solidity/libyul/optimiser/ExpressionSimplifier.cpp

56 lines
1.9 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/>.
*/
/**
* Optimiser component that uses the simplification rules to simplify expressions.
*/
#include <libyul/optimiser/ExpressionSimplifier.h>
#include <libyul/optimiser/SimplificationRules.h>
#include <libyul/optimiser/Semantics.h>
#include <libyul/optimiser/SSAValueTracker.h>
#include <libyul/AsmData.h>
#include <libdevcore/CommonData.h>
using namespace std;
using namespace dev;
using namespace yul;
void ExpressionSimplifier::visit(Expression& _expression)
{
ASTModifier::visit(_expression);
while (auto match = SimplificationRules::findFirstMatch(_expression, m_dialect, m_value))
{
// Do not apply the rule if it removes non-constant parts of the expression.
// TODO: The check could actually be less strict than "movable".
// We only require "Does not cause side-effects".
// Note: References to variables that are only assigned once are always movable,
// so if the value of the variable is not movable, the expression that references
// the variable still is.
if (match->removesNonConstants && !MovableChecker(m_dialect, _expression).movable())
return;
_expression = match->action().toExpression(locationOf(_expression));
}
}
void ExpressionSimplifier::run(Dialect const& _dialect, Block& _ast)
{
ExpressionSimplifier{_dialect}(_ast);
}