OCaml compiler library : Clflags.Compiler_pass

`sig
type t = Parsing | Typing | Scheduling | Emit
val of_string : string -> Clflags.Compiler_pass.t option
val to_string : Clflags.Compiler_pass.t -> string
val is_compilation_pass : Clflags.Compiler_pass.t -> bool
val available_pass_names :
filter:(Clflags.Compiler_pass.t -> bool) -> native:bool -> string list
val can_save_ir_after : Clflags.Compiler_pass.t -> bool
val compare : Clflags.Compiler_pass.t -> Clflags.Compiler_pass.t -> int
val to_output_filename : Clflags.Compiler_pass.t -> prefix:string -> string
val of_input_filename : string -> Clflags.Compiler_pass.t option
end`