path: root/test/libsolidity/GasMeter.cpp

/*
    This file is part of cpp-ethereum.

    cpp-ethereum 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.

    cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Unit tests for the gas estimator.
 */

#include <test/libsolidity/SolidityExecutionFramework.h>
#include <libevmasm/GasMeter.h>
#include <libevmasm/KnownState.h>
#include <libevmasm/PathGasMeter.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/interface/GasEstimator.h>
#include <libsolidity/interface/SourceReferenceFormatter.h>

using namespace std;
using namespace dev::eth;
using namespace dev::solidity;

namespace dev
{
namespace solidity
{
namespace test
{

class GasMeterTestFramework: public ExecutionFramework
{
public:
    GasMeterTestFramework() { }
    void compile(string const& _sourceCode)
    {
        m_compiler.setSource(_sourceCode);
        ETH_TEST_REQUIRE_NO_THROW(m_compiler.compile(), "Compiling contract failed");

        AssemblyItems const* items = m_compiler.runtimeAssemblyItems("");
        ASTNode const& sourceUnit = m_compiler.ast();
        BOOST_REQUIRE(items != nullptr);
        m_gasCosts = GasEstimator::breakToStatementLevel(
            GasEstimator::structuralEstimation(*items, vector<ASTNode const*>({&sourceUnit})),
            {&sourceUnit}
        );
    }

    void testCreationTimeGas(string const& _sourceCode)
    {
        EVMSchedule schedule;

        compileAndRun(_sourceCode);
        auto state = make_shared<KnownState>();
        PathGasMeter meter(*m_compiler.assemblyItems());
        GasMeter::GasConsumption gas = meter.estimateMax(0, state);
        u256 bytecodeSize(m_compiler.runtimeObject().bytecode.size());
        // costs for deployment
        gas += bytecodeSize * schedule.createDataGas;
        // costs for transaction
        gas += gasForTransaction(m_compiler.object().bytecode, true);

        BOOST_REQUIRE(!gas.isInfinite);
        BOOST_CHECK(gas.value == m_gasUsed);
    }

    /// Compares the gas computed by PathGasMeter for the given signature (but unknown arguments)
    /// against the actual gas usage computed by the VM on the given set of argument variants.
    void testRunTimeGas(string const& _sig, vector<bytes> _argumentVariants)
    {
        u256 gasUsed = 0;
        GasMeter::GasConsumption gas;
        FixedHash<4> hash(dev::sha3(_sig));
        for (bytes const& arguments: _argumentVariants)
        {
            sendMessage(hash.asBytes() + arguments, false, 0);
            gasUsed = max(gasUsed, m_gasUsed);
            gas = max(gas, gasForTransaction(hash.asBytes() + arguments, false));
        }

        gas += GasEstimator::functionalEstimation(
            *m_compiler.runtimeAssemblyItems(),
            _sig
        );
        BOOST_REQUIRE(!gas.isInfinite);
        BOOST_CHECK(gas.value == m_gasUsed);
    }

    static GasMeter::GasConsumption gasForTransaction(bytes const& _data, bool _isCreation)
    {
        EVMSchedule schedule;
        GasMeter::GasConsumption gas = _isCreation ? schedule.txCreateGas : schedule.txGas;
        for (auto i: _data)
            gas += i != 0 ? schedule.txDataNonZeroGas : schedule.txDataZeroGas;
        return gas;
    }

protected:
    map<ASTNode const*, eth::GasMeter::GasConsumption> m_gasCosts;
};

BOOST_FIXTURE_TEST_SUITE(GasMeterTests, GasMeterTestFramework)

BOOST_AUTO_TEST_CASE(non_overlapping_filtered_costs)
{
    char const* sourceCode = R"(
        contract test {
            bytes x;
            function f(uint a) returns (uint b) {
                x.length = a;
                for (; a < 200; ++a) {
                    x[a] = 9;
                    b = a * a;
                }
                return f(a - 1);
            }
        }
    )";
    compile(sourceCode);
    for (auto first = m_gasCosts.cbegin(); first != m_gasCosts.cend(); ++first)
    {
        auto second = first;
        for (++second; second != m_gasCosts.cend(); ++second)
            if (first->first->location().intersects(second->first->location()))
            {
                BOOST_CHECK_MESSAGE(false, "Source locations should not overlap!");
                auto scannerFromSource = [&](string const&) -> Scanner const& { return m_compiler.scanner(); };
                SourceReferenceFormatter::printSourceLocation(cout, &first->first->location(), scannerFromSource);
                SourceReferenceFormatter::printSourceLocation(cout, &second->first->location(), scannerFromSource);
            }
    }
}

BOOST_AUTO_TEST_CASE(simple_contract)
{
    // Tests a simple "deploy contract" code without constructor. The actual contract is not relevant.
    char const* sourceCode = R"(
        contract test {
            bytes32 public shaValue;
            function f(uint a) {
                shaValue = sha3(a);
            }
        }
    )";
    testCreationTimeGas(sourceCode);
}

BOOST_AUTO_TEST_CASE(store_sha3)
{
    char const* sourceCode = R"(
        contract test {
            bytes32 public shaValue;
            function test(uint a) {
                shaValue = sha3(a);
            }
        }
    )";
    testCreationTimeGas(sourceCode);
}

BOOST_AUTO_TEST_CASE(updating_store)
{
    char const* sourceCode = R"(
        contract test {
            uint data;
            uint data2;
            function test() {
                data = 1;
                data = 2;
                data2 = 0;
            }
        }
    )";
    testCreationTimeGas(sourceCode);
}

BOOST_AUTO_TEST_CASE(branches)
{
    char const* sourceCode = R"(
        contract test {
            uint data;
            uint data2;
            function f(uint x) {
                if (x > 7)
                    data2 = 1;
                else
                    data = 1;
            }
        }
    )";
    testCreationTimeGas(sourceCode);
    testRunTimeGas("f(uint256)", vector<bytes>{encodeArgs(2), encodeArgs(8)});
}

BOOST_AUTO_TEST_CASE(function_calls)
{
    char const* sourceCode = R"(
        contract test {
            uint data;
            uint data2;
            function f(uint x) {
                if (x > 7)
                    data2 = g(x**8) + 1;
                else
                    data = 1;
            }
            function g(uint x) internal returns (uint) {
                return data2;
            }
        }
    )";
    testCreationTimeGas(sourceCode);
    testRunTimeGas("f(uint256)", vector<bytes>{encodeArgs(2), encodeArgs(8)});
}

BOOST_AUTO_TEST_CASE(multiple_external_functions)
{
    char const* sourceCode = R"(
        contract test {
            uint data;
            uint data2;
            function f(uint x) {
                if (x > 7)
                    data2 = g(x**8) + 1;
                else
                    data = 1;
            }
            function g(uint x) returns (uint) {
                return data2;
            }
        }
    )";
    testCreationTimeGas(sourceCode);
    testRunTimeGas("f(uint256)", vector<bytes>{encodeArgs(2), encodeArgs(8)});
    testRunTimeGas("g(uint256)", vector<bytes>{encodeArgs(2)});
}

BOOST_AUTO_TEST_SUITE_END()

}
}
}