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[sledge] Fix bug in Sh.simplify

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Summary:
When a stem has an occurrence of an existential, say x, and x is
substituted out by different witnesses, say a and b, in two disjuncts,
then the connection to other occurrences of a and b are lost.

This diff fixes this problem by propagating the solved variables that
survive normalization down to subformulas, and not removing those
variables from subformulas.

Reviewed By: jvillard

Differential Revision: D25756583

fbshipit-source-id: dabda743f
master
Josh Berdine 4 years ago committed by Facebook GitHub Bot
parent c10ccafd43
commit cecd3db59f
2 changed files with 76 additions and 30 deletions
Show Stats Download Patch File Download Diff File

9
sledge/src/sh.ml
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@ -767,7 +767,7 @@ let remove_absent_xs ks q =
in in
{q with xs; djns} {q with xs; djns}
let rec simplify_ us rev_xss ancestor_subst q = let rec simplify_ us rev_xss survived ancestor_subst q =
[%Trace.call fun {pf} -> [%Trace.call fun {pf} ->
pf "%a@ %a@ %a" pp_vss (List.rev rev_xss) Context.Subst.pp pf "%a@ %a@ %a" pp_vss (List.rev rev_xss) Context.Subst.pp
ancestor_subst pp_raw q] ancestor_subst pp_raw q]
@ -795,14 +795,17 @@ let rec simplify_ us rev_xss ancestor_subst q =
{(norm subst {q with djns= emp.djns; ctx= emp.ctx}) with ctx= q.ctx} {(norm subst {q with djns= emp.djns; ctx= emp.ctx}) with ctx= q.ctx}
in in
(* recursively simplify subformulas *) (* recursively simplify subformulas *)
let survived = Var.Set.union survived (fv (elim_exists stem.xs stem)) in
let q = let q =
starN starN
( stem ( stem
:: List.map q.djns ~f:(fun djn -> :: List.map q.djns ~f:(fun djn ->
orN (List.map ~f:(simplify_ us rev_xss subst) djn) ) ) orN (List.map ~f:(simplify_ us rev_xss survived subst) djn) )
)
in in
if is_false q then false_ q.us if is_false q then false_ q.us
else else
let removed = Var.Set.diff removed survived in
let removed = let removed =
if Var.Set.is_empty removed then Var.Set.empty if Var.Set.is_empty removed then Var.Set.empty
else ( else (
@ -836,7 +839,7 @@ let simplify q =
let q = propagate_context Var.Set.empty Context.empty q in let q = propagate_context Var.Set.empty Context.empty q in
if is_false q then false_ q.us if is_false q then false_ q.us
else else
let q = simplify_ q.us [] Context.Subst.empty q in let q = simplify_ q.us [] Var.Set.empty Context.Subst.empty q in
q ) q )
|> |>
[%Trace.retn fun {pf} q' -> [%Trace.retn fun {pf} q' ->

87
sledge/src/test/sh_test.ml
Unescape View File

@ -16,7 +16,10 @@ let%test_module _ =
(* let () = (* let () =
* Trace.init ~margin:160 * Trace.init ~margin:160
* ~config:(Result.get_ok (Trace.parse "+Sh+Context+Arithmetic")) * ~config:
* (Result.get_ok
* (Trace.parse
* "+Sh.simplify+Sh.simplify_+Sh.norm+Sh.and_subst+Context.solve_and_elim+Context.partition_valid+Context.solve_for_vars+Context.apply_and_elim+Context.apply_subst+Context.elim"))
* () *) * () *)
[@@@warning "-32"] [@@@warning "-32"]
@ -36,16 +39,20 @@ let%test_module _ =
let c_, wrt = Var.fresh "c" ~wrt let c_, wrt = Var.fresh "c" ~wrt
let d_, wrt = Var.fresh "d" ~wrt let d_, wrt = Var.fresh "d" ~wrt
let e_, wrt = Var.fresh "e" ~wrt let e_, wrt = Var.fresh "e" ~wrt
let m_, wrt = Var.fresh "m" ~wrt
let x_, wrt = Var.fresh "x" ~wrt let x_, wrt = Var.fresh "x" ~wrt
let y_, wrt = Var.fresh "y" ~wrt let y_, wrt = Var.fresh "y" ~wrt
let z_, wrt = Var.fresh "z" ~wrt
let _ = wrt let _ = wrt
let a = Term.var a_ let a = Term.var a_
let b = Term.var b_ let b = Term.var b_
let c = Term.var c_ let c = Term.var c_
let d = Term.var d_ let d = Term.var d_
let e = Term.var e_ let e = Term.var e_
let m = Term.var m_
let x = Term.var x_ let x = Term.var x_
let y = Term.var y_ let y = Term.var y_
let z = Term.var z_
let eq_concat (siz, seq) ms = let eq_concat (siz, seq) ms =
Formula.eq (Term.sized ~siz ~seq) Formula.eq (Term.sized ~siz ~seq)
@ -61,7 +68,7 @@ let%test_module _ =
(seg {loc= x; bas= x; len= !16; siz= !8; cnt= a}) (seg {loc= x; bas= x; len= !16; siz= !8; cnt= a})
(seg {loc= x + !8; bas= x; len= !16; siz= !8; cnt= b})) ; (seg {loc= x + !8; bas= x; len= !16; siz= !8; cnt= b})) ;
[%expect {| [%expect {|
%x_6 -[)-> ⟨8,%a_1⟩^⟨8,%b_2⟩ |}] %x_7 -[)-> ⟨8,%a_1⟩^⟨8,%b_2⟩ |}]
let%expect_test _ = let%expect_test _ =
let p = exists ~$[x_] (extend_us ~$[x_] emp) in let p = exists ~$[x_] (extend_us ~$[x_] emp) in
@ -71,11 +78,11 @@ let%test_module _ =
pp (star p q) ; pp (star p q) ;
[%expect [%expect
{| {|
∃ %x_6 . emp ∃ %x_7 . emp
0 = %x_6 ∧ emp 0 = %x_7 ∧ emp
0 = %x_6 ∧ emp |}] 0 = %x_7 ∧ emp |}]
let%expect_test _ = let%expect_test _ =
let q = let q =
@ -91,11 +98,11 @@ let%test_module _ =
pp_djn (dnf q) ; pp_djn (dnf q) ;
[%expect [%expect
{| {|
( ( 0 = %x_6 ∧ emp) ∨ ( ( ( 1 = %y_7 ∧ emp) ∨ ( emp) )) ) ( ( 0 = %x_7 ∧ emp) ∨ ( ( ( 1 = %y_8 ∧ emp) ∨ ( emp) )) )
( (∃ %x_6, %x_7 . 2 = %x_7 ∧ (2 = %x_7) ∧ emp) ( (∃ %x_7, %x_8 . 2 = %x_8 ∧ (2 = %x_8) ∧ emp)
∨ (∃ %x_6 . 1 = %y_7 = %x_6 ∧ ((1 = %x_6) ∧ (1 = %y_7)) ∧ emp) ∨ (∃ %x_7 . 1 = %y_8 = %x_7 ∧ ((1 = %x_7) ∧ (1 = %y_8)) ∧ emp)
∨ ( 0 = %x_6 ∧ (0 = %x_6) ∧ emp) ∨ ( 0 = %x_7 ∧ (0 = %x_7) ∧ emp)
) |}] ) |}]
let%expect_test _ = let%expect_test _ =
@ -114,13 +121,13 @@ let%test_module _ =
pp_djn (dnf q) ; pp_djn (dnf q) ;
[%expect [%expect
{| {|
( ( emp) ∨ ( ( ( 1 = %y_7 ∧ emp) ∨ ( emp) )) ) ( ( emp) ∨ ( ( ( 1 = %y_8 ∧ emp) ∨ ( emp) )) )
( (∃ %x_6, %x_8, %x_9 . 2 = %x_9 ∧ (2 = %x_9) ∧ emp) ( (∃ %x_7, %x_9, %x_10 . 2 = %x_10 ∧ (2 = %x_10) ∧ emp)
∨ (∃ %x_6, %x_8 . ∨ (∃ %x_7, %x_9 .
1 = %x_8 = %y_7 ∧ ((1 = %y_7) ∧ (1 = %x_8)) 1 = %x_9 = %y_8 ∧ ((1 = %y_8) ∧ (1 = %x_9))
∧ emp) ∧ emp)
∨ (∃ %x_6 . 0 = %x_6 ∧ (0 = %x_6) ∧ emp) ∨ (∃ %x_7 . 0 = %x_7 ∧ (0 = %x_7) ∧ emp)
) |}] ) |}]
let%expect_test _ = let%expect_test _ =
@ -139,9 +146,9 @@ let%test_module _ =
pp (simplify q) ; pp (simplify q) ;
[%expect [%expect
{| {|
( ( emp) ∨ ( ( ( 1 = %y_7 ∧ emp) ∨ ( emp) )) ) ( ( emp) ∨ ( ( ( 1 = %y_8 ∧ emp) ∨ ( emp) )) )
( ( emp) ∨ ( 1 = %y_7 ∧ emp) ∨ ( emp) ) |}] ( ( emp) ∨ ( 1 = %y_8 ∧ emp) ∨ ( emp) ) |}]
let%expect_test _ = let%expect_test _ =
let q = exists ~$[x_] (of_eqs [(f x, x); (f y, y - !1)]) in let q = exists ~$[x_] (of_eqs [(f x, x); (f y, y - !1)]) in
@ -151,11 +158,11 @@ let%test_module _ =
pp q' ; pp q' ;
[%expect [%expect
{| {|
∃ %x_6 . %x_6 = f(%x_6) ∧ (-1 + %y_7) = f(%y_7) ∧ emp ∃ %x_7 . %x_7 = f(%x_7) ∧ (-1 + %y_8) = f(%y_8) ∧ emp
(-1 + %y_7) = f(%y_7) ∧ ((1 + f(%y_7)) = %y_7) ∧ emp (-1 + %y_8) = f(%y_8) ∧ ((1 + f(%y_8)) = %y_8) ∧ emp
(-1 + %y_7) = f(%y_7) ∧ emp |}] (-1 + %y_8) = f(%y_8) ∧ emp |}]
let%expect_test _ = let%expect_test _ =
let q = let q =
@ -178,7 +185,7 @@ let%test_module _ =
∃ %a_1, %c_3, %d_4, %e_5 . ∃ %a_1, %c_3, %d_4, %e_5 .
(⟨8,%a_1⟩^⟨8,%d_4⟩) = %e_5 ∧ (⟨16,%e_5⟩ = (⟨8,%a_1⟩^⟨8,%d_4⟩)) (⟨8,%a_1⟩^⟨8,%d_4⟩) = %e_5 ∧ (⟨16,%e_5⟩ = (⟨8,%a_1⟩^⟨8,%d_4⟩))
∧ emp ∧ emp
* ( ( tt ∧ (0 ≠ %x_6) ∧ emp) * ( ( tt ∧ (0 ≠ %x_7) ∧ emp)
∨ (∃ %b_2 . ∨ (∃ %b_2 .
(⟨4,%c_3⟩^⟨4,%b_2⟩) = %a_1 (⟨4,%c_3⟩^⟨4,%b_2⟩) = %a_1
∧ (⟨8,%a_1⟩ = (⟨4,%c_3⟩^⟨4,%b_2⟩)) ∧ (⟨8,%a_1⟩ = (⟨4,%c_3⟩^⟨4,%b_2⟩))
@ -187,7 +194,43 @@ let%test_module _ =
tt ∧ tt tt ∧ tt
∧ emp ∧ emp
* ( ( tt ∧ tt ∧ emp) ∨ ( tt ∧ (0 ≠ %x_6) ∧ emp) ) * ( ( tt ∧ tt ∧ emp) ∨ ( tt ∧ (0 ≠ %x_7) ∧ emp) )
( ( emp) ∨ ( (0 ≠ %x_6) ∧ emp) ) |}] ( ( emp) ∨ ( (0 ≠ %x_7) ∧ emp) ) |}]
let%expect_test _ =
let q =
exists
~$[b_; m_]
(star
(seg {loc= x; bas= b; len= m; siz= !8; cnt= !0})
(or_ (of_eqs [(b, y); (m, c)]) (of_eqs [(b, z); (m, c)])))
in
pp_raw q ;
let q' = simplify q in
pp_raw q' ;
pp q' ;
[%expect
{|
∃ %b_2, %m_6 .
tt ∧ tt
∧ %x_7 -[ %b_2, %m_6 )-> ⟨8,0⟩
* ( ( %b_2 = %y_8 ∧ %c_3 = %m_6
∧ ((%b_2 = %y_8) ∧ (%c_3 = %m_6))
∧ emp)
∨ ( %b_2 = %z_9 ∧ %c_3 = %m_6
∧ ((%b_2 = %z_9) ∧ (%c_3 = %m_6))
∧ emp)
)
∃ %b_2 .
tt ∧ tt
∧ %x_7 -[ %b_2, %c_3 )-> ⟨8,0⟩
* ( ( %b_2 = %z_9 ∧ (%b_2 = %z_9) ∧ emp)
∨ ( %b_2 = %y_8 ∧ (%b_2 = %y_8) ∧ emp)
)
∃ %b_2 .
%x_7 -[ %b_2, %c_3 )-> ⟨8,0⟩
* ( ( %b_2 = %z_9 ∧ emp) ∨ ( %b_2 = %y_8 ∧ emp) ) |}]
end ) end )

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