mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
86 lines
2.5 KiB
C++
86 lines
2.5 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/>.
|
|
*/
|
|
/**
|
|
* Optimiser component that turns complex expressions into multiple variable
|
|
* declarations.
|
|
*/
|
|
#pragma once
|
|
|
|
#include <libyul/AsmDataForward.h>
|
|
|
|
#include <libyul/optimiser/ASTWalker.h>
|
|
#include <libyul/optimiser/NameDispenser.h>
|
|
|
|
#include <vector>
|
|
|
|
namespace yul
|
|
{
|
|
|
|
class NameCollector;
|
|
struct Dialect;
|
|
|
|
|
|
/**
|
|
* Optimiser component that modifies an AST in place, turning complex
|
|
* expressions into simple expressions and multiple variable declarations.
|
|
*
|
|
* Code of the form
|
|
*
|
|
* sstore(mul(x, 4), mload(y))
|
|
*
|
|
* is transformed into
|
|
*
|
|
* let a1 := mload(y)
|
|
* let a2 := mul(x, 4)
|
|
* sstore(a2, a1)
|
|
*
|
|
* The transformation is not applied to loop conditions, because the loop control flow
|
|
* does not allow "outlining" the inner expressions in all cases.
|
|
*
|
|
* The final program should be in a form such that with the exception of a loop condition,
|
|
* function calls can only appear in the right-hand side of a variable declaration,
|
|
* assignments or expression statements and all arguments have to be constants or variables.
|
|
*/
|
|
class ExpressionSplitter: public ASTModifier
|
|
{
|
|
public:
|
|
explicit ExpressionSplitter(Dialect const& _dialect, NameDispenser& _nameDispenser):
|
|
m_dialect(_dialect), m_nameDispenser(_nameDispenser)
|
|
{ }
|
|
|
|
void operator()(FunctionalInstruction&) override;
|
|
void operator()(FunctionCall&) override;
|
|
void operator()(If&) override;
|
|
void operator()(Switch&) override;
|
|
void operator()(ForLoop&) override;
|
|
void operator()(Block& _block) override;
|
|
|
|
private:
|
|
/// Replaces the expression by a variable if it is a function call or functional
|
|
/// instruction. The declaration of the variable is appended to m_statementsToPrefix.
|
|
/// Recurses via visit().
|
|
void outlineExpression(Expression& _expr);
|
|
|
|
/// List of statements that should go in front of the currently visited AST element,
|
|
/// at the statement level.
|
|
std::vector<Statement> m_statementsToPrefix;
|
|
Dialect const& m_dialect;
|
|
NameDispenser& m_nameDispenser;
|
|
};
|
|
|
|
}
|