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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/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* Optimisation stage that removes unused variables and functions.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/YulString.h>
#include <libyul/ControlFlowSideEffects.h>
#include <map>
#include <set>
namespace solidity::yul
{
struct Dialect;
struct OptimiserStepContext;
/**
* Optimisation stage that removes unreachable code
*
* Unreachable code is any code within a block which is preceded by a
* leave, return, invalid, break, continue, selfdestruct or revert or
* a call to a user-defined function that never returns (either due to
* recursion or a call to return / revert / stop).
*
* Function definitions are retained as they might be called by earlier
* code and thus are considered reachable.
*
* Because variables declared in a for loop's init block have their scope extended to the loop body,
* we require ForLoopInitRewriter to run before this step.
*
* Prerequisite: ForLoopInitRewriter, Function Hoister, Function Grouper
*/
class DeadCodeEliminator: public ASTModifier
{
public:
static constexpr char const* name{"DeadCodeEliminator"};
static void run(OptimiserStepContext&, Block& _ast);
using ASTModifier::operator();
void operator()(ForLoop& _for) override;
void operator()(Block& _block) override;
private:
DeadCodeEliminator(
Dialect const& _dialect,
std::map<YulString, ControlFlowSideEffects> _sideEffects
): m_dialect(_dialect), m_functionSideEffects(move(_sideEffects)) {}
Dialect const& m_dialect;
std::map<YulString, ControlFlowSideEffects> m_functionSideEffects;
};
}