public void ComputeReturnValueTreatment(CorElementType type, TypeHandle thRetType, bool isVarArgMethod, out bool usesRetBuffer, out uint fpReturnSize)
{
usesRetBuffer = false;
fpReturnSize = 0;
switch (type)
{
case CorElementType.ELEMENT_TYPE_TYPEDBYREF:
throw new NotSupportedException();
case CorElementType.ELEMENT_TYPE_R4:
fpReturnSize = sizeof(float);
break;
case CorElementType.ELEMENT_TYPE_R8:
fpReturnSize = sizeof(double);
break;
case CorElementType.ELEMENT_TYPE_VALUETYPE:
{
Debug.Assert(!thRetType.IsNull() && thRetType.IsValueType());
if ((Architecture == TargetArchitecture.X64) && IsX64UnixABI)
{
SYSTEMV_AMD64_CORINFO_STRUCT_REG_PASSING_DESCRIPTOR descriptor;
SystemVStructClassificator.GetSystemVAmd64PassStructInRegisterDescriptor(thRetType.GetRuntimeTypeHandle(), out descriptor);
if (descriptor.passedInRegisters)
{
if (descriptor.eightByteCount == 1)
{
if (descriptor.eightByteClassifications0 == SystemVClassificationType.SystemVClassificationTypeSSE)
{
// Structs occupying just one eightbyte are treated as int / double
fpReturnSize = sizeof(double);
}
}
else
{
// Size of the struct is 16 bytes
fpReturnSize = 16;
// The lowest two bits of the size encode the order of the int and SSE fields
if (descriptor.eightByteClassifications0 == SystemVClassificationType.SystemVClassificationTypeSSE)
{
fpReturnSize += 1;
}
if (descriptor.eightByteClassifications0 == SystemVClassificationType.SystemVClassificationTypeSSE)
{
fpReturnSize += 2;
}
}
break;
}
}
else
{
if (thRetType.IsHomogeneousAggregate() && !isVarArgMethod)
{
int haElementSize = thRetType.GetHomogeneousAggregateElementSize();
fpReturnSize = 4 * (uint)haElementSize;
break;
}
uint size = (uint)thRetType.GetSize();
if (IsX86 || IsX64)
{
// Return value types of size which are not powers of 2 using a RetBuffArg
if ((size & (size - 1)) != 0)
{
usesRetBuffer = true;
break;
}
}
if (size <= EnregisteredReturnTypeIntegerMaxSize)
{
break;
}
}
}
// Value types are returned using return buffer by default
usesRetBuffer = true;
break;
default:
break;
}
}
