message: Fix basic block construction bug
diff: @@ -21,7 +21,9 @@ let process_instrs instrs =
  ~init:(block_name 0, [], [])
  ~f:(fun (name, block, blocks) (instr : Instr.t) ->
  match instr with
  - | Label name -> (name, block, blocks)
  + | Label label ->
  + if List.is_empty block then (label, [], blocks)
  + else (label, [], (name, List.rev block) :: blocks)
  | Jmp _
  | Br _
  | Ret _ ->
  