mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
75 lines
1.7 KiB
C++
75 lines
1.7 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/>.
|
|
*/
|
|
#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;
|
|
};
|
|
|
|
}
|