solidity/libsolidity/interface/GasEstimator.cpp

125 lines
3.6 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/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* @author Christian <c@ethdev.com>
* @date 2015
* Gas consumption estimator working alongside the AST.
*/
#include <libsolidity/interface/GasEstimator.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/ast/ASTVisitor.h>
#include <libsolidity/codegen/CompilerUtils.h>
#include <libevmasm/ControlFlowGraph.h>
#include <libevmasm/KnownState.h>
#include <libevmasm/PathGasMeter.h>
#include <libsolutil/FunctionSelector.h>
#include <libsolutil/Keccak256.h>
#include <functional>
#include <map>
#include <memory>
using namespace solidity;
using namespace solidity::evmasm;
using namespace solidity::frontend;
using namespace solidity::langutil;
GasEstimator::GasConsumption GasEstimator::functionalEstimation(
AssemblyItems const& _items,
std::string const& _signature
) const
{
auto state = std::make_shared<KnownState>();
if (!_signature.empty())
{
ExpressionClasses& classes = state->expressionClasses();
using Id = ExpressionClasses::Id;
using Ids = std::vector<Id>;
Id hashValue = classes.find(u256(util::selectorFromSignatureU32(_signature)));
Id calldata = classes.find(Instruction::CALLDATALOAD, Ids{classes.find(u256(0))});
if (!m_evmVersion.hasBitwiseShifting())
// div(calldataload(0), 1 << 224) equals to hashValue
classes.forceEqual(
hashValue,
Instruction::DIV,
Ids{calldata, classes.find(u256(1) << 224)}
);
else
// shr(0xe0, calldataload(0)) equals to hashValue
classes.forceEqual(
hashValue,
Instruction::SHR,
Ids{classes.find(u256(0xe0)), calldata}
);
// lt(calldatasize(), 4) equals to 0 (ignore the shortcut for fallback functions)
classes.forceEqual(
classes.find(u256(0)),
Instruction::LT,
Ids{classes.find(Instruction::CALLDATASIZE), classes.find(u256(4))}
);
}
return PathGasMeter::estimateMax(_items, m_evmVersion, 0, state);
}
GasEstimator::GasConsumption GasEstimator::functionalEstimation(
AssemblyItems const& _items,
size_t const& _offset,
FunctionDefinition const& _function
) const
{
auto state = std::make_shared<KnownState>();
unsigned parametersSize = CompilerUtils::sizeOnStack(_function.parameters());
if (parametersSize > 16)
return GasConsumption::infinite();
// Store an invalid return value on the stack, so that the path estimator breaks upon reaching
// the return jump.
AssemblyItem invalidTag(PushTag, u256(-0x10));
state->feedItem(invalidTag, true);
if (parametersSize > 0)
state->feedItem(swapInstruction(parametersSize));
return PathGasMeter::estimateMax(_items, m_evmVersion, _offset, state);
}
std::set<ASTNode const*> GasEstimator::finestNodesAtLocation(
std::vector<ASTNode const*> const& _roots
)
{
std::map<SourceLocation, ASTNode const*> locations;
std::set<ASTNode const*> nodes;
SimpleASTVisitor visitor(std::function<bool(ASTNode const&)>(), [&](ASTNode const& _n)
{
if (!locations.count(_n.location()))
{
locations[_n.location()] = &_n;
nodes.insert(&_n);
}
});
for (ASTNode const* root: _roots)
root->accept(visitor);
return nodes;
}