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SE: Add BitXorOperation #7246

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merged 9 commits into from
Jun 8, 2023
Merged

SE: Add BitXorOperation #7246

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SE: Add BitXorOperation
antonioaversa May 22, 2023
ec1a603
Increase coverage
antonioaversa May 25, 2023
eaf4215
Increase coverage 2
antonioaversa May 25, 2023
af7caca
Increase coverage and fix CanOverlap
antonioaversa May 25, 2023
72f1b86
Review 1
antonioaversa May 26, 2023
5b11d33
Fix UTs
antonioaversa May 26, 2023
9e7e43b
Revert changes adding mixed ranges
antonioaversa May 26, 2023
c0ae9ec
Increase coverage
antonioaversa May 30, 2023
6b5578c
SE: Improve XOROperation (#7310)
Tim-Pohlmann Jun 5, 2023
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58 changes: 58 additions & 0 deletions ...rc/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/Binary.Arithmetic.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,8 @@ internal sealed partial class Binary
BinaryOperatorKind.And => NumberConstraint.From(CalculateAndMin(left, right), CalculateAndMax(left, right)),
BinaryOperatorKind.Or when left.IsSingleValue && right.IsSingleValue => NumberConstraint.From(left.Min.Value | right.Min.Value),
BinaryOperatorKind.Or => NumberConstraint.From(CalculateOrMin(left, right), CalculateOrMax(left, right)),
BinaryOperatorKind.ExclusiveOr when left.IsSingleValue && right.IsSingleValue => NumberConstraint.From(left.Min.Value ^ right.Min.Value),
BinaryOperatorKind.ExclusiveOr => NumberConstraint.From(CalculateXorMin(left, right), CalculateXorMax(left, right)),
_ => null
};

Expand Down Expand Up @@ -213,6 +215,62 @@ private static NumberConstraint AccountForZero(NumberConstraint constraint)
}
}

private static BigInteger? CalculateXorMin(NumberConstraint left, NumberConstraint right)
{
// Takes advantage of the property a - b <= a ^ b for all a >= 0 and b >= 0
// If ranges overlap => at least 1 value belongs to both ranges => xor can yield 0
if (left.IsPositive && right.IsPositive)
{
if (left.Min > right.Max)
{
return left.Min.Value - right.Max.Value;
}
else if (right.Min > left.Max)
{
return right.Min.Value - left.Max.Value;
}
else
{
return 0;
}
}
else if (left.IsNegative && right.IsNegative)
{
if (right.Min > left.Max)
{
return right.Min.Value - left.Max.Value;
}
else if (left.Min > right.Max)
{
return left.Min.Value - right.Max.Value;
}
else
{
return 0;
}
}
else
{
return null;
}
}

private static BigInteger? CalculateXorMax(NumberConstraint left, NumberConstraint right)
{
if ((left.IsPositive && right.CanBePositive) || (right.IsPositive && left.CanBeNegative))
{
return left.Max.HasValue && right.Max.HasValue ? PositiveMagnitude(left.Max.Value | right.Max.Value) : null;
}
else if ((left.IsPositive && right.IsNegative) || (left.IsNegative && right.IsPositive))
{
return -1;
}
else
{
return null;
}
}

private static BigInteger? NegativeMagnitude(BigInteger value)
{
// For increasing powers of 2 with negative sign, we're looking for the longest chain of 1 from the MSB side
Expand Down
76 changes: 75 additions & 1 deletion ...sts/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Binary.cs
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Expand Up @@ -922,7 +922,7 @@ public void Binary_BitAnd_SingleValue(int left, int right, int expected)
var value = left & right;
Tag("Value", value);
""";
SETestContext.CreateCS(code).Validator.ValidateTag("Value", x => x.Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(expected)));
SETestContext.CreateCS(code).Validator.TagValue("Value").Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(expected));
}

[DataTestMethod]
Expand Down Expand Up @@ -1029,4 +1029,78 @@ public void Binary_BitOr_Range(string expression, int? expectedMin, int? expecte
SETestContext.CreateCS(code, "int i, int j").Validator.TagValue("Value").Should().HaveOnlyConstraints(ObjectConstraint.NotNull);
}
}

[DataTestMethod]
[DataRow(0b0000, 0b0000, 0b0000)]
[DataRow(0b0101, 0b0101, 0b0000)]
[DataRow(0b0101, 0b0001, 0b0100)]
[DataRow(0b1010, 0b0110, 0b1100)]
[DataRow(0b1010, 0b0000, 0b1010)]
[DataRow(0b1111, 0b1111, 0b0000)]
[DataRow(5, -5, -2)]
[DataRow(5, -4, -7)]
[DataRow(-5, -5, 0)]
[DataRow(-5, -4, 7)]
public void Binary_BitXor_SingleValue(int left, int right, int expected)
{
var code = $"""
var left = {left};
var right = {right};
var value = left ^ right;
Tag("Value", value);
""";
SETestContext.CreateCS(code).Validator.TagValue("Value").Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(expected));
}

[DataTestMethod]
[DataRow("i >= 4 && j >= 6", 0, null)]
[DataRow("i >= 4 && j >= -6", null, null)]
[DataRow("i >= 4 && j <= 6", null, null)]
[DataRow("i >= 4 && j <= -6", null, -1)]
[DataRow("i >= -4 && j >= 6", null, null)]
[DataRow("i >= -4 && j >= -6", null, null)]
[DataRow("i >= -4 && j <= 6", null, null)]
[DataRow("i >= -4 && j <= -6", null, null)] // exact range: null, -1
[DataRow("i == 4 && j >= 6", 2, null)]
[DataRow("i == 4 && j >= -6", null, null)] // exact range: -8, null
[DataRow("i == 4 && j <= 6", null, 7)]
[DataRow("i == 4 && j <= -6", null, -1)] // exact range: null, -2
[DataRow("i == -4 && j >= 6", null, null)] // exact range: null, -5
[DataRow("i == -4 && j >= -6", null, null)] // exact range: null, 7
[DataRow("i == -4 && j <= 6", null, null)] // exact range: -8, null
[DataRow("i == -4 && j <= -6", 2, null)] // exact range: 4, null
[DataRow("i <= 4 && j >= 6", null, null)]
[DataRow("i <= 4 && j >= -6", null, null)]
[DataRow("i <= 4 && j <= 6", null, null)]
[DataRow("i <= 4 && j <= -6", null, null)]
[DataRow("i <= -4 && j >= 6", null, null)] // exact range: null, -1
[DataRow("i <= -4 && j >= -6", null, null)]
[DataRow("i <= -4 && j <= 6", null, null)]
[DataRow("i <= -4 && j <= -6", 0, null)]
[DataRow("i >= 4 && j >= 6 && j <= 8", 0, null)]
[DataRow("i >= 4 && j >= 1 && j <= 3", 1, null)] // exact range: 4, null
[DataRow("i >= 4 && i <= 6 && j >= 6", 0, null)]
[DataRow("i >= 4 && i <= 6 && j >= 6 && j <= 8", 0, 15)] // exact range: 0, 14
[DataRow("i >= 4 && i <= 5 && j >= 6 && j <= 8", 1, 15)] // exact range: 2, 13
[DataRow("i >= -3 && i <= -1 && j >= -4 && j <=-2", 0, null)] // exact range: 0, 3
[DataRow("i >= -4 && i <= -3 && j >= -2 && j <=-1", 1, null)] // exact range: 2, 3
public void Binary_BitXor_Range(string expression, int? expectedMin, int? expectedMax)
{
var code = $$"""
if ({{expression}})
{
var value = i ^ j;
Tag("Value", value);
}
""";

if (expectedMin is not null || expectedMax is not null)
{
SETestContext.CreateCS(code, "int i, int j").Validator.TagValue("Value").Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(expectedMin, expectedMax));
}
else
{
SETestContext.CreateCS(code, "int i, int j").Validator.TagValue("Value").Should().HaveOnlyConstraints(ObjectConstraint.NotNull);
}
}
}
2 changes: 1 addition & 1 deletion ...onarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/CalculationsShouldNotOverflow.cs
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Expand Up @@ -115,7 +115,7 @@ public void BasicOperators()
_ = i * 2147483600; // Noncompliant

i = 2 ^ j;
_ = i * 2147483600; // FN
_ = i * 2147483600; // Noncompliant

i = 2 % j;
_ = i * 2147483600; // FN
Expand Down
2 changes: 1 addition & 1 deletion ...onarAnalyzer.UnitTest/TestCases/SymbolicExecution/Roslyn/CalculationsShouldNotOverflow.vb
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Expand Up @@ -76,7 +76,7 @@ Public Class Sample
__ = i * 2147483600 ' Noncompliant

i = 2 Xor j
__ = i * 2147483600 ' FN
__ = i * 2147483600 ' Noncompliant

i = 2 Mod j
__ = i * 2147483600 ' FN
Expand Down