solidity/libyul/optimiser/Semantics.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/>.
*/
/**
* Specific AST walkers that collect semantical facts.
*/
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#include <libyul/optimiser/Semantics.h>
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#include <libyul/Exceptions.h>
#include <libyul/AsmData.h>
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#include <libyul/Dialect.h>
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#include <libyul/backends/evm/EVMDialect.h>
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#include <libevmasm/SemanticInformation.h>
#include <libdevcore/CommonData.h>
using namespace std;
using namespace dev;
using namespace yul;
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MovableChecker::MovableChecker(Dialect const& _dialect):
m_dialect(_dialect)
{
}
MovableChecker::MovableChecker(Dialect const& _dialect, Expression const& _expression):
MovableChecker(_dialect)
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{
visit(_expression);
}
void MovableChecker::operator()(Identifier const& _identifier)
{
ASTWalker::operator()(_identifier);
m_variableReferences.emplace(_identifier.name);
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}
void MovableChecker::operator()(FunctionalInstruction const& _instr)
{
ASTWalker::operator()(_instr);
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if (!eth::SemanticInformation::movable(_instr.instruction))
m_movable = false;
if (!eth::SemanticInformation::sideEffectFree(_instr.instruction))
m_sideEffectFree = false;
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}
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void MovableChecker::operator()(FunctionCall const& _functionCall)
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{
ASTWalker::operator()(_functionCall);
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if (BuiltinFunction const* f = m_dialect.builtin(_functionCall.functionName.name))
{
if (!f->movable)
m_movable = false;
if (!f->sideEffectFree)
m_sideEffectFree = false;
}
else
{
m_movable = false;
m_sideEffectFree = false;
}
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}
void MovableChecker::visit(Statement const&)
{
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assertThrow(false, OptimizerException, "Movability for statement requested.");
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}
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pair<TerminationFinder::ControlFlow, size_t> TerminationFinder::firstUnconditionalControlFlowChange(
vector<Statement> const& _statements
)
{
for (size_t i = 0; i < _statements.size(); ++i)
{
ControlFlow controlFlow = controlFlowKind(_statements[i]);
if (controlFlow != ControlFlow::FlowOut)
return {controlFlow, i};
}
return {ControlFlow::FlowOut, size_t(-1)};
}
TerminationFinder::ControlFlow TerminationFinder::controlFlowKind(Statement const& _statement)
{
if (
_statement.type() == typeid(ExpressionStatement) &&
isTerminatingBuiltin(boost::get<ExpressionStatement>(_statement))
)
return ControlFlow::Terminate;
else if (_statement.type() == typeid(Break))
return ControlFlow::Break;
else if (_statement.type() == typeid(Continue))
return ControlFlow::Continue;
else
return ControlFlow::FlowOut;
}
bool TerminationFinder::isTerminatingBuiltin(ExpressionStatement const& _exprStmnt)
{
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if (_exprStmnt.expression.type() == typeid(FunctionalInstruction))
return eth::SemanticInformation::terminatesControlFlow(
boost::get<FunctionalInstruction>(_exprStmnt.expression).instruction
);
else if (_exprStmnt.expression.type() == typeid(FunctionCall))
if (auto const* dialect = dynamic_cast<EVMDialect const*>(&m_dialect))
if (auto const* builtin = dialect->builtin(boost::get<FunctionCall>(_exprStmnt.expression).functionName.name))
if (builtin->instruction)
return eth::SemanticInformation::terminatesControlFlow(*builtin->instruction);
return false;
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}