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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"
open Code
(* FIX: it should be possible to deal with tail-recursion in exception
handlers, but we have to adapt the code generator for that *)
let rec remove_last l =
match l with
| [] -> assert false
| [ _ ] -> []
| x :: r -> x :: remove_last r
let rec tail_call x f l =
match l with
| [] -> None
| [ Let (y, Apply { f = g; args; _ }) ] when Var.compare x y = 0 && Var.compare f g = 0
-> Some args
| _ :: rem -> tail_call x f rem
let rewrite_block (f, f_params, f_pc, args) pc blocks =
let block = Addr.Map.find pc blocks in
match block.branch with
| Return x -> (
match tail_call x f block.body with
| Some f_args when List.length f_params = List.length f_args ->
let m = Subst.build_mapping f_params f_args in
List.iter2 f_params f_args ~f:(fun p a -> Code.Var.propagate_name p a);
Addr.Map.add
pc
{ params = block.params
; body = remove_last block.body
; branch = Branch (f_pc, List.map args ~f:(fun x -> Var.Map.find x m))
}
blocks
| _ -> blocks)
| _ -> blocks
let rec traverse f pc visited blocks =
if not (Addr.Set.mem pc visited)
then
let visited = Addr.Set.add pc visited in
let blocks = rewrite_block f pc blocks in
let visited, blocks =
Code.fold_children_skip_try_body
blocks
pc
(fun pc (visited, blocks) ->
let visited, blocks = traverse f pc visited blocks in
visited, blocks)
(visited, blocks)
in
visited, blocks
else visited, blocks
let f p =
let t = Timer.make () in
let blocks =
fold_closures
p
(fun f params (pc, args) blocks ->
match f with
| Some f when List.length params = List.length args ->
let _, blocks = traverse (f, params, pc, args) pc Addr.Set.empty blocks in
blocks
| _ -> blocks)
p.blocks
in
if times () then Format.eprintf " tail calls: %a@." Timer.print t;
{ p with blocks }
|
