AStat/domains/interval.ml
2024-06-02 12:13:42 +02:00

156 lines
5.3 KiB
OCaml

open Naked
open Abstract_syntax_tree
module Interval : NAKED_VALUE_DOMAIN = struct
type t = { lower : Z.t; upper : Z.t }
let const a = { lower = a; upper = a }
let rand a b = { lower = Z.min a b; upper = Z.max a b }
let infty = Z.of_int64_unsigned Int64.max_int
let min_infty = Z.neg infty
let pos = rand Z.one infty
let neg = rand min_infty Z.minus_one
let rand3 a b c =
let mi = List.fold_left Z.min a [ a; b; c ] in
let ma = List.fold_left Z.max a [ a; b; c ] in
rand mi ma
let rand4 a b c d =
let mi = List.fold_left Z.min a [ a; b; c; d ] in
let ma = List.fold_left Z.max a [ a; b; c; d ] in
rand mi ma
let minus z = rand (Z.neg z.upper) (Z.neg z.lower)
let join z1 z2 = rand4 z1.lower z2.lower z1.upper z2.upper
let meet z1 z2 =
if Z.lt z1.upper z2.lower || Z.lt z2.upper z1.lower then raise Absurd
else rand (Z.max z1.lower z2.lower) (Z.min z1.upper z2.upper)
let widen z1 z2 =
rand
(if Z.lt z1.lower z2.lower then z1.lower else min_infty)
(if Z.gt z1.upper z2.upper then z1.upper else infty)
let narrow = meet
let subset z1 z2 = Z.geq z1.lower z2.lower && Z.leq z1.upper z2.upper
let binary z1 z2 = function
| AST_PLUS -> rand (Z.add z1.lower z2.lower) (Z.add z1.upper z2.upper)
| AST_MINUS -> rand (Z.sub z1.lower z2.upper) (Z.sub z1.upper z2.lower)
| AST_MULTIPLY ->
rand4 (Z.mul z1.lower z2.lower) (Z.mul z1.upper z2.lower)
(Z.mul z1.lower z2.upper) (Z.mul z1.upper z2.upper)
| AST_DIVIDE ->
if Z.sign z2.lower <> Z.sign z2.upper || Z.sign z2.lower = 0 then
raise Absurd
else
rand4 (Z.div z1.lower z2.lower) (Z.div z1.upper z2.lower)
(Z.div z1.lower z2.upper) (Z.div z1.upper z2.upper)
| AST_MODULO ->
if Z.sign z2.lower <> Z.sign z2.upper || Z.sign z2.lower = 0 then
raise Absurd
else
rand4 (Z.rem z1.lower z2.lower) (Z.rem z1.upper z2.lower)
(Z.rem z1.lower z2.upper) (Z.rem z1.upper z2.upper)
let is_only_zero z = Z.equal z.lower Z.zero && Z.equal z.upper Z.zero
let multiples_of z = if is_only_zero z then const Z.zero else raise NeedTop
let divisors_of z = if is_only_zero z then const Z.zero else raise NeedTop
let remainders z = if is_only_zero z then const Z.zero else raise NeedTop
let convex_sym z = if is_only_zero z then const Z.zero else raise NeedTop
let compatible z = function
| AST_EQUAL -> z
| AST_NOT_EQUAL -> raise NeedTop
| AST_LESS ->
if Z.equal z.lower min_infty then raise Absurd
else rand min_infty z.lower
| AST_LESS_EQUAL -> rand min_infty z.lower
| AST_GREATER ->
if Z.equal z.upper infty then raise Absurd else rand z.upper infty
| AST_GREATER_EQUAL -> rand z.upper infty
let rec compare z1 z2 = function
| AST_EQUAL ->
let z = meet z1 z2 in
(z, z)
| AST_NOT_EQUAL ->
if
Z.equal z1.lower z1.upper && Z.equal z1.upper z2.lower
&& Z.equal z2.lower z2.upper
then raise Absurd
else (z1, z2)
| AST_LESS ->
if Z.leq z2.upper z1.lower then raise Absurd
else
let r1 =
rand z1.lower
(if Z.geq z1.upper z2.upper then Z.pred z2.upper else z1.upper)
in
let r2 =
rand
(if Z.geq z1.lower z2.lower then Z.succ z1.lower else z2.lower)
z2.upper
in
(r1, r2)
| AST_LESS_EQUAL ->
if Z.lt z2.upper z1.lower then raise Absurd
else
let r1 = rand z1.lower (Z.min z1.upper z2.upper) in
let r2 = rand (Z.max z1.lower z2.lower) z2.upper in
(r1, r2)
| AST_GREATER ->
let r1, r2 = compare z2 z1 AST_LESS in
(r2, r1)
| AST_GREATER_EQUAL ->
let r1, r2 = compare z2 z1 AST_LESS_EQUAL in
(r2, r1)
let has_zero z = Z.leq z.lower Z.zero && Z.geq z.upper Z.zero
let has_one z = Z.leq z.lower Z.one && Z.geq z.upper Z.one
let has_minus_one z = Z.leq z.lower Z.minus_one && Z.geq z.upper Z.minus_one
let three_part z1 z2 op =
if has_one z2 then
if has_minus_one z2 then
let a = meet pos z2 in
let b = meet neg z2 in
join (binary z1 a op) (binary z1 b op)
else
let a = meet pos z2 in
binary z1 a op
else
let a = meet neg z2 in
binary z1 a op
let bwd_binary z1 z2 op r =
match op with
| AST_PLUS ->
(meet z1 (binary r z2 AST_MINUS), meet z2 (binary r z1 AST_MINUS))
| AST_MINUS ->
(meet z1 (binary r z2 AST_PLUS), meet z2 (binary z1 r AST_MINUS))
| AST_MULTIPLY ->
if is_only_zero z1 || is_only_zero z2 then
if has_zero r then
z1, z2
else raise Absurd
else
let z2' = meet z2 (three_part r z1 AST_DIVIDE) in
let z1' = meet z1 (three_part r z2 AST_DIVIDE) in
if has_zero r then
( (if has_zero z1' then join z1' (const Z.zero) else z1'),
if has_zero z2' then join z2' (const Z.zero) else z2' )
else (z1', z2')
| AST_DIVIDE ->
(meet z1 (binary r z2 AST_MULTIPLY), meet z2 (binary z1 r AST_DIVIDE))
| AST_MODULO -> (z1, z2)
let print fmt z =
Format.pp_print_string fmt "[";
Z.pp_print fmt z.lower;
Format.pp_print_string fmt "; ";
Z.pp_print fmt z.upper;
Format.pp_print_string fmt "]"
end