private PInvokeMarshallingILEmitter(MethodDesc targetMethod)
{
Debug.Assert(targetMethod.IsPInvoke);
Debug.Assert(RequiresMarshalling(targetMethod));
_targetMethod = targetMethod;
_importMetadata = targetMethod.GetPInvokeMethodMetadata();
_emitter = null;
_marshallingCodeStream = null;
}
private PInvokeILEmitter(MethodDesc targetMethod)
{
Debug.Assert(targetMethod.IsPInvoke);
_targetMethod = targetMethod;
_context = _targetMethod.Context;
_importMetadata = targetMethod.GetPInvokeMethodMetadata();
_emitter = null;
_marshallingCodeStream = null;
_returnValueMarshallingCodeStream = null;
_unmarshallingCodestream = null;
}
public PInvokeTargetNativeMethod(TypeDesc owningType, MethodSignature signature, PInvokeMetadata methodMetadata)
{
_owningType = owningType;
_signature = signature;
_methodMetadata = methodMetadata;
sequenceNumber = System.Threading.Interlocked.Increment(ref nativeMethodCounter);
}
public PInvokeTargetNativeMethod(TypeDesc owningType, MethodSignature signature, PInvokeMetadata methodMetadata)
{
_owningType = owningType;
_signature = signature;
_methodMetadata = methodMetadata;
}
public PInvokeLazyFixupField(DefType owningType, PInvokeMetadata pInvokeMetadata)
{
_owningType = owningType;
_pInvokeMetadata = pInvokeMetadata;
}
public MethodIL EmitIL()
{
MethodSignature targetMethodSignature = _targetMethod.Signature;
// We have 4 code streams:
// - _marshallingCodeStream is used to convert each argument into a native type and
// store that into the local
// - callsiteSetupCodeStream is used to used to load each previously generated local
// and call the actual target native method.
// - _returnValueMarshallingCodeStream is used to convert the native return value
// to managed one.
// - _unmarshallingCodestream is used to propagate [out] native arguments values to
// managed ones.
_emitter = new ILEmitter();
ILCodeStream fnptrLoadStream = _emitter.NewCodeStream();
_marshallingCodeStream = _emitter.NewCodeStream();
ILCodeStream callsiteSetupCodeStream = _emitter.NewCodeStream();
_returnValueMarshallingCodeStream = _emitter.NewCodeStream();
_unmarshallingCodestream = _emitter.NewCodeStream();
TypeDesc[] nativeParameterTypes = new TypeDesc[targetMethodSignature.Length];
//
// Parameter marshalling
//
//
// Convert each argument to something we can pass to native and store it in a local.
// Then load the local in the second code stream.
//
for (int i = 0; i < targetMethodSignature.Length; i++)
{
// TODO: throw if there's custom marshalling
_marshallingCodeStream.EmitLdArg(i);
TypeDesc nativeType = MarshalArgument(targetMethodSignature[i]);
nativeParameterTypes[i] = nativeType;
ILLocalVariable vMarshalledTypeTemp = _emitter.NewLocal(nativeType);
_marshallingCodeStream.EmitStLoc(vMarshalledTypeTemp);
callsiteSetupCodeStream.EmitLdLoc(vMarshalledTypeTemp);
}
//
// Return value marshalling
//
// TODO: throw if SetLastError is true
// TODO: throw if there's custom marshalling
TypeDesc nativeReturnType = MarshalReturnValue(targetMethodSignature.ReturnType);
if (UseLazyResolution(_targetMethod, _importMetadata.Module))
{
MetadataType lazyHelperType = _targetMethod.Context.GetHelperType("InteropHelpers");
FieldDesc lazyDispatchCell = new PInvokeLazyFixupField((DefType)_targetMethod.OwningType, _importMetadata);
fnptrLoadStream.Emit(ILOpcode.ldsflda, _emitter.NewToken(lazyDispatchCell));
fnptrLoadStream.Emit(ILOpcode.call, _emitter.NewToken(lazyHelperType.GetKnownMethod("ResolvePInvoke", null)));
MethodSignatureFlags unmanagedCallConv = PInvokeMetadata.GetUnmanagedCallingConvention(_importMetadata.Attributes);
MethodSignature nativeCalliSig = new MethodSignature(
targetMethodSignature.Flags | unmanagedCallConv, 0, nativeReturnType, nativeParameterTypes);
ILLocalVariable vNativeFunctionPointer = _emitter.NewLocal(_targetMethod.Context.GetWellKnownType(WellKnownType.IntPtr));
fnptrLoadStream.EmitStLoc(vNativeFunctionPointer);
callsiteSetupCodeStream.EmitLdLoc(vNativeFunctionPointer);
callsiteSetupCodeStream.Emit(ILOpcode.calli, _emitter.NewToken(nativeCalliSig));
}
else
{
// Eager call
PInvokeMetadata nativeImportMetadata =
new PInvokeMetadata(_importMetadata.Module, _importMetadata.Name ?? _targetMethod.Name, _importMetadata.Attributes);
MethodSignature nativeSig = new MethodSignature(
targetMethodSignature.Flags, 0, nativeReturnType, nativeParameterTypes);
MethodDesc nativeMethod =
new PInvokeTargetNativeMethod(_targetMethod.OwningType, nativeSig, nativeImportMetadata);
callsiteSetupCodeStream.Emit(ILOpcode.call, _emitter.NewToken(nativeMethod));
}
_unmarshallingCodestream.Emit(ILOpcode.ret);
return _emitter.Link(_targetMethod);
}