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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-4-9-30-40-41-42-66"]
open! Int_replace_polymorphic_compare
type lifter = Flambda.program -> Flambda.program
type def =
| Immutable of Variable.t * Flambda.named Flambda.With_free_variables.t
| Mutable of Mutable_variable.t * Variable.t * Lambda.value_kind
let rebuild_let (defs : def list) (body : Flambda.t) =
let module W = Flambda.With_free_variables in
List.fold_left (fun body def ->
match def with
| Immutable(var, def) ->
W.create_let_reusing_defining_expr var def body
| Mutable(var, initial_value, contents_kind) ->
Flambda.Let_mutable {var; initial_value; contents_kind; body})
body defs
let rec extract_let_expr (acc:def list) (let_expr:Flambda.let_expr) :
def list * Flambda.t Flambda.With_free_variables.t =
let module W = Flambda.With_free_variables in
let acc =
match let_expr with
| { var = v1; defining_expr = Expr (Let let2); _ } ->
let acc, body2 = extract_let_expr acc let2 in
Immutable(v1, W.expr body2) :: acc
| { var = v1; defining_expr = Expr (Let_mutable let_mut); _ } ->
let acc, body2 = extract_let_mutable acc let_mut in
Immutable(v1, W.expr body2) :: acc
| { var = v; _ } ->
Immutable(v, W.of_defining_expr_of_let let_expr) :: acc
in
let body = W.of_body_of_let let_expr in
extract acc body
and extract_let_mutable acc (let_mut : Flambda.let_mutable) =
let module W = Flambda.With_free_variables in
let { Flambda.var; initial_value; contents_kind; body } = let_mut in
let acc = Mutable(var, initial_value, contents_kind) :: acc in
extract acc (W.of_expr body)
and extract acc (expr : Flambda.t Flambda.With_free_variables.t) =
let module W = Flambda.With_free_variables in
match W.contents expr with
| Let let_expr ->
extract_let_expr acc let_expr
| Let_mutable let_mutable ->
extract_let_mutable acc let_mutable
| _ ->
acc, expr
let rec lift_lets_expr (expr:Flambda.t) ~toplevel : Flambda.t =
let module W = Flambda.With_free_variables in
match expr with
| Let let_expr ->
let defs, body = extract_let_expr [] let_expr in
let rev_defs = List.rev_map (lift_lets_def ~toplevel) defs in
let body = lift_lets_expr (W.contents body) ~toplevel in
rebuild_let (List.rev rev_defs) body
| Let_mutable let_mut ->
let defs, body = extract_let_mutable [] let_mut in
let rev_defs = List.rev_map (lift_lets_def ~toplevel) defs in
let body = lift_lets_expr (W.contents body) ~toplevel in
rebuild_let (List.rev rev_defs) body
| e ->
Flambda_iterators.map_subexpressions
(lift_lets_expr ~toplevel)
(lift_lets_named ~toplevel)
e
and lift_lets_def def ~toplevel =
let module W = Flambda.With_free_variables in
match def with
| Mutable _ -> def
| Immutable(var, named) ->
let named =
match W.contents named with
| Expr e -> W.expr (W.of_expr (lift_lets_expr e ~toplevel))
| Set_of_closures set when not toplevel ->
W.of_named
(Set_of_closures
(Flambda_iterators.map_function_bodies
~f:(lift_lets_expr ~toplevel) set))
| Symbol _ | Const _ | Allocated_const _ | Read_mutable _
| Read_symbol_field (_, _) | Project_closure _
| Move_within_set_of_closures _ | Project_var _
| Prim _ | Set_of_closures _ ->
named
in
Immutable(var, named)
and lift_lets_named _var (named:Flambda.named) ~toplevel : Flambda.named =
match named with
| Expr e ->
Expr (lift_lets_expr e ~toplevel)
| Set_of_closures set when not toplevel ->
Set_of_closures
(Flambda_iterators.map_function_bodies ~f:(lift_lets_expr ~toplevel) set)
| Symbol _ | Const _ | Allocated_const _ | Read_mutable _
| Read_symbol_field (_, _) | Project_closure _ | Move_within_set_of_closures _
| Project_var _ | Prim _ | Set_of_closures _ ->
named
module Sort_lets = Strongly_connected_components.Make (Variable)
let rebuild_let_rec (defs:(Variable.t * Flambda.named) list) body =
let map = Variable.Map.of_list defs in
let graph =
Variable.Map.map
(fun named ->
Variable.Set.filter (fun v -> Variable.Map.mem v map)
(Flambda.free_variables_named named))
map
in
let components =
Sort_lets.connected_components_sorted_from_roots_to_leaf graph
in
Array.fold_left (fun body (component:Sort_lets.component) ->
match component with
| No_loop v ->
let def = Variable.Map.find v map in
Flambda.create_let v def body
| Has_loop l ->
Flambda.Let_rec
(List.map (fun v -> v, Variable.Map.find v map) l,
body))
body components
let lift_let_rec program =
Flambda_iterators.map_exprs_at_toplevel_of_program program
~f:(Flambda_iterators.map_expr
(fun expr -> match expr with
| Let_rec (defs, body) ->
rebuild_let_rec defs body
| expr -> expr))
let lift_lets program =
let program = lift_let_rec program in
Flambda_iterators.map_exprs_at_toplevel_of_program program
~f:(lift_lets_expr ~toplevel:false)
let lifting_helper exprs ~evaluation_order ~create_body ~name =
let vars, lets =
(* [vars] corresponds elementwise to [exprs]; the order is unchanged. *)
List.fold_right (fun (flam : Flambda.t) (vars, lets) ->
match flam with
| Var v ->
(* Note that [v] is (statically) always an immutable variable. *)
v::vars, lets
| expr ->
let v =
Variable.create name ~current_compilation_unit:
(Compilation_unit.get_current_exn ())
in
v::vars, (v, expr)::lets)
exprs ([], [])
in
let lets =
match evaluation_order with
| `Right_to_left -> lets
| `Left_to_right -> List.rev lets
in
List.fold_left (fun body (v, expr) ->
Flambda.create_let v (Expr expr) body)
(create_body vars) lets
|
