| BF Cond Bool BlockId -- cond, annul?, target
| JMP AddrMode -- target
+
+ -- With a tabled jump we know all the possible destinations. Tabled
+ -- jump includes its list of destinations so we can work out what regs
+ -- are live across the jump.
+ --
+ | JMP_TBL AddrMode [BlockId]
+
| CALL (Either Imm Reg) Int Bool -- target, args, terminal
riZero :: RI -> Bool