mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
86 lines
2.5 KiB
C++
86 lines
2.5 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file PathGasMeter.cpp
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* @author Christian <c@ethdev.com>
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* @date 2015
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*/
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#pragma once
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#include <libevmasm/GasMeter.h>
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#include <liblangutil/EVMVersion.h>
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#include <set>
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#include <vector>
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#include <memory>
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namespace solidity::evmasm
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{
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class KnownState;
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struct GasPath
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{
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size_t index = 0;
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std::shared_ptr<KnownState> state;
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u256 largestMemoryAccess;
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GasMeter::GasConsumption gas;
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std::set<size_t> visitedJumpdests;
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};
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/**
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* Computes an upper bound on the gas usage of a computation starting at a certain position in
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* a list of AssemblyItems in a given state until the computation stops.
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* Can be used to estimate the gas usage of functions on any given input.
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*/
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class PathGasMeter
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{
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public:
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explicit PathGasMeter(AssemblyItems const& _items, langutil::EVMVersion _evmVersion);
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GasMeter::GasConsumption estimateMax(size_t _startIndex, std::shared_ptr<KnownState> const& _state);
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static GasMeter::GasConsumption estimateMax(
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AssemblyItems const& _items,
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langutil::EVMVersion _evmVersion,
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size_t _startIndex,
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std::shared_ptr<KnownState> const& _state
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)
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{
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return PathGasMeter(_items, _evmVersion).estimateMax(_startIndex, _state);
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}
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private:
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/// Adds a new path item to the queue, but only if we do not already have
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/// a higher gas usage at that point.
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/// This is not exact as different state might influence higher gas costs at a later
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/// point in time, but it greatly reduces computational overhead.
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void queue(std::unique_ptr<GasPath>&& _newPath);
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GasMeter::GasConsumption handleQueueItem();
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/// Map of jumpdest -> gas path, so not really a queue. We only have one queued up
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/// item per jumpdest, because of the behaviour of `queue` above.
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std::map<size_t, std::unique_ptr<GasPath>> m_queue;
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std::map<size_t, GasMeter::GasConsumption> m_highestGasUsagePerJumpdest;
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std::map<u256, size_t> m_tagPositions;
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AssemblyItems const& m_items;
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langutil::EVMVersion m_evmVersion;
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};
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}
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