/
ref_to_variables.ml
199 lines (194 loc) · 7.91 KB
/
ref_to_variables.ml
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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
let variables_not_used_as_local_reference (tree:Flambda.t) =
let set = ref Variable.Set.empty in
let rec loop_named (flam : Flambda.named) =
match flam with
(* Directly used block: does not prevent use as a variable *)
| Prim(Pfield _, [_], _)
| Prim(Poffsetref _, [_], _) -> ()
| Prim(Psetfield _, [_block; v], _) ->
(* block is not prevented to be used as a local reference, but v is *)
set := Variable.Set.add v !set
| Prim(_, _, _)
| Symbol _ |Const _ | Allocated_const _ | Read_mutable _
| Read_symbol_field _ | Project_closure _
| Move_within_set_of_closures _ | Project_var _ ->
set := Variable.Set.union !set (Flambda.free_variables_named flam)
| Set_of_closures set_of_closures ->
set := Variable.Set.union !set (Flambda.free_variables_named flam);
Variable.Map.iter (fun _ (function_decl : Flambda.function_declaration) ->
loop function_decl.body)
set_of_closures.function_decls.funs
| Expr e ->
loop e
and loop (flam : Flambda.t) =
match flam with
| Let { defining_expr; body; _ } ->
loop_named defining_expr;
loop body
| Let_rec (defs, body) ->
List.iter (fun (_var, named) -> loop_named named) defs;
loop body
| Var v ->
set := Variable.Set.add v !set
| Let_mutable { initial_value = v; body } ->
set := Variable.Set.add v !set;
loop body
| If_then_else (cond, ifso, ifnot) ->
set := Variable.Set.add cond !set;
loop ifso;
loop ifnot
| Switch (cond, { consts; blocks; failaction }) ->
set := Variable.Set.add cond !set;
List.iter (fun (_, branch) -> loop branch) consts;
List.iter (fun (_, branch) -> loop branch) blocks;
Option.iter loop failaction
| String_switch (cond, branches, default) ->
set := Variable.Set.add cond !set;
List.iter (fun (_, branch) -> loop branch) branches;
Option.iter loop default
| Static_catch (_, _, body, handler) ->
loop body;
loop handler
| Try_with (body, _, handler) ->
loop body;
loop handler
| While (cond, body) ->
loop cond;
loop body
| For { bound_var = _; from_value; to_value; direction = _; body; } ->
set := Variable.Set.add from_value !set;
set := Variable.Set.add to_value !set;
loop body
| Static_raise (_, args) ->
set := Variable.Set.union (Variable.Set.of_list args) !set
| Proved_unreachable | Apply _ | Send _ | Assign _ ->
set := Variable.Set.union !set (Flambda.free_variables flam)
in
loop tree;
!set
let variables_containing_ref (flam:Flambda.t) =
let map = ref Variable.Map.empty in
let aux (flam : Flambda.t) =
match flam with
| Let { var;
defining_expr = Prim(Pmakeblock(0, Asttypes.Mutable, _), l, _);
} ->
map := Variable.Map.add var (List.length l) !map
| _ -> ()
in
Flambda_iterators.iter aux (fun _ -> ()) flam;
!map
let eliminate_ref_of_expr flam =
let variables_not_used_as_local_reference =
variables_not_used_as_local_reference flam
in
let convertible_variables =
Variable.Map.filter
(fun v _ ->
not (Variable.Set.mem v variables_not_used_as_local_reference))
(variables_containing_ref flam)
in
if Variable.Map.cardinal convertible_variables = 0 then flam
else
let convertible_variables =
Variable.Map.mapi (fun v size ->
Array.init size (fun _ -> Mutable_variable.create_from_variable v))
convertible_variables
in
let convertible_variable v = Variable.Map.mem v convertible_variables in
let get_variable v field =
let arr = try Variable.Map.find v convertible_variables
with Not_found -> assert false in
if Array.length arr <= field
then None (* This case could apply when inlining code containing GADTS *)
else Some (arr.(field), Array.length arr)
in
let aux (flam : Flambda.t) : Flambda.t =
match flam with
| Let { var;
defining_expr = Prim(Pmakeblock(0, Asttypes.Mutable, shape), l,_);
body }
when convertible_variable var ->
let shape = match shape with
| None -> List.map (fun _ -> Lambda.Pgenval) l
| Some shape -> shape
in
let _, expr =
List.fold_left2 (fun (field,body) init kind ->
match get_variable var field with
| None -> assert false
| Some (field_var, _) ->
field+1,
(Let_mutable { var = field_var;
initial_value = init;
body;
contents_kind = kind } : Flambda.t))
(0,body) l shape in
expr
| Let _ | Let_mutable _
| Assign _ | Var _ | Apply _
| Let_rec _ | Switch _ | String_switch _
| Static_raise _ | Static_catch _
| Try_with _ | If_then_else _
| While _ | For _ | Send _ | Proved_unreachable ->
flam
and aux_named (named : Flambda.named) : Flambda.named =
match named with
| Prim(Pfield (field, _, _), [v], _)
when convertible_variable v ->
(match get_variable v field with
| None -> Expr Proved_unreachable
| Some (var,_) -> Read_mutable var)
| Prim(Poffsetref delta, [v], dbg)
when convertible_variable v ->
(match get_variable v 0 with
| None -> Expr Proved_unreachable
| Some (var,size) ->
if size = 1
then begin
let mut_name = Internal_variable_names.read_mutable in
let mut = Variable.create mut_name in
let new_value_name = Internal_variable_names.offsetted in
let new_value = Variable.create new_value_name in
let expr =
Flambda.create_let mut (Read_mutable var)
(Flambda.create_let new_value
(Prim(Poffsetint delta, [mut], dbg))
(Assign { being_assigned = var; new_value }))
in
Expr expr
end
else
Expr Proved_unreachable)
| Prim(Psetfield (field, _, _), [v; new_value], _)
when convertible_variable v ->
(match get_variable v field with
| None -> Expr Proved_unreachable
| Some (being_assigned,_) ->
Expr (Assign { being_assigned; new_value }))
| Prim _ | Symbol _ | Const _ | Allocated_const _ | Read_mutable _
| Read_symbol_field _ | Set_of_closures _ | Project_closure _
| Move_within_set_of_closures _ | Project_var _ | Expr _ ->
named
in
Flambda_iterators.map aux aux_named flam
let eliminate_ref (program:Flambda.program) =
Flambda_iterators.map_exprs_at_toplevel_of_program program
~f:eliminate_ref_of_expr