/*non-public*/
static boolean canConvert(Class<?> src, Class<?> dst) {
// short-circuit a few cases:
if (src == dst || dst == Object.class) return true;
// the remainder of this logic is documented in MethodHandle.asType
if (src.isPrimitive()) {
// can force void to an explicit null, a la reflect.Method.invoke
// can also force void to a primitive zero, by analogy
if (src == void.class) return true; // or !dst.isPrimitive()?
Wrapper sw = Wrapper.forPrimitiveType(src);
if (dst.isPrimitive()) {
// P->P must widen
return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
} else {
// P->R must box and widen
return dst.isAssignableFrom(sw.wrapperType());
}
} else if (dst.isPrimitive()) {
// any value can be dropped
if (dst == void.class) return true;
Wrapper dw = Wrapper.forPrimitiveType(dst);
// R->P must be able to unbox (from a dynamically chosen type) and widen
// For example:
// Byte/Number/Comparable/Object -> dw:Byte -> byte.
// Character/Comparable/Object -> dw:Character -> char
// Boolean/Comparable/Object -> dw:Boolean -> boolean
// This means that dw must be cast-compatible with src.
if (src.isAssignableFrom(dw.wrapperType())) {
return true;
}
// The above does not work if the source reference is strongly typed
// to a wrapper whose primitive must be widened. For example:
// Byte -> unbox:byte -> short/int/long/float/double
// Character -> unbox:char -> int/long/float/double
if (Wrapper.isWrapperType(src) && dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
// can unbox from src and then widen to dst
return true;
}
// We have already covered cases which arise due to runtime unboxing
// of a reference type which covers several wrapper types:
// Object -> cast:Integer -> unbox:int -> long/float/double
// Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
// An marginal case is Number -> dw:Character -> char, which would be OK if there were a
// subclass of Number which wraps a value that can convert to char.
// Since there is none, we don't need an extra check here to cover char or boolean.
return false;
} else {
// R->R always works, since null is always valid dynamically
return true;
}
}
private static int ftypeKind(Class<?> ftype) {
if (ftype.isPrimitive()) return Wrapper.forPrimitiveType(ftype).ordinal();
else if (VerifyType.isNullReferenceConversion(Object.class, ftype)) return FT_UNCHECKED_REF;
else return FT_CHECKED_REF;
}
private static LambdaForm makePreparedFieldLambdaForm(
byte formOp, boolean isVolatile, int ftypeKind) {
boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
boolean isStatic = (formOp >= AF_GETSTATIC);
boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
boolean needsCast = (ftypeKind == FT_CHECKED_REF);
Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
Class<?> ft = fw.primitiveType();
assert (ftypeKind(needsCast ? String.class : ft) == ftypeKind);
// getObject, putIntVolatile, etc.
StringBuilder nameBuilder = new StringBuilder();
if (isGetter) {
nameBuilder.append("get");
} else {
nameBuilder.append("put");
}
nameBuilder.append(fw.primitiveSimpleName());
nameBuilder.setCharAt(3, Character.toUpperCase(nameBuilder.charAt(3)));
if (isVolatile) {
nameBuilder.append("Volatile");
}
MethodType linkerType;
if (isGetter) linkerType = MethodType.methodType(ft, Object.class, long.class);
else linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
MemberName linker =
new MemberName(Unsafe.class, nameBuilder.toString(), linkerType, REF_invokeVirtual);
try {
linker =
IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);
} catch (ReflectiveOperationException ex) {
throw newInternalError(ex);
}
// What is the external type of the lambda form?
MethodType mtype;
if (isGetter) mtype = MethodType.methodType(ft);
else mtype = MethodType.methodType(void.class, ft);
mtype = mtype.basicType(); // erase short to int, etc.
if (!isStatic) mtype = mtype.insertParameterTypes(0, Object.class);
final int DMH_THIS = 0;
final int ARG_BASE = 1;
final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
// if this is for non-static access, the base pointer is stored at this index:
final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
// if this is for write access, the value to be written is stored at this index:
final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
int nameCursor = ARG_LIMIT;
final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
final int F_OFFSET = nameCursor++; // Either static offset or field offset.
final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
final int INIT_BAR = (needsInit ? nameCursor++ : -1);
final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
final int LINKER_CALL = nameCursor++;
final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
final int RESULT = nameCursor - 1; // either the call or the cast
Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
if (needsInit) names[INIT_BAR] = new Name(NF_ensureInitialized, names[DMH_THIS]);
if (needsCast && !isGetter)
names[PRE_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[SET_VALUE]);
Object[] outArgs = new Object[1 + linkerType.parameterCount()];
assert (outArgs.length == (isGetter ? 3 : 4));
outArgs[0] = UNSAFE;
if (isStatic) {
outArgs[1] = names[F_HOLDER] = new Name(NF_staticBase, names[DMH_THIS]);
outArgs[2] = names[F_OFFSET] = new Name(NF_staticOffset, names[DMH_THIS]);
} else {
outArgs[1] = names[OBJ_CHECK] = new Name(NF_checkBase, names[OBJ_BASE]);
outArgs[2] = names[F_OFFSET] = new Name(NF_fieldOffset, names[DMH_THIS]);
}
if (!isGetter) {
outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
}
for (Object a : outArgs) assert (a != null);
names[LINKER_CALL] = new Name(linker, outArgs);
if (needsCast && isGetter)
names[POST_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[LINKER_CALL]);
for (Name n : names) assert (n != null);
// add some detail to the lambdaForm debugname,
// significant only for debugging
if (isStatic) {
nameBuilder.append("Static");
} else {
nameBuilder.append("Field");
}
if (needsCast) nameBuilder.append("Cast");
if (needsInit) nameBuilder.append("Init");
return new LambdaForm(nameBuilder.toString(), ARG_LIMIT, names, RESULT);
}
/**
* The flavor of method handle which implements a constant reference to a class member.
*
* @author jrose
*/
class DirectMethodHandle extends MethodHandle {
final MemberName member;
// Constructors and factory methods in this class *must* be package scoped or private.
private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member) {
super(mtype, form);
if (!member.isResolved()) throw new InternalError();
if (member.getDeclaringClass().isInterface() && member.isMethod() && !member.isAbstract()) {
// Check for corner case: invokeinterface of Object method
MemberName m =
new MemberName(
Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());
m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null);
if (m != null && m.isPublic()) {
assert (member.getReferenceKind() == m.getReferenceKind()); // else this.form is wrong
member = m;
}
}
this.member = member;
}
// Factory methods:
static DirectMethodHandle make(byte refKind, Class<?> receiver, MemberName member) {
MethodType mtype = member.getMethodOrFieldType();
if (!member.isStatic()) {
if (!member.getDeclaringClass().isAssignableFrom(receiver) || member.isConstructor())
throw new InternalError(member.toString());
mtype = mtype.insertParameterTypes(0, receiver);
}
if (!member.isField()) {
if (refKind == REF_invokeSpecial) {
member = member.asSpecial();
LambdaForm lform = preparedLambdaForm(member);
return new Special(mtype, lform, member);
} else {
LambdaForm lform = preparedLambdaForm(member);
return new DirectMethodHandle(mtype, lform, member);
}
} else {
LambdaForm lform = preparedFieldLambdaForm(member);
if (member.isStatic()) {
long offset = MethodHandleNatives.staticFieldOffset(member);
Object base = MethodHandleNatives.staticFieldBase(member);
return new StaticAccessor(mtype, lform, member, base, offset);
} else {
long offset = MethodHandleNatives.objectFieldOffset(member);
assert (offset == (int) offset);
return new Accessor(mtype, lform, member, (int) offset);
}
}
}
static DirectMethodHandle make(Class<?> receiver, MemberName member) {
byte refKind = member.getReferenceKind();
if (refKind == REF_invokeSpecial) refKind = REF_invokeVirtual;
return make(refKind, receiver, member);
}
static DirectMethodHandle make(MemberName member) {
if (member.isConstructor()) return makeAllocator(member);
return make(member.getDeclaringClass(), member);
}
private static DirectMethodHandle makeAllocator(MemberName ctor) {
assert (ctor.isConstructor() && ctor.getName().equals("<init>"));
Class<?> instanceClass = ctor.getDeclaringClass();
ctor = ctor.asConstructor();
assert (ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;
MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);
LambdaForm lform = preparedLambdaForm(ctor);
MemberName init = ctor.asSpecial();
assert (init.getMethodType().returnType() == void.class);
return new Constructor(mtype, lform, ctor, init, instanceClass);
}
@Override
BoundMethodHandle rebind() {
return BoundMethodHandle.makeReinvoker(this);
}
@Override
MethodHandle copyWith(MethodType mt, LambdaForm lf) {
assert (this.getClass() == DirectMethodHandle.class); // must override in subclasses
return new DirectMethodHandle(mt, lf, member);
}
@Override
String internalProperties() {
return "\n& DMH.MN=" + internalMemberName();
}
//// Implementation methods.
@Override
@ForceInline
MemberName internalMemberName() {
return member;
}
private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();
/**
* Create a LF which can invoke the given method. Cache and share this structure among all methods
* with the same basicType and refKind.
*/
private static LambdaForm preparedLambdaForm(MemberName m) {
assert (m.isInvocable()) : m; // call preparedFieldLambdaForm instead
MethodType mtype = m.getInvocationType().basicType();
assert (!m.isMethodHandleInvoke()) : m;
int which;
switch (m.getReferenceKind()) {
case REF_invokeVirtual:
which = LF_INVVIRTUAL;
break;
case REF_invokeStatic:
which = LF_INVSTATIC;
break;
case REF_invokeSpecial:
which = LF_INVSPECIAL;
break;
case REF_invokeInterface:
which = LF_INVINTERFACE;
break;
case REF_newInvokeSpecial:
which = LF_NEWINVSPECIAL;
break;
default:
throw new InternalError(m.toString());
}
if (which == LF_INVSTATIC && shouldBeInitialized(m)) {
// precompute the barrier-free version:
preparedLambdaForm(mtype, which);
which = LF_INVSTATIC_INIT;
}
LambdaForm lform = preparedLambdaForm(mtype, which);
maybeCompile(lform, m);
assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
: Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
return lform;
}
private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {
LambdaForm lform = mtype.form().cachedLambdaForm(which);
if (lform != null) return lform;
lform = makePreparedLambdaForm(mtype, which);
return mtype.form().setCachedLambdaForm(which, lform);
}
static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {
boolean needsInit = (which == LF_INVSTATIC_INIT);
boolean doesAlloc = (which == LF_NEWINVSPECIAL);
String linkerName;
LambdaForm.Kind kind;
switch (which) {
case LF_INVVIRTUAL:
linkerName = "linkToVirtual";
kind = DIRECT_INVOKE_VIRTUAL;
break;
case LF_INVSTATIC:
linkerName = "linkToStatic";
kind = DIRECT_INVOKE_STATIC;
break;
case LF_INVSTATIC_INIT:
linkerName = "linkToStatic";
kind = DIRECT_INVOKE_STATIC_INIT;
break;
case LF_INVSPECIAL:
linkerName = "linkToSpecial";
kind = DIRECT_INVOKE_SPECIAL;
break;
case LF_INVINTERFACE:
linkerName = "linkToInterface";
kind = DIRECT_INVOKE_INTERFACE;
break;
case LF_NEWINVSPECIAL:
linkerName = "linkToSpecial";
kind = DIRECT_NEW_INVOKE_SPECIAL;
break;
default:
throw new InternalError("which=" + which);
}
MethodType mtypeWithArg = mtype.appendParameterTypes(MemberName.class);
if (doesAlloc)
mtypeWithArg =
mtypeWithArg
.insertParameterTypes(0, Object.class) // insert newly allocated obj
.changeReturnType(void.class); // <init> returns void
MemberName linker =
new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);
try {
linker =
IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, NoSuchMethodException.class);
} catch (ReflectiveOperationException ex) {
throw newInternalError(ex);
}
final int DMH_THIS = 0;
final int ARG_BASE = 1;
final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
int nameCursor = ARG_LIMIT;
final int NEW_OBJ = (doesAlloc ? nameCursor++ : -1);
final int GET_MEMBER = nameCursor++;
final int LINKER_CALL = nameCursor++;
Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
assert (names.length == nameCursor);
if (doesAlloc) {
// names = { argx,y,z,... new C, init method }
names[NEW_OBJ] = new Name(NF_allocateInstance, names[DMH_THIS]);
names[GET_MEMBER] = new Name(NF_constructorMethod, names[DMH_THIS]);
} else if (needsInit) {
names[GET_MEMBER] = new Name(NF_internalMemberNameEnsureInit, names[DMH_THIS]);
} else {
names[GET_MEMBER] = new Name(NF_internalMemberName, names[DMH_THIS]);
}
assert (findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]);
Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER + 1, Object[].class);
assert (outArgs[outArgs.length - 1] == names[GET_MEMBER]); // look, shifted args!
int result = LAST_RESULT;
if (doesAlloc) {
assert (outArgs[outArgs.length - 2] == names[NEW_OBJ]); // got to move this one
System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length - 2);
outArgs[0] = names[NEW_OBJ];
result = NEW_OBJ;
}
names[LINKER_CALL] = new Name(linker, outArgs);
String lambdaName = kind.defaultLambdaName + "_" + shortenSignature(basicTypeSignature(mtype));
LambdaForm lform = new LambdaForm(lambdaName, ARG_LIMIT, names, result, kind);
// This is a tricky bit of code. Don't send it through the LF interpreter.
lform.compileToBytecode();
return lform;
}
static Object findDirectMethodHandle(Name name) {
if (name.function == NF_internalMemberName
|| name.function == NF_internalMemberNameEnsureInit
|| name.function == NF_constructorMethod) {
assert (name.arguments.length == 1);
return name.arguments[0];
}
return null;
}
private static void maybeCompile(LambdaForm lform, MemberName m) {
if (lform.vmentry == null
&& VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
// Help along bootstrapping...
lform.compileToBytecode();
}
/** Static wrapper for DirectMethodHandle.internalMemberName. */
@ForceInline
/*non-public*/ static Object internalMemberName(Object mh) {
return ((DirectMethodHandle) mh).member;
}
/**
* Static wrapper for DirectMethodHandle.internalMemberName. This one also forces initialization.
*/
/*non-public*/ static Object internalMemberNameEnsureInit(Object mh) {
DirectMethodHandle dmh = (DirectMethodHandle) mh;
dmh.ensureInitialized();
return dmh.member;
}
/*non-public*/ static boolean shouldBeInitialized(MemberName member) {
switch (member.getReferenceKind()) {
case REF_invokeStatic:
case REF_getStatic:
case REF_putStatic:
case REF_newInvokeSpecial:
break;
default:
// No need to initialize the class on this kind of member.
return false;
}
Class<?> cls = member.getDeclaringClass();
if (cls == ValueConversions.class || cls == MethodHandleImpl.class || cls == Invokers.class) {
// These guys have lots of <clinit> DMH creation but we know
// the MHs will not be used until the system is booted.
return false;
}
if (VerifyAccess.isSamePackage(MethodHandle.class, cls)
|| VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
// It is a system class. It is probably in the process of
// being initialized, but we will help it along just to be safe.
if (UNSAFE.shouldBeInitialized(cls)) {
UNSAFE.ensureClassInitialized(cls);
}
return false;
}
return UNSAFE.shouldBeInitialized(cls);
}
private static class EnsureInitialized extends ClassValue<WeakReference<Thread>> {
@Override
protected WeakReference<Thread> computeValue(Class<?> type) {
UNSAFE.ensureClassInitialized(type);
if (UNSAFE.shouldBeInitialized(type))
// If the previous call didn't block, this can happen.
// We are executing inside <clinit>.
return new WeakReference<>(Thread.currentThread());
return null;
}
static final EnsureInitialized INSTANCE = new EnsureInitialized();
}
private void ensureInitialized() {
if (checkInitialized(member)) {
// The coast is clear. Delete the <clinit> barrier.
if (member.isField()) updateForm(preparedFieldLambdaForm(member));
else updateForm(preparedLambdaForm(member));
}
}
private static boolean checkInitialized(MemberName member) {
Class<?> defc = member.getDeclaringClass();
WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc);
if (ref == null) {
return true; // the final state
}
Thread clinitThread = ref.get();
// Somebody may still be running defc.<clinit>.
if (clinitThread == Thread.currentThread()) {
// If anybody is running defc.<clinit>, it is this thread.
if (UNSAFE.shouldBeInitialized(defc))
// Yes, we are running it; keep the barrier for now.
return false;
} else {
// We are in a random thread. Block.
UNSAFE.ensureClassInitialized(defc);
}
assert (!UNSAFE.shouldBeInitialized(defc));
// put it into the final state
EnsureInitialized.INSTANCE.remove(defc);
return true;
}
/*non-public*/ static void ensureInitialized(Object mh) {
((DirectMethodHandle) mh).ensureInitialized();
}
/** This subclass represents invokespecial instructions. */
static class Special extends DirectMethodHandle {
private Special(MethodType mtype, LambdaForm form, MemberName member) {
super(mtype, form, member);
}
@Override
boolean isInvokeSpecial() {
return true;
}
@Override
MethodHandle copyWith(MethodType mt, LambdaForm lf) {
return new Special(mt, lf, member);
}
}
/** This subclass handles constructor references. */
static class Constructor extends DirectMethodHandle {
final MemberName initMethod;
final Class<?> instanceClass;
private Constructor(
MethodType mtype,
LambdaForm form,
MemberName constructor,
MemberName initMethod,
Class<?> instanceClass) {
super(mtype, form, constructor);
this.initMethod = initMethod;
this.instanceClass = instanceClass;
assert (initMethod.isResolved());
}
@Override
MethodHandle copyWith(MethodType mt, LambdaForm lf) {
return new Constructor(mt, lf, member, initMethod, instanceClass);
}
}
/*non-public*/ static Object constructorMethod(Object mh) {
Constructor dmh = (Constructor) mh;
return dmh.initMethod;
}
/*non-public*/ static Object allocateInstance(Object mh) throws InstantiationException {
Constructor dmh = (Constructor) mh;
return UNSAFE.allocateInstance(dmh.instanceClass);
}
/** This subclass handles non-static field references. */
static class Accessor extends DirectMethodHandle {
final Class<?> fieldType;
final int fieldOffset;
private Accessor(MethodType mtype, LambdaForm form, MemberName member, int fieldOffset) {
super(mtype, form, member);
this.fieldType = member.getFieldType();
this.fieldOffset = fieldOffset;
}
@Override
Object checkCast(Object obj) {
return fieldType.cast(obj);
}
@Override
MethodHandle copyWith(MethodType mt, LambdaForm lf) {
return new Accessor(mt, lf, member, fieldOffset);
}
}
@ForceInline
/*non-public*/ static long fieldOffset(Object accessorObj) {
// Note: We return a long because that is what Unsafe.getObject likes.
// We store a plain int because it is more compact.
return ((Accessor) accessorObj).fieldOffset;
}
@ForceInline
/*non-public*/ static Object checkBase(Object obj) {
// Note that the object's class has already been verified,
// since the parameter type of the Accessor method handle
// is either member.getDeclaringClass or a subclass.
// This was verified in DirectMethodHandle.make.
// Therefore, the only remaining check is for null.
// Since this check is *not* guaranteed by Unsafe.getInt
// and its siblings, we need to make an explicit one here.
return Objects.requireNonNull(obj);
}
/** This subclass handles static field references. */
static class StaticAccessor extends DirectMethodHandle {
private final Class<?> fieldType;
private final Object staticBase;
private final long staticOffset;
private StaticAccessor(
MethodType mtype,
LambdaForm form,
MemberName member,
Object staticBase,
long staticOffset) {
super(mtype, form, member);
this.fieldType = member.getFieldType();
this.staticBase = staticBase;
this.staticOffset = staticOffset;
}
@Override
Object checkCast(Object obj) {
return fieldType.cast(obj);
}
@Override
MethodHandle copyWith(MethodType mt, LambdaForm lf) {
return new StaticAccessor(mt, lf, member, staticBase, staticOffset);
}
}
@ForceInline
/*non-public*/ static Object nullCheck(Object obj) {
return Objects.requireNonNull(obj);
}
@ForceInline
/*non-public*/ static Object staticBase(Object accessorObj) {
return ((StaticAccessor) accessorObj).staticBase;
}
@ForceInline
/*non-public*/ static long staticOffset(Object accessorObj) {
return ((StaticAccessor) accessorObj).staticOffset;
}
@ForceInline
/*non-public*/ static Object checkCast(Object mh, Object obj) {
return ((DirectMethodHandle) mh).checkCast(obj);
}
Object checkCast(Object obj) {
return member.getReturnType().cast(obj);
}
// Caching machinery for field accessors:
private static final byte AF_GETFIELD = 0,
AF_PUTFIELD = 1,
AF_GETSTATIC = 2,
AF_PUTSTATIC = 3,
AF_GETSTATIC_INIT = 4,
AF_PUTSTATIC_INIT = 5,
AF_LIMIT = 6;
// Enumerate the different field kinds using Wrapper,
// with an extra case added for checked references.
private static final int FT_LAST_WRAPPER = Wrapper.COUNT - 1,
FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(),
FT_CHECKED_REF = FT_LAST_WRAPPER + 1,
FT_LIMIT = FT_LAST_WRAPPER + 2;
private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {
return ((formOp * FT_LIMIT * 2) + (isVolatile ? FT_LIMIT : 0) + ftypeKind);
}
@Stable
private static final LambdaForm[] ACCESSOR_FORMS = new LambdaForm[afIndex(AF_LIMIT, false, 0)];
private static int ftypeKind(Class<?> ftype) {
if (ftype.isPrimitive()) return Wrapper.forPrimitiveType(ftype).ordinal();
else if (VerifyType.isNullReferenceConversion(Object.class, ftype)) return FT_UNCHECKED_REF;
else return FT_CHECKED_REF;
}
/**
* Create a LF which can access the given field. Cache and share this structure among all fields
* with the same basicType and refKind.
*/
private static LambdaForm preparedFieldLambdaForm(MemberName m) {
Class<?> ftype = m.getFieldType();
boolean isVolatile = m.isVolatile();
byte formOp;
switch (m.getReferenceKind()) {
case REF_getField:
formOp = AF_GETFIELD;
break;
case REF_putField:
formOp = AF_PUTFIELD;
break;
case REF_getStatic:
formOp = AF_GETSTATIC;
break;
case REF_putStatic:
formOp = AF_PUTSTATIC;
break;
default:
throw new InternalError(m.toString());
}
if (shouldBeInitialized(m)) {
// precompute the barrier-free version:
preparedFieldLambdaForm(formOp, isVolatile, ftype);
assert ((AF_GETSTATIC_INIT - AF_GETSTATIC) == (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
}
LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
maybeCompile(lform, m);
assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
: Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
return lform;
}
private static LambdaForm preparedFieldLambdaForm(
byte formOp, boolean isVolatile, Class<?> ftype) {
int ftypeKind = ftypeKind(ftype);
int afIndex = afIndex(formOp, isVolatile, ftypeKind);
LambdaForm lform = ACCESSOR_FORMS[afIndex];
if (lform != null) return lform;
lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind);
ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS
return lform;
}
private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();
private static LambdaForm makePreparedFieldLambdaForm(
byte formOp, boolean isVolatile, int ftypeKind) {
boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
boolean isStatic = (formOp >= AF_GETSTATIC);
boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
boolean needsCast = (ftypeKind == FT_CHECKED_REF);
Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
Class<?> ft = fw.primitiveType();
assert (ftypeKind(needsCast ? String.class : ft) == ftypeKind);
// getObject, putIntVolatile, etc.
StringBuilder nameBuilder = new StringBuilder();
if (isGetter) {
nameBuilder.append("get");
} else {
nameBuilder.append("put");
}
nameBuilder.append(fw.primitiveSimpleName());
nameBuilder.setCharAt(3, Character.toUpperCase(nameBuilder.charAt(3)));
if (isVolatile) {
nameBuilder.append("Volatile");
}
MethodType linkerType;
if (isGetter) linkerType = MethodType.methodType(ft, Object.class, long.class);
else linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
MemberName linker =
new MemberName(Unsafe.class, nameBuilder.toString(), linkerType, REF_invokeVirtual);
try {
linker =
IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);
} catch (ReflectiveOperationException ex) {
throw newInternalError(ex);
}
// What is the external type of the lambda form?
MethodType mtype;
if (isGetter) mtype = MethodType.methodType(ft);
else mtype = MethodType.methodType(void.class, ft);
mtype = mtype.basicType(); // erase short to int, etc.
if (!isStatic) mtype = mtype.insertParameterTypes(0, Object.class);
final int DMH_THIS = 0;
final int ARG_BASE = 1;
final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
// if this is for non-static access, the base pointer is stored at this index:
final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
// if this is for write access, the value to be written is stored at this index:
final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
int nameCursor = ARG_LIMIT;
final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
final int F_OFFSET = nameCursor++; // Either static offset or field offset.
final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
final int INIT_BAR = (needsInit ? nameCursor++ : -1);
final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
final int LINKER_CALL = nameCursor++;
final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
final int RESULT = nameCursor - 1; // either the call or the cast
Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
if (needsInit) names[INIT_BAR] = new Name(NF_ensureInitialized, names[DMH_THIS]);
if (needsCast && !isGetter)
names[PRE_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[SET_VALUE]);
Object[] outArgs = new Object[1 + linkerType.parameterCount()];
assert (outArgs.length == (isGetter ? 3 : 4));
outArgs[0] = UNSAFE;
if (isStatic) {
outArgs[1] = names[F_HOLDER] = new Name(NF_staticBase, names[DMH_THIS]);
outArgs[2] = names[F_OFFSET] = new Name(NF_staticOffset, names[DMH_THIS]);
} else {
outArgs[1] = names[OBJ_CHECK] = new Name(NF_checkBase, names[OBJ_BASE]);
outArgs[2] = names[F_OFFSET] = new Name(NF_fieldOffset, names[DMH_THIS]);
}
if (!isGetter) {
outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
}
for (Object a : outArgs) assert (a != null);
names[LINKER_CALL] = new Name(linker, outArgs);
if (needsCast && isGetter)
names[POST_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[LINKER_CALL]);
for (Name n : names) assert (n != null);
// add some detail to the lambdaForm debugname,
// significant only for debugging
if (isStatic) {
nameBuilder.append("Static");
} else {
nameBuilder.append("Field");
}
if (needsCast) nameBuilder.append("Cast");
if (needsInit) nameBuilder.append("Init");
return new LambdaForm(nameBuilder.toString(), ARG_LIMIT, names, RESULT);
}
/**
* Pre-initialized NamedFunctions for bootstrapping purposes. Factored in an inner class to delay
* initialization until first usage.
*/
static final NamedFunction NF_internalMemberName,
NF_internalMemberNameEnsureInit,
NF_ensureInitialized,
NF_fieldOffset,
NF_checkBase,
NF_staticBase,
NF_staticOffset,
NF_checkCast,
NF_allocateInstance,
NF_constructorMethod;
static {
try {
NamedFunction nfs[] = {
NF_internalMemberName =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("internalMemberName", Object.class)),
NF_internalMemberNameEnsureInit =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod(
"internalMemberNameEnsureInit", Object.class)),
NF_ensureInitialized =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("ensureInitialized", Object.class)),
NF_fieldOffset =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("fieldOffset", Object.class)),
NF_checkBase =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("checkBase", Object.class)),
NF_staticBase =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("staticBase", Object.class)),
NF_staticOffset =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("staticOffset", Object.class)),
NF_checkCast =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod(
"checkCast", Object.class, Object.class)),
NF_allocateInstance =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("allocateInstance", Object.class)),
NF_constructorMethod =
new NamedFunction(
DirectMethodHandle.class.getDeclaredMethod("constructorMethod", Object.class))
};
// Each nf must be statically invocable or we get tied up in our bootstraps.
assert (InvokerBytecodeGenerator.isStaticallyInvocable(nfs));
} catch (ReflectiveOperationException ex) {
throw newInternalError(ex);
}
}
static {
// The Holder class will contain pre-generated DirectMethodHandles resolved
// speculatively using MemberName.getFactory().resolveOrNull. However, that
// doesn't initialize the class, which subtly breaks inlining etc. By forcing
// initialization of the Holder class we avoid these issues.
UNSAFE.ensureClassInitialized(Holder.class);
}
/* Placeholder class for DirectMethodHandles generated ahead of time */
final class Holder {}
}
