path: root/libsolidity/formal/Z3Interface.cpp

/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <libsolidity/formal/Z3Interface.h>

#include <libsolidity/interface/Exceptions.h>

#include <libdevcore/CommonIO.h>

using namespace std;
using namespace dev;
using namespace dev::solidity::smt;

Z3Interface::Z3Interface():
    m_solver(m_context)
{
    // This needs to be set globally.
    z3::set_param("rewriter.pull_cheap_ite", true);
    // This needs to be set in the context.
    m_context.set("timeout", queryTimeout);
}

void Z3Interface::reset()
{
    m_constants.clear();
    m_functions.clear();
    m_solver.reset();
}

void Z3Interface::push()
{
    m_solver.push();
}

void Z3Interface::pop()
{
    m_solver.pop();
}

void Z3Interface::declareFunction(string _name, Sort _domain, Sort _codomain)
{
    m_functions.insert({_name, m_context.function(_name.c_str(), z3Sort(_domain), z3Sort(_codomain))});
}

void Z3Interface::declareInteger(string _name)
{
    m_constants.insert({_name, m_context.int_const(_name.c_str())});
}

void Z3Interface::declareBool(string _name)
{
    m_constants.insert({_name, m_context.bool_const(_name.c_str())});
}

void Z3Interface::addAssertion(Expression const& _expr)
{
    m_solver.add(toZ3Expr(_expr));
}

pair<CheckResult, vector<string>> Z3Interface::check(vector<Expression> const& _expressionsToEvaluate)
{
    CheckResult result;
    vector<string> values;
    try
    {
        switch (m_solver.check())
        {
        case z3::check_result::sat:
            result = CheckResult::SATISFIABLE;
            break;
        case z3::check_result::unsat:
            result = CheckResult::UNSATISFIABLE;
            break;
        case z3::check_result::unknown:
            result = CheckResult::UNKNOWN;
            break;
        default:
            solAssert(false, "");
        }

        if (result == CheckResult::SATISFIABLE && !_expressionsToEvaluate.empty())
        {
            z3::model m = m_solver.get_model();
            for (Expression const& e: _expressionsToEvaluate)
                values.push_back(toString(m.eval(toZ3Expr(e))));
        }
    }
    catch (z3::exception const&)
    {
        result = CheckResult::ERROR;
        values.clear();
    }

    return make_pair(result, values);
}

z3::expr Z3Interface::toZ3Expr(Expression const& _expr)
{
    if (_expr.arguments.empty() && m_constants.count(_expr.name))
        return m_constants.at(_expr.name);
    z3::expr_vector arguments(m_context);
    for (auto const& arg: _expr.arguments)
        arguments.push_back(toZ3Expr(arg));

    string const& n = _expr.name;
    if (m_functions.count(n))
        return m_functions.at(n)(arguments);
    else if (m_constants.count(n))
    {
        solAssert(arguments.empty(), "");
        return m_constants.at(n);
    }
    else if (arguments.empty())
    {
        if (n == "true")
            return m_context.bool_val(true);
        else if (n == "false")
            return m_context.bool_val(false);
        else
            // We assume it is an integer...
            return m_context.int_val(n.c_str());
    }

    solAssert(_expr.hasCorrectArity(), "");
    if (n == "ite")
        return z3::ite(arguments[0], arguments[1], arguments[2]);
    else if (n == "not")
        return !arguments[0];
    else if (n == "and")
        return arguments[0] && arguments[1];
    else if (n == "or")
        return arguments[0] || arguments[1];
    else if (n == "=")
        return arguments[0] == arguments[1];
    else if (n == "<")
        return arguments[0] < arguments[1];
    else if (n == "<=")
        return arguments[0] <= arguments[1];
    else if (n == ">")
        return arguments[0] > arguments[1];
    else if (n == ">=")
        return arguments[0] >= arguments[1];
    else if (n == "+")
        return arguments[0] + arguments[1];
    else if (n == "-")
        return arguments[0] - arguments[1];
    else if (n == "*")
        return arguments[0] * arguments[1];
    else if (n == "/")
        return arguments[0] / arguments[1];
    // Cannot reach here.
    solAssert(false, "");
    return arguments[0];
}

z3::sort Z3Interface::z3Sort(Sort _sort)
{
    switch (_sort)
    {
    case Sort::Bool:
        return m_context.bool_sort();
    case Sort::Int:
        return m_context.int_sort();
    default:
        break;
    }
    solAssert(false, "");
    // Cannot be reached.
    return m_context.int_sort();
}