Implement Binary.PreProcess and add simple tests

SonarSource · May 5, 2023 · d048521 · d048521
1 parent b529eb3
commit d048521
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diff --git a/analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/Binary.cs b/analyzers/src/SonarAnalyzer.Common/SymbolicExecution/Roslyn/OperationProcessors/Binary.cs
@@ -18,6 +18,7 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+using System.Numerics;
 using SonarAnalyzer.SymbolicExecution.Constraints;
 
 namespace SonarAnalyzer.SymbolicExecution.Roslyn.OperationProcessors;
@@ -44,6 +45,37 @@ protected override ProgramState LearnBranchingConstraint(ProgramState state, IBi
         return state;
     }
 
+    protected override ProgramState PreProcess(ProgramState state, IBinaryOperationWrapper operation)
+    {
+        if (Calculation(operation.OperatorKind) is { } calculation
+            && operation.LeftOperand?.TrackedSymbol() is { } leftSymbol
+            && operation.RightOperand?.TrackedSymbol() is { } rightSymbol
+            && state[leftSymbol]?.Constraint<NumberConstraint>() is { } leftNumber
+            && state[rightSymbol]?.Constraint<NumberConstraint>() is { } rightNumber)
+        {
+            state = state.SetOperationConstraint(operation.WrappedOperation, Calculate(leftNumber, rightNumber, calculation));
+        }
+        return state;
+    }
+
+    private static Func<BigInteger?, BigInteger?, BigInteger?> Calculation(BinaryOperatorKind kind) => kind switch
+    {
+        BinaryOperatorKind.Add => (a, b) => a + b,
+        BinaryOperatorKind.Subtract => (a, b) => a - b,
+        _ => null
+    };
+
+    private static NumberConstraint Calculate(NumberConstraint left, NumberConstraint right, Func<BigInteger?, BigInteger?, BigInteger?> calculation)
+    {
+        var min = left.Min is not null && right.Min is not null
+            ? calculation(left.Min, right.Min)
+            : null;
+        var max = left.Max is not null && right.Max is not null
+            ? calculation(left.Max, right.Max)
+            : null;
+        return NumberConstraint.From(min, max);
+    }
+
     private static ProgramState LearnBranchingEqualityConstraint<T>(ProgramState state, IBinaryOperationWrapper binary, bool falseBranch)
         where T : SymbolicConstraint
     {

diff --git a/...sts/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Binary.cs b/...sts/SonarAnalyzer.UnitTest/SymbolicExecution/Roslyn/RoslynSymbolicExecutionTest.Binary.cs
@@ -657,4 +657,30 @@ public void Binary_StringConcatenation_Compund_CS(string expression)
         validator.ValidateContainsOperation(OperationKind.Binary);
         validator.ValidateTag("S", x => x.Should().HaveOnlyConstraint(ObjectConstraint.Null)); // FIXME: s is not null here (https://github.com/SonarSource/sonar-dotnet/issues/7111)
     }
+
+    [TestMethod]
+    public void Binary_Add_UpdatesNumberConstraint_CS()
+    {
+        var code = """
+            var i = 42;
+            var j = 5;
+            var x = i + j;
+            Tag("X", x);
+            """;
+        var validator = SETestContext.CreateCS(code).Validator;
+        validator.ValidateTag("X", x => x.Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(47)));
+    }
+
+    [TestMethod]
+    public void Binary_Substract_UpdatesNumberConstraint_CS()
+    {
+        var code = """
+            var i = 42;
+            var j = 5;
+            var x = i - j;
+            Tag("X", x);
+            """;
+        var validator = SETestContext.CreateCS(code).Validator;
+        validator.ValidateTag("X", x => x.Should().HaveOnlyConstraints(ObjectConstraint.NotNull, NumberConstraint.From(37)));
+    }
 }