solidity/libyul/backends/evm/EVMMetrics.h
2020-01-07 15:51:50 +01:00

101 lines
2.8 KiB
C++

/*
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/>.
*/
/**
* Module providing metrics for the optimizer.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
#include <liblangutil/EVMVersion.h>
#include <libevmasm/Instruction.h>
namespace solidity::yul
{
struct EVMDialect;
/**
* Gas meter for expressions only involving literals, identifiers and
* EVM instructions.
*
* Assumes that EXP is not used with exponents larger than a single byte.
* Is not particularly exact for anything apart from arithmetic.
*/
class GasMeter
{
public:
GasMeter(EVMDialect const& _dialect, bool _isCreation, size_t _runs):
m_dialect(_dialect),
m_isCreation{_isCreation},
m_runs(_runs)
{}
/// @returns the full combined costs of deploying and evaluating the expression.
size_t costs(Expression const& _expression) const;
/// @returns the combined costs of deploying and running the instruction, not including
/// the costs for its arguments.
size_t instructionCosts(evmasm::Instruction _instruction) const;
private:
size_t combineCosts(std::pair<size_t, size_t> _costs) const;
EVMDialect const& m_dialect;
bool m_isCreation = false;
size_t m_runs;
};
class GasMeterVisitor: public ASTWalker
{
public:
static std::pair<size_t, size_t> costs(
Expression const& _expression,
EVMDialect const& _dialect,
bool _isCreation
);
static std::pair<size_t, size_t> instructionCosts(
evmasm::Instruction _instruction,
EVMDialect const& _dialect,
bool _isCreation = false
);
public:
GasMeterVisitor(EVMDialect const& _dialect, bool _isCreation):
m_dialect(_dialect),
m_isCreation{_isCreation}
{}
void operator()(FunctionCall const& _funCall) override;
void operator()(Literal const& _literal) override;
void operator()(Identifier const& _identifier) override;
private:
size_t singleByteDataGas() const;
/// Computes the cost of storing and executing the single instruction (excluding its arguments).
/// For EXP, it assumes that the exponent is at most 255.
/// Does not work particularly exact for anything apart from arithmetic.
void instructionCostsInternal(evmasm::Instruction _instruction);
EVMDialect const& m_dialect;
bool m_isCreation = false;
size_t m_runGas = 0;
size_t m_dataGas = 0;
};
}