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Structural gas estimator.

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chriseth 2015-05-06 10:43:59 +02:00
parent b9d7387e7a
commit 4d62c463d1
2 changed files with 171 additions and 0 deletions
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104
GasMeter.cpp Normal file
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/*
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
*/
#include "GasMeter.h"
#include <libevmcore/Params.h>
using namespace std;
using namespace dev;
using namespace dev::eth;
GasMeter::GasConsumption& GasMeter::GasConsumption::operator+=(GasConsumption const& _other)
{
isInfinite = isInfinite || _other.isInfinite;
if (isInfinite)
return *this;
bigint v = bigint(value) + _other.value;
if (v > std::numeric_limits<u256>::max())
isInfinite = true;
else
value = u256(v);
return *this;
}
GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item)
{
switch (_item.type()) {
case Push:
case PushTag:
return runGas(Instruction::PUSH1);
case Tag:
return runGas(Instruction::JUMPDEST);
case Operation:
{
GasConsumption gas = runGas(_item.instruction());
switch (_item.instruction())
{
case Instruction::SSTORE:
// @todo logic can be improved
gas += c_sstoreSetGas;
break;
case Instruction::SLOAD:
gas += c_sloadGas;
break;
case Instruction::MSTORE:
case Instruction::MSTORE8:
case Instruction::MLOAD:
case Instruction::RETURN:
case Instruction::SHA3:
case Instruction::CALLDATACOPY:
case Instruction::CODECOPY:
case Instruction::EXTCODECOPY:
case Instruction::LOG0:
case Instruction::LOG1:
case Instruction::LOG2:
case Instruction::LOG3:
case Instruction::LOG4:
case Instruction::CALL:
case Instruction::CALLCODE:
case Instruction::CREATE:
case Instruction::EXP:
// @todo logic can be improved
gas = GasConsumption::infinite();
break;
default:
break;
}
return gas;
break;
}
default:
break;
}
return GasConsumption::infinite();
}
GasMeter::GasConsumption GasMeter::runGas(Instruction _instruction)
{
if (_instruction == Instruction::JUMPDEST)
return GasConsumption(1);
int tier = instructionInfo(_instruction).gasPriceTier;
return tier == InvalidTier ? GasConsumption::infinite() : c_tierStepGas[tier];
}

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/*
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 <libevmasm/AssemblyItem.h>
namespace dev
{
namespace eth
{
/**
* Class that helps computing the maximum gas consumption for instructions.
*/
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& _otherS);
std::ostream& operator<<(std::ostream& _str) const;
u256 value;
bool isInfinite;
};
/// Returns an upper bound on the gas consumed by the given instruction.
GasConsumption estimateMax(AssemblyItem const& _item);
private:
static GasConsumption runGas(Instruction _instruction);
};
inline std::ostream& operator<<(std::ostream& _str, GasMeter::GasConsumption const& _consumption)
{
if (_consumption.isInfinite)
return _str << "inf";
else
return _str << _consumption.value;
}
}
}