1 /*
2 * Copyright (c) 2008, 2020, 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.access.JavaLangAccess;
29 import jdk.internal.access.SharedSecrets;
30 import jdk.internal.ref.CleanerFactory;
31 import sun.invoke.util.Wrapper;
32
33 import java.lang.invoke.MethodHandles.Lookup;
34 import java.lang.reflect.Field;
35
36 import static java.lang.invoke.MethodHandleNatives.Constants.*;
37 import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE;
38 import static java.lang.invoke.MethodHandleStatics.UNSAFE;
39 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
40
41 /**
42 * The JVM interface for the method handles package is all here.
43 * This is an interface internal and private to an implementation of JSR 292.
44 * <em>This class is not part of the JSR 292 standard.</em>
45 * @author jrose
46 */
47 class MethodHandleNatives {
48
49 private MethodHandleNatives() { } // static only
50
51 /// MemberName support
52
53 static native void init(MemberName self, Object ref);
54 static native void expand(MemberName self);
55 static native MemberName resolve(MemberName self, Class<?> caller, int lookupMode,
56 boolean speculativeResolve) throws LinkageError, ClassNotFoundException;
57 static native int getMembers(Class<?> defc, String matchName, String matchSig,
58 int matchFlags, Class<?> caller, int skip, MemberName[] results);
59
60 /// Field layout queries parallel to jdk.internal.misc.Unsafe:
61 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
62 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
63 static native Object staticFieldBase(MemberName self); // e.g., returns clazz
64 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
65
66 /// CallSite support
67
68 /** Tell the JVM that we need to change the target of a CallSite. */
69 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
70 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
71
72 static native void copyOutBootstrapArguments(Class<?> caller, int[] indexInfo,
73 int start, int end,
74 Object[] buf, int pos,
75 boolean resolve,
76 Object ifNotAvailable);
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 object constructor)
118 MN_IS_OBJECT_CONSTRUCTOR = 0x00020000, // object constructor
119 MN_IS_FIELD = 0x00040000, // field
120 MN_IS_TYPE = 0x00080000, // nested type
121 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
122 MN_TRUSTED_FINAL = 0x00200000, // trusted final field
123 MN_REFERENCE_KIND_SHIFT = 24, // refKind
124 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
125 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
126 MN_SEARCH_SUPERCLASSES = 0x00100000,
127 MN_SEARCH_INTERFACES = 0x00200000;
128
129 /**
130 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
131 */
132 static final byte
133 REF_NONE = 0, // null value
134 REF_getField = 1,
135 REF_getStatic = 2,
136 REF_putField = 3,
137 REF_putStatic = 4,
138 REF_invokeVirtual = 5,
139 REF_invokeStatic = 6,
140 REF_invokeSpecial = 7,
141 REF_newInvokeSpecial = 8,
142 REF_invokeInterface = 9,
143 REF_LIMIT = 10;
144
145 /**
146 * Flags for Lookup.ClassOptions
147 */
148 static final int
149 NESTMATE_CLASS = 0x00000001,
150 HIDDEN_CLASS = 0x00000002,
151 STRONG_LOADER_LINK = 0x00000004,
152 ACCESS_VM_ANNOTATIONS = 0x00000008;
153
154 /**
155 * Lookup modes
156 */
157 static final int
158 LM_MODULE = Lookup.MODULE,
159 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL,
160 LM_TRUSTED = -1;
161
162 }
163
164 static boolean refKindIsValid(int refKind) {
165 return (refKind > REF_NONE && refKind < REF_LIMIT);
166 }
167 static boolean refKindIsField(byte refKind) {
168 assert(refKindIsValid(refKind));
169 return (refKind <= REF_putStatic);
170 }
171 static boolean refKindIsGetter(byte refKind) {
172 assert(refKindIsValid(refKind));
173 return (refKind <= REF_getStatic);
174 }
175 static boolean refKindIsSetter(byte refKind) {
176 return refKindIsField(refKind) && !refKindIsGetter(refKind);
177 }
178 static boolean refKindIsMethod(byte refKind) {
179 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
180 }
181 static boolean refKindIsObjectConstructor(byte refKind) {
182 return (refKind == REF_newInvokeSpecial);
183 }
184 static boolean refKindHasReceiver(byte refKind) {
185 assert(refKindIsValid(refKind));
186 return (refKind & 1) != 0;
187 }
188 static boolean refKindIsStatic(byte refKind) {
189 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
190 }
191 static boolean refKindDoesDispatch(byte refKind) {
192 assert(refKindIsValid(refKind));
193 return (refKind == REF_invokeVirtual ||
194 refKind == REF_invokeInterface);
195 }
196 static {
197 final int HR_MASK = ((1 << REF_getField) |
198 (1 << REF_putField) |
199 (1 << REF_invokeVirtual) |
200 (1 << REF_invokeSpecial) |
201 (1 << REF_invokeInterface)
202 );
203 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
204 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
205 }
206 }
207 static String refKindName(byte refKind) {
208 assert(refKindIsValid(refKind));
209 return switch (refKind) {
210 case REF_getField -> "getField";
211 case REF_getStatic -> "getStatic";
212 case REF_putField -> "putField";
213 case REF_putStatic -> "putStatic";
214 case REF_invokeVirtual -> "invokeVirtual";
215 case REF_invokeStatic -> "invokeStatic";
216 case REF_invokeSpecial -> "invokeSpecial";
217 case REF_newInvokeSpecial -> "newInvokeSpecial";
218 case REF_invokeInterface -> "invokeInterface";
219 default -> "REF_???";
220 };
221 }
222
223 private static native int getNamedCon(int which, Object[] name);
224 static boolean verifyConstants() {
225 Object[] box = { null };
226 for (int i = 0; ; i++) {
227 box[0] = null;
228 int vmval = getNamedCon(i, box);
229 if (box[0] == null) break;
230 String name = (String) box[0];
231 try {
232 Field con = Constants.class.getDeclaredField(name);
233 int jval = con.getInt(null);
234 if (jval == vmval) continue;
235 String err = (name+": JVM has "+vmval+" while Java has "+jval);
236 if (name.equals("CONV_OP_LIMIT")) {
237 System.err.println("warning: "+err);
238 continue;
239 }
240 throw new InternalError(err);
241 } catch (NoSuchFieldException | IllegalAccessException ex) {
242 String err = (name+": JVM has "+vmval+" which Java does not define");
243 // ignore exotic ops the JVM cares about; we just wont issue them
244 //System.err.println("warning: "+err);
245 continue;
246 }
247 }
248 return true;
249 }
250 static {
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 int indexInCP,
262 Object bootstrapMethodObj,
263 Object nameObj, Object typeObj,
264 Object staticArguments,
265 Object[] appendixResult) {
266 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
267 Class<?> caller = (Class<?>)callerObj;
268 String name = nameObj.toString().intern();
269 MethodType type = (MethodType)typeObj;
270 if (!TRACE_METHOD_LINKAGE)
271 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
272 staticArguments, appendixResult);
273 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
274 staticArguments, appendixResult);
275 }
276 static MemberName linkCallSiteImpl(Class<?> caller,
277 MethodHandle bootstrapMethod,
278 String name, MethodType type,
279 Object staticArguments,
280 Object[] appendixResult) {
281 CallSite callSite = CallSite.makeSite(bootstrapMethod,
282 name,
283 type,
284 staticArguments,
285 caller);
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 "+caller.getName()+" "+
304 bsmReference+" "+
305 name+type+"/"+staticArglist);
306 try {
307 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
308 staticArguments, appendixResult);
309 System.out.println("linkCallSite => "+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 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
319 static Object linkDynamicConstant(Object callerObj,
320 int indexInCP,
321 Object bootstrapMethodObj,
322 Object nameObj, Object typeObj,
323 Object staticArguments) {
324 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
325 Class<?> caller = (Class<?>)callerObj;
326 String name = nameObj.toString().intern();
327 Class<?> type = (Class<?>)typeObj;
328 if (!TRACE_METHOD_LINKAGE)
329 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
330 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
331 }
332
333 static Object linkDynamicConstantImpl(Class<?> caller,
334 MethodHandle bootstrapMethod,
335 String name, Class<?> type,
336 Object staticArguments) {
337 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
338 }
339
340 private static String staticArglistForTrace(Object staticArguments) {
341 if (staticArguments instanceof Object[])
342 return "BSA="+java.util.Arrays.asList((Object[]) staticArguments);
343 if (staticArguments instanceof int[])
344 return "BSA@"+java.util.Arrays.toString((int[]) staticArguments);
345 if (staticArguments == null)
346 return "BSA0=null";
347 return "BSA1="+staticArguments;
348 }
349
350 // Tracing logic:
351 static Object linkDynamicConstantTracing(Class<?> caller,
352 MethodHandle bootstrapMethod,
353 String name, Class<?> type,
354 Object staticArguments) {
355 Object bsmReference = bootstrapMethod.internalMemberName();
356 if (bsmReference == null) bsmReference = bootstrapMethod;
357 String staticArglist = staticArglistForTrace(staticArguments);
358 System.out.println("linkDynamicConstant "+caller.getName()+" "+
359 bsmReference+" "+
360 name+type+"/"+staticArglist);
361 try {
362 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
363 System.out.println("linkDynamicConstantImpl => "+res);
364 return res;
365 } catch (Throwable ex) {
366 ex.printStackTrace(); // print now in case exception is swallowed
367 System.out.println("linkDynamicConstant => throw "+ex);
368 throw ex;
369 }
370 }
371
372 /** The JVM is requesting pull-mode bootstrap when it provides
373 * a tuple of the form int[]{ argc, vmindex }.
374 * The BSM is expected to call back to the JVM using the caller
375 * class and vmindex to resolve the static arguments.
376 */
377 static boolean staticArgumentsPulled(Object staticArguments) {
378 return staticArguments instanceof int[];
379 }
380
381 /** A BSM runs in pull-mode if and only if its sole arguments
382 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
383 * to those types, and it is not of variable arity.
384 * Excluding error cases, we can just test that the arity is a constant 2.
385 *
386 * NOTE: This method currently returns false, since pulling is not currently
387 * exposed to a BSM. When pull mode is supported the method block will be
388 * replaced with currently commented out code.
389 */
390 static boolean isPullModeBSM(MethodHandle bsm) {
391 return false;
392 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
393 }
394
395 /**
396 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
397 */
398 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
399 return MethodType.makeImpl(rtype, ptypes, true);
400 }
401
402 /**
403 * The JVM wants to link a call site that requires a dynamic type check.
404 * Name is a type-checking invoker, invokeExact or invoke.
405 * Return a JVM method (MemberName) to handle the invoking.
406 * The method assumes the following arguments on the stack:
407 * 0: the method handle being invoked
408 * 1-N: the arguments to the method handle invocation
409 * N+1: an optional, implicitly added argument (typically the given MethodType)
410 * <p>
411 * The nominal method at such a call site is an instance of
412 * a signature-polymorphic method (see @PolymorphicSignature).
413 * Such method instances are user-visible entities which are
414 * "split" from the generic placeholder method in {@code MethodHandle}.
415 * (Note that the placeholder method is not identical with any of
416 * its instances. If invoked reflectively, is guaranteed to throw an
417 * {@code UnsupportedOperationException}.)
418 * If the signature-polymorphic method instance is ever reified,
419 * it appears as a "copy" of the original placeholder
420 * (a native final member of {@code MethodHandle}) except
421 * that its type descriptor has shape required by the instance,
422 * and the method instance is <em>not</em> varargs.
423 * The method instance is also marked synthetic, since the
424 * method (by definition) does not appear in Java source code.
425 * <p>
426 * The JVM is allowed to reify this method as instance metadata.
427 * For example, {@code invokeBasic} is always reified.
428 * But the JVM may instead call {@code linkMethod}.
429 * If the result is an * ordered pair of a {@code (method, appendix)},
430 * the method gets all the arguments (0..N inclusive)
431 * plus the appendix (N+1), and uses the appendix to complete the call.
432 * In this way, one reusable method (called a "linker method")
433 * can perform the function of any number of polymorphic instance
434 * methods.
435 * <p>
436 * Linker methods are allowed to be weakly typed, with any or
437 * all references rewritten to {@code Object} and any primitives
438 * (except {@code long}/{@code float}/{@code double})
439 * rewritten to {@code int}.
440 * A linker method is trusted to return a strongly typed result,
441 * according to the specific method type descriptor of the
442 * signature-polymorphic instance it is emulating.
443 * This can involve (as necessary) a dynamic check using
444 * data extracted from the appendix argument.
445 * <p>
446 * The JVM does not inspect the appendix, other than to pass
447 * it verbatim to the linker method at every call.
448 * This means that the JDK runtime has wide latitude
449 * for choosing the shape of each linker method and its
450 * corresponding appendix.
451 * Linker methods should be generated from {@code LambdaForm}s
452 * so that they do not become visible on stack traces.
453 * <p>
454 * The {@code linkMethod} call is free to omit the appendix
455 * (returning null) and instead emulate the required function
456 * completely in the linker method.
457 * As a corner case, if N==255, no appendix is possible.
458 * In this case, the method returned must be custom-generated to
459 * perform any needed type checking.
460 * <p>
461 * If the JVM does not reify a method at a call site, but instead
462 * calls {@code linkMethod}, the corresponding call represented
463 * in the bytecodes may mention a valid method which is not
464 * representable with a {@code MemberName}.
465 * Therefore, use cases for {@code linkMethod} tend to correspond to
466 * special cases in reflective code such as {@code findVirtual}
467 * or {@code revealDirect}.
468 */
469 static MemberName linkMethod(Class<?> callerClass, int refKind,
470 Class<?> defc, String name, Object type,
471 Object[] appendixResult) {
472 if (!TRACE_METHOD_LINKAGE)
473 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
474 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
475 }
476 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
477 Class<?> defc, String name, Object type,
478 Object[] appendixResult) {
479 try {
480 if (refKind == REF_invokeVirtual) {
481 if (defc == MethodHandle.class) {
482 return Invokers.methodHandleInvokeLinkerMethod(
483 name, fixMethodType(callerClass, type), appendixResult);
484 } else if (defc == VarHandle.class) {
485 return varHandleOperationLinkerMethod(
486 name, fixMethodType(callerClass, type), appendixResult);
487 }
488 }
489 } catch (Error e) {
490 // Pass through an Error, including say StackOverflowError or
491 // OutOfMemoryError
492 throw e;
493 } catch (Throwable ex) {
494 // Wrap anything else in LinkageError
495 throw new LinkageError(ex.getMessage(), ex);
496 }
497 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
498 }
499 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
500 if (type instanceof MethodType)
501 return (MethodType) type;
502 else
503 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
504 }
505 // Tracing logic:
506 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
507 Class<?> defc, String name, Object type,
508 Object[] appendixResult) {
509 System.out.println("linkMethod "+defc.getName()+"."+
510 name+type+"/"+Integer.toHexString(refKind));
511 try {
512 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
513 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
514 return res;
515 } catch (Throwable ex) {
516 System.out.println("linkMethod => throw "+ex);
517 throw ex;
518 }
519 }
520
521 /**
522 * Obtain the method to link to the VarHandle operation.
523 * This method is located here and not in Invokers to avoid
524 * initializing that and other classes early on in VM bootup.
525 */
526 private static MemberName varHandleOperationLinkerMethod(String name,
527 MethodType mtype,
528 Object[] appendixResult) {
529 // Get the signature method type
530 final MethodType sigType = mtype.basicType();
531
532 // Get the access kind from the method name
533 VarHandle.AccessMode ak;
534 try {
535 ak = VarHandle.AccessMode.valueFromMethodName(name);
536 } catch (IllegalArgumentException e) {
537 throw MethodHandleStatics.newInternalError(e);
538 }
539
540 // Create the appendix descriptor constant
541 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
542 appendixResult[0] = ad;
543
544 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
545 // If not polymorphic in the return type, such as the compareAndSet
546 // methods that return boolean
547 Class<?> guardReturnType = sigType.returnType();
548 if (ak.at.isMonomorphicInReturnType) {
549 if (ak.at.returnType != mtype.returnType()) {
550 // The caller contains a different return type than that
551 // defined by the method
552 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
553 }
554 // Adjust the return type of the signature method type
555 guardReturnType = ak.at.returnType;
556 }
557
558 // Get the guard method type for linking
559 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
560 // VarHandle at start
561 guardParams[0] = VarHandle.class;
562 for (int i = 0; i < sigType.parameterCount(); i++) {
563 guardParams[i + 1] = sigType.parameterType(i);
564 }
565 // Access descriptor at end
566 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
567 MethodType guardType = MethodType.makeImpl(guardReturnType, guardParams, true);
568
569 MemberName linker = new MemberName(
570 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
571 guardType, REF_invokeStatic);
572
573 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
574 VarHandleGuards.class, LM_TRUSTED);
575 if (linker != null) {
576 return linker;
577 }
578 // Fall back to lambda form linkage if guard method is not available
579 // TODO Optionally log fallback ?
580 }
581 return Invokers.varHandleInvokeLinkerMethod(mtype);
582 }
583 static String getVarHandleGuardMethodName(MethodType guardType) {
584 String prefix = "guard_";
585 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
586
587 sb.append(prefix);
588 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
589 Class<?> pt = guardType.parameterType(i);
590 sb.append(getCharErasedType(pt));
591 }
592 sb.append('_').append(getCharErasedType(guardType.returnType()));
593 return sb.toString();
594 }
595 static char getCharErasedType(Class<?> pt) {
596 return Wrapper.forBasicType(pt).basicTypeChar();
597 }
598 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
599 return new NoSuchMethodError("VarHandle." + name + mtype);
600 }
601
602 /**
603 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
604 * It will make an up-call to this method. (Do not change the name or signature.)
605 * The type argument is a Class for field requests and a MethodType for non-fields.
606 * <p>
607 * Recent versions of the JVM may also pass a resolved MemberName for the type.
608 * In that case, the name is ignored and may be null.
609 */
610 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
611 Class<?> defc, String name, Object type) {
612 try {
613 Lookup lookup = IMPL_LOOKUP.in(callerClass);
614 assert(refKindIsValid(refKind));
615 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
616 } catch (ReflectiveOperationException ex) {
617 throw mapLookupExceptionToError(ex);
618 }
619 }
620
621 /**
622 * Map a reflective exception to a linkage error.
623 */
624 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
625 LinkageError err;
626 if (ex instanceof IllegalAccessException) {
627 Throwable cause = ex.getCause();
628 if (cause instanceof AbstractMethodError) {
629 return (AbstractMethodError) cause;
630 } else {
631 err = new IllegalAccessError(ex.getMessage());
632 }
633 } else if (ex instanceof NoSuchMethodException) {
634 err = new NoSuchMethodError(ex.getMessage());
635 } else if (ex instanceof NoSuchFieldException) {
636 err = new NoSuchFieldError(ex.getMessage());
637 } else {
638 err = new IncompatibleClassChangeError();
639 }
640 return initCauseFrom(err, ex);
641 }
642
643 /**
644 * Use best possible cause for err.initCause(), substituting the
645 * cause for err itself if the cause has the same (or better) type.
646 */
647 static <E extends Error> E initCauseFrom(E err, Exception ex) {
648 Throwable th = ex.getCause();
649 @SuppressWarnings("unchecked")
650 final Class<E> Eclass = (Class<E>) err.getClass();
651 if (Eclass.isInstance(th))
652 return Eclass.cast(th);
653 err.initCause(th == null ? ex : th);
654 return err;
655 }
656
657 /**
658 * Is this method a caller-sensitive method?
659 * I.e., does it call Reflection.getCallerClass or a similar method
660 * to ask about the identity of its caller?
661 */
662 static boolean isCallerSensitive(MemberName mem) {
663 if (!mem.isInvocable()) return false; // fields are not caller sensitive
664
665 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
666 }
667
668 static boolean canBeCalledVirtual(MemberName mem) {
669 assert(mem.isInvocable());
670 return mem.getName().equals("getContextClassLoader") &&
671 canBeCalledVirtual(mem, java.lang.Thread.class);
672 }
673
674 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
675 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
676 if (symbolicRefClass == definingClass) return true;
677 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
678 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
679 symbolicRefClass.isInterface()); // Mdef implements Msym
680 }
681
682 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
683 /*
684 * Returns the class data set by the VM in the Class::classData field.
685 *
686 * This is also invoked by LambdaForms as it cannot use condy via
687 * MethodHandles.classData due to bootstrapping issue.
688 */
689 static Object classData(Class<?> c) {
690 UNSAFE.ensureClassInitialized(c);
691 return JLA.classData(c);
692 }
693 }