heptagon/compiler/global/static.ml
2011-05-26 18:43:30 +02:00

213 lines
8.1 KiB
OCaml

(**************************************************************************)
(* *)
(* Heptagon *)
(* *)
(* Author : Marc Pouzet *)
(* Organization : Demons, LRI, University of Paris-Sud, Orsay *)
(* *)
(**************************************************************************)
(** This module defines static expressions, used in params and for constants.
const n: int = 3;
var x : int^n; var y : int^(n + 2);
x[n - 1], x[1 + 3],... *)
open Names
open Format
open Types
open Signature
open Modules
open Location
exception Not_static
(** Some evaluations are not possible *)
type eval_error = Division_by_zero
exception Evaluation_failed of eval_error * location
(** Some unknown operators could be used preventing the evaluation *)
type partial_eval_cause = Unknown_op of fun_name | Unknown_param of qualname
exception Partial_evaluation of partial_eval_cause * location
let message exn =
begin match exn with
| Evaluation_failed (e,loc) ->
(match e with
| Division_by_zero ->
eprintf "%aForbidden division by 0.@."
print_location loc
)
| Partial_evaluation (e,loc) ->
(match e with
| Unknown_op op ->
eprintf "%aUnknown operator %a.@."
Location.print_location loc
Global_printer.print_qualname op
| Unknown_param q ->
eprintf "%aUninstanciated param %a.@."
Location.print_location loc
Global_printer.print_qualname q
)
| _ -> raise exn
end;
raise Errors.Error
(** When not [partial],
@raise Partial_evaluation when the application of the operator can't be evaluated (only Unknown_op).
Otherwise keep as it is unknown operators. *)
let apply_op partial loc op se_list =
match se_list with
| [{ se_desc = Sint n1 }; { se_desc = Sint n2 }] ->
(match op with
| { qual = Pervasives; name = "+" } ->
Sint (n1 + n2)
| { qual = Pervasives; name = "-" } ->
Sint (n1 - n2)
| { qual = Pervasives; name = "*" } ->
Sint (n1 * n2)
| { qual = Pervasives; name = "/" } ->
if n2 = 0 then raise (Evaluation_failed (Division_by_zero, loc));
Sint (n1 / n2)
| { qual = Pervasives; name = "=" } ->
Sbool (n1 = n2)
| _ -> assert false (*TODO: add missing operators*)
)
| [{ se_desc = Sint n }] ->
(match op with
| { qual = Pervasives; name = "~-" } -> Sint (-n)
| _ -> assert false (*TODO: add missing operators*)
)
| _ -> if partial then Sop(op, se_list) (* partial evaluation *)
else raise (Partial_evaluation (Unknown_op op, loc))
(** When not [partial],
@raise Partial_evaluation when a static var cannot be evaluated, a local static parameter for example.
Otherwise evaluate in a best effort manner. *)
let rec eval_core partial env se = match se.se_desc with
| Sint _ | Sfloat _ | Sbool _ | Sstring _ | Sconstructor _ | Sfield _ -> se
| Svar ln ->
(try (* first try to find in global const env *)
let cd = find_const ln in
eval_core partial env cd.c_value
with Not_found -> (* then try to find in local env *)
(try
let se = QualEnv.find ln env in
(match se.se_desc with
| Svar ln' when ln'=ln -> (* prevent basic infinite loop *)
if partial then se else raise Not_found
| _ -> eval_core partial env se
)
with Not_found -> (* Could not evaluate the var *)
if partial then se
else raise (Partial_evaluation (Unknown_param ln, se.se_loc))
)
)
| Sop (op, se_list) ->
let se_list = List.map (eval_core partial env) se_list in
let se_desc = apply_op partial se.se_loc op se_list in
{ se with se_desc = se_desc }
| Sarray se_list ->
{ se with se_desc = Sarray (List.map (eval_core partial env) se_list) }
| Sarray_power (se, n_list) ->
{ se with se_desc = Sarray_power (eval_core partial env se, List.map (eval_core partial env) n_list) }
| Stuple se_list ->
{ se with se_desc = Stuple (List.map (eval_core partial env) se_list) }
| Srecord f_se_list ->
{ se with se_desc = Srecord
(List.map (fun (f,se) -> f, eval_core partial env se) f_se_list) }
(** [simplify env e] returns e simplified with the
variables values taken from [env] or from the global env with [find_const].
Every operator that can be computed is.
It can return static_exp with uninstanciated variables.*)
let simplify env se =
try eval_core true env se
with exn -> message exn
(** [eval env e] does the same as [simplify]
but if it returns, there are no variables nor op left.
@raise [Errors.Error] when it cannot fully evaluate. *)
let eval env se =
try eval_core false env se
with exn -> message exn
(** [int_of_static_exp env e] returns the value of the expression
[e] in the environment [env], mapping vars to integers.
@raise [Errors.Error] if it cannot be computed.*)
let int_of_static_exp env se = match (eval env se).se_desc with
| Sint i -> i
| _ -> Misc.internal_error "static int_of_static_exp" 1
(** [is_true env constr] returns whether the constraint is satisfied
in the environment (or None if this can be decided)
and a simplified constraint. *)
let is_true env =
function
| Cequal (e1, e2) when e1 = e2 ->
Some true, Cequal (simplify env e1, simplify env e2)
| Cequal (e1, e2) ->
let e1 = simplify env e1 in
let e2 = simplify env e2 in
(match e1.se_desc, e2.se_desc with
| Sint n1, Sint n2 -> Some (n1 = n2), Cequal (e1, e2)
| (_, _) -> None, Cequal (e1, e2))
| Clequal (e1, e2) ->
let e1 = simplify env e1 in
let e2 = simplify env e2 in
(match e1.se_desc, e2.se_desc with
| Sint n1, Sint n2 -> Some (n1 <= n2), Clequal (e1, e2)
| _, _ -> None, Clequal (e1, e2))
| Cfalse -> None, Cfalse
exception Solve_failed of size_constraint
(** [solve env constr_list solves a list of constraints. It
removes equations that can be decided and simplify others.
If one equation cannot be satisfied, it raises Solve_failed. ]*)
let rec solve const_env =
function
| [] -> []
| c :: l ->
let l = solve const_env l in
let (res, c) = is_true const_env c in
(match res with
| None -> c :: l
| Some v -> if not v then raise (Solve_failed c) else l)
(** Substitutes variables in the size exp with their value
in the map (mapping vars to size exps). *)
let rec static_exp_subst m se =
match se.se_desc with
| Svar qn -> (try QualEnv.find qn m with | Not_found -> se)
| Sop (op, se_list) ->
{ se with se_desc = Sop (op, List.map (static_exp_subst m) se_list) }
| Sarray_power (se, n_list) ->
{ se with se_desc = Sarray_power (static_exp_subst m se,
List.map (static_exp_subst m) n_list) }
| Sarray se_list ->
{ se with se_desc = Sarray (List.map (static_exp_subst m) se_list) }
| Stuple se_list ->
{ se with se_desc = Stuple (List.map (static_exp_subst m) se_list) }
| Srecord f_se_list ->
{ se with se_desc =
Srecord (List.map
(fun (f,se) -> f, static_exp_subst m se) f_se_list) }
| _ -> se
(** Substitutes variables in the constraint list with their value
in the map (mapping vars to size exps). *)
let instanciate_constr m constr =
let replace_one m = function
| Cequal (e1, e2) -> Cequal (static_exp_subst m e1, static_exp_subst m e2)
| Clequal (e1, e2) -> Clequal (static_exp_subst m e1, static_exp_subst m e2)
| Cfalse -> Cfalse in
List.map (replace_one m) constr