1 /*
2 * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.invoke;
27
28 import jdk.internal.misc.VM;
29 import jdk.internal.ref.CleanerFactory;
30 import sun.invoke.util.Wrapper;
31
32 import java.lang.invoke.MethodHandles.Lookup;
33 import java.lang.reflect.Field;
34
35 import static java.lang.invoke.MethodHandleNatives.Constants.*;
36 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE;
37 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
38
39 /**
40 * The JVM interface for the method handles package is all here.
41 * This is an interface internal and private to an implementation of JSR 292.
42 * <em>This class is not part of the JSR 292 standard.</em>
43 * @author jrose
44 */
45 class MethodHandleNatives {
46
47 private MethodHandleNatives() { } // static only
48
49 /// MemberName support
50
51 static native void init(MemberName self, Object ref);
52 static native void expand(MemberName self);
53 static native MemberName resolve(MemberName self, Class<?> caller, int lookupMode,
54 boolean speculativeResolve) throws LinkageError, ClassNotFoundException;
55 static native int getMembers(Class<?> defc, String matchName, String matchSig,
56 int matchFlags, Class<?> caller, int skip, MemberName[] results);
57
58 /// Field layout queries parallel to jdk.internal.misc.Unsafe:
59 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
60 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
61 static native Object staticFieldBase(MemberName self); // e.g., returns clazz
62 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
63
64 /// CallSite support
65
66 /** Tell the JVM that we need to change the target of a CallSite. */
67 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
68 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
69
70 static native void copyOutBootstrapArguments(Class<?> caller, int[] indexInfo,
71 int start, int end,
72 Object[] buf, int pos,
73 boolean resolve,
74 Object ifNotAvailable);
75
76 /** Represents a context to track nmethod dependencies on CallSite instance target. */
77 static class CallSiteContext implements Runnable {
78 //@Injected JVM_nmethodBucket* vmdependencies;
79 //@Injected jlong last_cleanup;
80
81 static CallSiteContext make(CallSite cs) {
82 final CallSiteContext newContext = new CallSiteContext();
83 // CallSite instance is tracked by a Cleanable which clears native
84 // structures allocated for CallSite context. Though the CallSite can
85 // become unreachable, its Context is retained by the Cleanable instance
86 // (which is referenced from Cleaner instance which is referenced from
87 // CleanerFactory class) until cleanup is performed.
88 CleanerFactory.cleaner().register(cs, newContext);
89 return newContext;
90 }
91
92 @Override
93 public void run() {
94 MethodHandleNatives.clearCallSiteContext(this);
95 }
96 }
97
98 /** Invalidate all recorded nmethods. */
99 private static native void clearCallSiteContext(CallSiteContext context);
100
101 private static native void registerNatives();
102 static {
103 registerNatives();
104 }
105
106 /**
107 * Compile-time constants go here. This collection exists not only for
108 * reference from clients, but also for ensuring the VM and JDK agree on the
109 * values of these constants (see {@link #verifyConstants()}).
110 */
111 static class Constants {
112 Constants() { } // static only
113
114 static final int
115 MN_IS_METHOD = 0x00010000, // method (not object constructor)
116 MN_IS_OBJECT_CONSTRUCTOR = 0x00020000, // object constructor
117 MN_IS_FIELD = 0x00040000, // field
118 MN_IS_TYPE = 0x00080000, // nested type
119 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
120 MN_TRUSTED_FINAL = 0x00200000, // trusted final field
121 MN_FLATTENED = 0x00400000, // flattened field
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 STRONG_LOADER_LINK = 0x00000004,
151 ACCESS_VM_ANNOTATIONS = 0x00000008;
152
153 /**
154 * Lookup modes
155 */
156 static final int
157 LM_MODULE = Lookup.MODULE,
158 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL,
159 LM_TRUSTED = -1;
160
161 }
162
163 static boolean refKindIsValid(int refKind) {
164 return (refKind > REF_NONE && refKind < REF_LIMIT);
165 }
166 static boolean refKindIsField(byte refKind) {
167 assert(refKindIsValid(refKind));
168 return (refKind <= REF_putStatic);
169 }
170 static boolean refKindIsGetter(byte refKind) {
171 assert(refKindIsValid(refKind));
172 return (refKind <= REF_getStatic);
173 }
174 static boolean refKindIsSetter(byte refKind) {
175 return refKindIsField(refKind) && !refKindIsGetter(refKind);
176 }
177 static boolean refKindIsMethod(byte refKind) {
178 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
179 }
180 static boolean refKindIsObjectConstructor(byte refKind) {
181 return (refKind == REF_newInvokeSpecial);
182 }
183 static boolean refKindHasReceiver(byte refKind) {
184 assert(refKindIsValid(refKind));
185 return (refKind & 1) != 0;
186 }
187 static boolean refKindIsStatic(byte refKind) {
188 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
189 }
190 static boolean refKindDoesDispatch(byte refKind) {
191 assert(refKindIsValid(refKind));
192 return (refKind == REF_invokeVirtual ||
193 refKind == REF_invokeInterface);
194 }
195 static {
196 final int HR_MASK = ((1 << REF_getField) |
197 (1 << REF_putField) |
198 (1 << REF_invokeVirtual) |
199 (1 << REF_invokeSpecial) |
200 (1 << REF_invokeInterface)
201 );
202 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
203 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
204 }
205 }
206 static String refKindName(byte refKind) {
207 assert(refKindIsValid(refKind));
208 return switch (refKind) {
209 case REF_getField -> "getField";
210 case REF_getStatic -> "getStatic";
211 case REF_putField -> "putField";
212 case REF_putStatic -> "putStatic";
213 case REF_invokeVirtual -> "invokeVirtual";
214 case REF_invokeStatic -> "invokeStatic";
215 case REF_invokeSpecial -> "invokeSpecial";
216 case REF_newInvokeSpecial -> "newInvokeSpecial";
217 case REF_invokeInterface -> "invokeInterface";
218 default -> "REF_???";
219 };
220 }
221
222 private static native int getNamedCon(int which, Object[] name);
223 static boolean verifyConstants() {
224 Object[] box = { null };
225 for (int i = 0; ; i++) {
226 box[0] = null;
227 int vmval = getNamedCon(i, box);
228 if (box[0] == null) break;
229 String name = (String) box[0];
230 try {
231 Field con = Constants.class.getDeclaredField(name);
232 int jval = con.getInt(null);
233 if (jval == vmval) continue;
234 String err = (name+": JVM has "+vmval+" while Java has "+jval);
235 if (name.equals("CONV_OP_LIMIT")) {
236 System.err.println("warning: "+err);
237 continue;
238 }
239 throw new InternalError(err);
240 } catch (NoSuchFieldException | IllegalAccessException ex) {
241 String err = (name+": JVM has "+vmval+" which Java does not define");
242 // ignore exotic ops the JVM cares about; we just won't issue them
243 //System.err.println("warning: "+err);
244 continue;
245 }
246 }
247 return true;
248 }
249 static {
250 VM.setJavaLangInvokeInited();
251 assert(verifyConstants());
252 }
253
254 // Up-calls from the JVM.
255 // These must NOT be public.
256
257 /**
258 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
259 */
260 static MemberName linkCallSite(Object callerObj,
261 Object bootstrapMethodObj,
262 Object nameObj, Object typeObj,
263 Object staticArguments,
264 Object[] appendixResult) {
265 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
266 Class<?> caller = (Class<?>)callerObj;
267 String name = nameObj.toString().intern();
268 MethodType type = (MethodType)typeObj;
269 if (!TRACE_METHOD_LINKAGE)
270 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
271 staticArguments, appendixResult);
272 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
273 staticArguments, appendixResult);
274 }
275 static MemberName linkCallSiteImpl(Class<?> caller,
276 MethodHandle bootstrapMethod,
277 String name, MethodType type,
278 Object staticArguments,
279 Object[] appendixResult) {
280 CallSite callSite = CallSite.makeSite(bootstrapMethod,
281 name,
282 type,
283 staticArguments,
284 caller);
285 if (callSite instanceof ConstantCallSite) {
286 appendixResult[0] = callSite.dynamicInvoker();
287 return Invokers.linkToTargetMethod(type);
288 } else {
289 appendixResult[0] = callSite;
290 return Invokers.linkToCallSiteMethod(type);
291 }
292 }
293 // Tracing logic:
294 static MemberName linkCallSiteTracing(Class<?> caller,
295 MethodHandle bootstrapMethod,
296 String name, MethodType type,
297 Object staticArguments,
298 Object[] appendixResult) {
299 Object bsmReference = bootstrapMethod.internalMemberName();
300 if (bsmReference == null) bsmReference = bootstrapMethod;
301 String staticArglist = staticArglistForTrace(staticArguments);
302 System.out.println("linkCallSite "+caller.getName()+" "+
303 bsmReference+" "+
304 name+type+"/"+staticArglist);
305 try {
306 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
307 staticArguments, appendixResult);
308 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
309 return res;
310 } catch (Throwable ex) {
311 ex.printStackTrace(); // print now in case exception is swallowed
312 System.out.println("linkCallSite => throw "+ex);
313 throw ex;
314 }
315 }
316
317 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
318 static Object linkDynamicConstant(Object callerObj,
319 Object bootstrapMethodObj,
320 Object nameObj, Object typeObj,
321 Object staticArguments) {
322 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
323 Class<?> caller = (Class<?>)callerObj;
324 String name = nameObj.toString().intern();
325 Class<?> type = (Class<?>)typeObj;
326 if (!TRACE_METHOD_LINKAGE)
327 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
328 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
329 }
330
331 static Object linkDynamicConstantImpl(Class<?> caller,
332 MethodHandle bootstrapMethod,
333 String name, Class<?> type,
334 Object staticArguments) {
335 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
336 }
337
338 private static String staticArglistForTrace(Object staticArguments) {
339 if (staticArguments instanceof Object[])
340 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments);
341 if (staticArguments instanceof int[])
342 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments);
343 if (staticArguments == null)
344 return "BSA0=null";
345 return "BSA1="+staticArguments;
346 }
347
348 // Tracing logic:
349 static Object linkDynamicConstantTracing(Class<?> caller,
350 MethodHandle bootstrapMethod,
351 String name, Class<?> type,
352 Object staticArguments) {
353 Object bsmReference = bootstrapMethod.internalMemberName();
354 if (bsmReference == null) bsmReference = bootstrapMethod;
355 String staticArglist = staticArglistForTrace(staticArguments);
356 System.out.println("linkDynamicConstant "+caller.getName()+" "+
357 bsmReference+" "+
358 name+type+"/"+staticArglist);
359 try {
360 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
361 System.out.println("linkDynamicConstantImpl => "+res);
362 return res;
363 } catch (Throwable ex) {
364 ex.printStackTrace(); // print now in case exception is swallowed
365 System.out.println("linkDynamicConstant => throw "+ex);
366 throw ex;
367 }
368 }
369
370 /** The JVM is requesting pull-mode bootstrap when it provides
371 * a tuple of the form int[]{ argc, vmindex }.
372 * The BSM is expected to call back to the JVM using the caller
373 * class and vmindex to resolve the static arguments.
374 */
375 static boolean staticArgumentsPulled(Object staticArguments) {
376 return staticArguments instanceof int[];
377 }
378
379 /** A BSM runs in pull-mode if and only if its sole arguments
380 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
381 * to those types, and it is not of variable arity.
382 * Excluding error cases, we can just test that the arity is a constant 2.
383 *
384 * NOTE: This method currently returns false, since pulling is not currently
385 * exposed to a BSM. When pull mode is supported the method block will be
386 * replaced with currently commented out code.
387 */
388 static boolean isPullModeBSM(MethodHandle bsm) {
389 return false;
390 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
391 }
392
393 /**
394 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
395 */
396 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
397 return MethodType.methodType(rtype, ptypes, true);
398 }
399
400 /**
401 * The JVM wants to link a call site that requires a dynamic type check.
402 * Name is a type-checking invoker, invokeExact or invoke.
403 * Return a JVM method (MemberName) to handle the invoking.
404 * The method assumes the following arguments on the stack:
405 * 0: the method handle being invoked
406 * 1-N: the arguments to the method handle invocation
407 * N+1: an optional, implicitly added argument (typically the given MethodType)
408 * <p>
409 * The nominal method at such a call site is an instance of
410 * a signature-polymorphic method (see @PolymorphicSignature).
411 * Such method instances are user-visible entities which are
412 * "split" from the generic placeholder method in {@code MethodHandle}.
413 * (Note that the placeholder method is not identical with any of
414 * its instances. If invoked reflectively, is guaranteed to throw an
415 * {@code UnsupportedOperationException}.)
416 * If the signature-polymorphic method instance is ever reified,
417 * it appears as a "copy" of the original placeholder
418 * (a native final member of {@code MethodHandle}) except
419 * that its type descriptor has shape required by the instance,
420 * and the method instance is <em>not</em> varargs.
421 * The method instance is also marked synthetic, since the
422 * method (by definition) does not appear in Java source code.
423 * <p>
424 * The JVM is allowed to reify this method as instance metadata.
425 * For example, {@code invokeBasic} is always reified.
426 * But the JVM may instead call {@code linkMethod}.
427 * If the result is an * ordered pair of a {@code (method, appendix)},
428 * the method gets all the arguments (0..N inclusive)
429 * plus the appendix (N+1), and uses the appendix to complete the call.
430 * In this way, one reusable method (called a "linker method")
431 * can perform the function of any number of polymorphic instance
432 * methods.
433 * <p>
434 * Linker methods are allowed to be weakly typed, with any or
435 * all references rewritten to {@code Object} and any primitives
436 * (except {@code long}/{@code float}/{@code double})
437 * rewritten to {@code int}.
438 * A linker method is trusted to return a strongly typed result,
439 * according to the specific method type descriptor of the
440 * signature-polymorphic instance it is emulating.
441 * This can involve (as necessary) a dynamic check using
442 * data extracted from the appendix argument.
443 * <p>
444 * The JVM does not inspect the appendix, other than to pass
445 * it verbatim to the linker method at every call.
446 * This means that the JDK runtime has wide latitude
447 * for choosing the shape of each linker method and its
448 * corresponding appendix.
449 * Linker methods should be generated from {@code LambdaForm}s
450 * so that they do not become visible on stack traces.
451 * <p>
452 * The {@code linkMethod} call is free to omit the appendix
453 * (returning null) and instead emulate the required function
454 * completely in the linker method.
455 * As a corner case, if N==255, no appendix is possible.
456 * In this case, the method returned must be custom-generated to
457 * perform any needed type checking.
458 * <p>
459 * If the JVM does not reify a method at a call site, but instead
460 * calls {@code linkMethod}, the corresponding call represented
461 * in the bytecodes may mention a valid method which is not
462 * representable with a {@code MemberName}.
463 * Therefore, use cases for {@code linkMethod} tend to correspond to
464 * special cases in reflective code such as {@code findVirtual}
465 * or {@code revealDirect}.
466 */
467 static MemberName linkMethod(Class<?> callerClass, int refKind,
468 Class<?> defc, String name, Object type,
469 Object[] appendixResult) {
470 if (!TRACE_METHOD_LINKAGE)
471 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
472 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
473 }
474 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
475 Class<?> defc, String name, Object type,
476 Object[] appendixResult) {
477 try {
478 if (refKind == REF_invokeVirtual) {
479 if (defc == MethodHandle.class) {
480 return Invokers.methodHandleInvokeLinkerMethod(
481 name, fixMethodType(callerClass, type), appendixResult);
482 } else if (defc == VarHandle.class) {
483 return varHandleOperationLinkerMethod(
484 name, fixMethodType(callerClass, type), appendixResult);
485 }
486 }
487 } catch (Error e) {
488 // Pass through an Error, including say StackOverflowError or
489 // OutOfMemoryError
490 throw e;
491 } catch (Throwable ex) {
492 // Wrap anything else in LinkageError
493 throw new LinkageError(ex.getMessage(), ex);
494 }
495 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
496 }
497 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
498 if (type instanceof MethodType)
499 return (MethodType) type;
500 else
501 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
502 }
503 // Tracing logic:
504 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
505 Class<?> defc, String name, Object type,
506 Object[] appendixResult) {
507 System.out.println("linkMethod "+defc.getName()+"."+
508 name+type+"/"+Integer.toHexString(refKind));
509 try {
510 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
511 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
512 return res;
513 } catch (Throwable ex) {
514 System.out.println("linkMethod => throw "+ex);
515 throw ex;
516 }
517 }
518
519 /**
520 * Obtain the method to link to the VarHandle operation.
521 * This method is located here and not in Invokers to avoid
522 * initializing that and other classes early on in VM bootup.
523 */
524 private static MemberName varHandleOperationLinkerMethod(String name,
525 MethodType mtype,
526 Object[] appendixResult) {
527 // Get the signature method type
528 final MethodType sigType = mtype.basicType();
529
530 // Get the access kind from the method name
531 VarHandle.AccessMode ak;
532 try {
533 ak = VarHandle.AccessMode.valueFromMethodName(name);
534 } catch (IllegalArgumentException e) {
535 throw MethodHandleStatics.newInternalError(e);
536 }
537
538 // Create the appendix descriptor constant
539 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
540 appendixResult[0] = ad;
541
542 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
543 // If not polymorphic in the return type, such as the compareAndSet
544 // methods that return boolean
545 Class<?> guardReturnType = sigType.returnType();
546 if (ak.at.isMonomorphicInReturnType) {
547 if (ak.at.returnType != mtype.returnType()) {
548 // The caller contains a different return type than that
549 // defined by the method
550 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
551 }
552 // Adjust the return type of the signature method type
553 guardReturnType = ak.at.returnType;
554 }
555
556 // Get the guard method type for linking
557 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
558 // VarHandle at start
559 guardParams[0] = VarHandle.class;
560 for (int i = 0; i < sigType.parameterCount(); i++) {
561 guardParams[i + 1] = sigType.parameterType(i);
562 }
563 // Access descriptor at end
564 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
565 MethodType guardType = MethodType.methodType(guardReturnType, guardParams, true);
566
567 MemberName linker = new MemberName(
568 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
569 guardType, REF_invokeStatic);
570
571 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
572 VarHandleGuards.class, LM_TRUSTED);
573 if (linker != null) {
574 return linker;
575 }
576 // Fall back to lambda form linkage if guard method is not available
577 // TODO Optionally log fallback ?
578 }
579 return Invokers.varHandleInvokeLinkerMethod(mtype);
580 }
581 static String getVarHandleGuardMethodName(MethodType guardType) {
582 String prefix = "guard_";
583 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
584
585 sb.append(prefix);
586 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
587 Class<?> pt = guardType.parameterType(i);
588 sb.append(getCharErasedType(pt));
589 }
590 sb.append('_').append(getCharErasedType(guardType.returnType()));
591 return sb.toString();
592 }
593 static char getCharErasedType(Class<?> pt) {
594 return Wrapper.forBasicType(pt).basicTypeChar();
595 }
596 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
597 return new NoSuchMethodError("VarHandle." + name + mtype);
598 }
599
600 /**
601 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
602 * It will make an up-call to this method. (Do not change the name or signature.)
603 * The type argument is a Class for field requests and a MethodType for non-fields.
604 * <p>
605 * Recent versions of the JVM may also pass a resolved MemberName for the type.
606 * In that case, the name is ignored and may be null.
607 */
608 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
609 Class<?> defc, String name, Object type) {
610 try {
611 Lookup lookup = IMPL_LOOKUP.in(callerClass);
612 assert(refKindIsValid(refKind));
613 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
614 } catch (ReflectiveOperationException ex) {
615 throw mapLookupExceptionToError(ex);
616 }
617 }
618
619 /**
620 * Map a reflective exception to a linkage error.
621 */
622 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
623 LinkageError err;
624 if (ex instanceof IllegalAccessException) {
625 Throwable cause = ex.getCause();
626 if (cause instanceof AbstractMethodError) {
627 return (AbstractMethodError) cause;
628 } else {
629 err = new IllegalAccessError(ex.getMessage());
630 }
631 } else if (ex instanceof NoSuchMethodException) {
632 err = new NoSuchMethodError(ex.getMessage());
633 } else if (ex instanceof NoSuchFieldException) {
634 err = new NoSuchFieldError(ex.getMessage());
635 } else {
636 err = new IncompatibleClassChangeError();
637 }
638 return initCauseFrom(err, ex);
639 }
640
641 /**
642 * Use best possible cause for err.initCause(), substituting the
643 * cause for err itself if the cause has the same (or better) type.
644 */
645 static <E extends Error> E initCauseFrom(E err, Exception ex) {
646 Throwable th = ex.getCause();
647 @SuppressWarnings("unchecked")
648 final Class<E> Eclass = (Class<E>) err.getClass();
649 if (Eclass.isInstance(th))
650 return Eclass.cast(th);
651 err.initCause(th == null ? ex : th);
652 return err;
653 }
654
655 /**
656 * Is this method a caller-sensitive method?
657 * I.e., does it call Reflection.getCallerClass or a similar method
658 * to ask about the identity of its caller?
659 */
660 static boolean isCallerSensitive(MemberName mem) {
661 if (!mem.isInvocable()) return false; // fields are not caller sensitive
662
663 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
664 }
665
666 static boolean canBeCalledVirtual(MemberName mem) {
667 assert(mem.isInvocable());
668 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class);
669 }
670
671 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
672 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
673 if (symbolicRefClass == definingClass) return true;
674 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
675 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
676 symbolicRefClass.isInterface()); // Mdef implements Msym
677 }
678 }