public override void Binary(BinaryOperator binaryOperator, BoxedExpression left, BoxedExpression right, BoxedExpression parent)
{
left.Dispatch(this);
if (this.Overflow)
{
return;
}
right.Dispatch(this);
if (this.Overflow)
{
return;
}
switch (binaryOperator)
{
case BinaryOperator.Add:
case BinaryOperator.Add_Ovf:
case BinaryOperator.Add_Ovf_Un:
{
// different signs, or both positive ==> no overflow
int leftSign, rightSign;
if (Facts.TrySign(pc, left, out leftSign) && Facts.TrySign(pc, right, out rightSign))
{
if (leftSign >= 0 || rightSign >= 0)
{
this.Overflow = false;
return;
}
}
// TODO: improve using upper bounds
this.Overflow = true;
return;
}
case BinaryOperator.Div:
case BinaryOperator.Div_Un:
case BinaryOperator.Rem:
case BinaryOperator.Rem_Un:
{
// TODO: improve using upper bounds
if (Facts.IsNonZero(pc, right) == ProofOutcome.True)
{
this.Overflow = false;
}
this.Overflow = true;
return;
}
case BinaryOperator.Mul:
case BinaryOperator.Mul_Ovf:
case BinaryOperator.Mul_Ovf_Un:
{
// TODO: improve using upper bounds
this.Overflow = true;
return;
}
case BinaryOperator.Sub:
case BinaryOperator.Sub_Ovf:
case BinaryOperator.Sub_Ovf_Un:
{
int leftSign, rightSign;
// if left is non-negative or right is non-positive ==> no undeflow
if (Facts.TrySign(pc, left, out leftSign) && Facts.TrySign(pc, right, out rightSign))
{
if (leftSign >= 0 || rightSign <= 0)
{
this.Overflow = false;
return;
}
}
this.Overflow = true;
return;
}
case BinaryOperator.And:
case BinaryOperator.Ceq:
case BinaryOperator.Cge:
case BinaryOperator.Cge_Un:
case BinaryOperator.Cgt:
case BinaryOperator.Cgt_Un:
case BinaryOperator.Cle:
case BinaryOperator.Cle_Un:
case BinaryOperator.Clt:
case BinaryOperator.Clt_Un:
case BinaryOperator.Cne_Un:
case BinaryOperator.Cobjeq:
case BinaryOperator.LogicalAnd:
case BinaryOperator.LogicalOr:
case BinaryOperator.Or:
case BinaryOperator.Shl:
case BinaryOperator.Shr:
case BinaryOperator.Shr_Un:
case BinaryOperator.Xor:
{
this.Overflow = false;
return;
}
default:
{
this.Overflow = true;
return;
}
}
}