1 /*
2 * Copyright (c) 2008, 2023, 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
56 //--- Field layout queries parallel to jdk.internal.misc.Unsafe:
57 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
58 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
59 static native Object staticFieldBase(MemberName self); // e.g., returns clazz
60 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
61
62 //--- CallSite support
63
64 /** Tell the JVM that we need to change the target of a CallSite. */
65 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
66 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
67
68 static native void copyOutBootstrapArguments(Class<?> caller, int[] indexInfo,
69 int start, int end,
70 Object[] buf, int pos,
71 boolean resolve,
72 Object ifNotAvailable);
73
74 /** Represents a context to track nmethod dependencies on CallSite instance target. */
75 static class CallSiteContext implements Runnable {
76 //@Injected JVM_nmethodBucket* vmdependencies;
77 //@Injected jlong last_cleanup;
78
79 static CallSiteContext make(CallSite cs) {
80 final CallSiteContext newContext = new CallSiteContext();
81 // CallSite instance is tracked by a Cleanable which clears native
82 // structures allocated for CallSite context. Though the CallSite can
83 // become unreachable, its Context is retained by the Cleanable instance
84 // (which is referenced from Cleaner instance which is referenced from
85 // CleanerFactory class) until cleanup is performed.
86 CleanerFactory.cleaner().register(cs, newContext);
87 return newContext;
88 }
89
90 @Override
91 public void run() {
92 MethodHandleNatives.clearCallSiteContext(this);
93 }
94 }
95
96 /** Invalidate all recorded nmethods. */
97 private static native void clearCallSiteContext(CallSiteContext context);
98
99 private static native void registerNatives();
100 static {
101 registerNatives();
102 }
103
104 /**
105 * Compile-time constants go here. This collection exists not only for
106 * reference from clients, but also for ensuring the VM and JDK agree on the
107 * values of these constants (see {@link #verifyConstants()}).
108 */
109 static class Constants {
110 Constants() { } // static only
111
112 static final int
113 MN_IS_METHOD = 0x00010000, // method (not constructor)
114 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
115 MN_IS_FIELD = 0x00040000, // field
116 MN_IS_TYPE = 0x00080000, // nested type
117 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
118 MN_TRUSTED_FINAL = 0x00200000, // trusted final field
119 MN_HIDDEN_MEMBER = 0x00400000, // members defined in a hidden class or with @Hidden
120 MN_REFERENCE_KIND_SHIFT = 24, // refKind
121 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT;
122
123 /**
124 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
125 */
126 static final byte
127 REF_NONE = 0, // null value
128 REF_getField = 1,
129 REF_getStatic = 2,
130 REF_putField = 3,
131 REF_putStatic = 4,
132 REF_invokeVirtual = 5,
133 REF_invokeStatic = 6,
134 REF_invokeSpecial = 7,
135 REF_newInvokeSpecial = 8,
136 REF_invokeInterface = 9,
137 REF_LIMIT = 10;
138
139 /**
140 * Flags for Lookup.ClassOptions
141 */
142 static final int
143 NESTMATE_CLASS = 0x00000001,
144 HIDDEN_CLASS = 0x00000002,
145 STRONG_LOADER_LINK = 0x00000004,
146 ACCESS_VM_ANNOTATIONS = 0x00000008;
147
148 /**
149 * Lookup modes
150 */
151 static final int
152 LM_MODULE = Lookup.MODULE,
153 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL,
154 LM_TRUSTED = -1;
155
156 }
157
158 static boolean refKindIsValid(int refKind) {
159 return (refKind > REF_NONE && refKind < REF_LIMIT);
160 }
161 static boolean refKindIsField(byte refKind) {
162 assert(refKindIsValid(refKind));
163 return (refKind <= REF_putStatic);
164 }
165 static boolean refKindIsGetter(byte refKind) {
166 assert(refKindIsValid(refKind));
167 return (refKind <= REF_getStatic);
168 }
169 static boolean refKindIsSetter(byte refKind) {
170 return refKindIsField(refKind) && !refKindIsGetter(refKind);
171 }
172 static boolean refKindIsMethod(byte refKind) {
173 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
174 }
175 static boolean refKindIsConstructor(byte refKind) {
176 return (refKind == REF_newInvokeSpecial);
177 }
178 static boolean refKindHasReceiver(byte refKind) {
179 assert(refKindIsValid(refKind));
180 return (refKind & 1) != 0;
181 }
182 static boolean refKindIsStatic(byte refKind) {
183 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
184 }
185 static boolean refKindDoesDispatch(byte refKind) {
186 assert(refKindIsValid(refKind));
187 return (refKind == REF_invokeVirtual ||
188 refKind == REF_invokeInterface);
189 }
190 static {
191 final int HR_MASK = ((1 << REF_getField) |
192 (1 << REF_putField) |
193 (1 << REF_invokeVirtual) |
194 (1 << REF_invokeSpecial) |
195 (1 << REF_invokeInterface)
196 );
197 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
198 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
199 }
200 }
201 static String refKindName(byte refKind) {
202 assert(refKindIsValid(refKind));
203 return switch (refKind) {
204 case REF_getField -> "getField";
205 case REF_getStatic -> "getStatic";
206 case REF_putField -> "putField";
207 case REF_putStatic -> "putStatic";
208 case REF_invokeVirtual -> "invokeVirtual";
209 case REF_invokeStatic -> "invokeStatic";
210 case REF_invokeSpecial -> "invokeSpecial";
211 case REF_newInvokeSpecial -> "newInvokeSpecial";
212 case REF_invokeInterface -> "invokeInterface";
213 default -> "REF_???";
214 };
215 }
216
217 private static native int getNamedCon(int which, Object[] name);
218 static boolean verifyConstants() {
219 Object[] box = { null };
220 for (int i = 0; ; i++) {
221 box[0] = null;
222 int vmval = getNamedCon(i, box);
223 if (box[0] == null) break;
224 String name = (String) box[0];
225 try {
226 Field con = Constants.class.getDeclaredField(name);
227 int jval = con.getInt(null);
228 if (jval == vmval) continue;
229 String err = (name+": JVM has "+vmval+" while Java has "+jval);
230 if (name.equals("CONV_OP_LIMIT")) {
231 System.err.println("warning: "+err);
232 continue;
233 }
234 throw new InternalError(err);
235 } catch (NoSuchFieldException | IllegalAccessException ex) {
236 String err = (name+": JVM has "+vmval+" which Java does not define");
237 // ignore exotic ops the JVM cares about; we just won't issue them
238 //System.err.println("warning: "+err);
239 continue;
240 }
241 }
242 return true;
243 }
244 static {
245 VM.setJavaLangInvokeInited();
246 assert(verifyConstants());
247 }
248
249 // Up-calls from the JVM.
250 // These must NOT be public.
251
252 /**
253 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
254 */
255 static MemberName linkCallSite(Object callerObj,
256 Object bootstrapMethodObj,
257 Object nameObj, Object typeObj,
258 Object staticArguments,
259 Object[] appendixResult) {
260 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
261 Class<?> caller = (Class<?>)callerObj;
262 String name = nameObj.toString().intern();
263 MethodType type = (MethodType)typeObj;
264 if (!TRACE_METHOD_LINKAGE)
265 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
266 staticArguments, appendixResult);
267 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
268 staticArguments, appendixResult);
269 }
270 static MemberName linkCallSiteImpl(Class<?> caller,
271 MethodHandle bootstrapMethod,
272 String name, MethodType type,
273 Object staticArguments,
274 Object[] appendixResult) {
275 CallSite callSite = CallSite.makeSite(bootstrapMethod,
276 name,
277 type,
278 staticArguments,
279 caller);
280 if (TRACE_METHOD_LINKAGE) {
281 MethodHandle target = callSite.getTarget();
282 System.out.println("linkCallSite target class => " + target.getClass().getName());
283 System.out.println("linkCallSite target => " + target.debugString(0));
284 }
285
286 if (callSite instanceof ConstantCallSite) {
287 appendixResult[0] = callSite.dynamicInvoker();
288 return Invokers.linkToTargetMethod(type);
289 } else {
290 appendixResult[0] = callSite;
291 return Invokers.linkToCallSiteMethod(type);
292 }
293 }
294 // Tracing logic:
295 static MemberName linkCallSiteTracing(Class<?> caller,
296 MethodHandle bootstrapMethod,
297 String name, MethodType type,
298 Object staticArguments,
299 Object[] appendixResult) {
300 Object bsmReference = bootstrapMethod.internalMemberName();
301 if (bsmReference == null) bsmReference = bootstrapMethod;
302 String staticArglist = staticArglistForTrace(staticArguments);
303 System.out.println("linkCallSite "+getCallerInfo(caller)+" "+
304 bsmReference+" "+
305 name+type+"/"+staticArglist);
306 try {
307 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
308 staticArguments, appendixResult);
309 System.out.println("linkCallSite linkage => "+res+" + "+appendixResult[0]);
310 return res;
311 } catch (Throwable ex) {
312 ex.printStackTrace(); // print now in case exception is swallowed
313 System.out.println("linkCallSite => throw "+ex);
314 throw ex;
315 }
316 }
317
318 /**
319 * Return a human-readable description of the caller. Something like
320 * "java.base/java.security.Security.<clinit>(Security.java:82)"
321 */
322 private static String getCallerInfo(Class<?> caller) {
323 for (StackTraceElement e : Thread.currentThread().getStackTrace()) {
324 if (e.getClassName().equals(caller.getName())) {
325 return e.toString();
326 }
327 }
328 // fallback if the caller is somehow missing from the stack.
329 return caller.getName();
330 }
331
332 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
333 static Object linkDynamicConstant(Object callerObj,
334 Object bootstrapMethodObj,
335 Object nameObj, Object typeObj,
336 Object staticArguments) {
337 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
338 Class<?> caller = (Class<?>)callerObj;
339 String name = nameObj.toString().intern();
340 Class<?> type = (Class<?>)typeObj;
341 if (!TRACE_METHOD_LINKAGE)
342 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
343 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
344 }
345
346 static Object linkDynamicConstantImpl(Class<?> caller,
347 MethodHandle bootstrapMethod,
348 String name, Class<?> type,
349 Object staticArguments) {
350 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
351 }
352
353 private static String staticArglistForTrace(Object staticArguments) {
354 if (staticArguments instanceof Object[] array)
355 return "BSA="+java.util.Arrays.asList(array);
356 if (staticArguments instanceof int[] array)
357 return "BSA@"+java.util.Arrays.toString(array);
358 if (staticArguments == null)
359 return "BSA0=null";
360 return "BSA1="+staticArguments;
361 }
362
363 // Tracing logic:
364 static Object linkDynamicConstantTracing(Class<?> caller,
365 MethodHandle bootstrapMethod,
366 String name, Class<?> type,
367 Object staticArguments) {
368 Object bsmReference = bootstrapMethod.internalMemberName();
369 if (bsmReference == null) bsmReference = bootstrapMethod;
370 String staticArglist = staticArglistForTrace(staticArguments);
371 System.out.println("linkDynamicConstant "+caller.getName()+" "+
372 bsmReference+" "+
373 name+type+"/"+staticArglist);
374 try {
375 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
376 System.out.println("linkDynamicConstantImpl => "+res);
377 return res;
378 } catch (Throwable ex) {
379 ex.printStackTrace(); // print now in case exception is swallowed
380 System.out.println("linkDynamicConstant => throw "+ex);
381 throw ex;
382 }
383 }
384
385 /** The JVM is requesting pull-mode bootstrap when it provides
386 * a tuple of the form int[]{ argc, vmindex }.
387 * The BSM is expected to call back to the JVM using the caller
388 * class and vmindex to resolve the static arguments.
389 */
390 static boolean staticArgumentsPulled(Object staticArguments) {
391 return staticArguments instanceof int[];
392 }
393
394 /** A BSM runs in pull-mode if and only if its sole arguments
395 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
396 * to those types, and it is not of variable arity.
397 * Excluding error cases, we can just test that the arity is a constant 2.
398 *
399 * NOTE: This method currently returns false, since pulling is not currently
400 * exposed to a BSM. When pull mode is supported the method block will be
401 * replaced with currently commented out code.
402 */
403 static boolean isPullModeBSM(MethodHandle bsm) {
404 return false;
405 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
406 }
407
408 /**
409 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
410 */
411 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
412 return MethodType.methodType(rtype, ptypes, true);
413 }
414
415 /**
416 * The JVM wants to link a call site that requires a dynamic type check.
417 * Name is a type-checking invoker, invokeExact or invoke.
418 * Return a JVM method (MemberName) to handle the invoking.
419 * The method assumes the following arguments on the stack:
420 * 0: the method handle being invoked
421 * 1-N: the arguments to the method handle invocation
422 * N+1: an optional, implicitly added argument (typically the given MethodType)
423 * <p>
424 * The nominal method at such a call site is an instance of
425 * a signature-polymorphic method (see @PolymorphicSignature).
426 * Such method instances are user-visible entities which are
427 * "split" from the generic placeholder method in {@code MethodHandle}.
428 * (Note that the placeholder method is not identical with any of
429 * its instances. If invoked reflectively, is guaranteed to throw an
430 * {@code UnsupportedOperationException}.)
431 * If the signature-polymorphic method instance is ever reified,
432 * it appears as a "copy" of the original placeholder
433 * (a native final member of {@code MethodHandle}) except
434 * that its type descriptor has shape required by the instance,
435 * and the method instance is <em>not</em> varargs.
436 * The method instance is also marked synthetic, since the
437 * method (by definition) does not appear in Java source code.
438 * <p>
439 * The JVM is allowed to reify this method as instance metadata.
440 * For example, {@code invokeBasic} is always reified.
441 * But the JVM may instead call {@code linkMethod}.
442 * If the result is an * ordered pair of a {@code (method, appendix)},
443 * the method gets all the arguments (0..N inclusive)
444 * plus the appendix (N+1), and uses the appendix to complete the call.
445 * In this way, one reusable method (called a "linker method")
446 * can perform the function of any number of polymorphic instance
447 * methods.
448 * <p>
449 * Linker methods are allowed to be weakly typed, with any or
450 * all references rewritten to {@code Object} and any primitives
451 * (except {@code long}/{@code float}/{@code double})
452 * rewritten to {@code int}.
453 * A linker method is trusted to return a strongly typed result,
454 * according to the specific method type descriptor of the
455 * signature-polymorphic instance it is emulating.
456 * This can involve (as necessary) a dynamic check using
457 * data extracted from the appendix argument.
458 * <p>
459 * The JVM does not inspect the appendix, other than to pass
460 * it verbatim to the linker method at every call.
461 * This means that the JDK runtime has wide latitude
462 * for choosing the shape of each linker method and its
463 * corresponding appendix.
464 * Linker methods should be generated from {@code LambdaForm}s
465 * so that they do not become visible on stack traces.
466 * <p>
467 * The {@code linkMethod} call is free to omit the appendix
468 * (returning null) and instead emulate the required function
469 * completely in the linker method.
470 * As a corner case, if N==255, no appendix is possible.
471 * In this case, the method returned must be custom-generated to
472 * perform any needed type checking.
473 * <p>
474 * If the JVM does not reify a method at a call site, but instead
475 * calls {@code linkMethod}, the corresponding call represented
476 * in the bytecodes may mention a valid method which is not
477 * representable with a {@code MemberName}.
478 * Therefore, use cases for {@code linkMethod} tend to correspond to
479 * special cases in reflective code such as {@code findVirtual}
480 * or {@code revealDirect}.
481 */
482 static MemberName linkMethod(Class<?> callerClass, int refKind,
483 Class<?> defc, String name, Object type,
484 Object[] appendixResult) {
485 if (!TRACE_METHOD_LINKAGE)
486 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
487 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
488 }
489 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
490 Class<?> defc, String name, Object type,
491 Object[] appendixResult) {
492 try {
493 if (refKind == REF_invokeVirtual) {
494 if (defc == MethodHandle.class) {
495 return Invokers.methodHandleInvokeLinkerMethod(
496 name, fixMethodType(callerClass, type), appendixResult);
497 } else if (defc == VarHandle.class) {
498 return varHandleOperationLinkerMethod(
499 name, fixMethodType(callerClass, type), appendixResult);
500 }
501 }
502 } catch (Error e) {
503 // Pass through an Error, including say StackOverflowError or
504 // OutOfMemoryError
505 throw e;
506 } catch (Throwable ex) {
507 // Wrap anything else in LinkageError
508 throw new LinkageError(ex.getMessage(), ex);
509 }
510 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
511 }
512 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
513 if (type instanceof MethodType mt)
514 return mt;
515 else
516 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
517 }
518 // Tracing logic:
519 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
520 Class<?> defc, String name, Object type,
521 Object[] appendixResult) {
522 System.out.println("linkMethod "+defc.getName()+"."+
523 name+type+"/"+Integer.toHexString(refKind));
524 try {
525 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
526 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
527 return res;
528 } catch (Throwable ex) {
529 System.out.println("linkMethod => throw "+ex);
530 throw ex;
531 }
532 }
533
534 /**
535 * Obtain the method to link to the VarHandle operation.
536 * This method is located here and not in Invokers to avoid
537 * initializing that and other classes early on in VM bootup.
538 */
539 private static MemberName varHandleOperationLinkerMethod(String name,
540 MethodType mtype,
541 Object[] appendixResult) {
542 // Get the signature method type
543 final MethodType sigType = mtype.basicType();
544
545 // Get the access kind from the method name
546 VarHandle.AccessMode ak;
547 try {
548 ak = VarHandle.AccessMode.valueFromMethodName(name);
549 } catch (IllegalArgumentException e) {
550 throw MethodHandleStatics.newInternalError(e);
551 }
552
553 // Create the appendix descriptor constant
554 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
555 appendixResult[0] = ad;
556
557 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
558 // If not polymorphic in the return type, such as the compareAndSet
559 // methods that return boolean
560 Class<?> guardReturnType = sigType.returnType();
561 if (ak.at.isMonomorphicInReturnType) {
562 if (ak.at.returnType != mtype.returnType()) {
563 // The caller contains a different return type than that
564 // defined by the method
565 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
566 }
567 // Adjust the return type of the signature method type
568 guardReturnType = ak.at.returnType;
569 }
570
571 // Get the guard method type for linking
572 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
573 // VarHandle at start
574 guardParams[0] = VarHandle.class;
575 for (int i = 0; i < sigType.parameterCount(); i++) {
576 guardParams[i + 1] = sigType.parameterType(i);
577 }
578 // Access descriptor at end
579 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
580 MethodType guardType = MethodType.methodType(guardReturnType, guardParams, true);
581
582 MemberName linker = new MemberName(
583 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
584 guardType, REF_invokeStatic);
585
586 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
587 VarHandleGuards.class, LM_TRUSTED);
588 if (linker != null) {
589 return linker;
590 }
591 // Fall back to lambda form linkage if guard method is not available
592 // TODO Optionally log fallback ?
593 }
594 return Invokers.varHandleInvokeLinkerMethod(mtype);
595 }
596 static String getVarHandleGuardMethodName(MethodType guardType) {
597 String prefix = "guard_";
598 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
599
600 sb.append(prefix);
601 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
602 Class<?> pt = guardType.parameterType(i);
603 sb.append(getCharType(pt));
604 }
605 sb.append('_').append(getCharType(guardType.returnType()));
606 return sb.toString();
607 }
608 static char getCharType(Class<?> pt) {
609 return Wrapper.forBasicType(pt).basicTypeChar();
610 }
611 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
612 return new NoSuchMethodError("VarHandle." + name + mtype);
613 }
614
615 /**
616 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
617 * It will make an up-call to this method. (Do not change the name or signature.)
618 * The type argument is a Class for field requests and a MethodType for non-fields.
619 * <p>
620 * Recent versions of the JVM may also pass a resolved MemberName for the type.
621 * In that case, the name is ignored and may be null.
622 */
623 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
624 Class<?> defc, String name, Object type) {
625 try {
626 Lookup lookup = IMPL_LOOKUP.in(callerClass);
627 assert(refKindIsValid(refKind));
628 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
629 } catch (ReflectiveOperationException ex) {
630 throw mapLookupExceptionToError(ex);
631 }
632 }
633
634 /**
635 * Map a reflective exception to a linkage error.
636 */
637 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
638 LinkageError err;
639 if (ex instanceof IllegalAccessException) {
640 Throwable cause = ex.getCause();
641 if (cause instanceof AbstractMethodError ame) {
642 return ame;
643 } else {
644 err = new IllegalAccessError(ex.getMessage());
645 }
646 } else if (ex instanceof NoSuchMethodException) {
647 err = new NoSuchMethodError(ex.getMessage());
648 } else if (ex instanceof NoSuchFieldException) {
649 err = new NoSuchFieldError(ex.getMessage());
650 } else {
651 err = new IncompatibleClassChangeError();
652 }
653 return initCauseFrom(err, ex);
654 }
655
656 /**
657 * Use best possible cause for err.initCause(), substituting the
658 * cause for err itself if the cause has the same (or better) type.
659 */
660 static <E extends Error> E initCauseFrom(E err, Exception ex) {
661 Throwable th = ex.getCause();
662 @SuppressWarnings("unchecked")
663 final Class<E> Eclass = (Class<E>) err.getClass();
664 if (Eclass.isInstance(th))
665 return Eclass.cast(th);
666 err.initCause(th == null ? ex : th);
667 return err;
668 }
669
670 /**
671 * Is this method a caller-sensitive method?
672 * I.e., does it call Reflection.getCallerClass or a similar method
673 * to ask about the identity of its caller?
674 */
675 static boolean isCallerSensitive(MemberName mem) {
676 if (!mem.isInvocable()) return false; // fields are not caller sensitive
677
678 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
679 }
680
681 static boolean canBeCalledVirtual(MemberName mem) {
682 assert(mem.isInvocable());
683 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class);
684 }
685
686 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
687 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
688 if (symbolicRefClass == definingClass) return true;
689 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
690 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
691 symbolicRefClass.isInterface()); // Mdef implements Msym
692 }
693 }