1 /*
2  * Copyright (c) 2008, 2018, 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.Unsafe;
29 import jdk.internal.vm.annotation.ForceInline;
30 import jdk.internal.vm.annotation.Stable;
31 import sun.invoke.util.ValueConversions;
32 import sun.invoke.util.VerifyAccess;
33 import sun.invoke.util.VerifyType;
34 import sun.invoke.util.Wrapper;
35 
36 import java.lang.ref.WeakReference;
37 import java.util.Arrays;
38 import java.util.Objects;
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 class DirectMethodHandle extends MethodHandle {
53     final MemberName member;
54 
55     // Constructors and factory methods in this class *must* be package scoped or private.
DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member)56     private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member) {
57         super(mtype, form);
58         if (!member.isResolved())  throw new InternalError();
59 
60         if (member.getDeclaringClass().isInterface() &&
61             member.getReferenceKind() == REF_invokeInterface &&
62             member.isMethod() && !member.isAbstract()) {
63             // Check for corner case: invokeinterface of Object method
64             MemberName m = new MemberName(Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());
65             m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null);
66             if (m != null && m.isPublic()) {
67                 assert(member.getReferenceKind() == m.getReferenceKind());  // else this.form is wrong
68                 member = m;
69             }
70         }
71 
72         this.member = member;
73     }
74 
75     // Factory methods:
make(byte refKind, Class<?> refc, MemberName member, Class<?> callerClass)76     static DirectMethodHandle make(byte refKind, Class<?> refc, MemberName member, Class<?> callerClass) {
77         MethodType mtype = member.getMethodOrFieldType();
78         if (!member.isStatic()) {
79             if (!member.getDeclaringClass().isAssignableFrom(refc) || member.isConstructor())
80                 throw new InternalError(member.toString());
81             mtype = mtype.insertParameterTypes(0, refc);
82         }
83         if (!member.isField()) {
84             // refKind reflects the original type of lookup via findSpecial or
85             // findVirtual etc.
86             switch (refKind) {
87                 case REF_invokeSpecial: {
88                     member = member.asSpecial();
89                     // if caller is an interface we need to adapt to get the
90                     // receiver check inserted
91                     if (callerClass == null) {
92                         throw new InternalError("callerClass must not be null for REF_invokeSpecial");
93                     }
94                     LambdaForm lform = preparedLambdaForm(member, callerClass.isInterface());
95                     return new Special(mtype, lform, member, callerClass);
96                 }
97                 case REF_invokeInterface: {
98                     // for interfaces we always need the receiver typecheck,
99                     // so we always pass 'true' to ensure we adapt if needed
100                     // to include the REF_invokeSpecial case
101                     LambdaForm lform = preparedLambdaForm(member, true);
102                     return new Interface(mtype, lform, member, refc);
103                 }
104                 default: {
105                     LambdaForm lform = preparedLambdaForm(member);
106                     return new DirectMethodHandle(mtype, lform, member);
107                 }
108             }
109         } else {
110             LambdaForm lform = preparedFieldLambdaForm(member);
111             if (member.isStatic()) {
112                 long offset = MethodHandleNatives.staticFieldOffset(member);
113                 Object base = MethodHandleNatives.staticFieldBase(member);
114                 return new StaticAccessor(mtype, lform, member, base, offset);
115             } else {
116                 long offset = MethodHandleNatives.objectFieldOffset(member);
117                 assert(offset == (int)offset);
118                 return new Accessor(mtype, lform, member, (int)offset);
119             }
120         }
121     }
make(Class<?> refc, MemberName member)122     static DirectMethodHandle make(Class<?> refc, MemberName member) {
123         byte refKind = member.getReferenceKind();
124         if (refKind == REF_invokeSpecial)
125             refKind =  REF_invokeVirtual;
126         return make(refKind, refc, member, null /* no callerClass context */);
127     }
make(MemberName member)128     static DirectMethodHandle make(MemberName member) {
129         if (member.isConstructor())
130             return makeAllocator(member);
131         return make(member.getDeclaringClass(), member);
132     }
makeAllocator(MemberName ctor)133     private static DirectMethodHandle makeAllocator(MemberName ctor) {
134         assert(ctor.isConstructor() && ctor.getName().equals("<init>"));
135         Class<?> instanceClass = ctor.getDeclaringClass();
136         ctor = ctor.asConstructor();
137         assert(ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;
138         MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);
139         LambdaForm lform = preparedLambdaForm(ctor);
140         MemberName init = ctor.asSpecial();
141         assert(init.getMethodType().returnType() == void.class);
142         return new Constructor(mtype, lform, ctor, init, instanceClass);
143     }
144 
145     @Override
rebind()146     BoundMethodHandle rebind() {
147         return BoundMethodHandle.makeReinvoker(this);
148     }
149 
150     @Override
copyWith(MethodType mt, LambdaForm lf)151     MethodHandle copyWith(MethodType mt, LambdaForm lf) {
152         assert(this.getClass() == DirectMethodHandle.class);  // must override in subclasses
153         return new DirectMethodHandle(mt, lf, member);
154     }
155 
156     @Override
internalProperties()157     String internalProperties() {
158         return "\n& DMH.MN="+internalMemberName();
159     }
160 
161     //// Implementation methods.
162     @Override
163     @ForceInline
internalMemberName()164     MemberName internalMemberName() {
165         return member;
166     }
167 
168     private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
169 
170     /**
171      * Create a LF which can invoke the given method.
172      * Cache and share this structure among all methods with
173      * the same basicType and refKind.
174      */
preparedLambdaForm(MemberName m, boolean adaptToSpecialIfc)175     private static LambdaForm preparedLambdaForm(MemberName m, boolean adaptToSpecialIfc) {
176         assert(m.isInvocable()) : m;  // call preparedFieldLambdaForm instead
177         MethodType mtype = m.getInvocationType().basicType();
178         assert(!m.isMethodHandleInvoke()) : m;
179         int which;
180         // MemberName.getReferenceKind represents the JVM optimized form of the call
181         // as distinct from the "kind" passed to DMH.make which represents the original
182         // bytecode-equivalent request. Specifically private/final methods that use a direct
183         // call have getReferenceKind adapted to REF_invokeSpecial, even though the actual
184         // invocation mode may be invokevirtual or invokeinterface.
185         switch (m.getReferenceKind()) {
186         case REF_invokeVirtual:    which = LF_INVVIRTUAL;    break;
187         case REF_invokeStatic:     which = LF_INVSTATIC;     break;
188         case REF_invokeSpecial:    which = LF_INVSPECIAL;    break;
189         case REF_invokeInterface:  which = LF_INVINTERFACE;  break;
190         case REF_newInvokeSpecial: which = LF_NEWINVSPECIAL; break;
191         default:  throw new InternalError(m.toString());
192         }
193         if (which == LF_INVSTATIC && shouldBeInitialized(m)) {
194             // precompute the barrier-free version:
195             preparedLambdaForm(mtype, which);
196             which = LF_INVSTATIC_INIT;
197         }
198         if (which == LF_INVSPECIAL && adaptToSpecialIfc) {
199             which = LF_INVSPECIAL_IFC;
200         }
201         LambdaForm lform = preparedLambdaForm(mtype, which);
202         maybeCompile(lform, m);
203         assert(lform.methodType().dropParameterTypes(0, 1)
204                 .equals(m.getInvocationType().basicType()))
205                 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
206         return lform;
207     }
208 
preparedLambdaForm(MemberName m)209     private static LambdaForm preparedLambdaForm(MemberName m) {
210         return preparedLambdaForm(m, false);
211     }
212 
preparedLambdaForm(MethodType mtype, int which)213     private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {
214         LambdaForm lform = mtype.form().cachedLambdaForm(which);
215         if (lform != null)  return lform;
216         lform = makePreparedLambdaForm(mtype, which);
217         return mtype.form().setCachedLambdaForm(which, lform);
218     }
219 
makePreparedLambdaForm(MethodType mtype, int which)220     static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {
221         boolean needsInit = (which == LF_INVSTATIC_INIT);
222         boolean doesAlloc = (which == LF_NEWINVSPECIAL);
223         boolean needsReceiverCheck = (which == LF_INVINTERFACE ||
224                                       which == LF_INVSPECIAL_IFC);
225 
226         String linkerName;
227         LambdaForm.Kind kind;
228         switch (which) {
229         case LF_INVVIRTUAL:    linkerName = "linkToVirtual";   kind = DIRECT_INVOKE_VIRTUAL;     break;
230         case LF_INVSTATIC:     linkerName = "linkToStatic";    kind = DIRECT_INVOKE_STATIC;      break;
231         case LF_INVSTATIC_INIT:linkerName = "linkToStatic";    kind = DIRECT_INVOKE_STATIC_INIT; break;
232         case LF_INVSPECIAL_IFC:linkerName = "linkToSpecial";   kind = DIRECT_INVOKE_SPECIAL_IFC; break;
233         case LF_INVSPECIAL:    linkerName = "linkToSpecial";   kind = DIRECT_INVOKE_SPECIAL;     break;
234         case LF_INVINTERFACE:  linkerName = "linkToInterface"; kind = DIRECT_INVOKE_INTERFACE;   break;
235         case LF_NEWINVSPECIAL: linkerName = "linkToSpecial";   kind = DIRECT_NEW_INVOKE_SPECIAL; break;
236         default:  throw new InternalError("which="+which);
237         }
238 
239         MethodType mtypeWithArg = mtype.appendParameterTypes(MemberName.class);
240         if (doesAlloc)
241             mtypeWithArg = mtypeWithArg
242                     .insertParameterTypes(0, Object.class)  // insert newly allocated obj
243                     .changeReturnType(void.class);          // <init> returns void
244         MemberName linker = new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);
245         try {
246             linker = IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, NoSuchMethodException.class);
247         } catch (ReflectiveOperationException ex) {
248             throw newInternalError(ex);
249         }
250         final int DMH_THIS    = 0;
251         final int ARG_BASE    = 1;
252         final int ARG_LIMIT   = ARG_BASE + mtype.parameterCount();
253         int nameCursor = ARG_LIMIT;
254         final int NEW_OBJ     = (doesAlloc ? nameCursor++ : -1);
255         final int GET_MEMBER  = nameCursor++;
256         final int CHECK_RECEIVER = (needsReceiverCheck ? nameCursor++ : -1);
257         final int LINKER_CALL = nameCursor++;
258         Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
259         assert(names.length == nameCursor);
260         if (doesAlloc) {
261             // names = { argx,y,z,... new C, init method }
262             names[NEW_OBJ] = new Name(getFunction(NF_allocateInstance), names[DMH_THIS]);
263             names[GET_MEMBER] = new Name(getFunction(NF_constructorMethod), names[DMH_THIS]);
264         } else if (needsInit) {
265             names[GET_MEMBER] = new Name(getFunction(NF_internalMemberNameEnsureInit), names[DMH_THIS]);
266         } else {
267             names[GET_MEMBER] = new Name(getFunction(NF_internalMemberName), names[DMH_THIS]);
268         }
269         assert(findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]);
270         Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER+1, Object[].class);
271         if (needsReceiverCheck) {
272             names[CHECK_RECEIVER] = new Name(getFunction(NF_checkReceiver), names[DMH_THIS], names[ARG_BASE]);
273             outArgs[0] = names[CHECK_RECEIVER];
274         }
275         assert(outArgs[outArgs.length-1] == names[GET_MEMBER]);  // look, shifted args!
276         int result = LAST_RESULT;
277         if (doesAlloc) {
278             assert(outArgs[outArgs.length-2] == names[NEW_OBJ]);  // got to move this one
279             System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length-2);
280             outArgs[0] = names[NEW_OBJ];
281             result = NEW_OBJ;
282         }
283         names[LINKER_CALL] = new Name(linker, outArgs);
284         LambdaForm lform = new LambdaForm(ARG_LIMIT, names, result, kind);
285 
286         // This is a tricky bit of code.  Don't send it through the LF interpreter.
287         lform.compileToBytecode();
288         return lform;
289     }
290 
findDirectMethodHandle(Name name)291     /* assert */ static Object findDirectMethodHandle(Name name) {
292         if (name.function.equals(getFunction(NF_internalMemberName)) ||
293             name.function.equals(getFunction(NF_internalMemberNameEnsureInit)) ||
294             name.function.equals(getFunction(NF_constructorMethod))) {
295             assert(name.arguments.length == 1);
296             return name.arguments[0];
297         }
298         return null;
299     }
300 
maybeCompile(LambdaForm lform, MemberName m)301     private static void maybeCompile(LambdaForm lform, MemberName m) {
302         if (lform.vmentry == null && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
303             // Help along bootstrapping...
304             lform.compileToBytecode();
305     }
306 
307     /** Static wrapper for DirectMethodHandle.internalMemberName. */
308     @ForceInline
internalMemberName(Object mh)309     /*non-public*/ static Object internalMemberName(Object mh) {
310         return ((DirectMethodHandle)mh).member;
311     }
312 
313     /** Static wrapper for DirectMethodHandle.internalMemberName.
314      * This one also forces initialization.
315      */
internalMemberNameEnsureInit(Object mh)316     /*non-public*/ static Object internalMemberNameEnsureInit(Object mh) {
317         DirectMethodHandle dmh = (DirectMethodHandle)mh;
318         dmh.ensureInitialized();
319         return dmh.member;
320     }
321 
322     /*non-public*/ static
shouldBeInitialized(MemberName member)323     boolean shouldBeInitialized(MemberName member) {
324         switch (member.getReferenceKind()) {
325         case REF_invokeStatic:
326         case REF_getStatic:
327         case REF_putStatic:
328         case REF_newInvokeSpecial:
329             break;
330         default:
331             // No need to initialize the class on this kind of member.
332             return false;
333         }
334         Class<?> cls = member.getDeclaringClass();
335         if (cls == ValueConversions.class ||
336             cls == MethodHandleImpl.class ||
337             cls == Invokers.class) {
338             // These guys have lots of <clinit> DMH creation but we know
339             // the MHs will not be used until the system is booted.
340             return false;
341         }
342         if (VerifyAccess.isSamePackage(MethodHandle.class, cls) ||
343             VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
344             // It is a system class.  It is probably in the process of
345             // being initialized, but we will help it along just to be safe.
346             if (UNSAFE.shouldBeInitialized(cls)) {
347                 UNSAFE.ensureClassInitialized(cls);
348             }
349             return false;
350         }
351         return UNSAFE.shouldBeInitialized(cls);
352     }
353 
354     private static class EnsureInitialized extends ClassValue<WeakReference<Thread>> {
355         @Override
computeValue(Class<?> type)356         protected WeakReference<Thread> computeValue(Class<?> type) {
357             UNSAFE.ensureClassInitialized(type);
358             if (UNSAFE.shouldBeInitialized(type))
359                 // If the previous call didn't block, this can happen.
360                 // We are executing inside <clinit>.
361                 return new WeakReference<>(Thread.currentThread());
362             return null;
363         }
364         static final EnsureInitialized INSTANCE = new EnsureInitialized();
365     }
366 
ensureInitialized()367     private void ensureInitialized() {
368         if (checkInitialized(member)) {
369             // The coast is clear.  Delete the <clinit> barrier.
370             if (member.isField())
371                 updateForm(preparedFieldLambdaForm(member));
372             else
373                 updateForm(preparedLambdaForm(member));
374         }
375     }
checkInitialized(MemberName member)376     private static boolean checkInitialized(MemberName member) {
377         Class<?> defc = member.getDeclaringClass();
378         WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc);
379         if (ref == null) {
380             return true;  // the final state
381         }
382         Thread clinitThread = ref.get();
383         // Somebody may still be running defc.<clinit>.
384         if (clinitThread == Thread.currentThread()) {
385             // If anybody is running defc.<clinit>, it is this thread.
386             if (UNSAFE.shouldBeInitialized(defc))
387                 // Yes, we are running it; keep the barrier for now.
388                 return false;
389         } else {
390             // We are in a random thread.  Block.
391             UNSAFE.ensureClassInitialized(defc);
392         }
393         assert(!UNSAFE.shouldBeInitialized(defc));
394         // put it into the final state
395         EnsureInitialized.INSTANCE.remove(defc);
396         return true;
397     }
398 
ensureInitialized(Object mh)399     /*non-public*/ static void ensureInitialized(Object mh) {
400         ((DirectMethodHandle)mh).ensureInitialized();
401     }
402 
403     /** This subclass represents invokespecial instructions. */
404     static class Special extends DirectMethodHandle {
405         private final Class<?> caller;
Special(MethodType mtype, LambdaForm form, MemberName member, Class<?> caller)406         private Special(MethodType mtype, LambdaForm form, MemberName member, Class<?> caller) {
407             super(mtype, form, member);
408             this.caller = caller;
409         }
410         @Override
isInvokeSpecial()411         boolean isInvokeSpecial() {
412             return true;
413         }
414         @Override
copyWith(MethodType mt, LambdaForm lf)415         MethodHandle copyWith(MethodType mt, LambdaForm lf) {
416             return new Special(mt, lf, member, caller);
417         }
checkReceiver(Object recv)418         Object checkReceiver(Object recv) {
419             if (!caller.isInstance(recv)) {
420                 String msg = String.format("Receiver class %s is not a subclass of caller class %s",
421                                            recv.getClass().getName(), caller.getName());
422                 throw new IncompatibleClassChangeError(msg);
423             }
424             return recv;
425         }
426     }
427 
428     /** This subclass represents invokeinterface instructions. */
429     static class Interface extends DirectMethodHandle {
430         private final Class<?> refc;
Interface(MethodType mtype, LambdaForm form, MemberName member, Class<?> refc)431         private Interface(MethodType mtype, LambdaForm form, MemberName member, Class<?> refc) {
432             super(mtype, form, member);
433             assert refc.isInterface() : refc;
434             this.refc = refc;
435         }
436         @Override
copyWith(MethodType mt, LambdaForm lf)437         MethodHandle copyWith(MethodType mt, LambdaForm lf) {
438             return new Interface(mt, lf, member, refc);
439         }
440         @Override
checkReceiver(Object recv)441         Object checkReceiver(Object recv) {
442             if (!refc.isInstance(recv)) {
443                 String msg = String.format("Receiver class %s does not implement the requested interface %s",
444                                            recv.getClass().getName(), refc.getName());
445                 throw new IncompatibleClassChangeError(msg);
446             }
447             return recv;
448         }
449     }
450 
451     /** Used for interface receiver type checks, by Interface and Special modes. */
checkReceiver(Object recv)452     Object checkReceiver(Object recv) {
453         throw new InternalError("Should only be invoked on a subclass");
454     }
455 
456 
457     /** This subclass handles constructor references. */
458     static class Constructor extends DirectMethodHandle {
459         final MemberName initMethod;
460         final Class<?>   instanceClass;
461 
Constructor(MethodType mtype, LambdaForm form, MemberName constructor, MemberName initMethod, Class<?> instanceClass)462         private Constructor(MethodType mtype, LambdaForm form, MemberName constructor,
463                             MemberName initMethod, Class<?> instanceClass) {
464             super(mtype, form, constructor);
465             this.initMethod = initMethod;
466             this.instanceClass = instanceClass;
467             assert(initMethod.isResolved());
468         }
469         @Override
copyWith(MethodType mt, LambdaForm lf)470         MethodHandle copyWith(MethodType mt, LambdaForm lf) {
471             return new Constructor(mt, lf, member, initMethod, instanceClass);
472         }
473     }
474 
constructorMethod(Object mh)475     /*non-public*/ static Object constructorMethod(Object mh) {
476         Constructor dmh = (Constructor)mh;
477         return dmh.initMethod;
478     }
479 
allocateInstance(Object mh)480     /*non-public*/ static Object allocateInstance(Object mh) throws InstantiationException {
481         Constructor dmh = (Constructor)mh;
482         return UNSAFE.allocateInstance(dmh.instanceClass);
483     }
484 
485     /** This subclass handles non-static field references. */
486     static class Accessor extends DirectMethodHandle {
487         final Class<?> fieldType;
488         final int      fieldOffset;
Accessor(MethodType mtype, LambdaForm form, MemberName member, int fieldOffset)489         private Accessor(MethodType mtype, LambdaForm form, MemberName member,
490                          int fieldOffset) {
491             super(mtype, form, member);
492             this.fieldType   = member.getFieldType();
493             this.fieldOffset = fieldOffset;
494         }
495 
checkCast(Object obj)496         @Override Object checkCast(Object obj) {
497             return fieldType.cast(obj);
498         }
499         @Override
copyWith(MethodType mt, LambdaForm lf)500         MethodHandle copyWith(MethodType mt, LambdaForm lf) {
501             return new Accessor(mt, lf, member, fieldOffset);
502         }
503     }
504 
505     @ForceInline
fieldOffset(Object accessorObj)506     /*non-public*/ static long fieldOffset(Object accessorObj) {
507         // Note: We return a long because that is what Unsafe.getObject likes.
508         // We store a plain int because it is more compact.
509         return ((Accessor)accessorObj).fieldOffset;
510     }
511 
512     @ForceInline
checkBase(Object obj)513     /*non-public*/ static Object checkBase(Object obj) {
514         // Note that the object's class has already been verified,
515         // since the parameter type of the Accessor method handle
516         // is either member.getDeclaringClass or a subclass.
517         // This was verified in DirectMethodHandle.make.
518         // Therefore, the only remaining check is for null.
519         // Since this check is *not* guaranteed by Unsafe.getInt
520         // and its siblings, we need to make an explicit one here.
521         return Objects.requireNonNull(obj);
522     }
523 
524     /** This subclass handles static field references. */
525     static class StaticAccessor extends DirectMethodHandle {
526         private final Class<?> fieldType;
527         private final Object   staticBase;
528         private final long     staticOffset;
529 
StaticAccessor(MethodType mtype, LambdaForm form, MemberName member, Object staticBase, long staticOffset)530         private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member,
531                                Object staticBase, long staticOffset) {
532             super(mtype, form, member);
533             this.fieldType    = member.getFieldType();
534             this.staticBase   = staticBase;
535             this.staticOffset = staticOffset;
536         }
537 
checkCast(Object obj)538         @Override Object checkCast(Object obj) {
539             return fieldType.cast(obj);
540         }
541         @Override
copyWith(MethodType mt, LambdaForm lf)542         MethodHandle copyWith(MethodType mt, LambdaForm lf) {
543             return new StaticAccessor(mt, lf, member, staticBase, staticOffset);
544         }
545     }
546 
547     @ForceInline
nullCheck(Object obj)548     /*non-public*/ static Object nullCheck(Object obj) {
549         return Objects.requireNonNull(obj);
550     }
551 
552     @ForceInline
staticBase(Object accessorObj)553     /*non-public*/ static Object staticBase(Object accessorObj) {
554         return ((StaticAccessor)accessorObj).staticBase;
555     }
556 
557     @ForceInline
staticOffset(Object accessorObj)558     /*non-public*/ static long staticOffset(Object accessorObj) {
559         return ((StaticAccessor)accessorObj).staticOffset;
560     }
561 
562     @ForceInline
checkCast(Object mh, Object obj)563     /*non-public*/ static Object checkCast(Object mh, Object obj) {
564         return ((DirectMethodHandle) mh).checkCast(obj);
565     }
566 
checkCast(Object obj)567     Object checkCast(Object obj) {
568         return member.getReturnType().cast(obj);
569     }
570 
571     // Caching machinery for field accessors:
572     static final byte
573             AF_GETFIELD        = 0,
574             AF_PUTFIELD        = 1,
575             AF_GETSTATIC       = 2,
576             AF_PUTSTATIC       = 3,
577             AF_GETSTATIC_INIT  = 4,
578             AF_PUTSTATIC_INIT  = 5,
579             AF_LIMIT           = 6;
580     // Enumerate the different field kinds using Wrapper,
581     // with an extra case added for checked references.
582     static final int
583             FT_LAST_WRAPPER    = Wrapper.COUNT-1,
584             FT_UNCHECKED_REF   = Wrapper.OBJECT.ordinal(),
585             FT_CHECKED_REF     = FT_LAST_WRAPPER+1,
586             FT_LIMIT           = FT_LAST_WRAPPER+2;
afIndex(byte formOp, boolean isVolatile, int ftypeKind)587     private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {
588         return ((formOp * FT_LIMIT * 2)
589                 + (isVolatile ? FT_LIMIT : 0)
590                 + ftypeKind);
591     }
592     @Stable
593     private static final LambdaForm[] ACCESSOR_FORMS
594             = new LambdaForm[afIndex(AF_LIMIT, false, 0)];
ftypeKind(Class<?> ftype)595     static int ftypeKind(Class<?> ftype) {
596         if (ftype.isPrimitive())
597             return Wrapper.forPrimitiveType(ftype).ordinal();
598         else if (VerifyType.isNullReferenceConversion(Object.class, ftype))
599             return FT_UNCHECKED_REF;
600         else
601             return FT_CHECKED_REF;
602     }
603 
604     /**
605      * Create a LF which can access the given field.
606      * Cache and share this structure among all fields with
607      * the same basicType and refKind.
608      */
preparedFieldLambdaForm(MemberName m)609     private static LambdaForm preparedFieldLambdaForm(MemberName m) {
610         Class<?> ftype = m.getFieldType();
611         boolean isVolatile = m.isVolatile();
612         byte formOp;
613         switch (m.getReferenceKind()) {
614         case REF_getField:      formOp = AF_GETFIELD;    break;
615         case REF_putField:      formOp = AF_PUTFIELD;    break;
616         case REF_getStatic:     formOp = AF_GETSTATIC;   break;
617         case REF_putStatic:     formOp = AF_PUTSTATIC;   break;
618         default:  throw new InternalError(m.toString());
619         }
620         if (shouldBeInitialized(m)) {
621             // precompute the barrier-free version:
622             preparedFieldLambdaForm(formOp, isVolatile, ftype);
623             assert((AF_GETSTATIC_INIT - AF_GETSTATIC) ==
624                    (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
625             formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
626         }
627         LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
628         maybeCompile(lform, m);
629         assert(lform.methodType().dropParameterTypes(0, 1)
630                 .equals(m.getInvocationType().basicType()))
631                 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
632         return lform;
633     }
preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype)634     private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype) {
635         int ftypeKind = ftypeKind(ftype);
636         int afIndex = afIndex(formOp, isVolatile, ftypeKind);
637         LambdaForm lform = ACCESSOR_FORMS[afIndex];
638         if (lform != null)  return lform;
639         lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind);
640         ACCESSOR_FORMS[afIndex] = lform;  // don't bother with a CAS
641         return lform;
642     }
643 
644     private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();
645 
getFieldKind(boolean isGetter, boolean isVolatile, Wrapper wrapper)646     private static Kind getFieldKind(boolean isGetter, boolean isVolatile, Wrapper wrapper) {
647         if (isGetter) {
648             if (isVolatile) {
649                 switch (wrapper) {
650                     case BOOLEAN: return GET_BOOLEAN_VOLATILE;
651                     case BYTE:    return GET_BYTE_VOLATILE;
652                     case SHORT:   return GET_SHORT_VOLATILE;
653                     case CHAR:    return GET_CHAR_VOLATILE;
654                     case INT:     return GET_INT_VOLATILE;
655                     case LONG:    return GET_LONG_VOLATILE;
656                     case FLOAT:   return GET_FLOAT_VOLATILE;
657                     case DOUBLE:  return GET_DOUBLE_VOLATILE;
658                     case OBJECT:  return GET_OBJECT_VOLATILE;
659                 }
660             } else {
661                 switch (wrapper) {
662                     case BOOLEAN: return GET_BOOLEAN;
663                     case BYTE:    return GET_BYTE;
664                     case SHORT:   return GET_SHORT;
665                     case CHAR:    return GET_CHAR;
666                     case INT:     return GET_INT;
667                     case LONG:    return GET_LONG;
668                     case FLOAT:   return GET_FLOAT;
669                     case DOUBLE:  return GET_DOUBLE;
670                     case OBJECT:  return GET_OBJECT;
671                 }
672             }
673         } else {
674             if (isVolatile) {
675                 switch (wrapper) {
676                     case BOOLEAN: return PUT_BOOLEAN_VOLATILE;
677                     case BYTE:    return PUT_BYTE_VOLATILE;
678                     case SHORT:   return PUT_SHORT_VOLATILE;
679                     case CHAR:    return PUT_CHAR_VOLATILE;
680                     case INT:     return PUT_INT_VOLATILE;
681                     case LONG:    return PUT_LONG_VOLATILE;
682                     case FLOAT:   return PUT_FLOAT_VOLATILE;
683                     case DOUBLE:  return PUT_DOUBLE_VOLATILE;
684                     case OBJECT:  return PUT_OBJECT_VOLATILE;
685                 }
686             } else {
687                 switch (wrapper) {
688                     case BOOLEAN: return PUT_BOOLEAN;
689                     case BYTE:    return PUT_BYTE;
690                     case SHORT:   return PUT_SHORT;
691                     case CHAR:    return PUT_CHAR;
692                     case INT:     return PUT_INT;
693                     case LONG:    return PUT_LONG;
694                     case FLOAT:   return PUT_FLOAT;
695                     case DOUBLE:  return PUT_DOUBLE;
696                     case OBJECT:  return PUT_OBJECT;
697                 }
698             }
699         }
700         throw new AssertionError("Invalid arguments");
701     }
702 
makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind)703     static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) {
704         boolean isGetter  = (formOp & 1) == (AF_GETFIELD & 1);
705         boolean isStatic  = (formOp >= AF_GETSTATIC);
706         boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
707         boolean needsCast = (ftypeKind == FT_CHECKED_REF);
708         Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
709         Class<?> ft = fw.primitiveType();
710         assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind);
711 
712         // getObject, putIntVolatile, etc.
713         Kind kind = getFieldKind(isGetter, isVolatile, fw);
714 
715         MethodType linkerType;
716         if (isGetter)
717             linkerType = MethodType.methodType(ft, Object.class, long.class);
718         else
719             linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
720         MemberName linker = new MemberName(Unsafe.class, kind.methodName, linkerType, REF_invokeVirtual);
721         try {
722             linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);
723         } catch (ReflectiveOperationException ex) {
724             throw newInternalError(ex);
725         }
726 
727         // What is the external type of the lambda form?
728         MethodType mtype;
729         if (isGetter)
730             mtype = MethodType.methodType(ft);
731         else
732             mtype = MethodType.methodType(void.class, ft);
733         mtype = mtype.basicType();  // erase short to int, etc.
734         if (!isStatic)
735             mtype = mtype.insertParameterTypes(0, Object.class);
736         final int DMH_THIS  = 0;
737         final int ARG_BASE  = 1;
738         final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
739         // if this is for non-static access, the base pointer is stored at this index:
740         final int OBJ_BASE  = isStatic ? -1 : ARG_BASE;
741         // if this is for write access, the value to be written is stored at this index:
742         final int SET_VALUE  = isGetter ? -1 : ARG_LIMIT - 1;
743         int nameCursor = ARG_LIMIT;
744         final int F_HOLDER  = (isStatic ? nameCursor++ : -1);  // static base if any
745         final int F_OFFSET  = nameCursor++;  // Either static offset or field offset.
746         final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
747         final int U_HOLDER  = nameCursor++;  // UNSAFE holder
748         final int INIT_BAR  = (needsInit ? nameCursor++ : -1);
749         final int PRE_CAST  = (needsCast && !isGetter ? nameCursor++ : -1);
750         final int LINKER_CALL = nameCursor++;
751         final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
752         final int RESULT    = nameCursor-1;  // either the call or the cast
753         Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
754         if (needsInit)
755             names[INIT_BAR] = new Name(getFunction(NF_ensureInitialized), names[DMH_THIS]);
756         if (needsCast && !isGetter)
757             names[PRE_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[SET_VALUE]);
758         Object[] outArgs = new Object[1 + linkerType.parameterCount()];
759         assert(outArgs.length == (isGetter ? 3 : 4));
760         outArgs[0] = names[U_HOLDER] = new Name(getFunction(NF_UNSAFE));
761         if (isStatic) {
762             outArgs[1] = names[F_HOLDER]  = new Name(getFunction(NF_staticBase), names[DMH_THIS]);
763             outArgs[2] = names[F_OFFSET]  = new Name(getFunction(NF_staticOffset), names[DMH_THIS]);
764         } else {
765             outArgs[1] = names[OBJ_CHECK] = new Name(getFunction(NF_checkBase), names[OBJ_BASE]);
766             outArgs[2] = names[F_OFFSET]  = new Name(getFunction(NF_fieldOffset), names[DMH_THIS]);
767         }
768         if (!isGetter) {
769             outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
770         }
771         for (Object a : outArgs)  assert(a != null);
772         names[LINKER_CALL] = new Name(linker, outArgs);
773         if (needsCast && isGetter)
774             names[POST_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[LINKER_CALL]);
775         for (Name n : names)  assert(n != null);
776 
777         LambdaForm form;
778         if (needsCast || needsInit) {
779             // can't use the pre-generated form when casting and/or initializing
780             form = new LambdaForm(ARG_LIMIT, names, RESULT);
781         } else {
782             form = new LambdaForm(ARG_LIMIT, names, RESULT, kind);
783         }
784 
785         if (LambdaForm.debugNames()) {
786             // add some detail to the lambdaForm debugname,
787             // significant only for debugging
788             StringBuilder nameBuilder = new StringBuilder(kind.methodName);
789             if (isStatic) {
790                 nameBuilder.append("Static");
791             } else {
792                 nameBuilder.append("Field");
793             }
794             if (needsCast) {
795                 nameBuilder.append("Cast");
796             }
797             if (needsInit) {
798                 nameBuilder.append("Init");
799             }
800             LambdaForm.associateWithDebugName(form, nameBuilder.toString());
801         }
802         return form;
803     }
804 
805     /**
806      * Pre-initialized NamedFunctions for bootstrapping purposes.
807      */
808     static final byte NF_internalMemberName = 0,
809             NF_internalMemberNameEnsureInit = 1,
810             NF_ensureInitialized = 2,
811             NF_fieldOffset = 3,
812             NF_checkBase = 4,
813             NF_staticBase = 5,
814             NF_staticOffset = 6,
815             NF_checkCast = 7,
816             NF_allocateInstance = 8,
817             NF_constructorMethod = 9,
818             NF_UNSAFE = 10,
819             NF_checkReceiver = 11,
820             NF_LIMIT = 12;
821 
822     private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT];
823 
getFunction(byte func)824     private static NamedFunction getFunction(byte func) {
825         NamedFunction nf = NFS[func];
826         if (nf != null) {
827             return nf;
828         }
829         // Each nf must be statically invocable or we get tied up in our bootstraps.
830         nf = NFS[func] = createFunction(func);
831         assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf));
832         return nf;
833     }
834 
835     private static final MethodType OBJ_OBJ_TYPE = MethodType.methodType(Object.class, Object.class);
836 
837     private static final MethodType LONG_OBJ_TYPE = MethodType.methodType(long.class, Object.class);
838 
createFunction(byte func)839     private static NamedFunction createFunction(byte func) {
840         try {
841             switch (func) {
842                 case NF_internalMemberName:
843                     return getNamedFunction("internalMemberName", OBJ_OBJ_TYPE);
844                 case NF_internalMemberNameEnsureInit:
845                     return getNamedFunction("internalMemberNameEnsureInit", OBJ_OBJ_TYPE);
846                 case NF_ensureInitialized:
847                     return getNamedFunction("ensureInitialized", MethodType.methodType(void.class, Object.class));
848                 case NF_fieldOffset:
849                     return getNamedFunction("fieldOffset", LONG_OBJ_TYPE);
850                 case NF_checkBase:
851                     return getNamedFunction("checkBase", OBJ_OBJ_TYPE);
852                 case NF_staticBase:
853                     return getNamedFunction("staticBase", OBJ_OBJ_TYPE);
854                 case NF_staticOffset:
855                     return getNamedFunction("staticOffset", LONG_OBJ_TYPE);
856                 case NF_checkCast:
857                     return getNamedFunction("checkCast", MethodType.methodType(Object.class, Object.class, Object.class));
858                 case NF_allocateInstance:
859                     return getNamedFunction("allocateInstance", OBJ_OBJ_TYPE);
860                 case NF_constructorMethod:
861                     return getNamedFunction("constructorMethod", OBJ_OBJ_TYPE);
862                 case NF_UNSAFE:
863                     MemberName member = new MemberName(MethodHandleStatics.class, "UNSAFE", Unsafe.class, REF_getField);
864                     return new NamedFunction(
865                             MemberName.getFactory()
866                                     .resolveOrFail(REF_getField, member, DirectMethodHandle.class, NoSuchMethodException.class));
867                 case NF_checkReceiver:
868                     member = new MemberName(DirectMethodHandle.class, "checkReceiver", OBJ_OBJ_TYPE, REF_invokeVirtual);
869                     return new NamedFunction(
870                         MemberName.getFactory()
871                             .resolveOrFail(REF_invokeVirtual, member, DirectMethodHandle.class, NoSuchMethodException.class));
872                 default:
873                     throw newInternalError("Unknown function: " + func);
874             }
875         } catch (ReflectiveOperationException ex) {
876             throw newInternalError(ex);
877         }
878     }
879 
getNamedFunction(String name, MethodType type)880     private static NamedFunction getNamedFunction(String name, MethodType type)
881         throws ReflectiveOperationException
882     {
883         MemberName member = new MemberName(DirectMethodHandle.class, name, type, REF_invokeStatic);
884         return new NamedFunction(
885             MemberName.getFactory()
886                 .resolveOrFail(REF_invokeStatic, member, DirectMethodHandle.class, NoSuchMethodException.class));
887     }
888 
889     static {
890         // The Holder class will contain pre-generated DirectMethodHandles resolved
891         // speculatively using MemberName.getFactory().resolveOrNull. However, that
892         // doesn't initialize the class, which subtly breaks inlining etc. By forcing
893         // initialization of the Holder class we avoid these issues.
894         UNSAFE.ensureClassInitialized(Holder.class);
895     }
896 
897     /* Placeholder class for DirectMethodHandles generated ahead of time */
898     final class Holder {}
899 }
900