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 WEAK_CLASS = 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 }