1 files changed, 443 insertions, 4 deletions

diff --git a/libsolidity/formal/SMTChecker.cpp b/libsolidity/formal/SMTChecker.cpp
index 0e559fae..b9e0e8f3 100644
--- a/libsolidity/formal/SMTChecker.cpp
+++ b/libsolidity/formal/SMTChecker.cpp
@@ -17,7 +17,6 @@
 
 #include <libsolidity/formal/SMTChecker.h>
 
-#include <libsolidity/formal/SMTCheckerImpl.h>
 
 #include <libsolidity/interface/ErrorReporter.h>
 
@@ -25,12 +24,452 @@ using namespace std;
 using namespace dev;
 using namespace dev::solidity;
 
-SMTChecker::SMTChecker(ErrorReporter& _errorReporter):
-	m_impl(make_shared<SMTCheckerImpl>(_errorReporter))
+SMTChecker::SMTChecker(ErrorReporter& _errorReporter, ReadFile::Callback const& _readFileCallback):
+	m_interface(_readFileCallback),
+	m_errorReporter(_errorReporter)
 {
 }
 
 void SMTChecker::analyze(SourceUnit const& _source)
 {
-	m_impl->analyze(_source);
+	bool pragmaFound = false;
+	for (auto const& node: _source.nodes())
+		if (auto const* pragma = dynamic_cast<PragmaDirective const*>(node.get()))
+			if (pragma->literals()[0] == "checkAssertionsZ3")
+				pragmaFound = true;
+	if (pragmaFound)
+	{
+		m_interface.reset();
+		m_currentSequenceCounter.clear();
+		_source.accept(*this);
+	}
+}
+
+void SMTChecker::endVisit(VariableDeclaration const& _varDecl)
+{
+	if (_varDecl.value())
+	{
+		m_errorReporter.warning(
+			_varDecl.location(),
+			"Assertion checker does not yet support this."
+		);
+	}
+	else if (_varDecl.isLocalOrReturn())
+		createVariable(_varDecl, true);
+	else if (_varDecl.isCallableParameter())
+		createVariable(_varDecl, false);
+}
+
+bool SMTChecker::visit(FunctionDefinition const& _function)
+{
+	if (!_function.modifiers().empty() || _function.isConstructor())
+		m_errorReporter.warning(
+			_function.location(),
+			"Assertion checker does not yet support constructors and functions with modifiers."
+		);
+	// TODO actually we probably also have to reset all local variables and similar things.
+	m_currentFunction = &_function;
+	m_interface.push();
+	return true;
+}
+
+void SMTChecker::endVisit(FunctionDefinition const&)
+{
+	// TOOD we could check for "reachability", i.e. satisfiability here.
+	m_interface.pop();
+	m_currentFunction = nullptr;
+}
+
+void SMTChecker::endVisit(VariableDeclarationStatement const& _varDecl)
+{
+	if (_varDecl.declarations().size() != 1)
+		m_errorReporter.warning(
+			_varDecl.location(),
+			"Assertion checker does not yet support such variable declarations."
+		);
+	else if (knownVariable(*_varDecl.declarations()[0]) && _varDecl.initialValue())
+		// TODO more checks?
+		// TODO add restrictions about type (might be assignment from smaller type)
+		m_interface.addAssertion(newValue(*_varDecl.declarations()[0]) == expr(*_varDecl.initialValue()));
+	else
+		m_errorReporter.warning(
+			_varDecl.location(),
+			"Assertion checker does not yet implement such variable declarations."
+		);
+}
+
+void SMTChecker::endVisit(ExpressionStatement const&)
+{
+}
+
+void SMTChecker::endVisit(Assignment const& _assignment)
+{
+	if (_assignment.assignmentOperator() != Token::Value::Assign)
+		m_errorReporter.warning(
+			_assignment.location(),
+			"Assertion checker does not yet implement compound assignment."
+		);
+	else if (_assignment.annotation().type->category() != Type::Category::Integer)
+		m_errorReporter.warning(
+			_assignment.location(),
+			"Assertion checker does not yet implement type " + _assignment.annotation().type->toString()
+		);
+	else if (Identifier const* identifier = dynamic_cast<Identifier const*>(&_assignment.leftHandSide()))
+	{
+		Declaration const* decl = identifier->annotation().referencedDeclaration;
+		if (knownVariable(*decl))
+			// TODO more checks?
+			// TODO add restrictions about type (might be assignment from smaller type)
+			m_interface.addAssertion(newValue(*decl) == expr(_assignment.rightHandSide()));
+		else
+			m_errorReporter.warning(
+				_assignment.location(),
+				"Assertion checker does not yet implement such assignments."
+			);
+	}
+	else
+		m_errorReporter.warning(
+			_assignment.location(),
+			"Assertion checker does not yet implement such assignments."
+		);
+}
+
+void SMTChecker::endVisit(TupleExpression const& _tuple)
+{
+	if (_tuple.isInlineArray() || _tuple.components().size() != 1)
+		m_errorReporter.warning(
+			_tuple.location(),
+			"Assertion checker does not yet implement tules and inline arrays."
+		);
+	else
+		m_interface.addAssertion(expr(_tuple) == expr(*_tuple.components()[0]));
+}
+
+void SMTChecker::endVisit(BinaryOperation const& _op)
+{
+	if (Token::isArithmeticOp(_op.getOperator()))
+		arithmeticOperation(_op);
+	else if (Token::isCompareOp(_op.getOperator()))
+		compareOperation(_op);
+	else if (Token::isBooleanOp(_op.getOperator()))
+		booleanOperation(_op);
+	else
+		m_errorReporter.warning(
+			_op.location(),
+			"Assertion checker does not yet implement this operator."
+		);
+}
+
+void SMTChecker::endVisit(FunctionCall const& _funCall)
+{
+	FunctionType const& funType = dynamic_cast<FunctionType const&>(*_funCall.expression().annotation().type);
+
+	std::vector<ASTPointer<Expression const>> const args = _funCall.arguments();
+	if (funType.kind() == FunctionType::Kind::Assert)
+	{
+		solAssert(args.size() == 1, "");
+		solAssert(args[0]->annotation().type->category() == Type::Category::Bool, "");
+		checkCondition(!(expr(*args[0])), _funCall.location(), "Assertion violation");
+		m_interface.addAssertion(expr(*args[0]));
+	}
+	else if (funType.kind() == FunctionType::Kind::Require)
+	{
+		solAssert(args.size() == 1, "");
+		solAssert(args[0]->annotation().type->category() == Type::Category::Bool, "");
+		m_interface.addAssertion(expr(*args[0]));
+		checkCondition(!(expr(*args[0])), _funCall.location(), "Unreachable code");
+		// TODO is there something meaningful we can check here?
+		// We can check whether the condition is always fulfilled or never fulfilled.
+	}
+}
+
+void SMTChecker::endVisit(Identifier const& _identifier)
+{
+	Declaration const* decl = _identifier.annotation().referencedDeclaration;
+	solAssert(decl, "");
+	if (dynamic_cast<IntegerType const*>(_identifier.annotation().type.get()))
+	{
+		m_interface.addAssertion(expr(_identifier) == currentValue(*decl));
+		return;
+	}
+	else if (FunctionType const* fun = dynamic_cast<FunctionType const*>(_identifier.annotation().type.get()))
+	{
+		if (fun->kind() == FunctionType::Kind::Assert || fun->kind() == FunctionType::Kind::Require)
+			return;
+		// TODO for others, clear our knowledge about storage and memory
+	}
+	m_errorReporter.warning(
+		_identifier.location(),
+		"Assertion checker does not yet support the type of this expression (" +
+		_identifier.annotation().type->toString() +
+		")."
+	);
+}
+
+void SMTChecker::endVisit(Literal const& _literal)
+{
+	Type const& type = *_literal.annotation().type;
+	if (type.category() == Type::Category::Integer || type.category() == Type::Category::RationalNumber)
+	{
+		if (RationalNumberType const* rational = dynamic_cast<RationalNumberType const*>(&type))
+			solAssert(!rational->isFractional(), "");
+
+		m_interface.addAssertion(expr(_literal) == smt::Expression(type.literalValue(&_literal)));
+	}
+	else
+		m_errorReporter.warning(
+			_literal.location(),
+			"Assertion checker does not yet support the type of this expression (" +
+			_literal.annotation().type->toString() +
+			")."
+		);
+}
+
+void SMTChecker::arithmeticOperation(BinaryOperation const& _op)
+{
+	switch (_op.getOperator())
+	{
+	case Token::Add:
+	case Token::Sub:
+	case Token::Mul:
+	{
+		solAssert(_op.annotation().commonType, "");
+		solAssert(_op.annotation().commonType->category() == Type::Category::Integer, "");
+		smt::Expression left(expr(_op.leftExpression()));
+		smt::Expression right(expr(_op.rightExpression()));
+		Token::Value op = _op.getOperator();
+		smt::Expression value(
+			op == Token::Add ? left + right :
+			op == Token::Sub ? left - right :
+			/*op == Token::Mul*/ left * right
+		);
+
+		// Overflow check
+		auto const& intType = dynamic_cast<IntegerType const&>(*_op.annotation().commonType);
+		checkCondition(
+			value < minValue(intType),
+			_op.location(),
+			"Underflow (resulting value less than " + intType.minValue().str() + ")",
+			"value",
+			&value
+		);
+		checkCondition(
+			value > maxValue(intType),
+			_op.location(),
+			"Overflow (resulting value larger than " + intType.maxValue().str() + ")",
+			"value",
+			&value
+		);
+
+		m_interface.addAssertion(expr(_op) == value);
+		break;
+	}
+	default:
+		m_errorReporter.warning(
+			_op.location(),
+			"Assertion checker does not yet implement this operator."
+		);
+	}
+}
+
+void SMTChecker::compareOperation(BinaryOperation const& _op)
+{
+	solAssert(_op.annotation().commonType, "");
+	if (_op.annotation().commonType->category() == Type::Category::Integer)
+	{
+		smt::Expression left(expr(_op.leftExpression()));
+		smt::Expression right(expr(_op.rightExpression()));
+		Token::Value op = _op.getOperator();
+		smt::Expression value = (
+			op == Token::Equal ? (left == right) :
+			op == Token::NotEqual ? (left != right) :
+			op == Token::LessThan ? (left < right) :
+			op == Token::LessThanOrEqual ? (left <= right) :
+			op == Token::GreaterThan ? (left > right) :
+			/*op == Token::GreaterThanOrEqual*/ (left >= right)
+		);
+		// TODO: check that other values for op are not possible.
+		m_interface.addAssertion(expr(_op) == value);
+	}
+	else
+		m_errorReporter.warning(
+			_op.location(),
+			"Assertion checker does not yet implement the type " + _op.annotation().commonType->toString() + " for comparisons"
+		);
+}
+
+void SMTChecker::booleanOperation(BinaryOperation const& _op)
+{
+	solAssert(_op.getOperator() == Token::And || _op.getOperator() == Token::Or, "");
+	solAssert(_op.annotation().commonType, "");
+	if (_op.annotation().commonType->category() == Type::Category::Bool)
+	{
+		if (_op.getOperator() == Token::And)
+			m_interface.addAssertion(expr(_op) == expr(_op.leftExpression()) && expr(_op.rightExpression()));
+		else
+			m_interface.addAssertion(expr(_op) == expr(_op.leftExpression()) || expr(_op.rightExpression()));
+	}
+	else
+		m_errorReporter.warning(
+			_op.location(),
+			"Assertion checker does not yet implement the type " + _op.annotation().commonType->toString() + " for boolean operations"
+		);
+}
+
+void SMTChecker::checkCondition(
+	smt::Expression _condition,
+	SourceLocation const& _location,
+	string const& _description,
+	string const& _additionalValueName,
+	smt::Expression* _additionalValue
+)
+{
+	m_interface.push();
+	m_interface.addAssertion(_condition);
+
+	vector<smt::Expression> expressionsToEvaluate;
+	if (m_currentFunction)
+	{
+		if (_additionalValue)
+			expressionsToEvaluate.emplace_back(*_additionalValue);
+		for (auto const& param: m_currentFunction->parameters())
+			if (knownVariable(*param))
+				expressionsToEvaluate.emplace_back(currentValue(*param));
+		for (auto const& var: m_currentFunction->localVariables())
+			if (knownVariable(*var))
+				expressionsToEvaluate.emplace_back(currentValue(*var));
+	}
+	smt::CheckResult result;
+	vector<string> values;
+	tie(result, values) = m_interface.check(expressionsToEvaluate);
+	switch (result)
+	{
+	case smt::CheckResult::SAT:
+	{
+		std::ostringstream message;
+		message << _description << " happens here";
+		size_t i = 0;
+		if (m_currentFunction)
+		{
+			message << " for:\n";
+			if (_additionalValue)
+				message << "  " << _additionalValueName << " = " << values.at(i++) << "\n";
+			for (auto const& param: m_currentFunction->parameters())
+				if (knownVariable(*param))
+					message << "  " << param->name() << " = " << values.at(i++) << "\n";
+			for (auto const& var: m_currentFunction->localVariables())
+				if (knownVariable(*var))
+					message << "  " << var->name() << " = " << values.at(i++) << "\n";
+		}
+		else
+			message << ".";
+		m_errorReporter.warning(_location, message.str());
+		break;
+	}
+	case smt::CheckResult::UNSAT:
+		break;
+	case smt::CheckResult::UNKNOWN:
+		m_errorReporter.warning(_location, _description + " might happen here.");
+		break;
+	case smt::CheckResult::ERROR:
+		m_errorReporter.warning(_location, "Error trying to invoke SMT solver.");
+		break;
+	default:
+		solAssert(false, "");
+	}
+	m_interface.pop();
+}
+
+void SMTChecker::createVariable(VariableDeclaration const& _varDecl, bool _setToZero)
+{
+	if (auto intType = dynamic_cast<IntegerType const*>(_varDecl.type().get()))
+	{
+		solAssert(m_currentSequenceCounter.count(&_varDecl) == 0, "");
+		solAssert(m_z3Variables.count(&_varDecl) == 0, "");
+		m_currentSequenceCounter[&_varDecl] = 0;
+		m_z3Variables.emplace(&_varDecl, m_interface.newFunction(uniqueSymbol(_varDecl), smt::Sort::Int, smt::Sort::Int));
+		if (_setToZero)
+			m_interface.addAssertion(currentValue(_varDecl) == 0);
+		else
+		{
+			m_interface.addAssertion(currentValue(_varDecl) >= minValue(*intType));
+			m_interface.addAssertion(currentValue(_varDecl) <= maxValue(*intType));
+		}
+	}
+	else
+		m_errorReporter.warning(
+			_varDecl.location(),
+			"Assertion checker does not yet support the type of this variable."
+		);
+}
+
+string SMTChecker::uniqueSymbol(Declaration const& _decl)
+{
+	return _decl.name() + "_" + to_string(_decl.id());
+}
+
+string SMTChecker::uniqueSymbol(Expression const& _expr)
+{
+	return "expr_" + to_string(_expr.id());
+}
+
+bool SMTChecker::knownVariable(Declaration const& _decl)
+{
+	return m_currentSequenceCounter.count(&_decl);
+}
+
+smt::Expression SMTChecker::currentValue(Declaration const& _decl)
+{
+	solAssert(m_currentSequenceCounter.count(&_decl), "");
+	return var(_decl)(m_currentSequenceCounter.at(&_decl));
+}
+
+smt::Expression SMTChecker::newValue(const Declaration& _decl)
+{
+	solAssert(m_currentSequenceCounter.count(&_decl), "");
+	m_currentSequenceCounter[&_decl]++;
+	return currentValue(_decl);
+}
+
+smt::Expression SMTChecker::minValue(IntegerType const& _t)
+{
+	return smt::Expression(_t.minValue());
+}
+
+smt::Expression SMTChecker::maxValue(IntegerType const& _t)
+{
+	return smt::Expression(_t.maxValue());
+}
+
+smt::Expression SMTChecker::expr(Expression const& _e)
+{
+	if (!m_z3Expressions.count(&_e))
+	{
+		solAssert(_e.annotation().type, "");
+		switch (_e.annotation().type->category())
+		{
+		case Type::Category::RationalNumber:
+		{
+			if (RationalNumberType const* rational = dynamic_cast<RationalNumberType const*>(_e.annotation().type.get()))
+				solAssert(!rational->isFractional(), "");
+			m_z3Expressions.emplace(&_e, m_interface.newInteger(uniqueSymbol(_e)));
+			break;
+		}
+		case Type::Category::Integer:
+			m_z3Expressions.emplace(&_e, m_interface.newInteger(uniqueSymbol(_e)));
+			break;
+		case Type::Category::Bool:
+			m_z3Expressions.emplace(&_e, m_interface.newBool(uniqueSymbol(_e)));
+			break;
+		default:
+			solAssert(false, "Type not implemented.");
+		}
+	}
+	return m_z3Expressions.at(&_e);
+}
+
+smt::Expression SMTChecker::var(Declaration const& _decl)
+{
+	solAssert(m_z3Variables.count(&_decl), "");
+	return m_z3Variables.at(&_decl);
 }