Fix decompiling comparison operators:

* add casts when comparing integers
* fix "unordered" float comparisons

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -325,13 +325,48 @@ namespace ICSharpCode.Decompiler.CSharp
 		{
 			var left = Translate(inst.Left);
 			var right = Translate(inst.Right);
-			// TODO: ensure the arguments are signed
-			// or with _Un: ensure the arguments are unsigned; and that float comparisons are performed unordered
-			return new BinaryOperatorExpression(left.Expression, op, right.Expression)
+			// Ensure the inputs have the correct sign:
+			KnownTypeCode inputType = KnownTypeCode.None;
+			switch (inst.OpType) {
+				case StackType.I8:
+					inputType = un ? KnownTypeCode.UInt64 : KnownTypeCode.Int64;
+					break;
+				case StackType.I:
+					inputType = un ? KnownTypeCode.UIntPtr : KnownTypeCode.IntPtr;
+					break;
+				case StackType.I4:
+					inputType = un ? KnownTypeCode.UInt32 : KnownTypeCode.Int32;
+					break;
+				case StackType.F:
+					if (un) {
+						// for floats, _Un means "unordered":
+						// clt_un returns 1 if left < right or if either input is not-a-number
+						// The C# operators never return true for NaN, so we need to use a negation:
+						// clt_un => !(left >= right)
+						// cgt_un => !(left <= right)
+						if (op == BinaryOperatorType.LessThan)
+							op = BinaryOperatorType.GreaterThanOrEqual;
+						else if (op == BinaryOperatorType.GreaterThan)
+							op = BinaryOperatorType.LessThanOrEqual;
+						else
+							throw new ArgumentException("op");
+					}
+					break;
+			}
+			if (inputType != KnownTypeCode.None) {
+				left = left.ConvertTo(compilation.FindType(inputType), this);
+				right = right.ConvertTo(compilation.FindType(inputType), this);
+			}
+			var result = new BinaryOperatorExpression(left.Expression, op, right.Expression)
 				.WithILInstruction(inst)
 				.WithRR(new OperatorResolveResult(compilation.FindType(TypeCode.Boolean),
 				                                  BinaryOperatorExpression.GetLinqNodeType(op, false),
 				                                  left.ResolveResult, right.ResolveResult));
+			if (un && inst.OpType == StackType.F) {
+				// add negation if we turned around the operator symbol above
+				result = LogicNot(result).WithILInstruction(inst);
+			}
+			return result;
 		}
 		
 		ExpressionWithResolveResult Assignment(TranslatedExpression left, TranslatedExpression right)
@@ -483,9 +518,11 @@ namespace ICSharpCode.Decompiler.CSharp
 			var target = TranslateTarget(method, inst.Arguments[0], func.OpCode == OpCode.LdFtn);
 			return new ObjectCreateExpression(ConvertType(inst.Method.DeclaringType), new MemberReferenceExpression(target, method.Name))
 				.WithILInstruction(inst)
-				.WithRR(new ConversionResolveResult(method.DeclaringType,
-				                                    new MemberResolveResult(target.ResolveResult, method),
-				                                    Conversion.MethodGroupConversion(method, func.OpCode == OpCode.LdVirtFtn, false))); // TODO handle extension methods capturing the first argument
+				.WithRR(new ConversionResolveResult(
+					method.DeclaringType,
+					new MemberResolveResult(target.ResolveResult, method),
+					// TODO handle extension methods capturing the first argument
+					Conversion.MethodGroupConversion(method, func.OpCode == OpCode.LdVirtFtn, false)));
 		}
 		
 		TranslatedExpression TranslateTarget(IMember member, ILInstruction target, bool nonVirtualInvocation)

ICSharpCode.Decompiler/Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -95,7 +95,6 @@
       <Project>{d68133bd-1e63-496e-9ede-4fbdbf77b486}</Project>
       <Name>Mono.Cecil</Name>
     </ProjectReference>
-
     <ProjectReference Include="..\..\NRefactory\ICSharpCode.NRefactory.CSharp\ICSharpCode.NRefactory.CSharp.csproj">
       <Project>{53dca265-3c3c-42f9-b647-f72ba678122b}</Project>
       <Name>ICSharpCode.NRefactory.CSharp</Name>
@@ -119,6 +118,7 @@
     <Compile Include="TestCases\CompoundAssignment.cs" />
     <Compile Include="TestCases\ControlFlow.cs" />
     <Compile Include="TestCases\DecimalFields.cs" />
+    <Compile Include="TestCases\FloatComparisons.cs" />
     <Compile Include="TestCases\Generics.cs" />
     <Compile Include="TestCases\HelloWorld.cs" />
     <Compile Include="TestCases\InitializerTests.cs" />

ICSharpCode.Decompiler/Tests/TestCases/FloatComparisons.cs

@@ -0,0 +1,51 @@
+// Copyright (c) 2016 Daniel Grunwald
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+
+namespace ICSharpCode.Decompiler.Tests.TestCases
+{
+	public class FloatComparisons
+	{
+		public static int Main()
+		{
+			// disable CompareOfFloatsByEqualityOperator
+			TestFloatOp("==", (a, b) => a == b);
+			TestFloatOp("!=", (a, b) => a != b);
+			TestFloatOp("<", (a, b) => a < b);
+			TestFloatOp(">", (a, b) => a > b);
+			TestFloatOp("<=", (a, b) => a <= b);
+			TestFloatOp(">=", (a, b) => a >= b);
+			TestFloatOp("!<", (a, b) => !(a < b));
+			TestFloatOp("!>", (a, b) => !(a > b));
+			TestFloatOp("!<=", (a, b) => !(a <= b));
+			TestFloatOp("!>=", (a, b) => !(a >= b));
+			return 0;
+		}
+		
+		static void TestFloatOp(string name, Func<float, float, bool> f)
+		{
+			float[] vals = { -1, 0, 3, float.PositiveInfinity, float.NaN };
+			for (int i = 0; i < vals.Length; i++) {
+				for (int j = 0; j < vals.Length; j++) {
+					Console.WriteLine("{0:r} {1} {2:r} = {3}", vals[i], name, vals[j], f(vals[i], vals[j]));
+				}
+			}
+		}
+	}
+}

ICSharpCode.Decompiler/Tests/TestRunner.cs

@@ -28,6 +28,12 @@ namespace ICSharpCode.Decompiler.Tests
 			}
 		}
 
+		[Test]
+		public void FloatComparisons()
+		{
+			TestCompileDecompileCompileOutputAll("FloatComparisons.cs");
+		}
+
 		[Test]
 		public void HelloWorld()
 		{