1 This is a list of TODO's without which the unwind code is *buggy*.
4 - All Preserved Registers (ar.unat, ar.rnat, ar.lc, ar.fpsr, ar.bsp, ar.bspstore)
5 - Implicit register saves via _when descriptor records.
6 - Multiple unwind label_states ( How do we do this without malloc ? )
7 - Floating Point registers.