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/********************* */
/*! \file bitvectors_and_arrays-new.cpp
** \verbatim
** Top contributors (to current version):
** Aina Niemetz
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief A simple demonstration of the solving capabilities of the CVC4
** bit-vector and array solvers.
**
**/
#include <iostream>
#include <cmath>
#include <cvc4/api/cvc4cpp.h>
using namespace std;
using namespace CVC4::api;
int main()
{
Solver slv;
slv.setOption("produce-models", "true"); // Produce Models
slv.setOption("output-language", "smtlib"); // output-language
slv.setLogic("QF_AUFBV"); // Set the logic
// Consider the following code (where size is some previously defined constant):
//
//
// Assert (current_array[0] > 0);
// for (unsigned i = 1; i < k; ++i) {
// current_array[i] = 2 * current_array[i - 1];
// Assert (current_array[i-1] < current_array[i]);
// }
//
// We want to check whether the assertion in the body of the for loop holds
// throughout the loop.
// Setting up the problem parameters
unsigned k = 4; // number of unrollings (should be a power of 2)
unsigned index_size = log2(k); // size of the index
// Sorts
Sort elementSort = slv.mkBitVectorSort(32);
Sort indexSort = slv.mkBitVectorSort(index_size);
Sort arraySort = slv.mkArraySort(indexSort, elementSort);
// Variables
Term current_array = slv.mkConst(arraySort, "current_array");
// Making a bit-vector constant
Term zero = slv.mkBitVector(index_size, 0u);
// Asserting that current_array[0] > 0
Term current_array0 = slv.mkTerm(SELECT, current_array, zero);
Term current_array0_gt_0 = slv.mkTerm(
BITVECTOR_SGT, current_array0, slv.mkBitVector(32, 0u));
slv.assertFormula(current_array0_gt_0);
// Building the assertions in the loop unrolling
Term index = slv.mkBitVector(index_size, 0u);
Term old_current = slv.mkTerm(SELECT, current_array, index);
Term two = slv.mkBitVector(32, 2u);
std::vector<Term> assertions;
for (unsigned i = 1; i < k; ++i) {
index = slv.mkBitVector(index_size, i);
Term new_current = slv.mkTerm(BITVECTOR_MULT, two, old_current);
// current[i] = 2 * current[i-1]
current_array = slv.mkTerm(STORE, current_array, index, new_current);
// current[i-1] < current [i]
Term current_slt_new_current = slv.mkTerm(BITVECTOR_SLT, old_current, new_current);
assertions.push_back(current_slt_new_current);
old_current = slv.mkTerm(SELECT, current_array, index);
}
Term query = slv.mkTerm(NOT, slv.mkTerm(AND, assertions));
cout << "Asserting " << query << " to CVC4 " << endl;
slv.assertFormula(query);
cout << "Expect sat. " << endl;
cout << "CVC4: " << slv.checkSatAssuming(slv.mkTrue()) << endl;
// Getting the model
cout << "The satisfying model is: " << endl;
cout << " current_array = " << slv.getValue(current_array) << endl;
cout << " current_array[0] = " << slv.getValue(current_array0) << endl;
return 0;
}
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