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;
137 ctor = ctor.asConstructor();
138 assert(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()) {
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 boolean checkInitialized() {
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 boolean initializingStill = UNSAFE.shouldBeInitialized(defc);
395 if (initializingStill && member.isStrict()) {
396 // while <clinit> is running, we track access to strict static fields
397 UNSAFE.notifyStrictStaticAccess(defc, staticOffset(this), member.isSetter());
398 }
399 return !initializingStill;
400 }
401
402 /*non-public*/
403 static void ensureInitialized(Object mh) {
404 ((DirectMethodHandle)mh).ensureInitialized();
405 }
406
407 /** This subclass represents invokespecial instructions. */
408 static final class Special extends DirectMethodHandle {
409 private final Class<?> caller;
410 private Special(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> caller) {
411 super(mtype, form, member, crackable);
412 this.caller = caller;
413 }
414 @Override
415 boolean isInvokeSpecial() {
416 return true;
417 }
418 @Override
419 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
420 return new Special(mt, lf, member, crackable, caller);
421 }
422 @Override
423 MethodHandle viewAsType(MethodType newType, boolean strict) {
424 assert(viewAsTypeChecks(newType, strict));
425 return new Special(newType, form, member, false, caller);
426 }
427 Object checkReceiver(Object recv) {
428 if (!caller.isInstance(recv)) {
429 if (recv != null) {
430 String msg = String.format("Receiver class %s is not a subclass of caller class %s",
431 recv.getClass().getName(), caller.getName());
432 throw new IncompatibleClassChangeError(msg);
433 } else {
434 String msg = String.format("Cannot invoke %s with null receiver", member);
435 throw new NullPointerException(msg);
436 }
437 }
438 return recv;
439 }
440 }
441
442 /** This subclass represents invokeinterface instructions. */
443 static final class Interface extends DirectMethodHandle {
444 private final Class<?> refc;
445 private Interface(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> refc) {
446 super(mtype, form, member, crackable);
447 assert(refc.isInterface()) : refc;
448 this.refc = refc;
449 }
450 @Override
451 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
452 return new Interface(mt, lf, member, crackable, refc);
453 }
454 @Override
455 MethodHandle viewAsType(MethodType newType, boolean strict) {
456 assert(viewAsTypeChecks(newType, strict));
457 return new Interface(newType, form, member, false, refc);
458 }
459 @Override
460 Object checkReceiver(Object recv) {
461 if (!refc.isInstance(recv)) {
462 if (recv != null) {
463 String msg = String.format("Receiver class %s does not implement the requested interface %s",
464 recv.getClass().getName(), refc.getName());
465 throw new IncompatibleClassChangeError(msg);
466 } else {
467 String msg = String.format("Cannot invoke %s with null receiver", member);
468 throw new NullPointerException(msg);
469 }
470 }
471 return recv;
472 }
473 }
474
475 /** Used for interface receiver type checks, by Interface and Special modes. */
476 Object checkReceiver(Object recv) {
477 throw new InternalError("Should only be invoked on a subclass");
478 }
479
480 /** This subclass handles constructor references. */
481 static final class Constructor extends DirectMethodHandle {
482 final MemberName initMethod;
483 final Class<?> instanceClass;
484
485 private Constructor(MethodType mtype, LambdaForm form, MemberName constructor,
486 boolean crackable, MemberName initMethod, Class<?> instanceClass) {
487 super(mtype, form, constructor, crackable);
488 this.initMethod = initMethod;
489 this.instanceClass = instanceClass;
490 assert(initMethod.isResolved());
491 }
492 @Override
493 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
494 return new Constructor(mt, lf, member, crackable, initMethod, instanceClass);
495 }
496 @Override
497 MethodHandle viewAsType(MethodType newType, boolean strict) {
498 assert(viewAsTypeChecks(newType, strict));
499 return new Constructor(newType, form, member, false, initMethod, instanceClass);
500 }
501 }
502
503 /*non-public*/
504 static Object constructorMethod(Object mh) {
505 Constructor dmh = (Constructor)mh;
506 return dmh.initMethod;
507 }
508
509 /*non-public*/
510 static Object allocateInstance(Object mh) throws InstantiationException {
511 Constructor dmh = (Constructor)mh;
512 return UNSAFE.allocateInstance(dmh.instanceClass);
513 }
514
515 /** This subclass handles non-static field references. */
516 static final class Accessor extends DirectMethodHandle {
517 final Class<?> fieldType;
518 final int fieldOffset;
519 final int layout;
520 private Accessor(MethodType mtype, LambdaForm form, MemberName member,
521 boolean crackable, int fieldOffset) {
522 super(mtype, form, member, crackable);
523 this.fieldType = member.getFieldType();
524 this.fieldOffset = fieldOffset;
525 this.layout = member.getLayout();
526 }
527
528 @Override Object checkCast(Object obj) {
529 return fieldType.cast(obj);
530 }
531 @Override
532 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
533 return new Accessor(mt, lf, member, crackable, fieldOffset);
534 }
535 @Override
536 MethodHandle viewAsType(MethodType newType, boolean strict) {
537 assert(viewAsTypeChecks(newType, strict));
538 return new Accessor(newType, form, member, false, fieldOffset);
539 }
540 }
541
542 @ForceInline
543 /*non-public*/
544 static long fieldOffset(Object accessorObj) {
545 // Note: We return a long because that is what Unsafe.getObject likes.
546 // We store a plain int because it is more compact.
547 return ((Accessor)accessorObj).fieldOffset;
548 }
549
550 @ForceInline
551 /*non-public*/
552 static Object checkBase(Object obj) {
553 // Note that the object's class has already been verified,
554 // since the parameter type of the Accessor method handle
555 // is either member.getDeclaringClass or a subclass.
556 // This was verified in DirectMethodHandle.make.
557 // Therefore, the only remaining check is for null.
558 // Since this check is *not* guaranteed by Unsafe.getInt
559 // and its siblings, we need to make an explicit one here.
560 return Objects.requireNonNull(obj);
561 }
562
563 /** This subclass handles static field references. */
564 static final class StaticAccessor extends DirectMethodHandle {
565 private final Class<?> fieldType;
566 private final Object staticBase;
567 private final long staticOffset;
568
569 private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member,
570 boolean crackable, Object staticBase, long staticOffset) {
571 super(mtype, form, member, crackable);
572 this.fieldType = member.getFieldType();
573 this.staticBase = staticBase;
574 this.staticOffset = staticOffset;
575 }
576
577 @Override Object checkCast(Object obj) {
578 return fieldType.cast(obj);
579 }
580 @Override
581 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
582 return new StaticAccessor(mt, lf, member, crackable, staticBase, staticOffset);
583 }
584 @Override
585 MethodHandle viewAsType(MethodType newType, boolean strict) {
586 assert(viewAsTypeChecks(newType, strict));
587 return new StaticAccessor(newType, form, member, false, staticBase, staticOffset);
588 }
589 }
590
591 @ForceInline
592 /*non-public*/
593 static Object nullCheck(Object obj) {
594 return Objects.requireNonNull(obj);
595 }
596
597 @ForceInline
598 /*non-public*/
599 static Object staticBase(Object accessorObj) {
600 return ((StaticAccessor)accessorObj).staticBase;
601 }
602
603 @ForceInline
604 /*non-public*/
605 static long staticOffset(Object accessorObj) {
606 return ((StaticAccessor)accessorObj).staticOffset;
607 }
608
609 @ForceInline
610 /*non-public*/
611 static Object checkCast(Object mh, Object obj) {
612 return ((DirectMethodHandle) mh).checkCast(obj);
613 }
614
615 @ForceInline
616 /*non-public*/ static Class<?> fieldType(Object accessorObj) {
617 return ((Accessor) accessorObj).fieldType;
618 }
619
620 @ForceInline
621 static int fieldLayout(Object accessorObj) {
622 return ((Accessor) accessorObj).layout;
623 }
624
625 @ForceInline
626 /*non-public*/ static Class<?> staticFieldType(Object accessorObj) {
627 return ((StaticAccessor) accessorObj).fieldType;
628 }
629
630 Object checkCast(Object obj) {
631 return member.getMethodType().returnType().cast(obj);
632 }
633
634 // Caching machinery for field accessors:
635 static final byte
636 AF_GETFIELD = 0,
637 AF_PUTFIELD = 1,
638 AF_GETSTATIC = 2,
639 AF_PUTSTATIC = 3,
640 AF_GETSTATIC_INIT = 4,
641 AF_PUTSTATIC_INIT = 5,
642 AF_LIMIT = 6;
643 // Enumerate the different field kinds using Wrapper,
644 // with an extra case added for checked references and value field access
645 static final int
646 FT_LAST_WRAPPER = Wrapper.COUNT-1,
647 FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(),
648 FT_CHECKED_REF = FT_LAST_WRAPPER+1,
649 FT_CHECKED_VALUE = FT_LAST_WRAPPER+2, // flat vs non-flat x null value vs null-restricted value
650 FT_LIMIT = FT_LAST_WRAPPER+6;
651 private static int afIndex(byte formOp, boolean isVolatile, boolean isFlat, boolean isNullRestricted, int ftypeKind) {
652 return ((formOp * FT_LIMIT * 2)
653 + (isVolatile ? FT_LIMIT : 0)
654 + (isFlat ? 1 : 0)
655 + (isNullRestricted ? 1 : 0)
656 + ftypeKind);
657 }
658 @Stable
659 private static final LambdaForm[] ACCESSOR_FORMS
660 = new LambdaForm[afIndex(AF_LIMIT, false, false, false, 0)];
661 static int ftypeKind(Class<?> ftype) {
662 if (ftype.isPrimitive()) {
663 return Wrapper.forPrimitiveType(ftype).ordinal();
664 } else if (ftype.isInterface() || ftype.isAssignableFrom(Object.class)) {
665 // retyping can be done without a cast
666 return FT_UNCHECKED_REF;
667 } else {
668 return ftype.isValue() ? FT_CHECKED_VALUE : FT_CHECKED_REF;
669 }
670 }
671
672 /**
673 * Create a LF which can access the given field.
674 * Cache and share this structure among all fields with
675 * the same basicType and refKind.
676 */
677 private static LambdaForm preparedFieldLambdaForm(MemberName m) {
678 Class<?> ftype = m.getFieldType();
679 byte formOp = switch (m.getReferenceKind()) {
680 case REF_getField -> AF_GETFIELD;
681 case REF_putField -> AF_PUTFIELD;
682 case REF_getStatic -> AF_GETSTATIC;
683 case REF_putStatic -> AF_PUTSTATIC;
684 default -> throw new InternalError(m.toString());
685 };
686 if (shouldBeInitialized(m)) {
687 // precompute the barrier-free version:
688 preparedFieldLambdaForm(formOp, m.isVolatile(), m.isFlat(), m.isNullRestricted(), ftype);
689 assert((AF_GETSTATIC_INIT - AF_GETSTATIC) ==
690 (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
691 formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
692 }
693 LambdaForm lform = preparedFieldLambdaForm(formOp, m.isVolatile(), m.isFlat(), m.isNullRestricted(), ftype);
694 maybeCompile(lform, m);
695 assert(lform.methodType().dropParameterTypes(0, 1)
696 .equals(m.getInvocationType().basicType()))
697 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
698 return lform;
699 }
700
701 private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile,
702 boolean isFlat, boolean isNullRestricted, Class<?> ftype) {
703 int ftypeKind = ftypeKind(ftype);
704 int afIndex = afIndex(formOp, isVolatile, isFlat, isNullRestricted, ftypeKind);
705 LambdaForm lform = ACCESSOR_FORMS[afIndex];
706 if (lform != null) return lform;
707 lform = makePreparedFieldLambdaForm(formOp, isVolatile,isFlat, isNullRestricted, ftypeKind);
708 ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS
709 return lform;
710 }
711
712 private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();
713
714 private static Kind getFieldKind(boolean isGetter, boolean isVolatile, boolean isFlat, Wrapper wrapper) {
715 if (isGetter) {
716 if (isVolatile) {
717 switch (wrapper) {
718 case BOOLEAN: return GET_BOOLEAN_VOLATILE;
719 case BYTE: return GET_BYTE_VOLATILE;
720 case SHORT: return GET_SHORT_VOLATILE;
721 case CHAR: return GET_CHAR_VOLATILE;
722 case INT: return GET_INT_VOLATILE;
723 case LONG: return GET_LONG_VOLATILE;
724 case FLOAT: return GET_FLOAT_VOLATILE;
725 case DOUBLE: return GET_DOUBLE_VOLATILE;
726 case OBJECT: return isFlat ? GET_FLAT_VALUE_VOLATILE : GET_REFERENCE_VOLATILE;
727 }
728 } else {
729 switch (wrapper) {
730 case BOOLEAN: return GET_BOOLEAN;
731 case BYTE: return GET_BYTE;
732 case SHORT: return GET_SHORT;
733 case CHAR: return GET_CHAR;
734 case INT: return GET_INT;
735 case LONG: return GET_LONG;
736 case FLOAT: return GET_FLOAT;
737 case DOUBLE: return GET_DOUBLE;
738 case OBJECT: return isFlat ? GET_FLAT_VALUE : GET_REFERENCE;
739 }
740 }
741 } else {
742 if (isVolatile) {
743 switch (wrapper) {
744 case BOOLEAN: return PUT_BOOLEAN_VOLATILE;
745 case BYTE: return PUT_BYTE_VOLATILE;
746 case SHORT: return PUT_SHORT_VOLATILE;
747 case CHAR: return PUT_CHAR_VOLATILE;
748 case INT: return PUT_INT_VOLATILE;
749 case LONG: return PUT_LONG_VOLATILE;
750 case FLOAT: return PUT_FLOAT_VOLATILE;
751 case DOUBLE: return PUT_DOUBLE_VOLATILE;
752 case OBJECT: return isFlat ? PUT_FLAT_VALUE_VOLATILE : PUT_REFERENCE_VOLATILE;
753 }
754 } else {
755 switch (wrapper) {
756 case BOOLEAN: return PUT_BOOLEAN;
757 case BYTE: return PUT_BYTE;
758 case SHORT: return PUT_SHORT;
759 case CHAR: return PUT_CHAR;
760 case INT: return PUT_INT;
761 case LONG: return PUT_LONG;
762 case FLOAT: return PUT_FLOAT;
763 case DOUBLE: return PUT_DOUBLE;
764 case OBJECT: return isFlat ? PUT_FLAT_VALUE : PUT_REFERENCE;
765 }
766 }
767 }
768 throw new AssertionError("Invalid arguments");
769 }
770
771 /** invoked by GenerateJLIClassesHelper */
772 static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftype) {
773 return makePreparedFieldLambdaForm(formOp, isVolatile, false, false, ftype);
774 }
775
776 private static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile,
777 boolean isFlat, boolean isNullRestricted, int ftypeKind) {
778 boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
779 boolean isStatic = (formOp >= AF_GETSTATIC);
780 boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
781 boolean needsCast = (ftypeKind == FT_CHECKED_REF || ftypeKind == FT_CHECKED_VALUE);
782 Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
783 Class<?> ft = fw.primitiveType();
784 assert(needsCast ? true : ftypeKind(ft) == ftypeKind);
785
786 // getObject, putIntVolatile, etc.
787 Kind kind = getFieldKind(isGetter, isVolatile, isFlat, fw);
788
789 MethodType linkerType;
790 if (isGetter) {
791 linkerType = isFlat
792 ? MethodType.methodType(ft, Object.class, long.class, int.class, Class.class)
793 : MethodType.methodType(ft, Object.class, long.class);
794 } else {
795 linkerType = isFlat
796 ? MethodType.methodType(void.class, Object.class, long.class, int.class, Class.class, ft)
797 : MethodType.methodType(void.class, Object.class, long.class, ft);
798 }
799 MemberName linker = new MemberName(Unsafe.class, kind.methodName, linkerType, REF_invokeVirtual);
800 try {
801 linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, LM_TRUSTED,
802 NoSuchMethodException.class);
803 } catch (ReflectiveOperationException ex) {
804 throw newInternalError(ex);
805 }
806
807 // What is the external type of the lambda form?
808 MethodType mtype;
809 if (isGetter)
810 mtype = MethodType.methodType(ft);
811 else
812 mtype = MethodType.methodType(void.class, ft);
813 mtype = mtype.basicType(); // erase short to int, etc.
814 if (!isStatic)
815 mtype = mtype.insertParameterTypes(0, Object.class);
816 final int DMH_THIS = 0;
817 final int ARG_BASE = 1;
818 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
819 // if this is for non-static access, the base pointer is stored at this index:
820 final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
821 // if this is for write access, the value to be written is stored at this index:
822 final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
823 int nameCursor = ARG_LIMIT;
824 final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
825 final int F_OFFSET = nameCursor++; // Either static offset or field offset.
826 final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
827 final int U_HOLDER = nameCursor++; // UNSAFE holder
828 final int INIT_BAR = (needsInit ? nameCursor++ : -1);
829 final int LAYOUT = (isFlat ? nameCursor++ : -1); // field must be instance
830 final int VALUE_TYPE = (isFlat ? nameCursor++ : -1);
831 final int NULL_CHECK = (isNullRestricted && !isGetter ? nameCursor++ : -1);
832 final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
833 final int LINKER_CALL = nameCursor++;
834 final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
835 final int RESULT = nameCursor-1; // either the call, or the cast
836 Name[] names = invokeArguments(nameCursor - ARG_LIMIT, mtype);
837 if (needsInit)
838 names[INIT_BAR] = new Name(getFunction(NF_ensureInitialized), names[DMH_THIS]);
839 if (!isGetter) {
840 if (isNullRestricted)
841 names[NULL_CHECK] = new Name(getFunction(NF_nullCheck), names[SET_VALUE]);
842 if (needsCast)
843 names[PRE_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[SET_VALUE]);
844 }
845 Object[] outArgs = new Object[1 + linkerType.parameterCount()];
846 assert (outArgs.length == (isGetter ? 3 : 4) + (isFlat ? 2 : 0));
847 outArgs[0] = names[U_HOLDER] = new Name(getFunction(NF_UNSAFE));
848 if (isStatic) {
849 outArgs[1] = names[F_HOLDER] = new Name(getFunction(NF_staticBase), names[DMH_THIS]);
850 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_staticOffset), names[DMH_THIS]);
851 } else {
852 outArgs[1] = names[OBJ_CHECK] = new Name(getFunction(NF_checkBase), names[OBJ_BASE]);
853 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_fieldOffset), names[DMH_THIS]);
854 }
855 int x = 3;
856 if (isFlat) {
857 assert !isStatic : "static field is flat form requested";
858 outArgs[x++] = names[LAYOUT] = new Name(getFunction(NF_fieldLayout), names[DMH_THIS]);
859 outArgs[x++] = names[VALUE_TYPE] = isStatic ? new Name(getFunction(NF_staticFieldType), names[DMH_THIS])
860 : new Name(getFunction(NF_fieldType), names[DMH_THIS]);
861 }
862 if (!isGetter) {
863 outArgs[x] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
864 }
865 for (Object a : outArgs) assert(a != null);
866 names[LINKER_CALL] = new Name(linker, outArgs);
867 if (needsCast && isGetter)
868 names[POST_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[LINKER_CALL]);
869 for (Name n : names) assert(n != null);
870
871 LambdaForm form;
872 if (needsCast || needsInit) {
873 // can't use the pre-generated form when casting and/or initializing
874 form = LambdaForm.create(ARG_LIMIT, names, RESULT);
875 } else {
876 form = LambdaForm.create(ARG_LIMIT, names, RESULT, kind);
877 }
878
879 if (LambdaForm.debugNames()) {
880 // add some detail to the lambdaForm debugname,
881 // significant only for debugging
882 StringBuilder nameBuilder = new StringBuilder(kind.methodName);
883 if (isStatic) {
884 nameBuilder.append("Static");
885 } else {
886 nameBuilder.append("Field");
887 }
888 if (needsCast) {
889 nameBuilder.append("Cast");
890 }
891 if (needsInit) {
892 nameBuilder.append("Init");
893 }
894 LambdaForm.associateWithDebugName(form, nameBuilder.toString());
895 }
896 return form;
897 }
898
899 /**
900 * Pre-initialized NamedFunctions for bootstrapping purposes.
901 */
902 static final byte NF_internalMemberName = 0,
903 NF_internalMemberNameEnsureInit = 1,
904 NF_ensureInitialized = 2,
905 NF_fieldOffset = 3,
906 NF_checkBase = 4,
907 NF_staticBase = 5,
908 NF_staticOffset = 6,
909 NF_checkCast = 7,
910 NF_allocateInstance = 8,
911 NF_constructorMethod = 9,
912 NF_UNSAFE = 10,
913 NF_checkReceiver = 11,
914 NF_fieldType = 12,
915 NF_staticFieldType = 13,
916 NF_fieldLayout = 14,
917 NF_nullCheck = 15,
918 NF_LIMIT = 16;
919
920 private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT];
921
922 private static NamedFunction getFunction(byte func) {
923 NamedFunction nf = NFS[func];
924 if (nf != null) {
925 return nf;
926 }
927 // Each nf must be statically invocable or we get tied up in our bootstraps.
928 nf = NFS[func] = createFunction(func);
929 assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf));
930 return nf;
931 }
932
933 private static final MethodType CLS_OBJ_TYPE = MethodType.methodType(Class.class, Object.class);
934 private static final MethodType INT_OBJ_TYPE = MethodType.methodType(int.class, Object.class);
935
936 private static final MethodType OBJ_OBJ_TYPE = MethodType.methodType(Object.class, Object.class);
937
938 private static final MethodType LONG_OBJ_TYPE = MethodType.methodType(long.class, Object.class);
939
940 private static NamedFunction createFunction(byte func) {
941 try {
942 switch (func) {
943 case NF_internalMemberName:
944 return getNamedFunction("internalMemberName", OBJ_OBJ_TYPE);
945 case NF_internalMemberNameEnsureInit:
946 return getNamedFunction("internalMemberNameEnsureInit", OBJ_OBJ_TYPE);
947 case NF_ensureInitialized:
948 return getNamedFunction("ensureInitialized", MethodType.methodType(void.class, Object.class));
949 case NF_fieldOffset:
950 return getNamedFunction("fieldOffset", LONG_OBJ_TYPE);
951 case NF_checkBase:
952 return getNamedFunction("checkBase", OBJ_OBJ_TYPE);
953 case NF_staticBase:
954 return getNamedFunction("staticBase", OBJ_OBJ_TYPE);
955 case NF_staticOffset:
956 return getNamedFunction("staticOffset", LONG_OBJ_TYPE);
957 case NF_checkCast:
958 return getNamedFunction("checkCast", MethodType.methodType(Object.class, Object.class, Object.class));
959 case NF_allocateInstance:
960 return getNamedFunction("allocateInstance", OBJ_OBJ_TYPE);
961 case NF_constructorMethod:
962 return getNamedFunction("constructorMethod", OBJ_OBJ_TYPE);
963 case NF_UNSAFE:
964 MemberName member = new MemberName(MethodHandleStatics.class, "UNSAFE", Unsafe.class, REF_getStatic);
965 return new NamedFunction(
966 MemberName.getFactory().resolveOrFail(REF_getStatic, member,
967 DirectMethodHandle.class, LM_TRUSTED,
968 NoSuchFieldException.class));
969 case NF_checkReceiver:
970 member = new MemberName(DirectMethodHandle.class, "checkReceiver", OBJ_OBJ_TYPE, REF_invokeVirtual);
971 return new NamedFunction(
972 MemberName.getFactory().resolveOrFail(REF_invokeVirtual, member,
973 DirectMethodHandle.class, LM_TRUSTED,
974 NoSuchMethodException.class));
975 case NF_fieldType:
976 return getNamedFunction("fieldType", CLS_OBJ_TYPE);
977 case NF_staticFieldType:
978 return getNamedFunction("staticFieldType", CLS_OBJ_TYPE);
979 case NF_nullCheck:
980 return getNamedFunction("nullCheck", OBJ_OBJ_TYPE);
981 case NF_fieldLayout:
982 return getNamedFunction("fieldLayout", INT_OBJ_TYPE);
983 default:
984 throw newInternalError("Unknown function: " + func);
985 }
986 } catch (ReflectiveOperationException ex) {
987 throw newInternalError(ex);
988 }
989 }
990
991 private static NamedFunction getNamedFunction(String name, MethodType type)
992 throws ReflectiveOperationException
993 {
994 MemberName member = new MemberName(DirectMethodHandle.class, name, type, REF_invokeStatic);
995 return new NamedFunction(
996 MemberName.getFactory().resolveOrFail(REF_invokeStatic, member,
997 DirectMethodHandle.class, LM_TRUSTED,
998 NoSuchMethodException.class));
999 }
1000
1001 static {
1002 // The Holder class will contain pre-generated DirectMethodHandles resolved
1003 // speculatively using MemberName.getFactory().resolveOrNull. However, that
1004 // doesn't initialize the class, which subtly breaks inlining etc. By forcing
1005 // initialization of the Holder class we avoid these issues.
1006 UNSAFE.ensureClassInitialized(Holder.class);
1007 }
1008
1009 /* Placeholder class for DirectMethodHandles generated ahead of time */
1010 final class Holder {}
1011 }