data JumpDest = DestBlockId BlockId | DestImm Imm
+getJumpDestBlockId :: JumpDest -> Maybe BlockId
+getJumpDestBlockId (DestBlockId bid) = Just bid
+getJumpDestBlockId _ = Nothing
canShortcut :: Instr -> Maybe JumpDest
canShortcut (JXX ALWAYS id) = Just (DestBlockId id)