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Implement handling PreserveSig = false for interfaces #1206

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merged 9 commits into from
Jun 8, 2021
Merged

Implement handling PreserveSig = false for interfaces #1206

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ba68a4b
Implement handling PerserveSig = false for interfaces
kant2002 Jun 7, 2021
f614212
Ignore delegating marshalling thunks
kant2002 Jun 7, 2021
15a5c68
I add special case for handling blittable types which are return type…
kant2002 Jun 7, 2021
48de7aa
Remove artificial constraing on PreserveSig=false
kant2002 Jun 7, 2021
0b5bb1c
Address PR feedback
kant2002 Jun 7, 2021
dbdb239
Fix
kant2002 Jun 8, 2021
5903921
Add simple tests for PreservSig=false functionality
kant2002 Jun 8, 2021
df9bdb1
Update src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs
kant2002 Jun 8, 2021
5e098f6
Reformat code based on PR feedback
kant2002 Jun 8, 2021
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29 changes: 21 additions & 8 deletions src/coreclr/tools/Common/TypeSystem/IL/Stubs/PInvokeILEmitter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,9 @@ private static Marshaller[] InitializeMarshallers(MethodDesc targetMethod, Inter
TypeDesc parameterType = (i == 0)
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(i == 0 && isHRSwapping) condition is repeated multiple times here. Also, I do not think you should need the check for DelegateMarshallingMethodThunk here. We should make sure to set PreserveSig=true for marshalled delegates earlier (UnmanagedFunctionPointerAttribute won't allow you to specify PreserveSig=false so we do not need to worry about handling it).

I think it would be a bit more efficient and readable like this:

TypeDesc parameterType;
bool isHRSwappedRetVal = false;
if (i == 0)
{
    //first item is the return type
    parameterType = methodSig.ReturnType;
    if (!flags.PreserveSig && !parameterType.IsVoid)
    {
        // PreserveSig = false can only show up an regular forward PInvokes
        Debug.Assert(direction == MarshalDirection.Forward);
    
        parameterType = methodSig.Context.GetByRefType(parameterType);
        isHRSwappedRetVal = true;
    }
}
else
{
    parameterType = methodSig[i - 1];
}

? methodSig.ReturnType //first item is the return type
: methodSig[i - 1];
marshallers[i] = Marshaller.CreateMarshaller(parameterType,
bool isHRSwapping = !flags.PreserveSig && !parameterType.IsVoid
&& targetMethod is not DelegateMarshallingMethodThunk;
marshallers[i] = Marshaller.CreateMarshaller((i == 0 && isHRSwapping) ? methodSig.Context.GetByRefType(parameterType): parameterType,
parameterIndex,
methodSig.GetEmbeddedSignatureData(),
MarshallerType.Argument,
Expand All @@ -108,8 +110,8 @@ private static Marshaller[] InitializeMarshallers(MethodDesc targetMethod, Inter
indexOffset + parameterMetadata.Index,
flags,
parameterMetadata.In,
parameterMetadata.Out,
parameterMetadata.Return
(i == 0 && isHRSwapping) ? true : parameterMetadata.Out,
(i == 0 && isHRSwapping) ? false : parameterMetadata.Return
);
}

Expand Down Expand Up @@ -231,16 +233,15 @@ private void EmitDelegateCall(DelegateMarshallingMethodThunk delegateMethod, PIn

private void EmitPInvokeCall(PInvokeILCodeStreams ilCodeStreams)
{
if (!_flags.PreserveSig && _targetMethod.Signature.ReturnType != _targetMethod.Context.GetWellKnownType(WellKnownType.Void))
throw new NotSupportedException();

ILEmitter emitter = ilCodeStreams.Emitter;
ILCodeStream fnptrLoadStream = ilCodeStreams.FunctionPointerLoadStream;
ILCodeStream callsiteSetupCodeStream = ilCodeStreams.CallsiteSetupCodeStream;
TypeSystemContext context = _targetMethod.Context;

bool isHRSwapping = !_flags.PreserveSig && _targetMethod.Signature.ReturnType != _targetMethod.Context.GetWellKnownType(WellKnownType.Void)
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== targetMethod.Context.GetWellKnownType(WellKnownType.Void) can be just IsVoid

&& _targetMethod is not DelegateMarshallingMethodThunk;
TypeDesc nativeReturnType = _flags.PreserveSig ? _marshallers[0].NativeParameterType : context.GetWellKnownType(WellKnownType.Int32);
TypeDesc[] nativeParameterTypes = new TypeDesc[_marshallers.Length - 1];
TypeDesc[] nativeParameterTypes = new TypeDesc[isHRSwapping ? _marshallers.Length : _marshallers.Length - 1];

// if the SetLastError flag is set in DllImport, clear the error code before doing P/Invoke
if (_flags.SetLastError)
Expand All @@ -254,6 +255,11 @@ private void EmitPInvokeCall(PInvokeILCodeStreams ilCodeStreams)
nativeParameterTypes[i - 1] = _marshallers[i].NativeParameterType;
}

if (isHRSwapping)
{
nativeParameterTypes[_marshallers.Length - 1] = _marshallers[0].NativeParameterType;
}

if (!_pInvokeILEmitterConfiguration.GenerateDirectCall(_targetMethod, out _))
{
MetadataType lazyHelperType = context.GetHelperType("InteropHelpers");
Expand Down Expand Up @@ -357,11 +363,18 @@ private MethodIL EmitIL()
cleanupCodestream.BeginHandler(tryFinally);

// Marshal the arguments
for (int i = 0; i < _marshallers.Length; i++)
bool isHRSwapping = !_flags.PreserveSig && _targetMethod.Signature.ReturnType != _targetMethod.Context.GetWellKnownType(WellKnownType.Void)
&& _targetMethod is not DelegateMarshallingMethodThunk;
for (int i = isHRSwapping ? 1 : 0; i < _marshallers.Length; i++)
{
_marshallers[i].EmitMarshallingIL(pInvokeILCodeStreams);
}

if (isHRSwapping)
{
_marshallers[0].EmitMarshallingIL(pInvokeILCodeStreams);
}

// make the call
switch (_targetMethod)
{
Expand Down
25 changes: 19 additions & 6 deletions src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -512,7 +512,7 @@ protected virtual void EmitMarshalReturnValueManagedToNative()

public virtual void LoadReturnValue(ILCodeStream codeStream)
{
Debug.Assert(Return);
Debug.Assert(Return || Index == 0);
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It would be nice to replace all Index == 0 checks with a property. It would make the code much easier to understand.


switch (MarshalDirection)
{
Expand Down Expand Up @@ -653,9 +653,18 @@ protected void PropagateFromByRefArg(ILCodeStream stream, Home home)
/// </summary>
protected void PropagateToByRefArg(ILCodeStream stream, Home home)
{
stream.EmitLdArg(Index - 1);
home.LoadValue(stream);
stream.EmitStInd(ManagedType);
// If by-ref arg has index == 0 then that argument is used for HR swapping and we just return that value.
if (Index == 0)
{
// Returning result would be handled by LoadReturnValue
return;
}
else
{
stream.EmitLdArg(Index - 1);
home.LoadValue(stream);
stream.EmitStInd(ManagedType);
}
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}

protected virtual void EmitMarshalArgumentManagedToNative()
Expand Down Expand Up @@ -903,7 +912,7 @@ class BlittableValueMarshaller : Marshaller
{
protected override void EmitMarshalArgumentManagedToNative()
{
if (IsNativeByRef && MarshalDirection == MarshalDirection.Forward)
if (IsNativeByRef && MarshalDirection == MarshalDirection.Forward && Index > 0)
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I would move the special case first and then leave the rest of the method intact.

if (IsHRSwappedRetVal)
{
    ...;
    return;
}

{
ILCodeStream marshallingCodeStream = _ilCodeStreams.MarshallingCodeStream;
ILEmitter emitter = _ilCodeStreams.Emitter;
Expand All @@ -917,10 +926,14 @@ protected override void EmitMarshalArgumentManagedToNative()
marshallingCodeStream.EmitStLoc(native);
_ilCodeStreams.CallsiteSetupCodeStream.EmitLdLoc(native);
}
else
else if (Index > 0)
{
_ilCodeStreams.CallsiteSetupCodeStream.EmitLdArg(Index - 1);
}
else
{
base.EmitMarshalArgumentManagedToNative();
}
}

protected override void EmitMarshalArgumentNativeToManaged()
Expand Down