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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/>.
*/
/**
* @author Christian <c@ethdev.com>
* @date 2015
* Gas consumption estimator working alongside the AST.
*/
#include "StructuralGasEstimator.h"
#include <map>
#include <functional>
#include <memory>
#include <libevmasm/ControlFlowGraph.h>
#include <libevmasm/KnownState.h>
#include <libsolidity/AST.h>
#include <libsolidity/ASTVisitor.h>
using namespace std;
using namespace dev;
using namespace dev::eth;
using namespace dev::solidity;
StructuralGasEstimator::ASTGasConsumptionSelfAccumulated StructuralGasEstimator::performEstimation(
AssemblyItems const& _items,
vector<ASTNode const*> const& _ast
)
{
solAssert(std::count(_ast.begin(), _ast.end(), nullptr) == 0, "");
map<SourceLocation, GasMeter::GasConsumption> particularCosts;
ControlFlowGraph cfg(_items);
for (BasicBlock const& block: cfg.optimisedBlocks())
{
assertThrow(!!block.startState, OptimizerException, "");
GasMeter meter(block.startState->copy());
auto const end = _items.begin() + block.end;
for (auto iter = _items.begin() + block.begin; iter != end; ++iter)
particularCosts[iter->getLocation()] += meter.estimateMax(*iter);
}
set<ASTNode const*> finestNodes = finestNodesAtLocation(_ast);
ASTGasConsumptionSelfAccumulated gasCosts;
auto onNode = [&](ASTNode const& _node)
{
if (!finestNodes.count(&_node))
return true;
gasCosts[&_node][0] = gasCosts[&_node][1] = particularCosts[_node.getLocation()];
return true;
};
auto onEdge = [&](ASTNode const& _parent, ASTNode const& _child)
{
gasCosts[&_parent][1] += gasCosts[&_child][1];
};
ASTReduce folder(onNode, onEdge);
for (ASTNode const* ast: _ast)
ast->accept(folder);
return gasCosts;
}
map<ASTNode const*, GasMeter::GasConsumption> StructuralGasEstimator::breakToStatementLevel(
ASTGasConsumptionSelfAccumulated const& _gasCosts,
vector<ASTNode const*> const& _roots
)
{
solAssert(std::count(_roots.begin(), _roots.end(), nullptr) == 0, "");
// first pass: statementDepth[node] is the distance from the deepend statement to node
// in direction of the tree root (or undefined if not possible)
map<ASTNode const*, int> statementDepth;
auto onNodeFirstPass = [&](ASTNode const& _node)
{
if (dynamic_cast<Statement const*>(&_node))
statementDepth[&_node] = 0;
return true;
};
auto onEdgeFirstPass = [&](ASTNode const& _parent, ASTNode const& _child)
{
if (statementDepth.count(&_child))
statementDepth[&_parent] = max(statementDepth[&_parent], statementDepth[&_child] + 1);
};
ASTReduce firstPass(onNodeFirstPass, onEdgeFirstPass);
for (ASTNode const* node: _roots)
node->accept(firstPass);
// we use the location of a node if
// - its statement depth is 0 or
// - its statement depth is undefined but the parent's statement depth is at least 1
map<ASTNode const*, GasMeter::GasConsumption> gasCosts;
auto onNodeSecondPass = [&](ASTNode const& _node)
{
return statementDepth.count(&_node);
};
auto onEdgeSecondPass = [&](ASTNode const& _parent, ASTNode const& _child)
{
bool useNode = false;
if (statementDepth.count(&_child))
useNode = statementDepth[&_child] == 0;
else
useNode = statementDepth.count(&_parent) && statementDepth.at(&_parent) > 0;
if (useNode)
gasCosts[&_child] = _gasCosts.at(&_child)[1];
};
ASTReduce secondPass(onNodeSecondPass, onEdgeSecondPass);
for (ASTNode const* node: _roots)
node->accept(secondPass);
// gasCosts should only contain non-overlapping locations
return gasCosts;
}
set<ASTNode const*> StructuralGasEstimator::finestNodesAtLocation(
vector<ASTNode const*> const& _roots
)
{
map<SourceLocation, ASTNode const*> locations;
set<ASTNode const*> nodes;
SimpleASTVisitor visitor(function<bool(ASTNode const&)>(), [&](ASTNode const& _n)
{
if (!locations.count(_n.getLocation()))
{
locations[_n.getLocation()] = &_n;
nodes.insert(&_n);
}
});
for (ASTNode const* root: _roots)
root->accept(visitor);
return nodes;
}
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