Merge branch 'krauthaufen-Cgt_Un-Cle_Un-fix'

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -460,12 +460,30 @@ namespace ICSharpCode.Decompiler.Ast
 						// can also mean Inequality, when used with object references
 						TypeReference arg1Type = byteCode.Arguments[0].InferredType;
 						if (arg1Type != null && !arg1Type.IsValueType) goto case ILCode.Cne;
+
+						// when comparing signed integral values using Cgt_Un with 0
+						// the Ast should actually contain InEquality since "(uint)a > 0u" is identical to "a != 0"
+						if (arg1Type.IsSignedIntegralType())
+						{
+							var p = arg2 as Ast.PrimitiveExpression;
+							if (p != null && p.Value.IsZero()) goto case ILCode.Cne;
+						}
+
 						goto case ILCode.Cgt;
 					}
 					case ILCode.Cle_Un: {
 						// can also mean Equality, when used with object references
 						TypeReference arg1Type = byteCode.Arguments[0].InferredType;
 						if (arg1Type != null && !arg1Type.IsValueType) goto case ILCode.Ceq;
+
+						// when comparing signed integral values using Cle_Un with 0
+						// the Ast should actually contain Equality since "(uint)a <= 0u" is identical to "a == 0"
+						if (arg1Type.IsSignedIntegralType())
+						{
+							var p = arg2 as Ast.PrimitiveExpression;
+							if (p != null && p.Value.IsZero()) goto case ILCode.Ceq;
+						}
+
 						goto case ILCode.Cle;
 					}
 					case ILCode.Cle: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.LessThanOrEqual, arg2);

ICSharpCode.Decompiler/CecilExtensions.cs

@@ -126,6 +126,41 @@ namespace ICSharpCode.Decompiler
 				return false;
 			return type.IsValueType || type.IsVoid();
 		}
+
+		/// <summary>
+		/// checks if the given TypeReference is one of the following types:
+		/// [sbyte, short, int, long, IntPtr]
+		/// </summary>
+		public static bool IsSignedIntegralType(this TypeReference type)
+		{
+			return type.MetadataType == MetadataType.SByte ||
+				   type.MetadataType == MetadataType.Int16 ||
+				   type.MetadataType == MetadataType.Int32 ||
+				   type.MetadataType == MetadataType.Int64 ||
+				   type.MetadataType == MetadataType.IntPtr;
+		}
+
+		/// <summary>
+		/// checks if the given value is a numeric zero-value.
+		/// NOTE that this only works for types: [sbyte, short, int, long, IntPtr, byte, ushort, uint, ulong, float, double and decimal]
+		/// </summary>
+		public static bool IsZero(this object value)
+		{
+			return value.Equals((sbyte)0) ||
+				   value.Equals((short)0) ||
+				   value.Equals(0) ||
+				   value.Equals(0L) ||
+				   value.Equals(IntPtr.Zero) ||
+				   value.Equals((byte)0) ||
+				   value.Equals((ushort)0) ||
+				   value.Equals(0u) ||
+				   value.Equals(0UL) ||
+				   value.Equals(0.0f) ||
+				   value.Equals(0.0) ||
+				   value.Equals((decimal)0);
+					
+		}
+
 		#endregion
 		
 		/// <summary>

ICSharpCode.Decompiler/Tests/ValueTypes.cs

@@ -168,4 +168,21 @@ public static class ValueTypes
 			Console.WriteLine("true");
 		}
 	}
+
+	public static void CompareNotEqual0IsReallyNotEqual(IComparable<int> a)
+	{
+		if (a.CompareTo(0) != 0)
+		{
+			Console.WriteLine("true");
+		}
+	}
+
+	public static void CompareEqual0IsReallyEqual(IComparable<int> a)
+	{
+		if (a.CompareTo(0) == 0)
+		{
+			Console.WriteLine("true");
+		}
+	}
+
 }