/* 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/>. */ /** @file PathGasMeter.cpp * @author Christian <c@ethdev.com> * @date 2015 */ #pragma once #include <libevmasm/GasMeter.h> #include <libsolidity/interface/EVMVersion.h> #include <set> #include <vector> #include <memory> namespace dev { namespace eth { class KnownState; struct GasPath { size_t index = 0; std::shared_ptr<KnownState> state; u256 largestMemoryAccess; GasMeter::GasConsumption gas; std::set<size_t> visitedJumpdests; }; /** * Computes an upper bound on the gas usage of a computation starting at a certain position in * a list of AssemblyItems in a given state until the computation stops. * Can be used to estimate the gas usage of functions on any given input. */ class PathGasMeter { public: explicit PathGasMeter(AssemblyItems const& _items, solidity::EVMVersion _evmVersion); GasMeter::GasConsumption estimateMax(size_t _startIndex, std::shared_ptr<KnownState> const& _state); private: /// Adds a new path item to the queue, but only if we do not already have /// a higher gas usage at that point. /// This is not exact as different state might influence higher gas costs at a later /// point in time, but it greatly reduces computational overhead. void queue(std::unique_ptr<GasPath>&& _newPath); GasMeter::GasConsumption handleQueueItem(); /// Map of jumpdest -> gas path, so not really a queue. We only have one queued up /// item per jumpdest, because of the behaviour of `queue` above. std::map<size_t, std::unique_ptr<GasPath>> m_queue; std::map<size_t, GasMeter::GasConsumption> m_highestGasUsagePerJumpdest; std::map<u256, size_t> m_tagPositions; AssemblyItems const& m_items; solidity::EVMVersion m_evmVersion; }; } }