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 assert(lform.methodType().dropParameterTypes(0, 1)
218 .equals(m.getInvocationType().basicType()))
219 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
220 return lform;
221 }
222
223 private static LambdaForm preparedLambdaForm(MemberName m) {
224 return preparedLambdaForm(m, false);
225 }
226
227 private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {
228 LambdaForm lform = mtype.form().cachedLambdaForm(which);
229 if (lform != null) return lform;
230 lform = makePreparedLambdaForm(mtype, which);
231 return mtype.form().setCachedLambdaForm(which, lform);
232 }
233
234 static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {
235 boolean needsInit = (which == LF_INVSTATIC_INIT);
236 boolean doesAlloc = (which == LF_NEWINVSPECIAL);
237 boolean needsReceiverCheck = (which == LF_INVINTERFACE ||
238 which == LF_INVSPECIAL_IFC);
239
240 String linkerName;
241 LambdaForm.Kind kind;
242 switch (which) {
243 case LF_INVVIRTUAL: linkerName = "linkToVirtual"; kind = DIRECT_INVOKE_VIRTUAL; break;
244 case LF_INVSTATIC: linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC; break;
245 case LF_INVSTATIC_INIT:linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC_INIT; break;
246 case LF_INVSPECIAL_IFC:linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL_IFC; break;
247 case LF_INVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL; break;
248 case LF_INVINTERFACE: linkerName = "linkToInterface"; kind = DIRECT_INVOKE_INTERFACE; break;
249 case LF_NEWINVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_NEW_INVOKE_SPECIAL; break;
250 default: throw new InternalError("which="+which);
251 }
252
253 MethodType mtypeWithArg;
254 if (doesAlloc) {
255 var ptypes = mtype.ptypes();
256 var newPtypes = new Class<?>[ptypes.length + 2];
257 newPtypes[0] = Object.class; // insert newly allocated obj
258 System.arraycopy(ptypes, 0, newPtypes, 1, ptypes.length);
259 newPtypes[newPtypes.length - 1] = MemberName.class;
260 mtypeWithArg = MethodType.methodType(void.class, newPtypes, true);
261 } else {
262 mtypeWithArg = mtype.appendParameterTypes(MemberName.class);
263 }
264 MemberName linker = new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);
265 try {
266 linker = IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, LM_TRUSTED,
267 NoSuchMethodException.class);
268 } catch (ReflectiveOperationException ex) {
269 throw newInternalError(ex);
270 }
271 final int DMH_THIS = 0;
272 final int ARG_BASE = 1;
273 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
274 int nameCursor = ARG_LIMIT;
275 final int NEW_OBJ = (doesAlloc ? nameCursor++ : -1);
276 final int GET_MEMBER = nameCursor++;
277 final int CHECK_RECEIVER = (needsReceiverCheck ? nameCursor++ : -1);
278 final int LINKER_CALL = nameCursor++;
279 Name[] names = invokeArguments(nameCursor - ARG_LIMIT, mtype);
280 assert(names.length == nameCursor);
281 if (doesAlloc) {
282 // names = { argx,y,z,... new C, init method }
283 names[NEW_OBJ] = new Name(getFunction(NF_allocateInstance), names[DMH_THIS]);
284 names[GET_MEMBER] = new Name(getFunction(NF_constructorMethod), names[DMH_THIS]);
285 } else if (needsInit) {
286 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberNameEnsureInit), names[DMH_THIS]);
287 } else {
288 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberName), names[DMH_THIS]);
289 }
290 assert(findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]);
291 Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER+1, Object[].class);
292 if (needsReceiverCheck) {
293 names[CHECK_RECEIVER] = new Name(getFunction(NF_checkReceiver), names[DMH_THIS], names[ARG_BASE]);
294 outArgs[0] = names[CHECK_RECEIVER];
295 }
296 assert(outArgs[outArgs.length-1] == names[GET_MEMBER]); // look, shifted args!
297 int result = LAST_RESULT;
298 if (doesAlloc) {
299 assert(outArgs[outArgs.length-2] == names[NEW_OBJ]); // got to move this one
300 System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length-2);
301 outArgs[0] = names[NEW_OBJ];
302 result = NEW_OBJ;
303 }
304 names[LINKER_CALL] = new Name(linker, outArgs);
305 LambdaForm lform = LambdaForm.create(ARG_LIMIT, names, result, kind);
306
307 // This is a tricky bit of code. Don't send it through the LF interpreter.
308 lform.compileToBytecode();
309 return lform;
310 }
311
312 /* assert */ static Object findDirectMethodHandle(Name name) {
313 if (name.function.equals(getFunction(NF_internalMemberName)) ||
314 name.function.equals(getFunction(NF_internalMemberNameEnsureInit)) ||
315 name.function.equals(getFunction(NF_constructorMethod))) {
316 assert(name.arguments.length == 1);
317 return name.arguments[0];
318 }
319 return null;
320 }
321
322 /** Static wrapper for DirectMethodHandle.internalMemberName. */
323 @ForceInline
324 /*non-public*/
325 static Object internalMemberName(Object mh) {
326 return ((DirectMethodHandle)mh).member;
327 }
328
329 /** Static wrapper for DirectMethodHandle.internalMemberName.
330 * This one also forces initialization.
331 */
332 /*non-public*/
333 static Object internalMemberNameEnsureInit(Object mh) {
334 DirectMethodHandle dmh = (DirectMethodHandle)mh;
335 dmh.ensureInitialized();
336 return dmh.member;
337 }
338
339 /*non-public*/
340 static boolean shouldBeInitialized(MemberName member) {
341 switch (member.getReferenceKind()) {
342 case REF_invokeStatic:
343 case REF_getStatic:
344 case REF_putStatic:
345 case REF_newInvokeSpecial:
346 break;
347 default:
348 // No need to initialize the class on this kind of member.
349 return false;
350 }
351 Class<?> cls = member.getDeclaringClass();
352 if (cls == ValueConversions.class ||
353 cls == MethodHandleImpl.class ||
354 cls == Invokers.class) {
355 // These guys have lots of <clinit> DMH creation but we know
356 // the MHs will not be used until the system is booted.
357 return false;
358 }
359 if (VerifyAccess.isSamePackage(MethodHandle.class, cls) ||
360 VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
361 // It is a system class. It is probably in the process of
362 // being initialized, but we will help it along just to be safe.
363 UNSAFE.ensureClassInitialized(cls);
364 return CDS.needsClassInitBarrier(cls);
365 }
366 return UNSAFE.shouldBeInitialized(cls) || CDS.needsClassInitBarrier(cls);
367 }
368
369 private void ensureInitialized() {
370 if (checkInitialized(member)) {
371 // The coast is clear. Delete the <clinit> barrier.
372 updateForm(new Function<>() {
373 public LambdaForm apply(LambdaForm oldForm) {
374 return (member.isField() ? preparedFieldLambdaForm(member)
375 : preparedLambdaForm(member));
376 }
377 });
378 }
379 }
380 private static boolean checkInitialized(MemberName member) {
381 Class<?> defc = member.getDeclaringClass();
382 UNSAFE.ensureClassInitialized(defc);
383 // Once we get here either defc was fully initialized by another thread, or
384 // defc was already being initialized by the current thread. In the latter case
385 // the barrier must remain. We can detect this simply by checking if initialization
386 // is still needed.
387 return !UNSAFE.shouldBeInitialized(defc);
388 }
389
390 /*non-public*/
391 static void ensureInitialized(Object mh) {
392 ((DirectMethodHandle)mh).ensureInitialized();
393 }
394
395 /** This subclass represents invokespecial instructions. */
396 static final class Special extends DirectMethodHandle {
397 private final Class<?> caller;
398 private Special(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> caller) {
399 super(mtype, form, member, crackable);
400 this.caller = caller;
401 }
402 @Override
403 boolean isInvokeSpecial() {
404 return true;
405 }
406 @Override
407 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
408 return new Special(mt, lf, member, crackable, caller);
409 }
410 @Override
411 MethodHandle viewAsType(MethodType newType, boolean strict) {
412 assert(viewAsTypeChecks(newType, strict));
413 return new Special(newType, form, member, false, caller);
414 }
415 Object checkReceiver(Object recv) {
416 if (!caller.isInstance(recv)) {
417 if (recv != null) {
418 String msg = String.format("Receiver class %s is not a subclass of caller class %s",
419 recv.getClass().getName(), caller.getName());
420 throw new IncompatibleClassChangeError(msg);
421 } else {
422 String msg = String.format("Cannot invoke %s with null receiver", member);
423 throw new NullPointerException(msg);
424 }
425 }
426 return recv;
427 }
428 }
429
430 /** This subclass represents invokeinterface instructions. */
431 static final class Interface extends DirectMethodHandle {
432 private final Class<?> refc;
433 private Interface(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> refc) {
434 super(mtype, form, member, crackable);
435 assert(refc.isInterface()) : refc;
436 this.refc = refc;
437 }
438 @Override
439 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
440 return new Interface(mt, lf, member, crackable, refc);
441 }
442 @Override
443 MethodHandle viewAsType(MethodType newType, boolean strict) {
444 assert(viewAsTypeChecks(newType, strict));
445 return new Interface(newType, form, member, false, refc);
446 }
447 @Override
448 Object checkReceiver(Object recv) {
449 if (!refc.isInstance(recv)) {
450 if (recv != null) {
451 String msg = String.format("Receiver class %s does not implement the requested interface %s",
452 recv.getClass().getName(), refc.getName());
453 throw new IncompatibleClassChangeError(msg);
454 } else {
455 String msg = String.format("Cannot invoke %s with null receiver", member);
456 throw new NullPointerException(msg);
457 }
458 }
459 return recv;
460 }
461 }
462
463 /** Used for interface receiver type checks, by Interface and Special modes. */
464 Object checkReceiver(Object recv) {
465 throw new InternalError("Should only be invoked on a subclass");
466 }
467
468 /** This subclass handles constructor references. */
469 static final class Constructor extends DirectMethodHandle {
470 final MemberName initMethod;
471 final Class<?> instanceClass;
472
473 private Constructor(MethodType mtype, LambdaForm form, MemberName constructor,
474 boolean crackable, MemberName initMethod, Class<?> instanceClass) {
475 super(mtype, form, constructor, crackable);
476 this.initMethod = initMethod;
477 this.instanceClass = instanceClass;
478 assert(initMethod.isResolved());
479 }
480 @Override
481 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
482 return new Constructor(mt, lf, member, crackable, initMethod, instanceClass);
483 }
484 @Override
485 MethodHandle viewAsType(MethodType newType, boolean strict) {
486 assert(viewAsTypeChecks(newType, strict));
487 return new Constructor(newType, form, member, false, initMethod, instanceClass);
488 }
489 }
490
491 /*non-public*/
492 static Object constructorMethod(Object mh) {
493 Constructor dmh = (Constructor)mh;
494 return dmh.initMethod;
495 }
496
497 /*non-public*/
498 static Object allocateInstance(Object mh) throws InstantiationException {
499 Constructor dmh = (Constructor)mh;
500 return UNSAFE.allocateInstance(dmh.instanceClass);
501 }
502
503 /** This subclass handles non-static field references. */
504 static final class Accessor extends DirectMethodHandle {
505 final Class<?> fieldType;
506 final int fieldOffset;
507 private Accessor(MethodType mtype, LambdaForm form, MemberName member,
508 boolean crackable, int fieldOffset) {
509 super(mtype, form, member, crackable);
510 this.fieldType = member.getFieldType();
511 this.fieldOffset = fieldOffset;
512 }
513
514 @Override Object checkCast(Object obj) {
515 return fieldType.cast(obj);
516 }
517 @Override
518 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
519 return new Accessor(mt, lf, member, crackable, fieldOffset);
520 }
521 @Override
522 MethodHandle viewAsType(MethodType newType, boolean strict) {
523 assert(viewAsTypeChecks(newType, strict));
524 return new Accessor(newType, form, member, false, fieldOffset);
525 }
526 }
527
528 @ForceInline
529 /*non-public*/
530 static long fieldOffset(Object accessorObj) {
531 // Note: We return a long because that is what Unsafe.getObject likes.
532 // We store a plain int because it is more compact.
533 return ((Accessor)accessorObj).fieldOffset;
534 }
535
536 @ForceInline
537 /*non-public*/
538 static Object checkBase(Object obj) {
539 // Note that the object's class has already been verified,
540 // since the parameter type of the Accessor method handle
541 // is either member.getDeclaringClass or a subclass.
542 // This was verified in DirectMethodHandle.make.
543 // Therefore, the only remaining check is for null.
544 // Since this check is *not* guaranteed by Unsafe.getInt
545 // and its siblings, we need to make an explicit one here.
546 return Objects.requireNonNull(obj);
547 }
548
549 /** This subclass handles static field references. */
550 static final class StaticAccessor extends DirectMethodHandle {
551 private final Class<?> fieldType;
552 private final Object staticBase;
553 private final long staticOffset;
554
555 private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member,
556 boolean crackable, Object staticBase, long staticOffset) {
557 super(mtype, form, member, crackable);
558 this.fieldType = member.getFieldType();
559 this.staticBase = staticBase;
560 this.staticOffset = staticOffset;
561 }
562
563 @Override Object checkCast(Object obj) {
564 return fieldType.cast(obj);
565 }
566 @Override
567 MethodHandle copyWith(MethodType mt, LambdaForm lf) {
568 return new StaticAccessor(mt, lf, member, crackable, staticBase, staticOffset);
569 }
570 @Override
571 MethodHandle viewAsType(MethodType newType, boolean strict) {
572 assert(viewAsTypeChecks(newType, strict));
573 return new StaticAccessor(newType, form, member, false, staticBase, staticOffset);
574 }
575 }
576
577 @ForceInline
578 /*non-public*/
579 static Object nullCheck(Object obj) {
580 return Objects.requireNonNull(obj);
581 }
582
583 @ForceInline
584 /*non-public*/
585 static Object staticBase(Object accessorObj) {
586 return ((StaticAccessor)accessorObj).staticBase;
587 }
588
589 @ForceInline
590 /*non-public*/
591 static long staticOffset(Object accessorObj) {
592 return ((StaticAccessor)accessorObj).staticOffset;
593 }
594
595 @ForceInline
596 /*non-public*/
597 static Object checkCast(Object mh, Object obj) {
598 return ((DirectMethodHandle) mh).checkCast(obj);
599 }
600
601 Object checkCast(Object obj) {
602 return member.getMethodType().returnType().cast(obj);
603 }
604
605 // Caching machinery for field accessors:
606 static final byte
607 AF_GETFIELD = 0,
608 AF_PUTFIELD = 1,
609 AF_GETSTATIC = 2,
610 AF_PUTSTATIC = 3,
611 AF_GETSTATIC_INIT = 4,
612 AF_PUTSTATIC_INIT = 5,
613 AF_LIMIT = 6;
614 // Enumerate the different field kinds using Wrapper,
615 // with an extra case added for checked references.
616 static final int
617 FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(),
618 FT_CHECKED_REF = Wrapper.VOID.ordinal(),
619 FT_LIMIT = Wrapper.COUNT;
620 private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {
621 return ((formOp * FT_LIMIT * 2)
622 + (isVolatile ? FT_LIMIT : 0)
623 + ftypeKind);
624 }
625 @Stable
626 private static final LambdaForm[] ACCESSOR_FORMS
627 = new LambdaForm[afIndex(AF_LIMIT, false, 0)];
628 static int ftypeKind(Class<?> ftype) {
629 if (ftype.isPrimitive()) {
630 return Wrapper.forPrimitiveType(ftype).ordinal();
631 } else if (ftype.isInterface() || ftype.isAssignableFrom(Object.class)) {
632 // retyping can be done without a cast
633 return FT_UNCHECKED_REF;
634 } else {
635 return FT_CHECKED_REF;
636 }
637 }
638
639 /**
640 * Create a LF which can access the given field.
641 * Cache and share this structure among all fields with
642 * the same basicType and refKind.
643 */
644 private static LambdaForm preparedFieldLambdaForm(MemberName m) {
645 Class<?> ftype = m.getFieldType();
646 boolean isVolatile = m.isVolatile();
647 byte formOp = switch (m.getReferenceKind()) {
648 case REF_getField -> AF_GETFIELD;
649 case REF_putField -> AF_PUTFIELD;
650 case REF_getStatic -> AF_GETSTATIC;
651 case REF_putStatic -> AF_PUTSTATIC;
652 default -> throw new InternalError(m.toString());
653 };
654 if (shouldBeInitialized(m)) {
655 // precompute the barrier-free version:
656 preparedFieldLambdaForm(formOp, isVolatile, ftype);
657 assert((AF_GETSTATIC_INIT - AF_GETSTATIC) ==
658 (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
659 formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
660 }
661 LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
662 assert(lform.methodType().dropParameterTypes(0, 1)
663 .equals(m.getInvocationType().basicType()))
664 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
665 return lform;
666 }
667 private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype) {
668 int ftypeKind = ftypeKind(ftype);
669 int afIndex = afIndex(formOp, isVolatile, ftypeKind);
670 LambdaForm lform = ACCESSOR_FORMS[afIndex];
671 if (lform != null) return lform;
672 lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind);
673 ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS
674 return lform;
675 }
676
677 private static final @Stable Wrapper[] ALL_WRAPPERS = Wrapper.values();
678
679 // Names in kind may overload but differ from their basic type
680 private static Kind getFieldKind(boolean isVolatile, boolean needsInit, boolean needsCast, Wrapper wrapper) {
681 if (isVolatile) {
682 if (needsInit) {
683 return switch (wrapper) {
684 case BYTE -> VOLATILE_FIELD_ACCESS_INIT_B;
685 case CHAR -> VOLATILE_FIELD_ACCESS_INIT_C;
686 case SHORT -> VOLATILE_FIELD_ACCESS_INIT_S;
687 case BOOLEAN -> VOLATILE_FIELD_ACCESS_INIT_Z;
688 default -> needsCast ? VOLATILE_FIELD_ACCESS_INIT_CAST : VOLATILE_FIELD_ACCESS_INIT;
689 };
690 } else {
691 return switch (wrapper) {
692 case BYTE -> VOLATILE_FIELD_ACCESS_B;
693 case CHAR -> VOLATILE_FIELD_ACCESS_C;
694 case SHORT -> VOLATILE_FIELD_ACCESS_S;
695 case BOOLEAN -> VOLATILE_FIELD_ACCESS_Z;
696 default -> needsCast ? VOLATILE_FIELD_ACCESS_CAST : VOLATILE_FIELD_ACCESS;
697 };
698 }
699 } else {
700 if (needsInit) {
701 return switch (wrapper) {
702 case BYTE -> FIELD_ACCESS_INIT_B;
703 case CHAR -> FIELD_ACCESS_INIT_C;
704 case SHORT -> FIELD_ACCESS_INIT_S;
705 case BOOLEAN -> FIELD_ACCESS_INIT_Z;
706 default -> needsCast ? FIELD_ACCESS_INIT_CAST : FIELD_ACCESS_INIT;
707 };
708 } else {
709 return switch (wrapper) {
710 case BYTE -> FIELD_ACCESS_B;
711 case CHAR -> FIELD_ACCESS_C;
712 case SHORT -> FIELD_ACCESS_S;
713 case BOOLEAN -> FIELD_ACCESS_Z;
714 default -> needsCast ? FIELD_ACCESS_CAST : FIELD_ACCESS;
715 };
716 }
717 }
718 }
719
720 private static String unsafeMethodName(boolean isGetter, boolean isVolatile, Wrapper wrapper) {
721 var name = switch (wrapper) {
722 case BOOLEAN -> "Boolean";
723 case BYTE -> "Byte";
724 case CHAR -> "Char";
725 case SHORT -> "Short";
726 case INT -> "Int";
727 case FLOAT -> "Float";
728 case LONG -> "Long";
729 case DOUBLE -> "Double";
730 case OBJECT -> "Reference";
731 case VOID -> throw new InternalError();
732 };
733 var sb = new StringBuilder(3 + name.length() + (isVolatile ? 8 : 0))
734 .append(isGetter ? "get" : "put")
735 .append(name);
736 if (isVolatile) {
737 sb.append("Volatile");
738 }
739 return sb.toString();
740 }
741
742 static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) {
743 boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
744 boolean isStatic = (formOp >= AF_GETSTATIC);
745 boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
746 boolean needsCast = (ftypeKind == FT_CHECKED_REF);
747 Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
748 Class<?> ft = fw.primitiveType();
749 assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind);
750
751 // getObject, putIntVolatile, etc.
752 String unsafeMethodName = unsafeMethodName(isGetter, isVolatile, fw);
753 // isGetter and isStatic is reflected in field type; basic type clash for subwords
754 Kind kind = getFieldKind(isVolatile, needsInit, needsCast, fw);
755
756 MethodType linkerType;
757 if (isGetter)
758 linkerType = MethodType.methodType(ft, Object.class, long.class);
759 else
760 linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
761 MemberName linker = new MemberName(Unsafe.class, unsafeMethodName, linkerType, REF_invokeVirtual);
762 try {
763 linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, LM_TRUSTED,
764 NoSuchMethodException.class);
765 } catch (ReflectiveOperationException ex) {
766 throw newInternalError(ex);
767 }
768
769 // What is the external type of the lambda form?
770 MethodType mtype;
771 if (isGetter)
772 mtype = MethodType.methodType(ft);
773 else
774 mtype = MethodType.methodType(void.class, ft);
775 mtype = mtype.basicType(); // erase short to int, etc.
776 if (!isStatic)
777 mtype = mtype.insertParameterTypes(0, Object.class);
778 final int DMH_THIS = 0;
779 final int ARG_BASE = 1;
780 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
781 // if this is for non-static access, the base pointer is stored at this index:
782 final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
783 // if this is for write access, the value to be written is stored at this index:
784 final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
785 int nameCursor = ARG_LIMIT;
786 final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
787 final int F_OFFSET = nameCursor++; // Either static offset or field offset.
788 final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
789 final int U_HOLDER = nameCursor++; // UNSAFE holder
790 final int INIT_BAR = (needsInit ? nameCursor++ : -1);
791 final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
792 final int LINKER_CALL = nameCursor++;
793 final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
794 final int RESULT = nameCursor-1; // either the call or the cast
795 Name[] names = invokeArguments(nameCursor - ARG_LIMIT, mtype);
796 if (needsInit)
797 names[INIT_BAR] = new Name(getFunction(NF_ensureInitialized), names[DMH_THIS]);
798 if (needsCast && !isGetter)
799 names[PRE_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[SET_VALUE]);
800 Object[] outArgs = new Object[1 + linkerType.parameterCount()];
801 assert(outArgs.length == (isGetter ? 3 : 4));
802 outArgs[0] = names[U_HOLDER] = new Name(getFunction(NF_UNSAFE));
803 if (isStatic) {
804 outArgs[1] = names[F_HOLDER] = new Name(getFunction(NF_staticBase), names[DMH_THIS]);
805 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_staticOffset), names[DMH_THIS]);
806 } else {
807 outArgs[1] = names[OBJ_CHECK] = new Name(getFunction(NF_checkBase), names[OBJ_BASE]);
808 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_fieldOffset), names[DMH_THIS]);
809 }
810 if (!isGetter) {
811 outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
812 }
813 for (Object a : outArgs) assert(a != null);
814 names[LINKER_CALL] = new Name(linker, outArgs);
815 if (needsCast && isGetter)
816 names[POST_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[LINKER_CALL]);
817 for (Name n : names) assert(n != null);
818
819 LambdaForm form = LambdaForm.create(ARG_LIMIT, names, RESULT, kind);
820
821 if (LambdaForm.debugNames()) {
822 // add some detail to the lambdaForm debugname,
823 // significant only for debugging
824 StringBuilder nameBuilder = new StringBuilder(unsafeMethodName);
825 if (isStatic) {
826 nameBuilder.append("Static");
827 } else {
828 nameBuilder.append("Field");
829 }
830 if (needsCast) {
831 nameBuilder.append("Cast");
832 }
833 if (needsInit) {
834 nameBuilder.append("Init");
835 }
836 LambdaForm.associateWithDebugName(form, nameBuilder.toString());
837 }
838
839 // NF_UNSAFE uses field form, avoid circular dependency in interpreter
840 form.compileToBytecode();
841 return form;
842 }
843
844 /**
845 * Pre-initialized NamedFunctions for bootstrapping purposes.
846 */
847 static final byte NF_internalMemberName = 0,
848 NF_internalMemberNameEnsureInit = 1,
849 NF_ensureInitialized = 2,
850 NF_fieldOffset = 3,
851 NF_checkBase = 4,
852 NF_staticBase = 5,
853 NF_staticOffset = 6,
854 NF_checkCast = 7,
855 NF_allocateInstance = 8,
856 NF_constructorMethod = 9,
857 NF_UNSAFE = 10,
858 NF_checkReceiver = 11,
859 NF_LIMIT = 12;
860
861 private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT];
862
863 private static NamedFunction getFunction(byte func) {
864 NamedFunction nf = NFS[func];
865 if (nf != null) {
866 return nf;
867 }
868 // Each nf must be statically invocable or we get tied up in our bootstraps.
869 nf = NFS[func] = createFunction(func);
870 assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf));
871 return nf;
872 }
873
874 private static final MethodType OBJ_OBJ_TYPE = MethodType.methodType(Object.class, Object.class);
875
876 private static final MethodType LONG_OBJ_TYPE = MethodType.methodType(long.class, Object.class);
877
878 private static NamedFunction createFunction(byte func) {
879 try {
880 switch (func) {
881 case NF_internalMemberName:
882 return getNamedFunction("internalMemberName", OBJ_OBJ_TYPE);
883 case NF_internalMemberNameEnsureInit:
884 return getNamedFunction("internalMemberNameEnsureInit", OBJ_OBJ_TYPE);
885 case NF_ensureInitialized:
886 return getNamedFunction("ensureInitialized", MethodType.methodType(void.class, Object.class));
887 case NF_fieldOffset:
888 return getNamedFunction("fieldOffset", LONG_OBJ_TYPE);
889 case NF_checkBase:
890 return getNamedFunction("checkBase", OBJ_OBJ_TYPE);
891 case NF_staticBase:
892 return getNamedFunction("staticBase", OBJ_OBJ_TYPE);
893 case NF_staticOffset:
894 return getNamedFunction("staticOffset", LONG_OBJ_TYPE);
895 case NF_checkCast:
896 return getNamedFunction("checkCast", MethodType.methodType(Object.class, Object.class, Object.class));
897 case NF_allocateInstance:
898 return getNamedFunction("allocateInstance", OBJ_OBJ_TYPE);
899 case NF_constructorMethod:
900 return getNamedFunction("constructorMethod", OBJ_OBJ_TYPE);
901 case NF_UNSAFE:
902 MemberName member = new MemberName(MethodHandleStatics.class, "UNSAFE", Unsafe.class, REF_getStatic);
903 return new NamedFunction(
904 MemberName.getFactory().resolveOrFail(REF_getStatic, member,
905 DirectMethodHandle.class, LM_TRUSTED,
906 NoSuchFieldException.class));
907 case NF_checkReceiver:
908 member = new MemberName(DirectMethodHandle.class, "checkReceiver", OBJ_OBJ_TYPE, REF_invokeVirtual);
909 return new NamedFunction(
910 MemberName.getFactory().resolveOrFail(REF_invokeVirtual, member,
911 DirectMethodHandle.class, LM_TRUSTED,
912 NoSuchMethodException.class));
913 default:
914 throw newInternalError("Unknown function: " + func);
915 }
916 } catch (ReflectiveOperationException ex) {
917 throw newInternalError(ex);
918 }
919 }
920
921 private static NamedFunction getNamedFunction(String name, MethodType type)
922 throws ReflectiveOperationException
923 {
924 MemberName member = new MemberName(DirectMethodHandle.class, name, type, REF_invokeStatic);
925 return new NamedFunction(
926 MemberName.getFactory().resolveOrFail(REF_invokeStatic, member,
927 DirectMethodHandle.class, LM_TRUSTED,
928 NoSuchMethodException.class));
929 }
930
931 static {
932 // The Holder class will contain pre-generated DirectMethodHandles resolved
933 // speculatively using MemberName.getFactory().resolveOrNull. However, that
934 // doesn't initialize the class, which subtly breaks inlining etc. By forcing
935 // initialization of the Holder class we avoid these issues.
936 UNSAFE.ensureClassInitialized(Holder.class);
937 }
938
939 /* Placeholder class for DirectMethodHandles generated ahead of time */
940 final class Holder {}
941 }