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Partial support for if statements.

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This commit is contained in:
chriseth
2017-08-23 17:37:35 +02:00
parent 5bfd5d98c1
commit 75f09f2a84
4 changed files with 128 additions and 16 deletions
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libsolidity/formal/SMTChecker.cpp
+94 -15
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@@ -25,6 +25,8 @@
#include <libsolidity/interface/ErrorReporter.h>
#include <boost/range/adaptor/map.hpp>
using namespace std;
using namespace dev;
using namespace dev::solidity;
@@ -51,6 +53,7 @@ void SMTChecker::analyze(SourceUnit const& _source)
{
m_interface->reset();
m_currentSequenceCounter.clear();
m_nextFreeSequenceCounter.clear();
_source.accept(*this);
}
}
@@ -89,10 +92,68 @@ void SMTChecker::endVisit(FunctionDefinition const&)
// We only handle local variables, so we clear everything.
// If we add storage variables, those should be cleared differently.
m_currentSequenceCounter.clear();
m_nextFreeSequenceCounter.clear();
m_interface->pop();
m_currentFunction = nullptr;
}
bool SMTChecker::visit(IfStatement const& _node)
{
_node.condition().accept(*this);
// TODO Check if condition is always true
auto countersAtStart = m_currentSequenceCounter;
m_interface->push();
m_interface->addAssertion(expr(_node.condition()));
_node.trueStatement().accept(*this);
auto countersAtEndOfTrue = m_currentSequenceCounter;
m_interface->pop();
decltype(m_currentSequenceCounter) countersAtEndOfFalse;
if (_node.falseStatement())
{
m_currentSequenceCounter = countersAtStart;
m_interface->push();
m_interface->addAssertion(!expr(_node.condition()));
_node.falseStatement()->accept(*this);
countersAtEndOfFalse = m_currentSequenceCounter;
m_interface->pop();
}
else
countersAtEndOfFalse = countersAtStart;
// Reset all values that have been touched.
// TODO this should use a previously generated side-effect structure
solAssert(countersAtEndOfFalse.size() == countersAtEndOfTrue.size(), "");
for (auto const& declCounter: countersAtEndOfTrue)
{
solAssert(countersAtEndOfFalse.count(declCounter.first), "");
auto decl = declCounter.first;
int trueCounter = countersAtEndOfTrue.at(decl);
int falseCounter = countersAtEndOfFalse.at(decl);
if (trueCounter == falseCounter)
continue; // Was not modified
newValue(*decl);
setValue(*decl, 0);
}
return false;
}
bool SMTChecker::visit(WhileStatement const& _node)
{
_node.condition().accept(*this);
//m_interface->push();
//m_interface->addAssertion(expr(_node.condition()));
// TDOO clear knowledge (increment sequence numbers and add bounds assertions ) apart from assertions
// TODO combine similar to if
return true;
}
void SMTChecker::endVisit(VariableDeclarationStatement const& _varDecl)
{
if (_varDecl.declarations().size() != 1)
@@ -100,10 +161,13 @@ void SMTChecker::endVisit(VariableDeclarationStatement const& _varDecl)
_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 if (knownVariable(*_varDecl.declarations()[0]))
{
if (_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(),
@@ -421,19 +485,15 @@ void SMTChecker::checkCondition(
void SMTChecker::createVariable(VariableDeclaration const& _varDecl, bool _setToZero)
{
if (auto intType = dynamic_cast<IntegerType const*>(_varDecl.type().get()))
if (dynamic_cast<IntegerType const*>(_varDecl.type().get()))
{
solAssert(m_currentSequenceCounter.count(&_varDecl) == 0, "");
solAssert(m_nextFreeSequenceCounter.count(&_varDecl) == 0, "");
solAssert(m_z3Variables.count(&_varDecl) == 0, "");
m_currentSequenceCounter[&_varDecl] = 0;
m_nextFreeSequenceCounter[&_varDecl] = 1;
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));
}
setValue(_varDecl, _setToZero);
}
else
m_errorReporter.warning(
@@ -460,16 +520,35 @@ bool SMTChecker::knownVariable(Declaration const& _decl)
smt::Expression SMTChecker::currentValue(Declaration const& _decl)
{
solAssert(m_currentSequenceCounter.count(&_decl), "");
return var(_decl)(m_currentSequenceCounter.at(&_decl));
return valueAtSequence(_decl, m_currentSequenceCounter.at(&_decl));
}
smt::Expression SMTChecker::newValue(const Declaration& _decl)
smt::Expression SMTChecker::valueAtSequence(const Declaration& _decl, int _sequence)
{
return var(_decl)(_sequence);
}
smt::Expression SMTChecker::newValue(Declaration const& _decl)
{
solAssert(m_currentSequenceCounter.count(&_decl), "");
m_currentSequenceCounter[&_decl]++;
solAssert(m_nextFreeSequenceCounter.count(&_decl), "");
m_currentSequenceCounter[&_decl] = m_nextFreeSequenceCounter[&_decl]++;
return currentValue(_decl);
}
void SMTChecker::setValue(Declaration const& _decl, bool _setToZero)
{
auto const& intType = dynamic_cast<IntegerType const&>(*_decl.type());
if (_setToZero)
m_interface->addAssertion(currentValue(_decl) == 0);
else
{
m_interface->addAssertion(currentValue(_decl) >= minValue(intType));
m_interface->addAssertion(currentValue(_decl) <= maxValue(intType));
}
}
smt::Expression SMTChecker::minValue(IntegerType const& _t)
{
return smt::Expression(_t.minValue());