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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/>.
*/
/**
* Base class to perform data flow analysis during AST walks.
* Tracks assignments and is used as base class for both Rematerialiser and
* Common Subexpression Eliminator.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/YulString.h>
#include <map>
#include <set>
namespace yul
{
/**
* Base class to perform data flow analysis during AST walks.
* Tracks assignments and is used as base class for both Rematerialiser and
* Common Subexpression Eliminator.
*
* A special zero constant expression is used for the default value of variables.
*
* Prerequisite: Disambiguator
*/
class DataFlowAnalyzer: public ASTModifier
{
public:
using ASTModifier::operator();
void operator()(Assignment& _assignment) override;
void operator()(VariableDeclaration& _varDecl) override;
void operator()(If& _if) override;
void operator()(Switch& _switch) override;
void operator()(FunctionDefinition&) override;
void operator()(ForLoop&) override;
void operator()(Block& _block) override;
protected:
/// Registers the assignment.
void handleAssignment(std::set<YulString> const& _names, Expression* _value);
/// Creates a new inner scope.
void pushScope(bool _functionScope);
/// Removes the innermost scope and clears all variables in it.
void popScope();
/// Clears information about the values assigned to the given variables,
/// for example at points where control flow is merged.
void clearValues(std::set<YulString> _names);
/// Returns true iff the variable is in scope.
bool inScope(YulString _variableName) const;
/// Current values of variables, always movable.
std::map<YulString, Expression const*> m_value;
/// m_references[a].contains(b) <=> the current expression assigned to a references b
std::map<YulString, std::set<YulString>> m_references;
/// m_referencedBy[b].contains(a) <=> the current expression assigned to a references b
std::map<YulString, std::set<YulString>> m_referencedBy;
struct Scope
{
explicit Scope(bool _isFunction): isFunction(_isFunction) {}
std::set<YulString> variables;
bool isFunction;
};
/// List of scopes.
std::vector<Scope> m_variableScopes;
};
}
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