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Merge pull request #9067 from ethereum/smt_fix_fp_again

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[SMTChecker] Fix BMC targets with FP
This commit is contained in:
Leonardo 2020-06-05 12:39:28 +02:00 committed by GitHub
commit 731e6466a0
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4 changed files with 51 additions and 11 deletions
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13
libsolidity/formal/BMC.cpp
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@ -604,7 +604,11 @@ void BMC::checkUnderflow(BMCVerificationTarget& _target, smtutil::Expression con
_target.type == VerificationTarget::Type::UnderOverflow,
""
);
auto intType = dynamic_cast<IntegerType const*>(_target.expression->annotation().type);
IntegerType const* intType = nullptr;
if (auto const* type = dynamic_cast<IntegerType const*>(_target.expression->annotation().type))
intType = type;
else
intType = TypeProvider::uint256();
solAssert(intType, "");
checkCondition(
_target.constraints && _constraints && _target.value < smt::minValue(*intType),
@ -626,7 +630,12 @@ void BMC::checkOverflow(BMCVerificationTarget& _target, smtutil::Expression cons
_target.type == VerificationTarget::Type::UnderOverflow,
""
);
auto intType = dynamic_cast<IntegerType const*>(_target.expression->annotation().type);
IntegerType const* intType = nullptr;
if (auto const* type = dynamic_cast<IntegerType const*>(_target.expression->annotation().type))
intType = type;
else
intType = TypeProvider::uint256();
solAssert(intType, "");
checkCondition(
_target.constraints && _constraints && _target.value > smt::maxValue(*intType),

29
libsolidity/formal/SMTEncoder.cpp
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@ -1213,7 +1213,7 @@ void SMTEncoder::arithmeticOperation(BinaryOperation const& _op)
{
auto type = _op.annotation().commonType;
solAssert(type, "");
if (type->category() == Type::Category::Integer)
if (type->category() == Type::Category::Integer || type->category() == Type::Category::FixedPoint)
{
switch (_op.getOperator())
{
@ -1266,13 +1266,21 @@ pair<smtutil::Expression, smtutil::Expression> SMTEncoder::arithmeticOperation(
};
solAssert(validOperators.count(_op), "");
solAssert(_commonType, "");
solAssert(_commonType->category() == Type::Category::Integer, "");
solAssert(
_commonType->category() == Type::Category::Integer || _commonType->category() == Type::Category::FixedPoint,
""
);
IntegerType const* intType = nullptr;
if (auto type = dynamic_cast<IntegerType const*>(_commonType))
intType = type;
else
intType = TypeProvider::uint256();
auto const& intType = dynamic_cast<IntegerType const&>(*_commonType);
smtutil::Expression valueNoMod(
_op == Token::Add ? _left + _right :
_op == Token::Sub ? _left - _right :
_op == Token::Div ? division(_left, _right, intType) :
_op == Token::Div ? division(_left, _right, *intType) :
_op == Token::Mul ? _left * _right :
/*_op == Token::Mod*/ _left % _right
);
@ -1280,20 +1288,23 @@ pair<smtutil::Expression, smtutil::Expression> SMTEncoder::arithmeticOperation(
if (_op == Token::Div || _op == Token::Mod)
m_context.addAssertion(_right != 0);
smtutil::Expression intValueRange = (0 - smt::minValue(intType)) + smt::maxValue(intType) + 1;
auto symbMin = smt::minValue(*intType);
auto symbMax = smt::maxValue(*intType);
smtutil::Expression intValueRange = (0 - symbMin) + symbMax + 1;
auto value = smtutil::Expression::ite(
valueNoMod > smt::maxValue(intType),
valueNoMod > symbMax,
valueNoMod % intValueRange,
smtutil::Expression::ite(
valueNoMod < smt::minValue(intType),
valueNoMod < symbMin,
valueNoMod % intValueRange,
valueNoMod
)
);
if (intType.isSigned())
if (intType->isSigned())
value = smtutil::Expression::ite(
value > smt::maxValue(intType),
value > symbMax,
value - intValueRange,
value
);

12
test/libsolidity/smtCheckerTests/operators/fixed_point_add.sol Normal file
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@ -0,0 +1,12 @@
pragma experimental SMTChecker;
contract test {
function f() internal pure {
ufixed a = uint64(1) + ufixed(2);
}
}
// ----
// Warning: (80-88): Unused local variable.
// Warning: (91-100): Type conversion is not yet fully supported and might yield false positives.
// Warning: (103-112): Type conversion is not yet fully supported and might yield false positives.
// Warning: (91-112): Underflow (resulting value less than 0) happens here
// Warning: (91-112): Overflow (resulting value larger than 2**256 - 1) happens here

8
test/libsolidity/smtCheckerTests/operators/fixed_point_compound_add.sol Normal file
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@ -0,0 +1,8 @@
pragma experimental SMTChecker;
contract C {
fixed[] b;
function f() internal { b[0] += 1; }
}
// ----
// Warning: (84-93): Underflow (resulting value less than 0) happens here
// Warning: (84-93): Overflow (resulting value larger than 2**256 - 1) happens here