Reduction speedup (a.k.a. better sharing):

[helm.git] / helm / software / components / ng_kernel / nCicReduction.ml

diff --git a/helm/software/components/ng_kernel/nCicReduction.ml b/helm/software/components/ng_kernel/nCicReduction.ml
index 2e13a5304b23b5adca91ef71dcb9c7d2f4349781..432ea9a45bd4c79e599181da2db0cd9038a06463 100644 (file)
--- a/helm/software/components/ng_kernel/nCicReduction.ml
+++ b/helm/software/components/ng_kernel/nCicReduction.ml
@@ -22,41 +22,56 @@ module type Strategy = sig
   type env_term
   type config = int * env_term list * C.term * stack_term list
   val to_env :
-   reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+   reduce: (delta:int -> config -> config * bool) -> 
+   unwind: (config -> C.term) ->
     config -> env_term
-  val from_stack : stack_term -> config
+  val from_stack : delta:int -> stack_term -> config
   val from_stack_list_for_unwind :
-   unwind: (config -> C.term) -> stack_term list -> C.term list
-  val from_env : env_term -> config
+    unwind: (config -> C.term) -> stack_term list -> C.term list
+  val from_env : delta:int -> env_term -> config
   val from_env_for_unwind :
-   unwind: (config -> C.term) -> env_term -> C.term
+    unwind: (config -> C.term) -> env_term -> C.term
   val stack_to_env :
-   reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+   reduce: (delta:int -> config -> config * bool) -> 
+   unwind: (config -> C.term) ->
     stack_term -> env_term
   val compute_to_env :
-   reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+   reduce: (delta:int -> config -> config * bool) -> 
+   unwind: (config -> C.term) ->
     int -> env_term list -> C.term -> env_term
   val compute_to_stack :
-   reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+   reduce: (delta:int -> config -> config * bool) -> 
+   unwind: (config -> C.term) ->
     config -> stack_term
  end
 ;;
 
-module CallByValueByNameForUnwind' = struct
+module CallByValueByNameForUnwind' : Strategy = struct
   type config = int * env_term list * C.term * stack_term list
-  and stack_term = config lazy_t * C.term lazy_t (* cbv, cbn *)
-  and env_term = config lazy_t * C.term lazy_t (* cbv, cbn *)
-  let to_env ~reduce ~unwind c = lazy (fst (reduce c)),lazy (unwind c)
-  let from_stack (c,_) = Lazy.force c
+  and stack_term = 
+       config Lazy.t * (int -> config) * C.term Lazy.t
+  and env_term = 
+        config Lazy.t    (* cbneed   ~delta:0       *)
+      * (int -> config)  (* cbvalue  ~delta         *)
+      * C.term Lazy.t    (* cbname   ~delta:max_int *)
+  let to_env ~reduce ~unwind c = 
+   lazy (fst (reduce ~delta:0 c)), 
+   (fun delta -> fst (reduce ~delta c)),
+   lazy (unwind c)
+  let from_stack ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta 
   let from_stack_list_for_unwind ~unwind:_ l = 
-   List.map (function (_,c) -> Lazy.force c) l
-  let from_env (c,_) = Lazy.force c
-  let from_env_for_unwind ~unwind:_ (_,c) = Lazy.force c
+   List.map (fun (_,_,c) -> Lazy.force c) l
+  let from_env ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta
+  let from_env_for_unwind ~unwind:_ (_,_,c) = Lazy.force c
   let stack_to_env ~reduce:_ ~unwind:_ config = config
   let compute_to_env ~reduce ~unwind k e t =
-   lazy (fst (reduce (k,e,t,[]))), lazy (unwind (k,e,t,[]))
+   lazy (fst (reduce ~delta:0 (k,e,t,[]))), 
+   (fun delta -> fst (reduce ~delta (k,e,t,[]))), 
+   lazy (unwind (k,e,t,[]))
   let compute_to_stack ~reduce ~unwind config = 
-   lazy (fst (reduce config)), lazy (unwind config)
+   lazy (fst (reduce ~delta:0 config)), 
+   (fun delta -> fst (reduce ~delta config)), 
+   lazy (unwind config)
  end
 ;;
 
@@ -87,7 +102,7 @@ module Reduction(RS : Strategy) = struct
   let rec reduce ~delta ?(subst = []) context : config -> config * bool = 
    let rec aux = function
      | k, e, C.Rel n, s when n <= k ->
-        let k',e',t',s' = RS.from_env (list_nth e (n-1)) in
+        let k',e',t',s' = RS.from_env ~delta (list_nth e (n-1)) in
         aux (k',e',t',s'@s)
      | k, _, C.Rel n, s as config (* when n > k *) ->
         let x= try Some (List.nth context (n - 1 - k)) with Failure _ -> None in
@@ -104,14 +119,15 @@ module Reduction(RS : Strategy) = struct
      | (_, _, C.Prod _, _)
      | (_, _, C.Lambda _, []) as config -> config, true
      | (k, e, C.Lambda (_,_,t), p::s) ->
-         aux (k+1, (RS.stack_to_env ~reduce:aux ~unwind p)::e, t,s)
+         aux (k+1, (RS.stack_to_env ~reduce:(reduce ~subst context) ~unwind p)::e, t,s)
      | (k, e, C.LetIn (_,_,m,t), s) ->
-        let m' = RS.compute_to_env ~reduce:aux ~unwind k e m in
+        let m' = RS.compute_to_env ~reduce:(reduce ~subst context) ~unwind k e m in
          aux (k+1, m'::e, t, s)
      | (_, _, C.Appl ([]|[_]), _) -> assert false
      | (k, e, C.Appl (he::tl), s) ->
         let tl' =
-         List.map (fun t->RS.compute_to_stack ~reduce:aux ~unwind (k,e,t,[])) tl
+         List.map (fun t->RS.compute_to_stack 
+           ~reduce:(reduce ~subst context) ~unwind (k,e,t,[])) tl
         in
          aux (k, e, he, tl' @ s)
      | (_, _, C.Const
@@ -128,7 +144,7 @@ module Reduction(RS : Strategy) = struct
            (_,Ref.Fix (fixno,recindex,height)) as refer) as head),s) as config ->
 (*         if delta >= height then config else *)
         (match
-          try Some (RS.from_stack (List.nth s recindex))
+          try Some (RS.from_stack ~delta (List.nth s recindex))
           with Failure _ -> None
         with 
         | None -> config, true
@@ -138,12 +154,14 @@ module Reduction(RS : Strategy) = struct
            | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c, _ 
               when delta >= height ->
                let new_s =
-                 replace recindex s (RS.compute_to_stack ~reduce:aux ~unwind c)
+                 replace recindex s (RS.compute_to_stack ~reduce:(reduce ~subst
+                 context) ~unwind c)
                in
                (0, [], head, new_s), false
            | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c, _ ->
                let new_s =
-                 replace recindex s (RS.compute_to_stack ~reduce:aux ~unwind c)
+                 replace recindex s (RS.compute_to_stack ~reduce:(reduce ~subst
+                 context) ~unwind c)
                in
                let _,_,_,_,body = List.nth fixes fixno in
                aux (0, [], body, new_s)
@@ -281,7 +299,7 @@ let alpha_eq ~test_lambda_source aux test_eq_only metasenv subst context t1 t2 =
 
    | (C.Appl (hd1::tl1),  C.Appl (hd2::tl2)) ->
        aux test_eq_only context hd1 hd2 &&
-       let relevance = !get_relevance ~metasenv ~subst context hd1 tl1 in
+        let relevance = !get_relevance ~metasenv ~subst context hd1 tl1 in
         (try
          HExtlib.list_forall_default3
           (fun t1 t2 b -> not b || aux true context t1 t2)
@@ -361,8 +379,8 @@ let are_convertible ~metasenv ~subst =
          HExtlib.list_forall_default3
            (fun t1 t2 b  ->
              not b ||
-             let t1 = RS.from_stack t1 in
-             let t2 = RS.from_stack t2 in
+             let t1 = RS.from_stack ~delta:max_int t1 in
+             let t2 = RS.from_stack ~delta:max_int t2 in
              convert_machines true (put_in_whd t1 t2)) s1 s2 true relevance
         with Invalid_argument _ -> false) || 
        (not (norm1 && norm2) && convert_machines test_eq_only (small_delta_step m1 m2))