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/*
* Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.lang.invoke;
import jdk.internal.ref.CleanerFactory;
import sun.invoke.util.Wrapper;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Field;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.TRACE_METHOD_LINKAGE;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
/**
* The JVM interface for the method handles package is all here.
* This is an interface internal and private to an implementation of JSR 292.
* This class is not part of the JSR 292 standard.
* @author jrose
*/
class MethodHandleNatives {
private MethodHandleNatives() { } // static only
/// MemberName support
static native void init(MemberName self, Object ref);
static native void expand(MemberName self);
static native MemberName resolve(MemberName self, Class caller) throws LinkageError, ClassNotFoundException;
static native int getMembers(Class defc, String matchName, String matchSig,
int matchFlags, Class caller, int skip, MemberName[] results);
/// Field layout queries parallel to jdk.internal.misc.Unsafe:
static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
static native Object staticFieldBase(MemberName self); // e.g., returns clazz
static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
/// CallSite support
/** Tell the JVM that we need to change the target of a CallSite. */
static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
/** Represents a context to track nmethod dependencies on CallSite instance target. */
static class CallSiteContext implements Runnable {
//@Injected JVM_nmethodBucket* vmdependencies;
static CallSiteContext make(CallSite cs) {
final CallSiteContext newContext = new CallSiteContext();
// CallSite instance is tracked by a Cleanable which clears native
// structures allocated for CallSite context. Though the CallSite can
// become unreachable, its Context is retained by the Cleanable instance
// (which is referenced from Cleaner instance which is referenced from
// CleanerFactory class) until cleanup is performed.
CleanerFactory.cleaner().register(cs, newContext);
return newContext;
}
@Override
public void run() {
MethodHandleNatives.clearCallSiteContext(this);
}
}
/** Invalidate all recorded nmethods. */
private static native void clearCallSiteContext(CallSiteContext context);
private static native void registerNatives();
static {
registerNatives();
}
/**
* Compile-time constants go here. This collection exists not only for
* reference from clients, but also for ensuring the VM and JDK agree on the
* values of these constants (see {@link #verifyConstants()}).
*/
static class Constants {
Constants() { } // static only
static final int
MN_IS_METHOD = 0x00010000, // method (not constructor)
MN_IS_CONSTRUCTOR = 0x00020000, // constructor
MN_IS_FIELD = 0x00040000, // field
MN_IS_TYPE = 0x00080000, // nested type
MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
MN_REFERENCE_KIND_SHIFT = 24, // refKind
MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
// The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
MN_SEARCH_SUPERCLASSES = 0x00100000,
MN_SEARCH_INTERFACES = 0x00200000;
/**
* Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
*/
static final byte
REF_NONE = 0, // null value
REF_getField = 1,
REF_getStatic = 2,
REF_putField = 3,
REF_putStatic = 4,
REF_invokeVirtual = 5,
REF_invokeStatic = 6,
REF_invokeSpecial = 7,
REF_newInvokeSpecial = 8,
REF_invokeInterface = 9,
REF_LIMIT = 10;
}
static boolean refKindIsValid(int refKind) {
return (refKind > REF_NONE && refKind < REF_LIMIT);
}
static boolean refKindIsField(byte refKind) {
assert(refKindIsValid(refKind));
return (refKind <= REF_putStatic);
}
static boolean refKindIsGetter(byte refKind) {
assert(refKindIsValid(refKind));
return (refKind <= REF_getStatic);
}
static boolean refKindIsSetter(byte refKind) {
return refKindIsField(refKind) && !refKindIsGetter(refKind);
}
static boolean refKindIsMethod(byte refKind) {
return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
}
static boolean refKindIsConstructor(byte refKind) {
return (refKind == REF_newInvokeSpecial);
}
static boolean refKindHasReceiver(byte refKind) {
assert(refKindIsValid(refKind));
return (refKind & 1) != 0;
}
static boolean refKindIsStatic(byte refKind) {
return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
}
static boolean refKindDoesDispatch(byte refKind) {
assert(refKindIsValid(refKind));
return (refKind == REF_invokeVirtual ||
refKind == REF_invokeInterface);
}
static {
final int HR_MASK = ((1 << REF_getField) |
(1 << REF_putField) |
(1 << REF_invokeVirtual) |
(1 << REF_invokeSpecial) |
(1 << REF_invokeInterface)
);
for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
assert(refKindHasReceiver(refKind) == (((1< caller = (Class)callerObj;
String name = nameObj.toString().intern();
MethodType type = (MethodType)typeObj;
if (!TRACE_METHOD_LINKAGE)
return linkCallSiteImpl(caller, bootstrapMethod, name, type,
staticArguments, appendixResult);
return linkCallSiteTracing(caller, bootstrapMethod, name, type,
staticArguments, appendixResult);
}
static MemberName linkCallSiteImpl(Class caller,
MethodHandle bootstrapMethod,
String name, MethodType type,
Object staticArguments,
Object[] appendixResult) {
CallSite callSite = CallSite.makeSite(bootstrapMethod,
name,
type,
staticArguments,
caller);
if (callSite instanceof ConstantCallSite) {
appendixResult[0] = callSite.dynamicInvoker();
return Invokers.linkToTargetMethod(type);
} else {
appendixResult[0] = callSite;
return Invokers.linkToCallSiteMethod(type);
}
}
// Tracing logic:
static MemberName linkCallSiteTracing(Class caller,
MethodHandle bootstrapMethod,
String name, MethodType type,
Object staticArguments,
Object[] appendixResult) {
Object bsmReference = bootstrapMethod.internalMemberName();
if (bsmReference == null) bsmReference = bootstrapMethod;
Object staticArglist = (staticArguments instanceof Object[] ?
java.util.Arrays.asList((Object[]) staticArguments) :
staticArguments);
System.out.println("linkCallSite "+caller.getName()+" "+
bsmReference+" "+
name+type+"/"+staticArglist);
try {
MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
staticArguments, appendixResult);
System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
return res;
} catch (Throwable ex) {
System.out.println("linkCallSite => throw "+ex);
throw ex;
}
}
/**
* The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
*/
static MethodType findMethodHandleType(Class rtype, Class[] ptypes) {
return MethodType.makeImpl(rtype, ptypes, true);
}
/**
* The JVM wants to link a call site that requires a dynamic type check.
* Name is a type-checking invoker, invokeExact or invoke.
* Return a JVM method (MemberName) to handle the invoking.
* The method assumes the following arguments on the stack:
* 0: the method handle being invoked
* 1-N: the arguments to the method handle invocation
* N+1: an optional, implicitly added argument (typically the given MethodType)
*
* The nominal method at such a call site is an instance of
* a signature-polymorphic method (see @PolymorphicSignature).
* Such method instances are user-visible entities which are
* "split" from the generic placeholder method in {@code MethodHandle}.
* (Note that the placeholder method is not identical with any of
* its instances. If invoked reflectively, is guaranteed to throw an
* {@code UnsupportedOperationException}.)
* If the signature-polymorphic method instance is ever reified,
* it appears as a "copy" of the original placeholder
* (a native final member of {@code MethodHandle}) except
* that its type descriptor has shape required by the instance,
* and the method instance is not varargs.
* The method instance is also marked synthetic, since the
* method (by definition) does not appear in Java source code.
*
* The JVM is allowed to reify this method as instance metadata.
* For example, {@code invokeBasic} is always reified.
* But the JVM may instead call {@code linkMethod}.
* If the result is an * ordered pair of a {@code (method, appendix)},
* the method gets all the arguments (0..N inclusive)
* plus the appendix (N+1), and uses the appendix to complete the call.
* In this way, one reusable method (called a "linker method")
* can perform the function of any number of polymorphic instance
* methods.
*
* Linker methods are allowed to be weakly typed, with any or
* all references rewritten to {@code Object} and any primitives
* (except {@code long}/{@code float}/{@code double})
* rewritten to {@code int}.
* A linker method is trusted to return a strongly typed result,
* according to the specific method type descriptor of the
* signature-polymorphic instance it is emulating.
* This can involve (as necessary) a dynamic check using
* data extracted from the appendix argument.
*
* The JVM does not inspect the appendix, other than to pass
* it verbatim to the linker method at every call.
* This means that the JDK runtime has wide latitude
* for choosing the shape of each linker method and its
* corresponding appendix.
* Linker methods should be generated from {@code LambdaForm}s
* so that they do not become visible on stack traces.
*
* The {@code linkMethod} call is free to omit the appendix
* (returning null) and instead emulate the required function
* completely in the linker method.
* As a corner case, if N==255, no appendix is possible.
* In this case, the method returned must be custom-generated to
* to perform any needed type checking.
*
* If the JVM does not reify a method at a call site, but instead
* calls {@code linkMethod}, the corresponding call represented
* in the bytecodes may mention a valid method which is not
* representable with a {@code MemberName}.
* Therefore, use cases for {@code linkMethod} tend to correspond to
* special cases in reflective code such as {@code findVirtual}
* or {@code revealDirect}.
*/
static MemberName linkMethod(Class callerClass, int refKind,
Class defc, String name, Object type,
Object[] appendixResult) {
if (!TRACE_METHOD_LINKAGE)
return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
}
static MemberName linkMethodImpl(Class callerClass, int refKind,
Class defc, String name, Object type,
Object[] appendixResult) {
try {
if (refKind == REF_invokeVirtual) {
if (defc == MethodHandle.class) {
return Invokers.methodHandleInvokeLinkerMethod(
name, fixMethodType(callerClass, type), appendixResult);
} else if (defc == VarHandle.class) {
return varHandleOperationLinkerMethod(
name, fixMethodType(callerClass, type), appendixResult);
}
}
} catch (Error e) {
// Pass through an Error, including say StackOverflowError or
// OutOfMemoryError
throw e;
} catch (Throwable ex) {
// Wrap anything else in LinkageError
throw new LinkageError(ex.getMessage(), ex);
}
throw new LinkageError("no such method "+defc.getName()+"."+name+type);
}
private static MethodType fixMethodType(Class callerClass, Object type) {
if (type instanceof MethodType)
return (MethodType) type;
else
return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
}
// Tracing logic:
static MemberName linkMethodTracing(Class callerClass, int refKind,
Class defc, String name, Object type,
Object[] appendixResult) {
System.out.println("linkMethod "+defc.getName()+"."+
name+type+"/"+Integer.toHexString(refKind));
try {
MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
return res;
} catch (Throwable ex) {
System.out.println("linkMethod => throw "+ex);
throw ex;
}
}
/**
* Obtain the method to link to the VarHandle operation.
* This method is located here and not in Invokers to avoid
* intializing that and other classes early on in VM bootup.
*/
private static MemberName varHandleOperationLinkerMethod(String name,
MethodType mtype,
Object[] appendixResult) {
// Get the signature method type
final MethodType sigType = mtype.basicType();
// Get the access kind from the method name
VarHandle.AccessMode ak;
try {
ak = VarHandle.AccessMode.valueFromMethodName(name);
} catch (IllegalArgumentException e) {
throw MethodHandleStatics.newInternalError(e);
}
// Create the appendix descriptor constant
VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
appendixResult[0] = ad;
if (MethodHandleStatics.VAR_HANDLE_GUARDS) {
// If not polymorphic in the return type, such as the compareAndSet
// methods that return boolean
Class guardReturnType = sigType.returnType();
if (ak.at.isMonomorphicInReturnType) {
if (ak.at.returnType != mtype.returnType()) {
// The caller contains a different return type than that
// defined by the method
throw newNoSuchMethodErrorOnVarHandle(name, mtype);
}
// Adjust the return type of the signature method type
guardReturnType = ak.at.returnType;
}
// Get the guard method type for linking
final Class[] guardParams = new Class[sigType.parameterCount() + 2];
// VarHandle at start
guardParams[0] = VarHandle.class;
for (int i = 0; i < sigType.parameterCount(); i++) {
guardParams[i + 1] = sigType.parameterType(i);
}
// Access descriptor at end
guardParams[guardParams.length - 1] = VarHandle.AccessDescriptor.class;
MethodType guardType = MethodType.makeImpl(guardReturnType, guardParams, true);
MemberName linker = new MemberName(
VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
guardType, REF_invokeStatic);
linker = MemberName.getFactory().resolveOrNull(REF_invokeStatic, linker,
VarHandleGuards.class);
if (linker != null) {
return linker;
}
// Fall back to lambda form linkage if guard method is not available
// TODO Optionally log fallback ?
}
return Invokers.varHandleInvokeLinkerMethod(ak, mtype);
}
static String getVarHandleGuardMethodName(MethodType guardType) {
String prefix = "guard_";
StringBuilder sb = new StringBuilder(prefix.length() + guardType.parameterCount());
sb.append(prefix);
for (int i = 1; i < guardType.parameterCount() - 1; i++) {
Class pt = guardType.parameterType(i);
sb.append(getCharType(pt));
}
sb.append('_').append(getCharType(guardType.returnType()));
return sb.toString();
}
static char getCharType(Class pt) {
return Wrapper.forBasicType(pt).basicTypeChar();
}
static NoSuchMethodError newNoSuchMethodErrorOnVarHandle(String name, MethodType mtype) {
return new NoSuchMethodError("VarHandle." + name + mtype);
}
/**
* The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
* It will make an up-call to this method. (Do not change the name or signature.)
* The type argument is a Class for field requests and a MethodType for non-fields.
*
* Recent versions of the JVM may also pass a resolved MemberName for the type.
* In that case, the name is ignored and may be null.
*/
static MethodHandle linkMethodHandleConstant(Class callerClass, int refKind,
Class defc, String name, Object type) {
try {
Lookup lookup = IMPL_LOOKUP.in(callerClass);
assert(refKindIsValid(refKind));
return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
} catch (IllegalAccessException ex) {
Throwable cause = ex.getCause();
if (cause instanceof AbstractMethodError) {
throw (AbstractMethodError) cause;
} else {
Error err = new IllegalAccessError(ex.getMessage());
throw initCauseFrom(err, ex);
}
} catch (NoSuchMethodException ex) {
Error err = new NoSuchMethodError(ex.getMessage());
throw initCauseFrom(err, ex);
} catch (NoSuchFieldException ex) {
Error err = new NoSuchFieldError(ex.getMessage());
throw initCauseFrom(err, ex);
} catch (ReflectiveOperationException ex) {
Error err = new IncompatibleClassChangeError();
throw initCauseFrom(err, ex);
}
}
/**
* Use best possible cause for err.initCause(), substituting the
* cause for err itself if the cause has the same (or better) type.
*/
private static Error initCauseFrom(Error err, Exception ex) {
Throwable th = ex.getCause();
if (err.getClass().isInstance(th))
return (Error) th;
err.initCause(th == null ? ex : th);
return err;
}
/**
* Is this method a caller-sensitive method?
* I.e., does it call Reflection.getCallerClass or a similar method
* to ask about the identity of its caller?
*/
static boolean isCallerSensitive(MemberName mem) {
if (!mem.isInvocable()) return false; // fields are not caller sensitive
return mem.isCallerSensitive() || canBeCalledVirtual(mem);
}
static boolean canBeCalledVirtual(MemberName mem) {
assert(mem.isInvocable());
Class defc = mem.getDeclaringClass();
switch (mem.getName()) {
case "checkMemberAccess":
return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
case "getContextClassLoader":
return canBeCalledVirtual(mem, java.lang.Thread.class);
}
return false;
}
static boolean canBeCalledVirtual(MemberName symbolicRef, Class definingClass) {
Class symbolicRefClass = symbolicRef.getDeclaringClass();
if (symbolicRefClass == definingClass) return true;
if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
symbolicRefClass.isInterface()); // Mdef implements Msym
}
}