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 constructor)
116 MN_IS_CONSTRUCTOR = 0x00020000, // 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_REFERENCE_KIND_SHIFT = 24, // refKind
122 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
123 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
124 MN_SEARCH_SUPERCLASSES = 0x00100000,
125 MN_SEARCH_INTERFACES = 0x00200000;
126
127 /**
128 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
129 */
130 static final byte
131 REF_NONE = 0, // null value
132 REF_getField = 1,
133 REF_getStatic = 2,
134 REF_putField = 3,
135 REF_putStatic = 4,
136 REF_invokeVirtual = 5,
137 REF_invokeStatic = 6,
138 REF_invokeSpecial = 7,
139 REF_newInvokeSpecial = 8,
140 REF_invokeInterface = 9,
141 REF_LIMIT = 10;
142
143 /**
144 * Flags for Lookup.ClassOptions
145 */
146 static final int
147 NESTMATE_CLASS = 0x00000001,
148 HIDDEN_CLASS = 0x00000002,
149 STRONG_LOADER_LINK = 0x00000004,
150 ACCESS_VM_ANNOTATIONS = 0x00000008;
151
152 /**
153 * Lookup modes
154 */
155 static final int
156 LM_MODULE = Lookup.MODULE,
157 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL,
158 LM_TRUSTED = -1;
159
160 }
161
162 static boolean refKindIsValid(int refKind) {
163 return (refKind > REF_NONE && refKind < REF_LIMIT);
164 }
165 static boolean refKindIsField(byte refKind) {
166 assert(refKindIsValid(refKind));
167 return (refKind <= REF_putStatic);
168 }
169 static boolean refKindIsGetter(byte refKind) {
170 assert(refKindIsValid(refKind));
171 return (refKind <= REF_getStatic);
172 }
173 static boolean refKindIsSetter(byte refKind) {
174 return refKindIsField(refKind) && !refKindIsGetter(refKind);
175 }
176 static boolean refKindIsMethod(byte refKind) {
177 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
178 }
179 static boolean refKindIsConstructor(byte refKind) {
180 return (refKind == REF_newInvokeSpecial);
181 }
182 static boolean refKindHasReceiver(byte refKind) {
183 assert(refKindIsValid(refKind));
184 return (refKind & 1) != 0;
185 }
186 static boolean refKindIsStatic(byte refKind) {
187 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
188 }
189 static boolean refKindDoesDispatch(byte refKind) {
190 assert(refKindIsValid(refKind));
191 return (refKind == REF_invokeVirtual ||
192 refKind == REF_invokeInterface);
193 }
194 static {
195 final int HR_MASK = ((1 << REF_getField) |
196 (1 << REF_putField) |
197 (1 << REF_invokeVirtual) |
198 (1 << REF_invokeSpecial) |
199 (1 << REF_invokeInterface)
200 );
201 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
202 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
203 }
204 }
205 static String refKindName(byte refKind) {
206 assert(refKindIsValid(refKind));
207 return switch (refKind) {
208 case REF_getField -> "getField";
209 case REF_getStatic -> "getStatic";
210 case REF_putField -> "putField";
211 case REF_putStatic -> "putStatic";
212 case REF_invokeVirtual -> "invokeVirtual";
213 case REF_invokeStatic -> "invokeStatic";
214 case REF_invokeSpecial -> "invokeSpecial";
215 case REF_newInvokeSpecial -> "newInvokeSpecial";
216 case REF_invokeInterface -> "invokeInterface";
217 default -> "REF_???";
218 };
219 }
220
221 private static native int getNamedCon(int which, Object[] name);
222 static boolean verifyConstants() {
223 Object[] box = { null };
224 for (int i = 0; ; i++) {
225 box[0] = null;
226 int vmval = getNamedCon(i, box);
227 if (box[0] == null) break;
228 String name = (String) box[0];
229 try {
230 Field con = Constants.class.getDeclaredField(name);
231 int jval = con.getInt(null);
232 if (jval == vmval) continue;
233 String err = (name+": JVM has "+vmval+" while Java has "+jval);
234 if (name.equals("CONV_OP_LIMIT")) {
235 System.err.println("warning: "+err);
236 continue;
237 }
238 throw new InternalError(err);
239 } catch (NoSuchFieldException | IllegalAccessException ex) {
240 String err = (name+": JVM has "+vmval+" which Java does not define");
241 // ignore exotic ops the JVM cares about; we just won't issue them
242 //System.err.println("warning: "+err);
243 continue;
244 }
245 }
246 return true;
247 }
248 static {
249 VM.setJavaLangInvokeInited();
250 assert(verifyConstants());
251 }
252
253 // Up-calls from the JVM.
254 // These must NOT be public.
255
256 /**
257 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
258 */
259 static MemberName linkCallSite(Object callerObj,
260 Object bootstrapMethodObj,
261 Object nameObj, Object typeObj,
262 Object staticArguments,
263 Object[] appendixResult) {
264 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
265 Class<?> caller = (Class<?>)callerObj;
266 String name = nameObj.toString().intern();
267 MethodType type = (MethodType)typeObj;
268 if (!TRACE_METHOD_LINKAGE)
269 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
270 staticArguments, appendixResult);
271 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
272 staticArguments, appendixResult);
273 }
274 static MemberName linkCallSiteImpl(Class<?> caller,
275 MethodHandle bootstrapMethod,
276 String name, MethodType type,
277 Object staticArguments,
278 Object[] appendixResult) {
279 CallSite callSite = CallSite.makeSite(bootstrapMethod,
280 name,
281 type,
282 staticArguments,
283 caller);
284 if (TRACE_METHOD_LINKAGE) {
285 MethodHandle target = callSite.getTarget();
286 System.out.println("linkCallSite target class => " + target.getClass().getName());
287 System.out.println("linkCallSite target => " + target.debugString(0));
288 }
289
290 if (callSite instanceof ConstantCallSite) {
291 appendixResult[0] = callSite.dynamicInvoker();
292 return Invokers.linkToTargetMethod(type);
293 } else {
294 appendixResult[0] = callSite;
295 return Invokers.linkToCallSiteMethod(type);
296 }
297 }
298 // Tracing logic:
299 static MemberName linkCallSiteTracing(Class<?> caller,
300 MethodHandle bootstrapMethod,
301 String name, MethodType type,
302 Object staticArguments,
303 Object[] appendixResult) {
304 Object bsmReference = bootstrapMethod.internalMemberName();
305 if (bsmReference == null) bsmReference = bootstrapMethod;
306 String staticArglist = staticArglistForTrace(staticArguments);
307 System.out.println("linkCallSite "+getCallerInfo(caller)+" "+
308 bsmReference+" "+
309 name+type+"/"+staticArglist);
310 try {
311 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
312 staticArguments, appendixResult);
313 System.out.println("linkCallSite linkage => "+res+" + "+appendixResult[0]);
314 return res;
315 } catch (Throwable ex) {
316 ex.printStackTrace(); // print now in case exception is swallowed
317 System.out.println("linkCallSite => throw "+ex);
318 throw ex;
319 }
320 }
321
322 /**
323 * Return a human-readable description of the caller. Something like
324 * "java.base/java.security.Security.<clinit>(Security.java:82)"
325 */
326 private static String getCallerInfo(Class<?> caller) {
327 for (StackTraceElement e : Thread.currentThread().getStackTrace()) {
328 if (e.getClassName().equals(caller.getName())) {
329 return e.toString();
330 }
331 }
332 // fallback if the caller is somehow missing from the stack.
333 return caller.getName();
334 }
335
336 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
337 static Object linkDynamicConstant(Object callerObj,
338 Object bootstrapMethodObj,
339 Object nameObj, Object typeObj,
340 Object staticArguments) {
341 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
342 Class<?> caller = (Class<?>)callerObj;
343 String name = nameObj.toString().intern();
344 Class<?> type = (Class<?>)typeObj;
345 if (!TRACE_METHOD_LINKAGE)
346 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
347 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
348 }
349
350 static Object linkDynamicConstantImpl(Class<?> caller,
351 MethodHandle bootstrapMethod,
352 String name, Class<?> type,
353 Object staticArguments) {
354 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
355 }
356
357 private static String staticArglistForTrace(Object staticArguments) {
358 if (staticArguments instanceof Object[])
359 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments);
360 if (staticArguments instanceof int[])
361 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments);
362 if (staticArguments == null)
363 return "BSA0=null";
364 return "BSA1="+staticArguments;
365 }
366
367 // Tracing logic:
368 static Object linkDynamicConstantTracing(Class<?> caller,
369 MethodHandle bootstrapMethod,
370 String name, Class<?> type,
371 Object staticArguments) {
372 Object bsmReference = bootstrapMethod.internalMemberName();
373 if (bsmReference == null) bsmReference = bootstrapMethod;
374 String staticArglist = staticArglistForTrace(staticArguments);
375 System.out.println("linkDynamicConstant "+caller.getName()+" "+
376 bsmReference+" "+
377 name+type+"/"+staticArglist);
378 try {
379 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
380 System.out.println("linkDynamicConstantImpl => "+res);
381 return res;
382 } catch (Throwable ex) {
383 ex.printStackTrace(); // print now in case exception is swallowed
384 System.out.println("linkDynamicConstant => throw "+ex);
385 throw ex;
386 }
387 }
388
389 /** The JVM is requesting pull-mode bootstrap when it provides
390 * a tuple of the form int[]{ argc, vmindex }.
391 * The BSM is expected to call back to the JVM using the caller
392 * class and vmindex to resolve the static arguments.
393 */
394 static boolean staticArgumentsPulled(Object staticArguments) {
395 return staticArguments instanceof int[];
396 }
397
398 /** A BSM runs in pull-mode if and only if its sole arguments
399 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
400 * to those types, and it is not of variable arity.
401 * Excluding error cases, we can just test that the arity is a constant 2.
402 *
403 * NOTE: This method currently returns false, since pulling is not currently
404 * exposed to a BSM. When pull mode is supported the method block will be
405 * replaced with currently commented out code.
406 */
407 static boolean isPullModeBSM(MethodHandle bsm) {
408 return false;
409 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
410 }
411
412 /**
413 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
414 */
415 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
416 return MethodType.methodType(rtype, ptypes, true);
417 }
418
419 /**
420 * The JVM wants to link a call site that requires a dynamic type check.
421 * Name is a type-checking invoker, invokeExact or invoke.
422 * Return a JVM method (MemberName) to handle the invoking.
423 * The method assumes the following arguments on the stack:
424 * 0: the method handle being invoked
425 * 1-N: the arguments to the method handle invocation
426 * N+1: an optional, implicitly added argument (typically the given MethodType)
427 * <p>
428 * The nominal method at such a call site is an instance of
429 * a signature-polymorphic method (see @PolymorphicSignature).
430 * Such method instances are user-visible entities which are
431 * "split" from the generic placeholder method in {@code MethodHandle}.
432 * (Note that the placeholder method is not identical with any of
433 * its instances. If invoked reflectively, is guaranteed to throw an
434 * {@code UnsupportedOperationException}.)
435 * If the signature-polymorphic method instance is ever reified,
436 * it appears as a "copy" of the original placeholder
437 * (a native final member of {@code MethodHandle}) except
438 * that its type descriptor has shape required by the instance,
439 * and the method instance is <em>not</em> varargs.
440 * The method instance is also marked synthetic, since the
441 * method (by definition) does not appear in Java source code.
442 * <p>
443 * The JVM is allowed to reify this method as instance metadata.
444 * For example, {@code invokeBasic} is always reified.
445 * But the JVM may instead call {@code linkMethod}.
446 * If the result is an * ordered pair of a {@code (method, appendix)},
447 * the method gets all the arguments (0..N inclusive)
448 * plus the appendix (N+1), and uses the appendix to complete the call.
449 * In this way, one reusable method (called a "linker method")
450 * can perform the function of any number of polymorphic instance
451 * methods.
452 * <p>
453 * Linker methods are allowed to be weakly typed, with any or
454 * all references rewritten to {@code Object} and any primitives
455 * (except {@code long}/{@code float}/{@code double})
456 * rewritten to {@code int}.
457 * A linker method is trusted to return a strongly typed result,
458 * according to the specific method type descriptor of the
459 * signature-polymorphic instance it is emulating.
460 * This can involve (as necessary) a dynamic check using
461 * data extracted from the appendix argument.
462 * <p>
463 * The JVM does not inspect the appendix, other than to pass
464 * it verbatim to the linker method at every call.
465 * This means that the JDK runtime has wide latitude
466 * for choosing the shape of each linker method and its
467 * corresponding appendix.
468 * Linker methods should be generated from {@code LambdaForm}s
469 * so that they do not become visible on stack traces.
470 * <p>
471 * The {@code linkMethod} call is free to omit the appendix
472 * (returning null) and instead emulate the required function
473 * completely in the linker method.
474 * As a corner case, if N==255, no appendix is possible.
475 * In this case, the method returned must be custom-generated to
476 * perform any needed type checking.
477 * <p>
478 * If the JVM does not reify a method at a call site, but instead
479 * calls {@code linkMethod}, the corresponding call represented
480 * in the bytecodes may mention a valid method which is not
481 * representable with a {@code MemberName}.
482 * Therefore, use cases for {@code linkMethod} tend to correspond to
483 * special cases in reflective code such as {@code findVirtual}
484 * or {@code revealDirect}.
485 */
486 static MemberName linkMethod(Class<?> callerClass, int refKind,
487 Class<?> defc, String name, Object type,
488 Object[] appendixResult) {
489 if (!TRACE_METHOD_LINKAGE)
490 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
491 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
492 }
493 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
494 Class<?> defc, String name, Object type,
495 Object[] appendixResult) {
496 try {
497 if (refKind == REF_invokeVirtual) {
498 if (defc == MethodHandle.class) {
499 return Invokers.methodHandleInvokeLinkerMethod(
500 name, fixMethodType(callerClass, type), appendixResult);
501 } else if (defc == VarHandle.class) {
502 return varHandleOperationLinkerMethod(
503 name, fixMethodType(callerClass, type), appendixResult);
504 }
505 }
506 } catch (Error e) {
507 // Pass through an Error, including say StackOverflowError or
508 // OutOfMemoryError
509 throw e;
510 } catch (Throwable ex) {
511 // Wrap anything else in LinkageError
512 throw new LinkageError(ex.getMessage(), ex);
513 }
514 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
515 }
516 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
517 if (type instanceof MethodType)
518 return (MethodType) type;
519 else
520 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
521 }
522 // Tracing logic:
523 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
524 Class<?> defc, String name, Object type,
525 Object[] appendixResult) {
526 System.out.println("linkMethod "+defc.getName()+"."+
527 name+type+"/"+Integer.toHexString(refKind));
528 try {
529 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
530 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
531 return res;
532 } catch (Throwable ex) {
533 System.out.println("linkMethod => throw "+ex);
534 throw ex;
535 }
536 }
537
538 /**
539 * Obtain the method to link to the VarHandle operation.
540 * This method is located here and not in Invokers to avoid
541 * initializing that and other classes early on in VM bootup.
542 */
543 private static MemberName varHandleOperationLinkerMethod(String name,
544 MethodType mtype,
545 Object[] appendixResult) {
546 // Get the signature method type
547 final MethodType sigType = mtype.basicType();
548
549 // Get the access kind from the method name
550 VarHandle.AccessMode ak;
551 try {
552 ak = VarHandle.AccessMode.valueFromMethodName(name);
553 } catch (IllegalArgumentException e) {
554 throw MethodHandleStatics.newInternalError(e);
555 }
556
557 // Create the appendix descriptor constant
558 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
559 appendixResult[0] = ad;
560
561 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
562 // If not polymorphic in the return type, such as the compareAndSet
563 // methods that return boolean
564 Class<?> guardReturnType = sigType.returnType();
565 if (ak.at.isMonomorphicInReturnType) {
566 if (ak.at.returnType != mtype.returnType()) {
567 // The caller contains a different return type than that
568 // defined by the method
569 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
570 }
571 // Adjust the return type of the signature method type
572 guardReturnType = ak.at.returnType;
573 }
574
575 // Get the guard method type for linking
576 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
577 // VarHandle at start
578 guardParams[0] = VarHandle.class;
579 for (int i = 0; i < sigType.parameterCount(); i++) {
580 guardParams[i + 1] = sigType.parameterType(i);
581 }
582 // Access descriptor at end
583 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
584 MethodType guardType = MethodType.methodType(guardReturnType, guardParams, true);
585
586 MemberName linker = new MemberName(
587 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
588 guardType, REF_invokeStatic);
589
590 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
591 VarHandleGuards.class, LM_TRUSTED);
592 if (linker != null) {
593 return linker;
594 }
595 // Fall back to lambda form linkage if guard method is not available
596 // TODO Optionally log fallback ?
597 }
598 return Invokers.varHandleInvokeLinkerMethod(mtype);
599 }
600 static String getVarHandleGuardMethodName(MethodType guardType) {
601 String prefix = "guard_";
602 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
603
604 sb.append(prefix);
605 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
606 Class<?> pt = guardType.parameterType(i);
607 sb.append(getCharType(pt));
608 }
609 sb.append('_').append(getCharType(guardType.returnType()));
610 return sb.toString();
611 }
612 static char getCharType(Class<?> pt) {
613 return Wrapper.forBasicType(pt).basicTypeChar();
614 }
615 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
616 return new NoSuchMethodError("VarHandle." + name + mtype);
617 }
618
619 /**
620 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
621 * It will make an up-call to this method. (Do not change the name or signature.)
622 * The type argument is a Class for field requests and a MethodType for non-fields.
623 * <p>
624 * Recent versions of the JVM may also pass a resolved MemberName for the type.
625 * In that case, the name is ignored and may be null.
626 */
627 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
628 Class<?> defc, String name, Object type) {
629 try {
630 Lookup lookup = IMPL_LOOKUP.in(callerClass);
631 assert(refKindIsValid(refKind));
632 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
633 } catch (ReflectiveOperationException ex) {
634 throw mapLookupExceptionToError(ex);
635 }
636 }
637
638 /**
639 * Map a reflective exception to a linkage error.
640 */
641 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
642 LinkageError err;
643 if (ex instanceof IllegalAccessException) {
644 Throwable cause = ex.getCause();
645 if (cause instanceof AbstractMethodError) {
646 return (AbstractMethodError) cause;
647 } else {
648 err = new IllegalAccessError(ex.getMessage());
649 }
650 } else if (ex instanceof NoSuchMethodException) {
651 err = new NoSuchMethodError(ex.getMessage());
652 } else if (ex instanceof NoSuchFieldException) {
653 err = new NoSuchFieldError(ex.getMessage());
654 } else {
655 err = new IncompatibleClassChangeError();
656 }
657 return initCauseFrom(err, ex);
658 }
659
660 /**
661 * Use best possible cause for err.initCause(), substituting the
662 * cause for err itself if the cause has the same (or better) type.
663 */
664 static <E extends Error> E initCauseFrom(E err, Exception ex) {
665 Throwable th = ex.getCause();
666 @SuppressWarnings("unchecked")
667 final Class<E> Eclass = (Class<E>) err.getClass();
668 if (Eclass.isInstance(th))
669 return Eclass.cast(th);
670 err.initCause(th == null ? ex : th);
671 return err;
672 }
673
674 /**
675 * Is this method a caller-sensitive method?
676 * I.e., does it call Reflection.getCallerClass or a similar method
677 * to ask about the identity of its caller?
678 */
679 static boolean isCallerSensitive(MemberName mem) {
680 if (!mem.isInvocable()) return false; // fields are not caller sensitive
681
682 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
683 }
684
685 static boolean canBeCalledVirtual(MemberName mem) {
686 assert(mem.isInvocable());
687 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class);
688 }
689
690 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
691 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
692 if (symbolicRefClass == definingClass) return true;
693 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
694 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
695 symbolicRefClass.isInterface()); // Mdef implements Msym
696 }
697 }