mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
103 lines
3.1 KiB
C++
103 lines
3.1 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 undoes what the ExpressionSplitter did, i.e.
|
|
* it more or less inlines variable declarations.
|
|
*/
|
|
#pragma once
|
|
|
|
#include <libyul/ASTDataForward.h>
|
|
|
|
#include <libyul/optimiser/ASTWalker.h>
|
|
|
|
#include <map>
|
|
|
|
namespace dev
|
|
{
|
|
namespace yul
|
|
{
|
|
|
|
class NameCollector;
|
|
|
|
|
|
/**
|
|
* Optimiser component that modifies an AST in place, turning sequences
|
|
* of variable declarations into complex expressions, if the variables
|
|
* are declared in the right order. This component does the opposite
|
|
* of ExpressionSplitter.
|
|
* Since the order of opcode or function evaluation is unchanged,
|
|
* this transformation does not need to care about conflicting opcodes.
|
|
*
|
|
* Code of the form
|
|
*
|
|
* let a1 := mload(y)
|
|
* let a2 := mul(x, 4)
|
|
* sstore(a2, a1)
|
|
*
|
|
* is transformed into
|
|
*
|
|
* sstore(mul(x, 4), mload(y))
|
|
*
|
|
* The transformation is not applied to loop conditions, because those are
|
|
* evaluated with each loop.
|
|
*
|
|
* The component can be applied to sub-blocks of the AST, you do not
|
|
* need to pass a full AST.
|
|
*
|
|
* Prerequisites: Disambiguator
|
|
*
|
|
* Implementation note: We visit the AST, modifying it in place.
|
|
* The class starts counting references and will only replace variables
|
|
* that have exactly one reference. It keeps a "latest statement pointer"
|
|
* which always points to the statement right before the current statement.
|
|
* Any function call or opcode will reset this pointer. If an identifier
|
|
* is encountered that was declared in the "latest statement", it is replaced
|
|
* by the value of the declaration, the "latest statement" is replaced
|
|
* by an empty block and the pointer is decremented.
|
|
* A block also resets the latest statement pointer.
|
|
*/
|
|
class ExpressionJoiner: public ASTModifier
|
|
{
|
|
public:
|
|
virtual void operator()(FunctionalInstruction&) override;
|
|
virtual void operator()(FunctionCall&) override;
|
|
virtual void operator()(If&) override;
|
|
virtual void operator()(Switch&) override;
|
|
virtual void operator()(Block& _block) override;
|
|
|
|
using ASTModifier::visit;
|
|
virtual void visit(Expression& _e) override;
|
|
|
|
static void run(Block& _ast);
|
|
private:
|
|
explicit ExpressionJoiner(Block& _ast);
|
|
|
|
void handleArguments(std::vector<Expression>& _arguments);
|
|
|
|
void decrementLatestStatementPointer();
|
|
void resetLatestStatementPointer();
|
|
Statement* latestStatement();
|
|
bool isLatestStatementVarDeclOf(Identifier const& _identifier);
|
|
|
|
Block* m_currentBlock = nullptr;
|
|
size_t m_latestStatementInBlock = 0;
|
|
std::map<std::string, size_t> m_references;
|
|
};
|
|
|
|
}
|
|
}
|