private MethodIL EmitIL()
{
// 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.
ILEmitter emitter = new ILEmitter();
ILCodeStream fnptrLoadStream = emitter.NewCodeStream();
ILCodeStream marshallingCodeStream = emitter.NewCodeStream();
ILCodeStream callsiteSetupCodeStream = emitter.NewCodeStream();
ILCodeStream returnValueMarshallingCodeStream = emitter.NewCodeStream();
ILCodeStream unmarshallingCodestream = emitter.NewCodeStream();
// Marshal the arguments
for (int i = 0; i < _marshallers.Length; i++)
{
Marshaller marshaller = _marshallers[i];
marshaller.EmitMarshallingIL(emitter, marshallingCodeStream, callsiteSetupCodeStream, unmarshallingCodestream, returnValueMarshallingCodeStream);
}
// make the call
TypeDesc nativeReturnType = _marshallers[0].NativeType;
TypeDesc[] nativeParameterTypes = new TypeDesc[_marshallers.Length - 1];
for (int i = 1; i < _marshallers.Length; i++)
{
nativeParameterTypes[i - 1] = _marshallers[i].NativeType;
}
MethodDesc targetMethod = _methodData.TargetMethod;
PInvokeMetadata importMetadata = _methodData.ImportMetadata;
PInvokeILEmitterConfiguration pinvokeILEmitterConfiguration = _methodData.PInvokeILEmitterConfiguration;
// if the SetLastError flag is set in DllImport, clear the error code before doing P/Invoke
if ((importMetadata.Attributes & PInvokeAttributes.SetLastError) == PInvokeAttributes.SetLastError)
{
callsiteSetupCodeStream.Emit(ILOpcode.call, emitter.NewToken(
_methodData.PInvokeMarshal.GetKnownMethod("ClearLastWin32Error", null)));
}
if (MarshalHelpers.UseLazyResolution(targetMethod, importMetadata.Module, pinvokeILEmitterConfiguration))
{
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(
targetMethod.Signature.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(
targetMethod.Signature.Flags, 0, nativeReturnType, nativeParameterTypes);
MethodDesc nativeMethod =
new PInvokeTargetNativeMethod(targetMethod.OwningType, nativeSig, nativeImportMetadata, pinvokeILEmitterConfiguration.GetNextNativeMethodId());
callsiteSetupCodeStream.Emit(ILOpcode.call, emitter.NewToken(nativeMethod));
}
// if the SetLastError flag is set in DllImport, call the PInvokeMarshal.SaveLastWin32Error so that last error can be used later
// by calling PInvokeMarshal.GetLastWin32Error
if ((importMetadata.Attributes & PInvokeAttributes.SetLastError) == PInvokeAttributes.SetLastError)
{
callsiteSetupCodeStream.Emit(ILOpcode.call, emitter.NewToken(
_methodData.PInvokeMarshal.GetKnownMethod("SaveLastWin32Error", null)));
}
unmarshallingCodestream.Emit(ILOpcode.ret);
return(emitter.Link(targetMethod));
}
