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114 lines
2.4 KiB
Text
114 lines
2.4 KiB
Text
; File name: loop_unrolling.smt2
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;
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; Copyright (c) March, 2021 - Matteo Nicoli
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;
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;
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; Let's start considering a simple C program involving an iteration:
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;
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; #define DIM 2
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;
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; /* uninterpreted functions */
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; long get_number();
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; void fill_array(long *A);
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;
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; int main()
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; {
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; long x = get_number();
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; long A[DIM];
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; long i = 0;
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; long found = 0;
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;
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; fill_array(A);
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;
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; while(i < DIM) {
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; if(x == A[i])
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; found = 1;
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; i++;
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; }
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; }
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;
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; Below, we can see its SSA representation in SMT-LIB2.
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; Our goal is to verify that, at the end of the program, the variable `found`
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; is equal to 1 if, and only if, `x` is an element of the array.
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(declare-const x Int)
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(declare-const A (Array Int Int))
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(declare-const i_0 Int)
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(declare-const found_0 Int)
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(declare-const found_1 Int)
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(declare-const found_2 Int)
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(declare-const i_1 Int)
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(declare-const i_2 Int)
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; Pre-condition: variables initialization
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(assert
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(and
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(= i_0 0)
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(= found_0 0)
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)
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)
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; Transition function
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(define-fun body ((f_0 Int) (f Int) (i_0 Int) (i_1 Int)(_A (Array Int Int)) (_x Int)) Bool
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(and
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(= f (ite (= _x (select _A i_0)) 1 f_0))
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(= i_1 (+ i_0 1))
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)
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)
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; Post-condition function
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(define-fun post ((_f Int) (_i Int) (_x Int) (_A (Array Int Int))) Bool
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(=
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(= _f 1)
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(= _x (select _A _i))
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)
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)
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; Transition function is called DIM times:
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; for practical reasons, we are considering here DIM = 2
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(assert (body found_0 found_1 i_0 i_1 A x))
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(assert (body found_1 found_2 i_1 i_2 A x))
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(push)
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(echo "Bounded model checking with loop unrolling")
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(echo "------------------------------------------")
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; Post-condition (negated) is called DIM times
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(assert
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(not
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(or
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(post found_2 i_0 x A)
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(post found_2 i_1 x A)
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)
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)
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)
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(echo "Testing the validity of the post-condition: `unsat expected`")
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; `unsat` expected
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(check-sat)
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(pop)
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; Post-condition (called DIM times)
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(assert
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(or
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(post found_2 i_0 x A)
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(post found_2 i_1 x A)
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)
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)
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(echo "Getting a model; `sat` expected: ")
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; `sat` expected
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(check-sat)
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(echo "------------------------------------------")
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(echo "Model: ")
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(get-value (x A found_2))
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(exit)
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