1 /*
2 * Copyright (c) 2008, 2025, 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.CDS;
29 import jdk.internal.misc.Unsafe;
30 import jdk.internal.vm.annotation.ForceInline;
31 import jdk.internal.vm.annotation.Stable;
32 import sun.invoke.util.ValueConversions;
33 import sun.invoke.util.VerifyAccess;
34 import sun.invoke.util.Wrapper;
35
36 import java.util.Arrays;
37 import java.util.Objects;
38 import java.util.function.Function;
39
40 import static java.lang.invoke.LambdaForm.*;
41 import static java.lang.invoke.LambdaForm.Kind.*;
42 import static java.lang.invoke.MethodHandleNatives.Constants.*;
43 import static java.lang.invoke.MethodHandleStatics.UNSAFE;
44 import static java.lang.invoke.MethodHandleStatics.newInternalError;
45 import static java.lang.invoke.MethodTypeForm.*;
46
47 /**
48 * The flavor of method handle which implements a constant reference
49 * to a class member.
50 * @author jrose
51 */
52 sealed class DirectMethodHandle extends MethodHandle {
53 final MemberName member;
54 final boolean crackable;
55
56 // Constructors and factory methods in this class *must* be package scoped or private.
57 private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member, boolean crackable) {
58 super(mtype, form);
59 if (!member.isResolved()) throw new InternalError();
60
61 if (member.getDeclaringClass().isInterface() &&
62 member.getReferenceKind() == REF_invokeInterface &&
63 member.isMethod() && !member.isAbstract()) {
64 // Check for corner case: invokeinterface of Object method
65 MemberName m = new MemberName(Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());
66 m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null, LM_TRUSTED);
67 if (m != null && m.isPublic()) {
68 assert(member.getReferenceKind() == m.getReferenceKind()); // else this.form is wrong
69 member = m;
70 }
71 }
72
73 this.member = member;
74 this.crackable = crackable;
75 }
76
77 // Factory methods:
78 static DirectMethodHandle make(byte refKind, Class<?> refc, MemberName member, Class<?> callerClass) {
79 MethodType mtype = member.getMethodOrFieldType();
80 if (!member.isStatic()) {
81 if (!member.getDeclaringClass().isAssignableFrom(refc) || member.isConstructor())
82 throw new InternalError(member.toString());
83 mtype = mtype.insertParameterTypes(0, refc);
84 }
85 if (!member.isField()) {
86 // refKind reflects the original type of lookup via findSpecial or
87 // findVirtual etc.
88 return switch (refKind) {
89 case REF_invokeSpecial -> {
90 member = member.asSpecial();
91 // if caller is an interface we need to adapt to get the
92 // receiver check inserted
93 if (callerClass == null) {
94 throw new InternalError("callerClass must not be null for REF_invokeSpecial");
95 }
96 LambdaForm lform = preparedLambdaForm(member, callerClass.isInterface());
97 yield new Special(mtype, lform, member, true, callerClass);
98 }
99 case REF_invokeInterface -> {
100 // for interfaces we always need the receiver typecheck,
101 // so we always pass 'true' to ensure we adapt if needed
102 // to include the REF_invokeSpecial case
103 LambdaForm lform = preparedLambdaForm(member, true);
104 yield new Interface(mtype, lform, member, true, refc);
105 }
106 default -> {
107 LambdaForm lform = preparedLambdaForm(member);
108 yield new DirectMethodHandle(mtype, lform, member, true);
109 }
110 };
111 } else {
112 LambdaForm lform = preparedFieldLambdaForm(member);
113 if (member.isStatic()) {
114 long offset = MethodHandleNatives.staticFieldOffset(member);
115 Object base = MethodHandleNatives.staticFieldBase(member);
116 return new StaticAccessor(mtype, lform, member, true, base, offset);
117 } else {
118 long offset = MethodHandleNatives.objectFieldOffset(member);
119 assert(offset == (int)offset);
120 return new Accessor(mtype, lform, member, true, (int)offset);
121 }
122 }
123 }
124 static DirectMethodHandle make(Class<?> refc, MemberName member) {
125 byte refKind = member.getReferenceKind();
126 if (refKind == REF_invokeSpecial)
127 refKind = REF_invokeVirtual;
128 return make(refKind, refc, member, null /* no callerClass context */);
129 }
130 static DirectMethodHandle make(MemberName member) {
131 if (member.isConstructor())
132 return makeAllocator(member.getDeclaringClass(), member);
133 return make(member.getDeclaringClass(), member);
134 }
135 static DirectMethodHandle makeAllocator(Class<?> instanceClass, MemberName ctor) {
136 assert(ctor.isConstructor() && ctor.getName().equals("<init>"));
137 ctor = ctor.asConstructor();
138 assert(ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;
139 MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);
140 LambdaForm lform = preparedLambdaForm(ctor);
141 MemberName init = ctor.asSpecial();
142 assert(init.getMethodType().returnType() == void.class);
143 return new Constructor(mtype, lform, ctor, true, init, instanceClass);
144 }
145
146 @Override
147 BoundMethodHandle rebind() {
148 return BoundMethodHandle.makeReinvoker(this);
149 }
150
151 @Override
152 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
153 assert(this.getClass() == DirectMethodHandle.class); // must override in subclasses
154 return new DirectMethodHandle(mt, lf, member, crackable);
155 }
156
157 @Override
158 MethodHandle viewAsType(MethodType newType, boolean strict) {
159 // No actual conversions, just a new view of the same method.
160 // However, we must not expose a DMH that is crackable into a
161 // MethodHandleInfo, so we return a cloned, uncrackable DMH
162 assert(viewAsTypeChecks(newType, strict));
163 assert(this.getClass() == DirectMethodHandle.class); // must override in subclasses
164 return new DirectMethodHandle(newType, form, member, false);
165 }
166
167 @Override
168 boolean isCrackable() {
169 return crackable;
170 }
171
172 @Override
173 String internalProperties(int indentLevel) {
174 return "\n" + debugPrefix(indentLevel) + "& DMH.MN=" + internalMemberName();
175 }
176
177 //// Implementation methods.
178 @Override
179 @ForceInline
180 MemberName internalMemberName() {
181 return member;
182 }
183
184 private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
185
186 /**
187 * Create a LF which can invoke the given method.
188 * Cache and share this structure among all methods with
189 * the same basicType and refKind.
190 */
191 private static LambdaForm preparedLambdaForm(MemberName m, boolean adaptToSpecialIfc) {
192 assert(m.isInvocable()) : m; // call preparedFieldLambdaForm instead
193 MethodType mtype = m.getInvocationType().basicType();
194 assert(!m.isMethodHandleInvoke()) : m;
195 // MemberName.getReferenceKind represents the JVM optimized form of the call
196 // as distinct from the "kind" passed to DMH.make which represents the original
197 // bytecode-equivalent request. Specifically private/final methods that use a direct
198 // call have getReferenceKind adapted to REF_invokeSpecial, even though the actual
199 // invocation mode may be invokevirtual or invokeinterface.
200 int which = switch (m.getReferenceKind()) {
201 case REF_invokeVirtual -> LF_INVVIRTUAL;
202 case REF_invokeStatic -> LF_INVSTATIC;
203 case REF_invokeSpecial -> LF_INVSPECIAL;
204 case REF_invokeInterface -> LF_INVINTERFACE;
205 case REF_newInvokeSpecial -> LF_NEWINVSPECIAL;
206 default -> throw new InternalError(m.toString());
207 };
208 if (which == LF_INVSTATIC && shouldBeInitialized(m)) {
209 // precompute the barrier-free version:
210 preparedLambdaForm(mtype, which);
211 which = LF_INVSTATIC_INIT;
212 }
213 if (which == LF_INVSPECIAL && adaptToSpecialIfc) {
214 which = LF_INVSPECIAL_IFC;
215 }
216 LambdaForm lform = preparedLambdaForm(mtype, which);
217 maybeCompile(lform, m);
218 assert(lform.methodType().dropParameterTypes(0, 1)
219 .equals(m.getInvocationType().basicType()))
220 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
221 return lform;
222 }
223
224 private static LambdaForm preparedLambdaForm(MemberName m) {
225 return preparedLambdaForm(m, false);
226 }
227
228 private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {
229 LambdaForm lform = mtype.form().cachedLambdaForm(which);
230 if (lform != null) return lform;
231 lform = makePreparedLambdaForm(mtype, which);
232 return mtype.form().setCachedLambdaForm(which, lform);
233 }
234
235 static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {
236 boolean needsInit = (which == LF_INVSTATIC_INIT);
237 boolean doesAlloc = (which == LF_NEWINVSPECIAL);
238 boolean needsReceiverCheck = (which == LF_INVINTERFACE ||
239 which == LF_INVSPECIAL_IFC);
240
241 String linkerName;
242 LambdaForm.Kind kind;
243 switch (which) {
244 case LF_INVVIRTUAL: linkerName = "linkToVirtual"; kind = DIRECT_INVOKE_VIRTUAL; break;
245 case LF_INVSTATIC: linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC; break;
246 case LF_INVSTATIC_INIT:linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC_INIT; break;
247 case LF_INVSPECIAL_IFC:linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL_IFC; break;
248 case LF_INVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL; break;
249 case LF_INVINTERFACE: linkerName = "linkToInterface"; kind = DIRECT_INVOKE_INTERFACE; break;
250 case LF_NEWINVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_NEW_INVOKE_SPECIAL; break;
251 default: throw new InternalError("which="+which);
252 }
253
254 MethodType mtypeWithArg;
255 if (doesAlloc) {
256 var ptypes = mtype.ptypes();
257 var newPtypes = new Class<?>[ptypes.length + 2];
258 newPtypes[0] = Object.class; // insert newly allocated obj
259 System.arraycopy(ptypes, 0, newPtypes, 1, ptypes.length);
260 newPtypes[newPtypes.length - 1] = MemberName.class;
261 mtypeWithArg = MethodType.methodType(void.class, newPtypes, true);
262 } else {
263 mtypeWithArg = mtype.appendParameterTypes(MemberName.class);
264 }
265 MemberName linker = new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);
266 try {
267 linker = IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, LM_TRUSTED,
268 NoSuchMethodException.class);
269 } catch (ReflectiveOperationException ex) {
270 throw newInternalError(ex);
271 }
272 final int DMH_THIS = 0;
273 final int ARG_BASE = 1;
274 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
275 int nameCursor = ARG_LIMIT;
276 final int NEW_OBJ = (doesAlloc ? nameCursor++ : -1);
277 final int GET_MEMBER = nameCursor++;
278 final int CHECK_RECEIVER = (needsReceiverCheck ? nameCursor++ : -1);
279 final int LINKER_CALL = nameCursor++;
280 Name[] names = invokeArguments(nameCursor - ARG_LIMIT, mtype);
281 assert(names.length == nameCursor);
282 if (doesAlloc) {
283 // names = { argx,y,z,... new C, init method }
284 names[NEW_OBJ] = new Name(getFunction(NF_allocateInstance), names[DMH_THIS]);
285 names[GET_MEMBER] = new Name(getFunction(NF_constructorMethod), names[DMH_THIS]);
286 } else if (needsInit) {
287 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberNameEnsureInit), names[DMH_THIS]);
288 } else {
289 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberName), names[DMH_THIS]);
290 }
291 assert(findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]);
292 Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER+1, Object[].class);
293 if (needsReceiverCheck) {
294 names[CHECK_RECEIVER] = new Name(getFunction(NF_checkReceiver), names[DMH_THIS], names[ARG_BASE]);
295 outArgs[0] = names[CHECK_RECEIVER];
296 }
297 assert(outArgs[outArgs.length-1] == names[GET_MEMBER]); // look, shifted args!
298 int result = LAST_RESULT;
299 if (doesAlloc) {
300 assert(outArgs[outArgs.length-2] == names[NEW_OBJ]); // got to move this one
301 System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length-2);
302 outArgs[0] = names[NEW_OBJ];
303 result = NEW_OBJ;
304 }
305 names[LINKER_CALL] = new Name(linker, outArgs);
306 LambdaForm lform = LambdaForm.create(ARG_LIMIT, names, result, kind);
307
308 // This is a tricky bit of code. Don't send it through the LF interpreter.
309 lform.compileToBytecode();
310 return lform;
311 }
312
313 /* assert */ static Object findDirectMethodHandle(Name name) {
314 if (name.function.equals(getFunction(NF_internalMemberName)) ||
315 name.function.equals(getFunction(NF_internalMemberNameEnsureInit)) ||
316 name.function.equals(getFunction(NF_constructorMethod))) {
317 assert(name.arguments.length == 1);
318 return name.arguments[0];
319 }
320 return null;
321 }
322
323 private static void maybeCompile(LambdaForm lform, MemberName m) {
324 if (lform.vmentry == null && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
325 // Help along bootstrapping...
326 lform.compileToBytecode();
327 }
328
329 /** Static wrapper for DirectMethodHandle.internalMemberName. */
330 @ForceInline
331 /*non-public*/
332 static Object internalMemberName(Object mh) {
333 return ((DirectMethodHandle)mh).member;
334 }
335
336 /** Static wrapper for DirectMethodHandle.internalMemberName.
337 * This one also forces initialization.
338 */
339 /*non-public*/
340 static Object internalMemberNameEnsureInit(Object mh) {
341 DirectMethodHandle dmh = (DirectMethodHandle)mh;
342 dmh.ensureInitialized();
343 return dmh.member;
344 }
345
346 /*non-public*/
347 static boolean shouldBeInitialized(MemberName member) {
348 switch (member.getReferenceKind()) {
349 case REF_invokeStatic:
350 case REF_getStatic:
351 case REF_putStatic:
352 case REF_newInvokeSpecial:
353 break;
354 default:
355 // No need to initialize the class on this kind of member.
356 return false;
357 }
358 Class<?> cls = member.getDeclaringClass();
359 if (cls == ValueConversions.class ||
360 cls == MethodHandleImpl.class ||
361 cls == Invokers.class) {
362 // These guys have lots of <clinit> DMH creation but we know
363 // the MHs will not be used until the system is booted.
364 return false;
365 }
366 if (VerifyAccess.isSamePackage(MethodHandle.class, cls) ||
367 VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
368 // It is a system class. It is probably in the process of
369 // being initialized, but we will help it along just to be safe.
370 UNSAFE.ensureClassInitialized(cls);
371 return CDS.needsClassInitBarrier(cls);
372 }
373 return UNSAFE.shouldBeInitialized(cls) || CDS.needsClassInitBarrier(cls);
374 }
375
376 private void ensureInitialized() {
377 if (checkInitialized(member)) {
378 // The coast is clear. Delete the <clinit> barrier.
379 updateForm(new Function<>() {
380 public LambdaForm apply(LambdaForm oldForm) {
381 return (member.isField() ? preparedFieldLambdaForm(member)
382 : preparedLambdaForm(member));
383 }
384 });
385 }
386 }
387 private static boolean checkInitialized(MemberName member) {
388 Class<?> defc = member.getDeclaringClass();
389 UNSAFE.ensureClassInitialized(defc);
390 // Once we get here either defc was fully initialized by another thread, or
391 // defc was already being initialized by the current thread. In the latter case
392 // the barrier must remain. We can detect this simply by checking if initialization
393 // is still needed.
394 return !UNSAFE.shouldBeInitialized(defc);
395 }
396
397 /*non-public*/
398 static void ensureInitialized(Object mh) {
399 ((DirectMethodHandle)mh).ensureInitialized();
400 }
401
402 /** This subclass represents invokespecial instructions. */
403 static final class Special extends DirectMethodHandle {
404 private final Class<?> caller;
405 private Special(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> caller) {
406 super(mtype, form, member, crackable);
407 this.caller = caller;
408 }
409 @Override
410 boolean isInvokeSpecial() {
411 return true;
412 }
413 @Override
414 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
415 return new Special(mt, lf, member, crackable, caller);
416 }
417 @Override
418 MethodHandle viewAsType(MethodType newType, boolean strict) {
419 assert(viewAsTypeChecks(newType, strict));
420 return new Special(newType, form, member, false, caller);
421 }
422 Object checkReceiver(Object recv) {
423 if (!caller.isInstance(recv)) {
424 if (recv != null) {
425 String msg = String.format("Receiver class %s is not a subclass of caller class %s",
426 recv.getClass().getName(), caller.getName());
427 throw new IncompatibleClassChangeError(msg);
428 } else {
429 String msg = String.format("Cannot invoke %s with null receiver", member);
430 throw new NullPointerException(msg);
431 }
432 }
433 return recv;
434 }
435 }
436
437 /** This subclass represents invokeinterface instructions. */
438 static final class Interface extends DirectMethodHandle {
439 private final Class<?> refc;
440 private Interface(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> refc) {
441 super(mtype, form, member, crackable);
442 assert(refc.isInterface()) : refc;
443 this.refc = refc;
444 }
445 @Override
446 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
447 return new Interface(mt, lf, member, crackable, refc);
448 }
449 @Override
450 MethodHandle viewAsType(MethodType newType, boolean strict) {
451 assert(viewAsTypeChecks(newType, strict));
452 return new Interface(newType, form, member, false, refc);
453 }
454 @Override
455 Object checkReceiver(Object recv) {
456 if (!refc.isInstance(recv)) {
457 if (recv != null) {
458 String msg = String.format("Receiver class %s does not implement the requested interface %s",
459 recv.getClass().getName(), refc.getName());
460 throw new IncompatibleClassChangeError(msg);
461 } else {
462 String msg = String.format("Cannot invoke %s with null receiver", member);
463 throw new NullPointerException(msg);
464 }
465 }
466 return recv;
467 }
468 }
469
470 /** Used for interface receiver type checks, by Interface and Special modes. */
471 Object checkReceiver(Object recv) {
472 throw new InternalError("Should only be invoked on a subclass");
473 }
474
475 /** This subclass handles constructor references. */
476 static final class Constructor extends DirectMethodHandle {
477 final MemberName initMethod;
478 final Class<?> instanceClass;
479
480 private Constructor(MethodType mtype, LambdaForm form, MemberName constructor,
481 boolean crackable, MemberName initMethod, Class<?> instanceClass) {
482 super(mtype, form, constructor, crackable);
483 this.initMethod = initMethod;
484 this.instanceClass = instanceClass;
485 assert(initMethod.isResolved());
486 }
487 @Override
488 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
489 return new Constructor(mt, lf, member, crackable, initMethod, instanceClass);
490 }
491 @Override
492 MethodHandle viewAsType(MethodType newType, boolean strict) {
493 assert(viewAsTypeChecks(newType, strict));
494 return new Constructor(newType, form, member, false, initMethod, instanceClass);
495 }
496 }
497
498 /*non-public*/
499 static Object constructorMethod(Object mh) {
500 Constructor dmh = (Constructor)mh;
501 return dmh.initMethod;
502 }
503
504 /*non-public*/
505 static Object allocateInstance(Object mh) throws InstantiationException {
506 Constructor dmh = (Constructor)mh;
507 return UNSAFE.allocateInstance(dmh.instanceClass);
508 }
509
510 /** This subclass handles non-static field references. */
511 static final class Accessor extends DirectMethodHandle {
512 final Class<?> fieldType;
513 final int fieldOffset;
514 private Accessor(MethodType mtype, LambdaForm form, MemberName member,
515 boolean crackable, int fieldOffset) {
516 super(mtype, form, member, crackable);
517 this.fieldType = member.getFieldType();
518 this.fieldOffset = fieldOffset;
519 }
520
521 @Override Object checkCast(Object obj) {
522 return fieldType.cast(obj);
523 }
524 @Override
525 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
526 return new Accessor(mt, lf, member, crackable, fieldOffset);
527 }
528 @Override
529 MethodHandle viewAsType(MethodType newType, boolean strict) {
530 assert(viewAsTypeChecks(newType, strict));
531 return new Accessor(newType, form, member, false, fieldOffset);
532 }
533 }
534
535 @ForceInline
536 /*non-public*/
537 static long fieldOffset(Object accessorObj) {
538 // Note: We return a long because that is what Unsafe.getObject likes.
539 // We store a plain int because it is more compact.
540 return ((Accessor)accessorObj).fieldOffset;
541 }
542
543 @ForceInline
544 /*non-public*/
545 static Object checkBase(Object obj) {
546 // Note that the object's class has already been verified,
547 // since the parameter type of the Accessor method handle
548 // is either member.getDeclaringClass or a subclass.
549 // This was verified in DirectMethodHandle.make.
550 // Therefore, the only remaining check is for null.
551 // Since this check is *not* guaranteed by Unsafe.getInt
552 // and its siblings, we need to make an explicit one here.
553 return Objects.requireNonNull(obj);
554 }
555
556 /** This subclass handles static field references. */
557 static final class StaticAccessor extends DirectMethodHandle {
558 private final Class<?> fieldType;
559 private final Object staticBase;
560 private final long staticOffset;
561
562 private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member,
563 boolean crackable, Object staticBase, long staticOffset) {
564 super(mtype, form, member, crackable);
565 this.fieldType = member.getFieldType();
566 this.staticBase = staticBase;
567 this.staticOffset = staticOffset;
568 }
569
570 @Override Object checkCast(Object obj) {
571 return fieldType.cast(obj);
572 }
573 @Override
574 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
575 return new StaticAccessor(mt, lf, member, crackable, staticBase, staticOffset);
576 }
577 @Override
578 MethodHandle viewAsType(MethodType newType, boolean strict) {
579 assert(viewAsTypeChecks(newType, strict));
580 return new StaticAccessor(newType, form, member, false, staticBase, staticOffset);
581 }
582 }
583
584 @ForceInline
585 /*non-public*/
586 static Object nullCheck(Object obj) {
587 return Objects.requireNonNull(obj);
588 }
589
590 @ForceInline
591 /*non-public*/
592 static Object staticBase(Object accessorObj) {
593 return ((StaticAccessor)accessorObj).staticBase;
594 }
595
596 @ForceInline
597 /*non-public*/
598 static long staticOffset(Object accessorObj) {
599 return ((StaticAccessor)accessorObj).staticOffset;
600 }
601
602 @ForceInline
603 /*non-public*/
604 static Object checkCast(Object mh, Object obj) {
605 return ((DirectMethodHandle) mh).checkCast(obj);
606 }
607
608 Object checkCast(Object obj) {
609 return member.getMethodType().returnType().cast(obj);
610 }
611
612 // Caching machinery for field accessors:
613 static final byte
614 AF_GETFIELD = 0,
615 AF_PUTFIELD = 1,
616 AF_GETSTATIC = 2,
617 AF_PUTSTATIC = 3,
618 AF_GETSTATIC_INIT = 4,
619 AF_PUTSTATIC_INIT = 5,
620 AF_LIMIT = 6;
621 // Enumerate the different field kinds using Wrapper,
622 // with an extra case added for checked references.
623 static final int
624 FT_LAST_WRAPPER = Wrapper.COUNT-1,
625 FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(),
626 FT_CHECKED_REF = FT_LAST_WRAPPER+1,
627 FT_LIMIT = FT_LAST_WRAPPER+2;
628 private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {
629 return ((formOp * FT_LIMIT * 2)
630 + (isVolatile ? FT_LIMIT : 0)
631 + ftypeKind);
632 }
633 @Stable
634 private static final LambdaForm[] ACCESSOR_FORMS
635 = new LambdaForm[afIndex(AF_LIMIT, false, 0)];
636 static int ftypeKind(Class<?> ftype) {
637 if (ftype.isPrimitive()) {
638 return Wrapper.forPrimitiveType(ftype).ordinal();
639 } else if (ftype.isInterface() || ftype.isAssignableFrom(Object.class)) {
640 // retyping can be done without a cast
641 return FT_UNCHECKED_REF;
642 } else {
643 return FT_CHECKED_REF;
644 }
645 }
646
647 /**
648 * Create a LF which can access the given field.
649 * Cache and share this structure among all fields with
650 * the same basicType and refKind.
651 */
652 private static LambdaForm preparedFieldLambdaForm(MemberName m) {
653 Class<?> ftype = m.getFieldType();
654 boolean isVolatile = m.isVolatile();
655 byte formOp = switch (m.getReferenceKind()) {
656 case REF_getField -> AF_GETFIELD;
657 case REF_putField -> AF_PUTFIELD;
658 case REF_getStatic -> AF_GETSTATIC;
659 case REF_putStatic -> AF_PUTSTATIC;
660 default -> throw new InternalError(m.toString());
661 };
662 if (shouldBeInitialized(m)) {
663 // precompute the barrier-free version:
664 preparedFieldLambdaForm(formOp, isVolatile, ftype);
665 assert((AF_GETSTATIC_INIT - AF_GETSTATIC) ==
666 (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
667 formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
668 }
669 LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
670 maybeCompile(lform, m);
671 assert(lform.methodType().dropParameterTypes(0, 1)
672 .equals(m.getInvocationType().basicType()))
673 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
674 return lform;
675 }
676 private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype) {
677 int ftypeKind = ftypeKind(ftype);
678 int afIndex = afIndex(formOp, isVolatile, ftypeKind);
679 LambdaForm lform = ACCESSOR_FORMS[afIndex];
680 if (lform != null) return lform;
681 lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind);
682 ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS
683 return lform;
684 }
685
686 private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();
687
688 private static Kind getFieldKind(boolean isGetter, boolean isVolatile, Wrapper wrapper) {
689 if (isGetter) {
690 if (isVolatile) {
691 switch (wrapper) {
692 case BOOLEAN: return GET_BOOLEAN_VOLATILE;
693 case BYTE: return GET_BYTE_VOLATILE;
694 case SHORT: return GET_SHORT_VOLATILE;
695 case CHAR: return GET_CHAR_VOLATILE;
696 case INT: return GET_INT_VOLATILE;
697 case LONG: return GET_LONG_VOLATILE;
698 case FLOAT: return GET_FLOAT_VOLATILE;
699 case DOUBLE: return GET_DOUBLE_VOLATILE;
700 case OBJECT: return GET_REFERENCE_VOLATILE;
701 }
702 } else {
703 switch (wrapper) {
704 case BOOLEAN: return GET_BOOLEAN;
705 case BYTE: return GET_BYTE;
706 case SHORT: return GET_SHORT;
707 case CHAR: return GET_CHAR;
708 case INT: return GET_INT;
709 case LONG: return GET_LONG;
710 case FLOAT: return GET_FLOAT;
711 case DOUBLE: return GET_DOUBLE;
712 case OBJECT: return GET_REFERENCE;
713 }
714 }
715 } else {
716 if (isVolatile) {
717 switch (wrapper) {
718 case BOOLEAN: return PUT_BOOLEAN_VOLATILE;
719 case BYTE: return PUT_BYTE_VOLATILE;
720 case SHORT: return PUT_SHORT_VOLATILE;
721 case CHAR: return PUT_CHAR_VOLATILE;
722 case INT: return PUT_INT_VOLATILE;
723 case LONG: return PUT_LONG_VOLATILE;
724 case FLOAT: return PUT_FLOAT_VOLATILE;
725 case DOUBLE: return PUT_DOUBLE_VOLATILE;
726 case OBJECT: return PUT_REFERENCE_VOLATILE;
727 }
728 } else {
729 switch (wrapper) {
730 case BOOLEAN: return PUT_BOOLEAN;
731 case BYTE: return PUT_BYTE;
732 case SHORT: return PUT_SHORT;
733 case CHAR: return PUT_CHAR;
734 case INT: return PUT_INT;
735 case LONG: return PUT_LONG;
736 case FLOAT: return PUT_FLOAT;
737 case DOUBLE: return PUT_DOUBLE;
738 case OBJECT: return PUT_REFERENCE;
739 }
740 }
741 }
742 throw new AssertionError("Invalid arguments");
743 }
744
745 static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) {
746 boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
747 boolean isStatic = (formOp >= AF_GETSTATIC);
748 boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
749 boolean needsCast = (ftypeKind == FT_CHECKED_REF);
750 Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
751 Class<?> ft = fw.primitiveType();
752 assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind);
753
754 // getObject, putIntVolatile, etc.
755 Kind kind = getFieldKind(isGetter, isVolatile, fw);
756
757 MethodType linkerType;
758 if (isGetter)
759 linkerType = MethodType.methodType(ft, Object.class, long.class);
760 else
761 linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
762 MemberName linker = new MemberName(Unsafe.class, kind.methodName, linkerType, REF_invokeVirtual);
763 try {
764 linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, LM_TRUSTED,
765 NoSuchMethodException.class);
766 } catch (ReflectiveOperationException ex) {
767 throw newInternalError(ex);
768 }
769
770 // What is the external type of the lambda form?
771 MethodType mtype;
772 if (isGetter)
773 mtype = MethodType.methodType(ft);
774 else
775 mtype = MethodType.methodType(void.class, ft);
776 mtype = mtype.basicType(); // erase short to int, etc.
777 if (!isStatic)
778 mtype = mtype.insertParameterTypes(0, Object.class);
779 final int DMH_THIS = 0;
780 final int ARG_BASE = 1;
781 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
782 // if this is for non-static access, the base pointer is stored at this index:
783 final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
784 // if this is for write access, the value to be written is stored at this index:
785 final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
786 int nameCursor = ARG_LIMIT;
787 final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
788 final int F_OFFSET = nameCursor++; // Either static offset or field offset.
789 final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
790 final int U_HOLDER = nameCursor++; // UNSAFE holder
791 final int INIT_BAR = (needsInit ? nameCursor++ : -1);
792 final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
793 final int LINKER_CALL = nameCursor++;
794 final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
795 final int RESULT = nameCursor-1; // either the call or the cast
796 Name[] names = invokeArguments(nameCursor - ARG_LIMIT, mtype);
797 if (needsInit)
798 names[INIT_BAR] = new Name(getFunction(NF_ensureInitialized), names[DMH_THIS]);
799 if (needsCast && !isGetter)
800 names[PRE_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[SET_VALUE]);
801 Object[] outArgs = new Object[1 + linkerType.parameterCount()];
802 assert(outArgs.length == (isGetter ? 3 : 4));
803 outArgs[0] = names[U_HOLDER] = new Name(getFunction(NF_UNSAFE));
804 if (isStatic) {
805 outArgs[1] = names[F_HOLDER] = new Name(getFunction(NF_staticBase), names[DMH_THIS]);
806 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_staticOffset), names[DMH_THIS]);
807 } else {
808 outArgs[1] = names[OBJ_CHECK] = new Name(getFunction(NF_checkBase), names[OBJ_BASE]);
809 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_fieldOffset), names[DMH_THIS]);
810 }
811 if (!isGetter) {
812 outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
813 }
814 for (Object a : outArgs) assert(a != null);
815 names[LINKER_CALL] = new Name(linker, outArgs);
816 if (needsCast && isGetter)
817 names[POST_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[LINKER_CALL]);
818 for (Name n : names) assert(n != null);
819
820 LambdaForm form;
821 if (needsCast || needsInit) {
822 // can't use the pre-generated form when casting and/or initializing
823 form = LambdaForm.create(ARG_LIMIT, names, RESULT);
824 } else {
825 form = LambdaForm.create(ARG_LIMIT, names, RESULT, kind);
826 }
827
828 if (LambdaForm.debugNames()) {
829 // add some detail to the lambdaForm debugname,
830 // significant only for debugging
831 StringBuilder nameBuilder = new StringBuilder(kind.methodName);
832 if (isStatic) {
833 nameBuilder.append("Static");
834 } else {
835 nameBuilder.append("Field");
836 }
837 if (needsCast) {
838 nameBuilder.append("Cast");
839 }
840 if (needsInit) {
841 nameBuilder.append("Init");
842 }
843 LambdaForm.associateWithDebugName(form, nameBuilder.toString());
844 }
845 return form;
846 }
847
848 /**
849 * Pre-initialized NamedFunctions for bootstrapping purposes.
850 */
851 static final byte NF_internalMemberName = 0,
852 NF_internalMemberNameEnsureInit = 1,
853 NF_ensureInitialized = 2,
854 NF_fieldOffset = 3,
855 NF_checkBase = 4,
856 NF_staticBase = 5,
857 NF_staticOffset = 6,
858 NF_checkCast = 7,
859 NF_allocateInstance = 8,
860 NF_constructorMethod = 9,
861 NF_UNSAFE = 10,
862 NF_checkReceiver = 11,
863 NF_LIMIT = 12;
864
865 private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT];
866
867 private static NamedFunction getFunction(byte func) {
868 NamedFunction nf = NFS[func];
869 if (nf != null) {
870 return nf;
871 }
872 // Each nf must be statically invocable or we get tied up in our bootstraps.
873 nf = NFS[func] = createFunction(func);
874 assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf));
875 return nf;
876 }
877
878 private static final MethodType OBJ_OBJ_TYPE = MethodType.methodType(Object.class, Object.class);
879
880 private static final MethodType LONG_OBJ_TYPE = MethodType.methodType(long.class, Object.class);
881
882 private static NamedFunction createFunction(byte func) {
883 try {
884 switch (func) {
885 case NF_internalMemberName:
886 return getNamedFunction("internalMemberName", OBJ_OBJ_TYPE);
887 case NF_internalMemberNameEnsureInit:
888 return getNamedFunction("internalMemberNameEnsureInit", OBJ_OBJ_TYPE);
889 case NF_ensureInitialized:
890 return getNamedFunction("ensureInitialized", MethodType.methodType(void.class, Object.class));
891 case NF_fieldOffset:
892 return getNamedFunction("fieldOffset", LONG_OBJ_TYPE);
893 case NF_checkBase:
894 return getNamedFunction("checkBase", OBJ_OBJ_TYPE);
895 case NF_staticBase:
896 return getNamedFunction("staticBase", OBJ_OBJ_TYPE);
897 case NF_staticOffset:
898 return getNamedFunction("staticOffset", LONG_OBJ_TYPE);
899 case NF_checkCast:
900 return getNamedFunction("checkCast", MethodType.methodType(Object.class, Object.class, Object.class));
901 case NF_allocateInstance:
902 return getNamedFunction("allocateInstance", OBJ_OBJ_TYPE);
903 case NF_constructorMethod:
904 return getNamedFunction("constructorMethod", OBJ_OBJ_TYPE);
905 case NF_UNSAFE:
906 MemberName member = new MemberName(MethodHandleStatics.class, "UNSAFE", Unsafe.class, REF_getStatic);
907 return new NamedFunction(
908 MemberName.getFactory().resolveOrFail(REF_getStatic, member,
909 DirectMethodHandle.class, LM_TRUSTED,
910 NoSuchFieldException.class));
911 case NF_checkReceiver:
912 member = new MemberName(DirectMethodHandle.class, "checkReceiver", OBJ_OBJ_TYPE, REF_invokeVirtual);
913 return new NamedFunction(
914 MemberName.getFactory().resolveOrFail(REF_invokeVirtual, member,
915 DirectMethodHandle.class, LM_TRUSTED,
916 NoSuchMethodException.class));
917 default:
918 throw newInternalError("Unknown function: " + func);
919 }
920 } catch (ReflectiveOperationException ex) {
921 throw newInternalError(ex);
922 }
923 }
924
925 private static NamedFunction getNamedFunction(String name, MethodType type)
926 throws ReflectiveOperationException
927 {
928 MemberName member = new MemberName(DirectMethodHandle.class, name, type, REF_invokeStatic);
929 return new NamedFunction(
930 MemberName.getFactory().resolveOrFail(REF_invokeStatic, member,
931 DirectMethodHandle.class, LM_TRUSTED,
932 NoSuchMethodException.class));
933 }
934
935 static {
936 // The Holder class will contain pre-generated DirectMethodHandles resolved
937 // speculatively using MemberName.getFactory().resolveOrNull. However, that
938 // doesn't initialize the class, which subtly breaks inlining etc. By forcing
939 // initialization of the Holder class we avoid these issues.
940 UNSAFE.ensureClassInitialized(Holder.class);
941 }
942
943 /* Placeholder class for DirectMethodHandles generated ahead of time */
944 final class Holder {}
945 }