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|
(* Js_of_ocaml compiler
* http://www.ocsigen.org/js_of_ocaml/
* Copyright (C) 2010 Jérôme Vouillon
* Laboratoire PPS - CNRS Université Paris Diderot
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, with linking exception;
* either version 2.1 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*)
open! Stdlib
let times = Debug.find "times"
let stats = Debug.find "stats"
open Code
(****)
let pure pure_funs x = Var.Set.mem x pure_funs
let empty = Var.Set.empty
let pure_expr pure_funs e =
match e with
| Block _ | Field _ | Closure _ | Constant _ -> true
| Special (Alias_prim _) -> true
| Apply { f; exact; _ } ->
exact && (Var.Set.mem f pure_funs || Shape.State.is_pure_fun f)
| Prim (p, _l) -> (
match p with
| Extern f -> Primitive.is_pure f
| _ -> true)
let pure_instr pure_funs i =
match i with
| Let (_, e) -> pure_expr pure_funs e
| Event _ | Assign _ -> true
| Set_field _ | Offset_ref _ | Array_set _ -> false
(****)
let rec traverse blocks pc visited pure_blocks funs =
if BitSet.mem visited pc
then BitSet.mem pure_blocks pc
else (
BitSet.set visited pc;
let pure = block blocks pc visited pure_blocks funs in
let pure =
fold_children
blocks
pc
(fun pc pure ->
let pure' = traverse blocks pc visited pure_blocks funs in
pure && pure')
pure
in
if pure then BitSet.set pure_blocks pc;
pure)
and block blocks pc visited pure_blocks funs =
let b = Addr.Map.find pc blocks in
let pure =
match b.branch with
| Raise _ -> false
| _ -> true
in
List.fold_left b.body ~init:pure ~f:(fun pure i ->
(match i with
| Let (x, Closure (_, (pc, _), _)) ->
let pure = traverse blocks pc visited pure_blocks funs in
if pure then funs := Var.Set.add x !funs
| _ -> ());
pure && pure_instr !funs i)
type t = Var.Set.t
let f p =
let t = Timer.make () in
let visited = BitSet.create' p.free_pc in
let pure = BitSet.create' p.free_pc in
let funs = ref Var.Set.empty in
let _ = traverse p.blocks p.start visited pure funs in
if times () then Format.eprintf " pure funs.: %a@." Timer.print t;
if stats () then Format.eprintf "Stats - pure functions: %d@." (Var.Set.cardinal !funs);
!funs
|
