diff options
| -rw-r--r-- | sched/simplify.ml | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/sched/simplify.ml b/sched/simplify.ml index db8125b..c47a9d0 100644 --- a/sched/simplify.ml +++ b/sched/simplify.ml @@ -3,6 +3,7 @@ (* Order of simplifications : - cascade slices and selects + - transform k = SLICE i j var when var = CONCAT var' var'' - simplify stupid things (a xor 0 = a, a and 0 = 0, etc.) transform k = SLICE i i var into k = SELECT i var - transform k = SELECT 0 var into k = var when var is also one bit @@ -51,6 +52,59 @@ let cascade_slices p = p_vars = p.p_vars; }, !usefull +(* If + var = CONCAT a b + x = SLICE i j var + or + y = SELECT i var + then x or y may be simplified +*) +let pass_concat p = + let usefull = ref false in + let concats = Hashtbl.create 42 in + List.iter (fun (n, eq) -> match eq with + | Econcat(x, y) -> + let s1 = match x with + | Aconst(a) -> Array.length a + | Avar(z) -> Env.find z p.p_vars + in let s2 = match y with + | Aconst(a) -> Array.length a + | Avar(z) -> Env.find z p.p_vars + in + Hashtbl.add concats n (x, s1, y, s2) + | _ -> ()) p.p_eqs; + let eqs_new = List.map + (fun (n, eq) -> (n, match eq with + | Eselect(i, Avar(n)) -> + begin try + let (x, s1, y, s2) = Hashtbl.find concats n in + usefull := true; + if i < s1 then + Eselect(i, x) + else + Eselect(i-s1, y) + with Not_found -> eq end + | Eslice(i, j, Avar(n)) -> + begin try + let (x, s1, y, s2) = Hashtbl.find concats n in + if j < s1 then begin + usefull := true; + Eslice(i, j, x) + end else if i >= s1 then begin + usefull := true; + Eslice(i - s1, j - s1, y) + end else eq + with Not_found -> eq end + | _ -> eq)) + p.p_eqs in + { + p_eqs = eqs_new; + p_inputs = p.p_inputs; + p_outputs = p.p_outputs; + p_vars = p.p_vars; + }, !usefull + + (* Simplifies some trivial arithmetic possibilites : a and 1 = a a and 0 = 0 @@ -270,9 +324,10 @@ let rec simplify_with steps p = if use then simplify_with steps pp else pp let simplify p = - let p = simplify_with [ topo_sort, "topo_sort" ] p in let p = simplify_with [ + topo_sort, "topo_sort"; cascade_slices, "cascade_slices"; + pass_concat, "pass_concat"; arith_simplify, "arith_simplify"; select_to_id, "select_to_id"; same_eq_simplify, "same_eq_simplify"; |