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Fix meet of arrays with different partitioning expressions #486

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Merged
merged 4 commits into from
Dec 9, 2021
Merged

Fix meet of arrays with different partitioning expressions #486

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4d29f15
Fix issue with illegal value after meet from invaraint
michael-schwarz Dec 9, 2021
576fa79
Simplify example
michael-schwarz Dec 9, 2021
a361da0
Also fix narrow
michael-schwarz Dec 9, 2021
8cc19e0
comment
michael-schwarz Dec 9, 2021
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19 changes: 17 additions & 2 deletions src/cdomains/arrayDomain.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -567,8 +567,23 @@ struct
let smart_widen = smart_widen_with_length None
let smart_leq = smart_leq_with_length None

let meet a b = normalize @@ meet a b
let narrow a b = normalize @@ narrow a b
let meet (e1,v1) (e2,v2) = normalize @@
match e1,e2 with
| `Lifted e1e, `Lifted e2e when not (Basetype.CilExp.equal e1e e2e) ->
(* partitioned according to two different expressions -> meet can not be element-wise *)
(* arrays can not be partitioned according to multiple expressions, arbitrary prefer the first one here *)
(* TODO: do smart things if the relationship between e1e and e2e is known *)
(e1,v1)
| _ -> meet (e1,v1) (e2,v2)

let narrow (e1,v1) (e2,v2) = normalize @@
match e1,e2 with
| `Lifted e1e, `Lifted e2e when not (Basetype.CilExp.equal e1e e2e) ->
(* partitioned according to two different expressions -> narrow can not be element-wise *)
(* arrays can not be partitioned according to multiple expressions, arbitrary prefer the first one here *)
(* TODO: do smart things if the relationship between e1e and e2e is known *)
(e1,v1)
| _ -> narrow (e1,v1) (e2,v2)

let update_length _ x = x
end
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16 changes: 16 additions & 0 deletions tests/regression/22-partitioned_arrays/16-refine-meet.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
// PARAM: --enable exp.partition-arrays.enabled
int garr[7];

int main(int argc, char **argv)
{
// Call to a function with a missing fundef causes invalidation of garr
fundef_missing();

garr[0] = 8;


if (garr[1] == 1) {
// Statement so CIL doesn't optimize the if out
int ret = 12;
}
}