invariant_params.mli

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(*                                                                        *)
(*                                 OCaml                                  *)
(*                                                                        *)
(*                       Pierre Chambart, OCamlPro                        *)
(*           Mark Shinwell and Leo White, Jane Street Europe              *)
(*                                                                        *)
(*   Copyright 2013--2016 OCamlPro SAS                                    *)
(*   Copyright 2014--2016 Jane Street Group LLC                           *)
(*                                                                        *)
(*   All rights reserved.  This file is distributed under the terms of    *)
(*   the GNU Lesser General Public License version 2.1, with the          *)
(*   special exception on linking described in the file LICENSE.          *)
(*                                                                        *)
(**************************************************************************)

[@@@ocaml.warning "+a-4-9-30-40-41-42"]

(* [invariant_params_in_recursion] calculates the set of parameters whose
   values are known not to change during the execution of a recursive
   function.  As such, occurrences of the parameters may always be replaced
   by the corresponding values.

   For example, [x] would be in [invariant_params] for both of the following
   functions:

     let rec f x y = (f x y) + (f x (y+1))

     let rec f x l = List.iter (f x) l

   For invariant parameters it also computes the set of parameters of functions
   in the set of closures that are always aliased to it. For example in the set
   of closures:

     let rec f x y = (f x y) + (f x (y+1)) + g x
     and g z = z + 1

   The map of aliases is

     x -> { x; z }
*)
val invariant_params_in_recursion
   : Flambda.function_declarations
  -> backend:(module Backend_intf.S)
  -> Variable.Set.t Variable.Map.t

val invariant_param_sources
   : Flambda.function_declarations
  -> backend:(module Backend_intf.S)
  -> Variable.Pair.Set.t Variable.Map.t

(* CR-soon mshinwell: think about whether this function should
   be in this file.  Should it be called "unused_parameters"? *)
val unused_arguments
   : Flambda.function_declarations
  -> backend:(module Backend_intf.S)
  -> Variable.Set.t