path: root/libsolidity/formal/SMTChecker.h

/*
    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 <libsolidity/formal/SolverInterface.h>

#include <libsolidity/ast/ASTVisitor.h>

#include <libsolidity/interface/ReadFile.h>

#include <map>
#include <string>

namespace dev
{
namespace solidity
{

class VariableUsage;
class ErrorReporter;

class SMTChecker: private ASTConstVisitor
{
public:
    SMTChecker(ErrorReporter& _errorReporter, ReadCallback::Callback const& _readCallback);

    void analyze(SourceUnit const& _sources);

private:
    // TODO: Check that we do not have concurrent reads and writes to a variable,
    // because the order of expression evaluation is undefined
    // TODO: or just force a certain order, but people might have a different idea about that.

    virtual void endVisit(VariableDeclaration const& _node) override;
    virtual bool visit(FunctionDefinition const& _node) override;
    virtual void endVisit(FunctionDefinition const& _node) override;
    virtual bool visit(IfStatement const& _node) override;
    virtual bool visit(WhileStatement const& _node) override;
    virtual void endVisit(VariableDeclarationStatement const& _node) override;
    virtual void endVisit(ExpressionStatement const& _node) override;
    virtual void endVisit(Assignment const& _node) override;
    virtual void endVisit(TupleExpression const& _node) override;
    virtual void endVisit(BinaryOperation const& _node) override;
    virtual void endVisit(FunctionCall const& _node) override;
    virtual void endVisit(Identifier const& _node) override;
    virtual void endVisit(Literal const& _node) override;

    void arithmeticOperation(BinaryOperation const& _op);
    void compareOperation(BinaryOperation const& _op);
    void booleanOperation(BinaryOperation const& _op);

    void assignment(Declaration const& _variable, Expression const& _value);

    // Visits the branch given by the statement, pushes and pops the SMT checker.
    // @param _condition if present, asserts that this condition is true within the branch.
    void visitBranch(Statement const& _statement, smt::Expression const* _condition = nullptr);
    void visitBranch(Statement const& _statement, smt::Expression _condition);

    void checkCondition(
        smt::Expression _condition,
        SourceLocation const& _location,
        std::string const& _description,
        std::string const& _additionalValueName = "",
        smt::Expression* _additionalValue = nullptr
    );

    void initializeLocalVariables(FunctionDefinition const& _function);
    void resetVariables(std::vector<Declaration const*> _variables);
    void createVariable(VariableDeclaration const& _varDecl);

    static std::string uniqueSymbol(Declaration const& _decl);
    static std::string uniqueSymbol(Expression const& _expr);

    /// @returns true if _delc is a variable that is known at the current point, i.e.
    /// has a valid sequence number
    bool knownVariable(Declaration const& _decl);
    /// @returns an expression denoting the value of the variable declared in @a _decl
    /// at the current point.
    smt::Expression currentValue(Declaration const& _decl);
    /// @returns an expression denoting the value of the variable declared in @a _decl
    /// at the given sequence point. Does not ensure that this sequence point exists.
    smt::Expression valueAtSequence(Declaration const& _decl, int _sequence);
    /// Allocates a new sequence number for the declaration, updates the current
    /// sequence number to this value and returns the expression.
    smt::Expression newValue(Declaration const& _decl);

    /// Sets the value of the declaration to zero.
    void setZeroValue(Declaration const& _decl);
    /// Resets the variable to an unknown value (in its range).
    void setUnknownValue(Declaration const& decl);

    static smt::Expression minValue(IntegerType const& _t);
    static smt::Expression maxValue(IntegerType const& _t);

    using VariableSequenceCounters = std::map<Declaration const*, int>;

    /// Returns the expression corresponding to the AST node. Creates a new expression
    /// if it does not exist yet.
    smt::Expression expr(Expression const& _e);
    /// Returns the function declaration corresponding to the given variable.
    /// The function takes one argument which is the "sequence number".
    smt::Expression var(Declaration const& _decl);

    std::shared_ptr<smt::SolverInterface> m_interface;
    std::shared_ptr<VariableUsage> m_variableUsage;
    bool m_conditionalExecutionHappened = false;
    std::map<Declaration const*, int> m_currentSequenceCounter;
    std::map<Declaration const*, int> m_nextFreeSequenceCounter;
    std::map<Expression const*, smt::Expression> m_expressions;
    std::map<Declaration const*, smt::Expression> m_variables;
    ErrorReporter& m_errorReporter;

    FunctionDefinition const* m_currentFunction = nullptr;
};

}
}