exception Error of string
-external register_exns : exn -> unit = "llvm_register_irreader_exns"
-let _ = register_exns (Error "")
+let _ = Callback.register_exception "Llvm_irreader.Error" (Error "")
external parse_ir : Llvm.llcontext -> Llvm.llmemorybuffer -> Llvm.llmodule
= "llvm_parse_ir"