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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/>.
*/
/**
* Optimiser component that undoes what the ExpressionSplitter did, i.e.
* it more or less inlines variable declarations.
*/
#include <libyul/optimiser/ExpressionJoiner.h>
#include <libyul/optimiser/NameCollector.h>
#include <libyul/optimiser/Utilities.h>
#include <libyul/Exceptions.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libdevcore/CommonData.h>
#include <boost/range/adaptor/reversed.hpp>
using namespace std;
using namespace dev;
using namespace dev::yul;
using namespace dev::solidity;
void ExpressionJoiner::operator()(FunctionalInstruction& _instruction)
{
handleArguments(_instruction.arguments);
}
void ExpressionJoiner::operator()(FunctionCall& _funCall)
{
handleArguments(_funCall.arguments);
}
void ExpressionJoiner::operator()(If& _if)
{
visit(*_if.condition);
(*this)(_if.body);
}
void ExpressionJoiner::operator()(Switch& _switch)
{
visit(*_switch.expression);
for (auto& _case: _switch.cases)
// Do not visit the case expression, nothing to join there.
(*this)(_case.body);
}
void ExpressionJoiner::operator()(Block& _block)
{
resetLatestStatementPointer();
for (size_t i = 0; i < _block.statements.size(); ++i)
{
visit(_block.statements[i]);
m_currentBlock = &_block;
m_latestStatementInBlock = i;
}
removeEmptyBlocks(_block);
resetLatestStatementPointer();
}
void ExpressionJoiner::visit(Expression& _e)
{
if (_e.type() == typeid(Identifier))
{
Identifier const& identifier = boost::get<Identifier>(_e);
if (isLatestStatementVarDeclOf(identifier) && m_references[identifier.name] == 1)
{
VariableDeclaration& varDecl = boost::get<VariableDeclaration>(*latestStatement());
assertThrow(varDecl.variables.size() == 1, OptimizerException, "");
assertThrow(varDecl.value, OptimizerException, "");
_e = std::move(*varDecl.value);
// Delete the variable declaration (also get the moved-from structure back into a sane state)
*latestStatement() = Block();
decrementLatestStatementPointer();
}
}
else
ASTModifier::visit(_e);
}
void ExpressionJoiner::run(Block& _ast)
{
ExpressionJoiner{_ast}(_ast);
}
ExpressionJoiner::ExpressionJoiner(Block& _ast)
{
ReferencesCounter counter;
counter(_ast);
m_references = counter.references();
}
void ExpressionJoiner::handleArguments(vector<Expression>& _arguments)
{
// We have to fill from left to right, but we can only
// fill if everything to the right is just an identifier
// or a literal.
// Also we only descend into function calls if everything
// on the right is an identifier or literal.
size_t i = _arguments.size();
for (Expression const& arg: _arguments | boost::adaptors::reversed)
{
--i;
if (arg.type() != typeid(Identifier) && arg.type() != typeid(Literal))
break;
}
// i points to the last element that is neither an identifier nor a literal,
// or to the first element if all of them are identifiers or literals.
for (; i < _arguments.size(); ++i)
visit(_arguments.at(i));
}
void ExpressionJoiner::decrementLatestStatementPointer()
{
if (!m_currentBlock)
return;
if (m_latestStatementInBlock > 0)
--m_latestStatementInBlock;
else
resetLatestStatementPointer();
}
void ExpressionJoiner::resetLatestStatementPointer()
{
m_currentBlock = nullptr;
m_latestStatementInBlock = size_t(-1);
}
Statement* ExpressionJoiner::latestStatement()
{
if (!m_currentBlock)
return nullptr;
else
return &m_currentBlock->statements.at(m_latestStatementInBlock);
}
bool ExpressionJoiner::isLatestStatementVarDeclOf(Identifier const& _identifier)
{
Statement const* statement = latestStatement();
if (!statement || statement->type() != typeid(VariableDeclaration))
return false;
VariableDeclaration const& varDecl = boost::get<VariableDeclaration>(*statement);
if (varDecl.variables.size() != 1 || !varDecl.value)
return false;
return varDecl.variables.at(0).name == _identifier.name;
}
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