Arguments are the N top-most elements of the stack. Top-most argument is first. Thus elements have to be pushed on stack in reverse order.
Operation will pop N elements from the stack.
| NaryInstr (Oper* op)
Caller must not delete / modify operation.
|op||operation of this instruction|
| ~NaryInstr ()
| INSTR_VISITABLE ()
|const Oper& op ()
Returns: operation associated with this instruction.