solidity/libyul/optimiser/CircularReferencesPruner.cpp

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/*
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/>.
*/
#include <libyul/optimiser/CircularReferencesPruner.h>
#include <libyul/optimiser/CallGraphGenerator.h>
#include <libyul/optimiser/OptimizerUtilities.h>
#include <libyul/AsmData.h>
#include <libsolutil/Algorithms.h>
using namespace std;
using namespace solidity::yul;
void CircularReferencesPruner::run(OptimiserStepContext& _context, Block& _ast)
{
CircularReferencesPruner{_context.reservedIdentifiers}(_ast);
}
void CircularReferencesPruner::operator()(Block& _block)
{
set<YulString> functionsToKeep =
functionsCalledFromOutermostContext(CallGraphGenerator::callGraph(_block));
for (auto&& statement: _block.statements)
if (holds_alternative<FunctionDefinition>(statement))
{
FunctionDefinition const& funDef = std::get<FunctionDefinition>(statement);
if (!functionsToKeep.count(funDef.name))
statement = Block{};
}
removeEmptyBlocks(_block);
}
set<YulString> CircularReferencesPruner::functionsCalledFromOutermostContext(CallGraph const& _callGraph)
{
set<YulString> verticesToTraverse = m_reservedIdentifiers;
verticesToTraverse.insert(YulString(""));
return util::BreadthFirstSearch<YulString>{{verticesToTraverse.begin(), verticesToTraverse.end()}}.run(
[&_callGraph](YulString _function, auto&& _addChild) {
if (_callGraph.functionCalls.count(_function))
for (auto const& callee: _callGraph.functionCalls.at(_function))
if (_callGraph.functionCalls.count(callee))
_addChild(callee);
}).visited;
}