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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/>.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
namespace yul
{
class AssignmentCounter;
/**
* Reverses the SSA transformation.
*
* In particular, the SSA transform will rewrite
*
* a := E
*
* to
*
* let a_1 := E
* a := a_1
*
* To undo this kind of transformation, the SSAReverser changes this back to
*
* a := E
* let a_1 := a
*
* Secondly, the SSA transform will rewrite
*
* let a := E
* to
*
* let a_1 := E
* let a := a_1
*
* To undo this kind of transformation, the SSAReverser changes this back to
*
* let a := E
* let a_1 := a
*
* After that the CSE can replace references of a_1 by references to a,
* after which the unused pruner can remove the declaration of a_1.
*
* Prerequisites: Disambiguator
*
*/
class SSAReverser: public ASTModifier
{
public:
using ASTModifier::operator();
void operator()(Block& _block) override;
static void run(Block& _block);
private:
SSAReverser(AssignmentCounter const& _assignmentCounter): m_assignmentCounter(_assignmentCounter) {}
AssignmentCounter const& m_assignmentCounter;
};
}
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