mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
53 lines
1.8 KiB
C++
53 lines
1.8 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/>.
|
|
*/
|
|
// SPDX-License-Identifier: GPL-3.0
|
|
|
|
#pragma once
|
|
|
|
#include <libyul/optimiser/OptimiserStep.h>
|
|
|
|
namespace solidity::yul
|
|
{
|
|
|
|
/**
|
|
* UnusedFunctionParameterPruner: Optimiser step that removes unused parameters in a function.
|
|
*
|
|
* If a parameter is unused, like `c` and `y` in, `function f(a,b,c) -> x, y { x := div(a,b) }`
|
|
*
|
|
* We remove the parameter and create a new "linking" function as follows:
|
|
*
|
|
* `function f(a,b) -> x { x := div(a,b) }`
|
|
* `function f2(a,b,c) -> x, y { x := f(a,b) }`
|
|
*
|
|
* and replace all references to `f` by `f2`.
|
|
* The inliner should be run afterwards to make sure that all references to `f2` are replaced by
|
|
* `f`.
|
|
*
|
|
* Prerequisites: Disambiguator, FunctionHoister, LiteralRematerialiser
|
|
*
|
|
* The step LiteralRematerialiser is not required for correctness. It helps deal with cases such as:
|
|
* `function f(x) -> y { revert(y, y} }` where the literal `y` will be replaced by its value `0`,
|
|
* allowing us to rewrite the function.
|
|
*/
|
|
struct UnusedFunctionParameterPruner
|
|
{
|
|
static constexpr char const* name{"UnusedFunctionParameterPruner"};
|
|
static void run(OptimiserStepContext& _context, Block& _ast);
|
|
};
|
|
|
|
}
|