mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
/*
|
|
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/>.
|
|
*/
|
|
/** @file GasMeter.cpp
|
|
* @author Christian <c@ethdev.com>
|
|
* @date 2015
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <ostream>
|
|
#include <tuple>
|
|
#include <libevmasm/ExpressionClasses.h>
|
|
#include <libevmasm/AssemblyItem.h>
|
|
#include <libethcore/ChainOperationParams.h>
|
|
|
|
namespace dev
|
|
{
|
|
namespace eth
|
|
{
|
|
|
|
class KnownState;
|
|
|
|
// TODO: FIXME: HOMESTEAD: XXX: @chfast populate m_schedule from an ExtVMFace instance via ExtVMFace::evmSchedule.
|
|
|
|
/**
|
|
* Class that helps computing the maximum gas consumption for instructions.
|
|
* Has to be initialized with a certain known state that will be automatically updated for
|
|
* each call to estimateMax. These calls have to supply strictly subsequent AssemblyItems.
|
|
* A new gas meter has to be constructed (with a new state) for control flow changes.
|
|
*/
|
|
class GasMeter
|
|
{
|
|
public:
|
|
struct GasConsumption
|
|
{
|
|
GasConsumption(u256 _value = 0, bool _infinite = false): value(_value), isInfinite(_infinite) {}
|
|
static GasConsumption infinite() { return GasConsumption(0, true); }
|
|
|
|
GasConsumption& operator+=(GasConsumption const& _other);
|
|
bool operator<(GasConsumption const& _other) const { return this->tuple() < _other.tuple(); }
|
|
|
|
std::tuple<bool const&, u256 const&> tuple() const { return std::tie(isInfinite, value); }
|
|
|
|
u256 value;
|
|
bool isInfinite;
|
|
};
|
|
|
|
/// Constructs a new gas meter given the current state.
|
|
explicit GasMeter(std::shared_ptr<KnownState> const& _state, u256 const& _largestMemoryAccess = 0):
|
|
m_state(_state), m_largestMemoryAccess(_largestMemoryAccess) {}
|
|
|
|
/// @returns an upper bound on the gas consumed by the given instruction and updates
|
|
/// the state.
|
|
GasConsumption estimateMax(AssemblyItem const& _item);
|
|
|
|
u256 const& largestMemoryAccess() const { return m_largestMemoryAccess; }
|
|
|
|
u256 runGas(Instruction _instruction) const { return runGas(_instruction, m_schedule); }
|
|
static u256 runGas(Instruction _instruction, EVMSchedule const& _es);
|
|
|
|
private:
|
|
/// @returns _multiplier * (_value + 31) / 32, if _value is a known constant and infinite otherwise.
|
|
GasConsumption wordGas(u256 const& _multiplier, ExpressionClasses::Id _value);
|
|
/// @returns the gas needed to access the given memory position.
|
|
/// @todo this assumes that memory was never accessed before and thus over-estimates gas usage.
|
|
GasConsumption memoryGas(ExpressionClasses::Id _position);
|
|
/// @returns the memory gas for accessing the memory at a specific offset for a number of bytes
|
|
/// given as values on the stack at the given relative positions.
|
|
GasConsumption memoryGas(int _stackPosOffset, int _stackPosSize);
|
|
|
|
std::shared_ptr<KnownState> m_state;
|
|
/// Largest point where memory was accessed since the creation of this object.
|
|
u256 m_largestMemoryAccess;
|
|
|
|
EVMSchedule m_schedule;
|
|
};
|
|
|
|
inline std::ostream& operator<<(std::ostream& _str, GasMeter::GasConsumption const& _consumption)
|
|
{
|
|
if (_consumption.isInfinite)
|
|
return _str << "[???]";
|
|
else
|
|
return _str << std::dec << _consumption.value;
|
|
}
|
|
|
|
|
|
}
|
|
}
|