1 /*
2 * Copyright (c) 2008, 2024, 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 private static native void registerNatives();
75 static {
76 registerNatives();
77 }
78
79 /**
80 * Compile-time constants go here. This collection exists not only for
81 * reference from clients, but also for ensuring the VM and JDK agree on the
82 * values of these constants (see {@link #verifyConstants()}).
83 */
84 static class Constants {
85 Constants() { } // static only
86
87 static final int
88 MN_IS_METHOD = 0x00010000, // method (not constructor) 89 MN_IS_CONSTRUCTOR = 0x00020000, // constructor 90 MN_IS_FIELD = 0x00040000, // field 91 MN_IS_TYPE = 0x00080000, // nested type 92 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected 93 MN_TRUSTED_FINAL = 0x00200000, // trusted final field 94 MN_HIDDEN_MEMBER = 0x00400000, // members defined in a hidden class or with @Hidden 95 MN_REFERENCE_KIND_SHIFT = 24, // refKind 96 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT;
97
98 /**
99 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
100 */
101 static final byte
102 REF_NONE = 0, // null value
103 REF_getField = 1,
104 REF_getStatic = 2,
105 REF_putField = 3,
106 REF_putStatic = 4,
107 REF_invokeVirtual = 5,
108 REF_invokeStatic = 6,
109 REF_invokeSpecial = 7,
110 REF_newInvokeSpecial = 8,
111 REF_invokeInterface = 9,
112 REF_LIMIT = 10;
113
114 /**
115 * Flags for Lookup.ClassOptions
116 */
117 static final int
118 NESTMATE_CLASS = 0x00000001,
119 HIDDEN_CLASS = 0x00000002,
120 STRONG_LOADER_LINK = 0x00000004,
121 ACCESS_VM_ANNOTATIONS = 0x00000008;
122
123 /**
124 * Lookup modes
125 */
126 static final int
127 LM_MODULE = Lookup.MODULE,
128 LM_UNCONDITIONAL = Lookup.UNCONDITIONAL,
129 LM_TRUSTED = -1;
130
131 }
132
133 static boolean refKindIsValid(int refKind) {
134 return (refKind > REF_NONE && refKind < REF_LIMIT);
135 }
136 static boolean refKindIsField(byte refKind) {
137 assert(refKindIsValid(refKind));
138 return (refKind <= REF_putStatic);
139 }
140 static boolean refKindIsGetter(byte refKind) {
141 assert(refKindIsValid(refKind));
142 return (refKind <= REF_getStatic);
143 }
144 static boolean refKindIsSetter(byte refKind) {
145 return refKindIsField(refKind) && !refKindIsGetter(refKind);
146 }
147 static boolean refKindIsMethod(byte refKind) {
148 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
149 }
150 static boolean refKindIsConstructor(byte refKind) {
151 return (refKind == REF_newInvokeSpecial);
152 }
153 static boolean refKindHasReceiver(byte refKind) {
154 assert(refKindIsValid(refKind));
155 return (refKind & 1) != 0;
156 }
157 static boolean refKindIsStatic(byte refKind) {
158 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
159 }
160 static boolean refKindDoesDispatch(byte refKind) {
161 assert(refKindIsValid(refKind));
162 return (refKind == REF_invokeVirtual ||
163 refKind == REF_invokeInterface);
164 }
165 static {
166 final int HR_MASK = ((1 << REF_getField) |
167 (1 << REF_putField) |
168 (1 << REF_invokeVirtual) |
169 (1 << REF_invokeSpecial) |
170 (1 << REF_invokeInterface)
171 );
172 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
173 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
174 }
175 }
176 static String refKindName(byte refKind) {
177 assert(refKindIsValid(refKind));
178 return switch (refKind) {
179 case REF_getField -> "getField";
180 case REF_getStatic -> "getStatic";
181 case REF_putField -> "putField";
182 case REF_putStatic -> "putStatic";
183 case REF_invokeVirtual -> "invokeVirtual";
184 case REF_invokeStatic -> "invokeStatic";
185 case REF_invokeSpecial -> "invokeSpecial";
186 case REF_newInvokeSpecial -> "newInvokeSpecial";
187 case REF_invokeInterface -> "invokeInterface";
188 default -> "REF_???";
189 };
190 }
191
192 private static native int getNamedCon(int which, Object[] name);
193 static boolean verifyConstants() {
194 Object[] box = { null };
195 for (int i = 0; ; i++) {
196 box[0] = null;
197 int vmval = getNamedCon(i, box);
198 if (box[0] == null) break;
199 String name = (String) box[0];
200 try {
201 Field con = Constants.class.getDeclaredField(name);
202 int jval = con.getInt(null);
203 if (jval == vmval) continue;
204 String err = (name+": JVM has "+vmval+" while Java has "+jval);
205 if (name.equals("CONV_OP_LIMIT")) {
206 System.err.println("warning: "+err);
207 continue;
208 }
209 throw new InternalError(err);
210 } catch (NoSuchFieldException | IllegalAccessException ex) {
211 String err = (name+": JVM has "+vmval+" which Java does not define");
212 // ignore exotic ops the JVM cares about; we just won't issue them
213 //System.err.println("warning: "+err);
214 continue;
215 }
216 }
217 return true;
218 }
219 static {
220 VM.setJavaLangInvokeInited();
221 assert(verifyConstants());
222 }
223
224 // Up-calls from the JVM.
225 // These must NOT be public.
226
227 /**
228 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
229 */
230 static MemberName linkCallSite(Object callerObj,
231 Object bootstrapMethodObj,
232 Object nameObj, Object typeObj,
233 Object staticArguments,
234 Object[] appendixResult) {
235 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
236 Class<?> caller = (Class<?>)callerObj;
237 String name = nameObj.toString().intern();
238 MethodType type = (MethodType)typeObj;
239 if (!TRACE_METHOD_LINKAGE)
240 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
241 staticArguments, appendixResult);
242 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
243 staticArguments, appendixResult);
244 }
245 static MemberName linkCallSiteImpl(Class<?> caller,
246 MethodHandle bootstrapMethod,
247 String name, MethodType type,
248 Object staticArguments,
249 Object[] appendixResult) {
250 CallSite callSite = CallSite.makeSite(bootstrapMethod,
251 name,
252 type,
253 staticArguments,
254 caller);
255 if (TRACE_METHOD_LINKAGE) {
256 MethodHandle target = callSite.getTarget();
257 System.out.println("linkCallSite target class => " + target.getClass().getName());
258 System.out.println("linkCallSite target => " + target.debugString(0));
259 }
260
261 if (callSite instanceof ConstantCallSite) {
262 appendixResult[0] = callSite.dynamicInvoker();
263 return Invokers.linkToTargetMethod(type);
264 } else {
265 appendixResult[0] = callSite;
266 return Invokers.linkToCallSiteMethod(type);
267 }
268 }
269 // Tracing logic:
270 static MemberName linkCallSiteTracing(Class<?> caller,
271 MethodHandle bootstrapMethod,
272 String name, MethodType type,
273 Object staticArguments,
274 Object[] appendixResult) {
275 Object bsmReference = bootstrapMethod.internalMemberName();
276 if (bsmReference == null) bsmReference = bootstrapMethod;
277 String staticArglist = staticArglistForTrace(staticArguments);
278 System.out.println("linkCallSite "+getCallerInfo(caller)+" "+
279 bsmReference+" "+
280 name+type+"/"+staticArglist);
281 try {
282 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
283 staticArguments, appendixResult);
284 System.out.println("linkCallSite linkage => "+res+" + "+appendixResult[0]);
285 return res;
286 } catch (Throwable ex) {
287 ex.printStackTrace(); // print now in case exception is swallowed
288 System.out.println("linkCallSite => throw "+ex);
289 throw ex;
290 }
291 }
292
293 /**
294 * Return a human-readable description of the caller. Something like
295 * "java.base/java.security.Security.<clinit>(Security.java:82)"
296 */
297 private static String getCallerInfo(Class<?> caller) {
298 for (StackTraceElement e : Thread.currentThread().getStackTrace()) {
299 if (e.getClassName().equals(caller.getName())) {
300 return e.toString();
301 }
302 }
303 // fallback if the caller is somehow missing from the stack.
304 return caller.getName();
305 }
306
307 // this implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
308 static Object linkDynamicConstant(Object callerObj,
309 Object bootstrapMethodObj,
310 Object nameObj, Object typeObj,
311 Object staticArguments) {
312 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
313 Class<?> caller = (Class<?>)callerObj;
314 String name = nameObj.toString().intern();
315 Class<?> type = (Class<?>)typeObj;
316 if (!TRACE_METHOD_LINKAGE)
317 return linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
318 return linkDynamicConstantTracing(caller, bootstrapMethod, name, type, staticArguments);
319 }
320
321 static Object linkDynamicConstantImpl(Class<?> caller,
322 MethodHandle bootstrapMethod,
323 String name, Class<?> type,
324 Object staticArguments) {
325 return ConstantBootstraps.makeConstant(bootstrapMethod, name, type, staticArguments, caller);
326 }
327
328 private static String staticArglistForTrace(Object staticArguments) {
329 if (staticArguments instanceof Object[] array)
330 return "BSA="+java.util.Arrays.asList(array);
331 if (staticArguments instanceof int[] array)
332 return "BSA@"+java.util.Arrays.toString(array);
333 if (staticArguments == null)
334 return "BSA0=null";
335 return "BSA1="+staticArguments;
336 }
337
338 // Tracing logic:
339 static Object linkDynamicConstantTracing(Class<?> caller,
340 MethodHandle bootstrapMethod,
341 String name, Class<?> type,
342 Object staticArguments) {
343 Object bsmReference = bootstrapMethod.internalMemberName();
344 if (bsmReference == null) bsmReference = bootstrapMethod;
345 String staticArglist = staticArglistForTrace(staticArguments);
346 System.out.println("linkDynamicConstant "+caller.getName()+" "+
347 bsmReference+" "+
348 name+type+"/"+staticArglist);
349 try {
350 Object res = linkDynamicConstantImpl(caller, bootstrapMethod, name, type, staticArguments);
351 System.out.println("linkDynamicConstantImpl => "+res);
352 return res;
353 } catch (Throwable ex) {
354 ex.printStackTrace(); // print now in case exception is swallowed
355 System.out.println("linkDynamicConstant => throw "+ex);
356 throw ex;
357 }
358 }
359
360 /** The JVM is requesting pull-mode bootstrap when it provides
361 * a tuple of the form int[]{ argc, vmindex }.
362 * The BSM is expected to call back to the JVM using the caller
363 * class and vmindex to resolve the static arguments.
364 */
365 static boolean staticArgumentsPulled(Object staticArguments) {
366 return staticArguments instanceof int[];
367 }
368
369 /** A BSM runs in pull-mode if and only if its sole arguments
370 * are (Lookup, BootstrapCallInfo), or can be converted pairwise
371 * to those types, and it is not of variable arity.
372 * Excluding error cases, we can just test that the arity is a constant 2.
373 *
374 * NOTE: This method currently returns false, since pulling is not currently
375 * exposed to a BSM. When pull mode is supported the method block will be
376 * replaced with currently commented out code.
377 */
378 static boolean isPullModeBSM(MethodHandle bsm) {
379 return false;
380 // return bsm.type().parameterCount() == 2 && !bsm.isVarargsCollector();
381 }
382
383 /**
384 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
385 */
386 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
387 return MethodType.methodType(rtype, ptypes, true);
388 }
389
390 /**
391 * The JVM wants to link a call site that requires a dynamic type check.
392 * Name is a type-checking invoker, invokeExact or invoke.
393 * Return a JVM method (MemberName) to handle the invoking.
394 * The method assumes the following arguments on the stack:
395 * 0: the method handle being invoked
396 * 1-N: the arguments to the method handle invocation
397 * N+1: an optional, implicitly added argument (typically the given MethodType)
398 * <p>
399 * The nominal method at such a call site is an instance of
400 * a signature-polymorphic method (see @PolymorphicSignature).
401 * Such method instances are user-visible entities which are
402 * "split" from the generic placeholder method in {@code MethodHandle}.
403 * (Note that the placeholder method is not identical with any of
404 * its instances. If invoked reflectively, is guaranteed to throw an
405 * {@code UnsupportedOperationException}.)
406 * If the signature-polymorphic method instance is ever reified,
407 * it appears as a "copy" of the original placeholder
408 * (a native final member of {@code MethodHandle}) except
409 * that its type descriptor has shape required by the instance,
410 * and the method instance is <em>not</em> varargs.
411 * The method instance is also marked synthetic, since the
412 * method (by definition) does not appear in Java source code.
413 * <p>
414 * The JVM is allowed to reify this method as instance metadata.
415 * For example, {@code invokeBasic} is always reified.
416 * But the JVM may instead call {@code linkMethod}.
417 * If the result is an * ordered pair of a {@code (method, appendix)},
418 * the method gets all the arguments (0..N inclusive)
419 * plus the appendix (N+1), and uses the appendix to complete the call.
420 * In this way, one reusable method (called a "linker method")
421 * can perform the function of any number of polymorphic instance
422 * methods.
423 * <p>
424 * Linker methods are allowed to be weakly typed, with any or
425 * all references rewritten to {@code Object} and any primitives
426 * (except {@code long}/{@code float}/{@code double})
427 * rewritten to {@code int}.
428 * A linker method is trusted to return a strongly typed result,
429 * according to the specific method type descriptor of the
430 * signature-polymorphic instance it is emulating.
431 * This can involve (as necessary) a dynamic check using
432 * data extracted from the appendix argument.
433 * <p>
434 * The JVM does not inspect the appendix, other than to pass
435 * it verbatim to the linker method at every call.
436 * This means that the JDK runtime has wide latitude
437 * for choosing the shape of each linker method and its
438 * corresponding appendix.
439 * Linker methods should be generated from {@code LambdaForm}s
440 * so that they do not become visible on stack traces.
441 * <p>
442 * The {@code linkMethod} call is free to omit the appendix
443 * (returning null) and instead emulate the required function
444 * completely in the linker method.
445 * As a corner case, if N==255, no appendix is possible.
446 * In this case, the method returned must be custom-generated to
447 * perform any needed type checking.
448 * <p>
449 * If the JVM does not reify a method at a call site, but instead
450 * calls {@code linkMethod}, the corresponding call represented
451 * in the bytecodes may mention a valid method which is not
452 * representable with a {@code MemberName}.
453 * Therefore, use cases for {@code linkMethod} tend to correspond to
454 * special cases in reflective code such as {@code findVirtual}
455 * or {@code revealDirect}.
456 */
457 static MemberName linkMethod(Class<?> callerClass, int refKind,
458 Class<?> defc, String name, Object type,
459 Object[] appendixResult) {
460 if (!TRACE_METHOD_LINKAGE)
461 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
462 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
463 }
464 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
465 Class<?> defc, String name, Object type,
466 Object[] appendixResult) {
467 try {
468 if (refKind == REF_invokeVirtual) {
469 if (defc == MethodHandle.class) {
470 return Invokers.methodHandleInvokeLinkerMethod(
471 name, fixMethodType(callerClass, type), appendixResult);
472 } else if (defc == VarHandle.class) {
473 return varHandleOperationLinkerMethod(
474 name, fixMethodType(callerClass, type), appendixResult);
475 }
476 }
477 } catch (Error e) {
478 // Pass through an Error, including say StackOverflowError or
479 // OutOfMemoryError
480 throw e;
481 } catch (Throwable ex) {
482 // Wrap anything else in LinkageError
483 throw new LinkageError(ex.getMessage(), ex);
484 }
485 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
486 }
487 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
488 if (type instanceof MethodType mt)
489 return mt;
490 else
491 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
492 }
493 // Tracing logic:
494 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
495 Class<?> defc, String name, Object type,
496 Object[] appendixResult) {
497 System.out.println("linkMethod "+defc.getName()+"."+
498 name+type+"/"+Integer.toHexString(refKind));
499 try {
500 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
501 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
502 return res;
503 } catch (Throwable ex) {
504 System.out.println("linkMethod => throw "+ex);
505 throw ex;
506 }
507 }
508
509 /**
510 * Obtain the method to link to the VarHandle operation.
511 * This method is located here and not in Invokers to avoid
512 * initializing that and other classes early on in VM bootup.
513 */
514 private static MemberName varHandleOperationLinkerMethod(String name,
515 MethodType mtype,
516 Object[] appendixResult) {
517 // Get the signature method type
518 final MethodType sigType = mtype.basicType();
519
520 // Get the access kind from the method name
521 VarHandle.AccessMode ak;
522 try {
523 ak = VarHandle.AccessMode.valueFromMethodName(name);
524 } catch (IllegalArgumentException e) {
525 throw MethodHandleStatics.newInternalError(e);
526 }
527
528 // Create the appendix descriptor constant
529 VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
530 appendixResult[0] = ad;
531
532 if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
533 // If not polymorphic in the return type, such as the compareAndSet
534 // methods that return boolean
535 Class<?> guardReturnType = sigType.returnType();
536 if (ak.at.isMonomorphicInReturnType) {
537 if (ak.at.returnType != mtype.returnType()) {
538 // The caller contains a different return type than that
539 // defined by the method
540 throw newNoSuchMethodErrorOnVarHandle(name, mtype);
541 }
542 // Adjust the return type of the signature method type
543 guardReturnType = ak.at.returnType;
544 }
545
546 // Get the guard method type for linking
547 final Class<?>[] guardParams = new Class<?>[sigType.parameterCount() + 2];
548 // VarHandle at start
549 guardParams[0] = VarHandle.class;
550 for (int i = 0; i < sigType.parameterCount(); i++) {
551 guardParams[i + 1] = sigType.parameterType(i);
552 }
553 // Access descriptor at end
554 guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
555 MethodType guardType = MethodType.methodType(guardReturnType, guardParams, true);
556
557 MemberName linker = new MemberName(
558 VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
559 guardType, REF_invokeStatic);
560
561 linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
562 VarHandleGuards.class, LM_TRUSTED);
563 if (linker != null) {
564 return linker;
565 }
566 // Fall back to lambda form linkage if guard method is not available
567 // TODO Optionally log fallback ?
568 }
569 return Invokers.varHandleInvokeLinkerMethod(mtype);
570 }
571 static String getVarHandleGuardMethodName(MethodType guardType) {
572 String prefix = "guard_";
573 StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
574
575 sb.append(prefix);
576 for (int i = 1; i < guardType.parameterCount() - 1; i++) {
577 Class<?> pt = guardType.parameterType(i);
578 sb.append(getCharType(pt));
579 }
580 sb.append('_').append(getCharType(guardType.returnType()));
581 return sb.toString();
582 }
583 static char getCharType(Class<?> pt) {
584 return Wrapper.forBasicType(pt).basicTypeChar();
585 }
586 static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
587 return new NoSuchMethodError("VarHandle." + name + mtype);
588 }
589
590 /**
591 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
592 * It will make an up-call to this method. (Do not change the name or signature.)
593 * The type argument is a Class for field requests and a MethodType for non-fields.
594 * <p>
595 * Recent versions of the JVM may also pass a resolved MemberName for the type.
596 * In that case, the name is ignored and may be null.
597 */
598 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
599 Class<?> defc, String name, Object type) {
600 try {
601 Lookup lookup = IMPL_LOOKUP.in(callerClass);
602 assert(refKindIsValid(refKind));
603 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
604 } catch (ReflectiveOperationException ex) {
605 throw mapLookupExceptionToError(ex);
606 }
607 }
608
609 /**
610 * Map a reflective exception to a linkage error.
611 */
612 static LinkageError mapLookupExceptionToError(ReflectiveOperationException ex) {
613 LinkageError err;
614 if (ex instanceof IllegalAccessException) {
615 Throwable cause = ex.getCause();
616 if (cause instanceof AbstractMethodError ame) {
617 return ame;
618 } else {
619 err = new IllegalAccessError(ex.getMessage());
620 }
621 } else if (ex instanceof NoSuchMethodException) {
622 err = new NoSuchMethodError(ex.getMessage());
623 } else if (ex instanceof NoSuchFieldException) {
624 err = new NoSuchFieldError(ex.getMessage());
625 } else {
626 err = new IncompatibleClassChangeError();
627 }
628 return initCauseFrom(err, ex);
629 }
630
631 /**
632 * Use best possible cause for err.initCause(), substituting the
633 * cause for err itself if the cause has the same (or better) type.
634 */
635 static <E extends Error> E initCauseFrom(E err, Exception ex) {
636 Throwable th = ex.getCause();
637 @SuppressWarnings("unchecked")
638 final Class<E> Eclass = (Class<E>) err.getClass();
639 if (Eclass.isInstance(th))
640 return Eclass.cast(th);
641 err.initCause(th == null ? ex : th);
642 return err;
643 }
644
645 /**
646 * Is this method a caller-sensitive method?
647 * I.e., does it call Reflection.getCallerClass or a similar method
648 * to ask about the identity of its caller?
649 */
650 static boolean isCallerSensitive(MemberName mem) {
651 if (!mem.isInvocable()) return false; // fields are not caller sensitive
652
653 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
654 }
655
656 static boolean canBeCalledVirtual(MemberName mem) {
657 assert(mem.isInvocable());
658 return mem.getName().equals("getContextClassLoader") && canBeCalledVirtual(mem, java.lang.Thread.class);
659 }
660
661 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
662 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
663 if (symbolicRefClass == definingClass) return true;
664 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
665 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
666 symbolicRefClass.isInterface()); // Mdef implements Msym
667 }
668
669 //--- AOTCache support
670
671 /**
672 * In normal execution, this is set to true, so that LambdaFormEditor and MethodTypeForm will
673 * use soft references to allow class unloading.
674 *
675 * When dumping the AOTCache, this is set to false so that no cached heap objects will
676 * contain soft references (which are not yet supported by AOTCache - see JDK-8341587). AOTCache
677 * only stores LambdaFormEditors and MethodTypeForms for classes in the boot/platform/app loaders.
678 * Such classes will never be unloaded, so it's OK to use hard references.
679 */
680 static final boolean USE_SOFT_CACHE;
681
682 static {
683 USE_SOFT_CACHE = Boolean.parseBoolean(
684 System.getProperty("java.lang.invoke.MethodHandleNatives.USE_SOFT_CACHE", "true"));
685 }
686 }
--- EOF ---