heptagon/compiler/global/clocks.ml
2011-05-26 15:56:59 +02:00

134 lines
3.6 KiB
OCaml

(**************************************************************************)
(* *)
(* Heptagon *)
(* *)
(* Author : Marc Pouzet *)
(* Organization : Demons, LRI, University of Paris-Sud, Orsay *)
(* *)
(**************************************************************************)
open Names
open Idents
open Types
type ct =
| Ck of ck
| Cprod of ct list
and ck =
| Cbase
| Cvar of link ref
| Con of ck * constructor_name * var_ident
and link =
| Cindex of int
| Clink of ck
exception Unify
let invalid_clock = Cprod []
let index = ref 0
let gen_index () = (incr index; !index)
(** returns a new clock variable *)
let fresh_clock () = Cvar { contents = Cindex (gen_index ()); }
(** returns a new clock type corresponding to the data type [ty] *)
let rec fresh_ct ty = match ty with
| Tprod ty_list ->
(match ty_list with
| [] -> Ck (fresh_clock())
| _ -> Cprod (List.map fresh_ct ty_list))
| Tarray (t, _) -> fresh_ct t
| Tid _ | Tinvalid -> Ck (fresh_clock())
(** returns the canonic (short) representant of a [ck]
and update it to this value. *)
let rec ck_repr ck = match ck with
| Cbase | Con _
| Cvar { contents = Cindex _ } -> ck
| Cvar (({ contents = Clink ck } as link)) ->
let ck = ck_repr ck in
link.contents <- Clink ck;
ck
(** verifies that index is fresh in ck. *)
let rec occur_check index ck =
let ck = ck_repr ck in
match ck with
| Cbase -> ()
| Cvar { contents = Cindex n } when index <> n -> ()
| Con (ck, _, _) -> occur_check index ck
| _ -> raise Unify
(** unify ck *)
and unify_ck ck1 ck2 =
let ck1 = ck_repr ck1 in
let ck2 = ck_repr ck2 in
if ck1 == ck2 then ()
else
match (ck1, ck2) with
| Cbase, Cbase -> ()
| Cvar { contents = Cindex n1 }, Cvar { contents = Cindex n2 } when n1 = n2 -> ()
| Con (ck1, c1, n1), Con (ck2, c2, n2) when (c1 = c2) & (n1 = n2) ->
unify_ck ck1 ck2
| Cvar ({ contents = Cindex n } as v), ck
| ck, Cvar ({ contents = Cindex n } as v) ->
occur_check n ck;
v.contents <- Clink ck
| _ -> raise Unify
(** unify ct *)
let rec unify t1 t2 =
if t1 == t2 then () else
match (t1, t2) with
| (Ck (Cbase | Cvar { contents = Cindex _; }), Cprod [])
| (Cprod [], Ck (Cbase | Cvar { contents = Cindex _; })) -> ()
| (Ck ck1, Ck ck2) -> unify_ck ck1 ck2
| (Cprod t1_list, Cprod t2_list) -> unify_list t1_list t2_list
| _ -> raise Unify
and unify_list t1_list t2_list =
try List.iter2 unify t1_list t2_list
with _ -> raise Unify
let rec skeleton ck = function
| Tprod ty_list ->
(match ty_list with
| [x] -> Ck ck
| l -> Cprod (List.map (skeleton ck) l))
| Tarray _ | Tid _ | Tinvalid -> Ck ck
let unprod ct =
let rec f acc ct = match ct with
| Ck ck -> ck::acc
| Cprod ct_l -> List.fold_left f acc ct_l
in
f [] ct
let prod ck_l = match ck_l with
| [ck] -> Ck ck
| _ -> Cprod (List.map (fun ck -> Ck ck) ck_l)
let rec root_ck_of ck = match ck_repr ck with
| Cbase
| Cvar { contents = Cindex _ } -> ck
| Con(ck,_,_) -> root_ck_of ck
| Cvar { contents = Clink _ } -> Misc.internal_error "Clocks, wrong repr"
let rec last_clock ct = match ct with
| Ck ck -> ck
| Cprod l -> last_clock (Misc.last_element l)