private unsafe void InvokeFunction(IntPtr obj, IntPtr stackPtr, IntPtr result)
{
// TODO: Move this entire function into C++ for better performance? C++ should only need the managedFunctionInvoker
// function and the rest should be do-able in C++. Use C++ anonymous function capture to hold onto managedFunctionInvoker
// and then invoke it from C++.
// TODO: Use ContainerVoidPtrToValuePtr(param, paramsBuffer, 0) instead of GetOffset_ForUFunction?
// - ArrayDim isn't available on params so it should be safe (and maybe faster?) to use GetOffset_ForUFunction
// - "Arrays aren't allowed as function parameters" - HeaderParser::GetVarNameAndDim
// TODO: Inline this as generated IL code in the target invoker func without the loops and with less copying
// NOTE: We shouldn't have to call prop->InitializeValue/InitializeValue_InContainer as the caller should have
// already initialized param memory which we will be processing. (InitializeValue is used for structs which
// have a custom default constructor which needs to be called in order to create a valid default value).
// It seems non-native bools also require InitializeValue (see UBoolProperty::SetBoolSize).
// Use XXXX_generated.h files as reference for checking we are doing things somewhat correctly here
// ScriptCore.cpp / Stack.h / ScriptMacros.h - P_GET_XXXX / FFrame::StepXXXX mostly handle the native code path
FFrame *stack = (FFrame *)stackPtr;
UFunction.FuncInvokerManaged managedFunctionInvoker;
if (managedInvokersByAddress.TryGetValue(stack->CurrentNativeFunction, out managedFunctionInvoker))
{
// FirstPropertyToInit only seems to be used by BP functions (FKismetCompilerContext::SetCalculatedMetaDataAndFlags)
// If this isn't the case then we need to ensure we use this to init these params by calling InitializeValue_InContainer
Debug.Assert(Native_UFunction.Get_FirstPropertyToInit(stack->CurrentNativeFunction) == IntPtr.Zero);
if (stack->Code != IntPtr.Zero)
{
// If stack->Code is set that means the function is being called by a BP function. stack->Code should hold
// the VM opcodes / param memory which need to be obtained by using stack->Step() for each parameter which
// also advances stack->Code
HandleInvokeFunctionFromBP(obj, stack, result, managedFunctionInvoker);
}
else
{
// If stack->Code is nullptr that means this function is being called by a native code path (such as a direct
// call to UObject::ProcessEvent(). We should get the parameters from stack->PropertyChainForCompiledIn
// which should initially point to function->Children.
HandleInvokeFunctionFromNative(obj, stack, result, managedFunctionInvoker);
}
}
else
{
// The managed __Invoker function doesn't exist. This is will happen if ManagedUnrealFunctionInfo.BPImplementation
// is true or CodeGeneratorSettings.UseImplicitBlueprintImplementableEvent is true with no _Implementation method.
// (otherwise this is pretty bad and very silent - possibly add some additional logging if this ever happens)
// This will advance the VM stack->Code address and satisfy the memory for the caller
Native_UObject.SkipFunction(stack->Object, stackPtr, result, stack->CurrentNativeFunction);
}
}
private unsafe void HandleInvokeFunctionFromNative(IntPtr obj, FFrame *stack, IntPtr result,
UFunction.FuncInvokerManaged managedFunctionInvoker)
{
IntPtr function = stack->CurrentNativeFunction;
IntPtr paramsBuffer = stack->Locals;
// Call the managed function invoker which will marshal the params from the native params buffer and then call the
// target managed function
managedFunctionInvoker(paramsBuffer, obj);
// Copy out params back from the locals buffer
if (Native_UFunction.HasAnyFunctionFlags(function, EFunctionFlags.HasOutParms))
{
// This assumes that UProperty will be itterated in the exact same order as the caller created stack->OutParms
// (we could iterate stack->OutParms until nullptr but it isn't null terminated on release builds)
FOutParmRec *outParms = stack->OutParmsPtr;
foreach (IntPtr paramProp in new NativeReflection.NativeFieldIterator(Runtime.Classes.UProperty, function, false))
{
EPropertyFlags paramFlags = Native_UProperty.GetPropertyFlags(paramProp);
if ((paramFlags & EPropertyFlags.OutParm) == EPropertyFlags.OutParm &&
(paramFlags & EPropertyFlags.ConstParm) != EPropertyFlags.ConstParm)
{
Debug.Assert(outParms->Property == paramProp);
// - REMOVING the DestroyValue call. The issue with this DestroyValue call is that PropAddr
// and paramsBuffer can (will?) be refering to the same data which we should have set in
// managedFunctionInvoker. So a call to DestroyValue would be destroying the data we want!
// Though if PropAddr is for some reason still holding onto unknown memory this will leak
// memory and we will need to investigate further.
// - The "refering to the same data" is because of the params Memcpy in UObject::ProcessEvent.
// They wont have the same address but their inital data will be the same and as such
// things like FString data pointer would be pointing to the same address.
// - We may still need to call DestroyValue in the BP/VM code path above.
// Destroy the existing memory (this assumed the existing memory is valid or at least memzerod)
//Native_UProperty.DestroyValue(paramProp, outParms->PropAddr);
// A raw memcpy should be OK since the managed invoker should have set this memory appropriately.
FMemory.Memcpy(outParms->PropAddr,
paramsBuffer + Native_UProperty.GetOffset_ForUFunction(paramProp),
Native_UProperty.Get_ElementSize(paramProp));// Should be ArrayDim*ElementSize but ArrayDim should always be 1 for params
outParms = outParms->NextOutParamPtr;
}
}
}
// We assume that the caller will clean up the memory held by stack->Locals so we don't iterate over the
// DestructorLink as we do in HandleInvokeFunctionFromBP. HandleInvokeFunctionFromBP needs to as it creates
// copies of data when calling stack->Step() which don't occur here as we use the existing stack->Locals buffer.
}
private unsafe void HandleInvokeFunctionFromBP(IntPtr obj, FFrame *stack, IntPtr result,
UFunction.FuncInvokerManaged managedFunctionInvoker)
{
// NOTE: ScriptCore.cpp uses PropertiesSize instead of ParamsSize. Is it ever any different? (it says alignment
// may make them different) If it is different we should probably use PropertiesSize (including in generated code /
// IL) as ScriptCore.cpp uses a memcpy of our memory.
Debug.Assert(Native_UStruct.Get_PropertiesSize(stack->CurrentNativeFunction) ==
Native_UFunction.Get_ParmsSize(stack->CurrentNativeFunction));
IntPtr function = stack->CurrentNativeFunction;
int paramsSize = Native_UFunction.Get_ParmsSize(function);
int numParams = Native_UFunction.Get_NumParms(function);
bool hasOutParams = Native_UFunction.HasAnyFunctionFlags(function, EFunctionFlags.HasOutParms);
IntPtr *outParamsBufferPtr = stackalloc IntPtr[numParams];
byte * paramsBufferPtr = stackalloc byte[paramsSize];
IntPtr paramsBuffer = (IntPtr)paramsBufferPtr;
// We could skip this memzero as stackalloc will (always?) zero memory even though the spec states
// "The content of the newly allocated memory is undefined."
// https://github.com/dotnet/coreclr/issues/1279
FMemory.Memzero(paramsBuffer, paramsSize);
if (hasOutParams)
{
int paramIndex = 0;
foreach (IntPtr param in new NativeReflection.NativeFieldIterator(Runtime.Classes.UProperty, function, false))
{
// Not required but using for Debug.Assert() when getting the value
stack->MostRecentPropertyAddress = IntPtr.Zero;
stack->Step(stack->Object, paramsBuffer + Native_UProperty.GetOffset_ForUFunction(param));
outParamsBufferPtr[paramIndex] = stack->MostRecentPropertyAddress;
if (Native_UProperty.HasAnyPropertyFlags(param, EPropertyFlags.ReturnParm))
{
// This should be UObject::execEndFunctionParms which will just do "stack->Code--;" for allowing
// the caller to use PFINISH aftwards
outParamsBufferPtr[paramIndex] = result;
}
paramIndex++;
}
}
else
{
foreach (IntPtr param in new NativeReflection.NativeFieldIterator(Runtime.Classes.UProperty, function, false))
{
stack->Step(stack->Object, paramsBuffer + Native_UProperty.GetOffset_ForUFunction(param));
}
}
stack->PFinish();// Skip EX_EndFunctionParms
// Call the managed function invoker which will marshal the params from the native params buffer and then call the
// target managed function
managedFunctionInvoker(paramsBuffer, obj);
// Copy out params from the temp buffer
if (hasOutParams)
{
int paramIndex = 0;
foreach (IntPtr paramProp in new NativeReflection.NativeFieldIterator(Runtime.Classes.UProperty, function, false))
{
if (Native_UProperty.HasAnyPropertyFlags(paramProp, EPropertyFlags.OutParm))
{
Debug.Assert(outParamsBufferPtr[paramIndex] != IntPtr.Zero);
// - See "REMOVING the DestroyValue call" below.
// Destroy the existing memory (this assumed the existing memory is valid or at least memzerod)
//Native_UProperty.DestroyValue(paramProp, outParamsBufferPtr[paramIndex]);
// A raw memcpy should be OK since the managed invoker should have set this memory appropriately.
FMemory.Memcpy(outParamsBufferPtr[paramIndex],
paramsBuffer + Native_UProperty.GetOffset_ForUFunction(paramProp),
Native_UProperty.Get_ElementSize(paramProp));// Should be ArrayDim*ElementSize but ArrayDim should always be 1 for params
}
paramIndex++;
}
}
// Parameters are copied when calling stack->Step(). We are responsible for destroying non-blittable types
// which were copied (FString, TArray, etc). For C++ this works out well due to the copy constructors etc.
//
// Example where an FString is constructed from stack->Step():
// UObject::execStringConst(...) { *(FString*)RESULT_PARAM = (ANSICHAR*)Stack.Code; }
//
// For C# it might be better if we reimplemented all of the IMPLEMENT_VM_FUNCTION functions to reduce the amount
// of copying as we currently need ANOTHER copy to get it from the temp buffer into a C# type (which is done
// inside the managedFunctionInvoker function)
foreach (IntPtr paramProp in new NativeReflection.NativeFieldIterator(Runtime.Classes.UProperty, function,
EFieldIteratorType.Destructor, false))
{
// When is this ever false? It seems to be checked in UObject::ProcessEvent()
// "Destroy local variables except function parameters." - used for BP locals?
Debug.Assert(Native_UProperty.IsInContainer(paramProp, paramsSize));
// Out params are copied to the memory maintained by the caller so only destroy "by value" parameters.
if (!Native_UProperty.HasAnyPropertyFlags(paramProp, EPropertyFlags.OutParm))
{
Native_UProperty.DestroyValue_InContainer(paramProp, paramsBuffer);
}
}
}
