throwable th = ex.getCause();
628 @SuppressWarnings("unchecked")
629 final Class<E> Eclass = (Class<E>) err.getClass();
630 if (Eclass.isInstance(th))
631 return Eclass.cast(th);
632 err.initCause(th == null ? ex : th);
633 return err;
634 }
635
636 /**
637 * Is this method a caller-sensitive method?
638 * I.e., does it call Reflection.getCallerClass or a similar method
639 * to ask about the identity of its caller?
640 */
641 static boolean isCallerSensitive(MemberName mem) {
642 if (!mem.isInvocable()) return false; // fields are not caller sensitive
643
644 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
645 }
646
647 static boolean canBeCalledVirtual(MemberName mem) {
648 assert(mem.isInvocable());
649 switch (mem.getName()) {
650 case "getContextClassLoader":
651 return canBeCalledVirtual(mem, java.lang.Thread.class);
652 }
653 return false;
654 }
655
656 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
657 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
658 if (symbolicRefClass == definingClass) return true;
659 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
660 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
661 symbolicRefClass.isInterface()); // Mdef implements Msym
662 }
663 }