llvm dev - Nov 2014 - [LLVMdev] DAGOperand problem

Hi,

I'm having trouble trying to use a DAGOperand to abstract between a
RegisterClass and a custom Operand.

I have something like this:

class SrcModifiers<ValueType vt,
                   RegisterClass regclass> : OperandWithDefaultOps<vt,
(ops (i32 0))> {
  let MIOperandInfo = (ops regclass, i32imm:$modifiers);
}

and I would like to factor instruction definitions to use this or just a
register class for an operand. I would like to do something like:
 
 field DAGOperand Src2Op64 = !if(HasModifiers, SrcModifiers<Src2VT,
Src2RC>, Src2RC);

However I'm getting an error I don't understand just from the use of the
custom operand. Reducing this to just

  DAGOperand Src2Op64 = SrcModifiers<Src2VT, Src2RC64>;

gives me this error (twice):
 error: Record `anonymous_690', field `Type' does not have a def
initializer!
  DAGOperand Src2Op64 = SrcModifiers<Src2VT, Src2RC64>;
                                           ^

Type is a field of Operand which is theoretically set by the vt parameter to
Operand. DAGOperand is also the superclass without Type, so I don’t know why it
would care about it either. Why this doesn't work? Is this a bug in
tablegen?

Thanks,

Matt