Fix #1168: Extend MatchCompEquals and MatchCompNotEquals to work with multiple nested logic.not instructions

ICSharpCode.Decompiler/IL/Instructions/PatternMatching.cs

@@ -327,11 +327,16 @@ namespace ICSharpCode.Decompiler.IL
 		/// </summary>
 		public bool MatchCompEquals(out ILInstruction left, out ILInstruction right)
 		{
-			if (this.MatchLogicNot(out var arg) && arg is Comp nestedComp && nestedComp.Kind == ComparisonKind.Inequality && !nestedComp.IsLifted) {
-				left = nestedComp.Left;
-				right = nestedComp.Right;
-				return true;
-			} else if (this is Comp comp && comp.Kind == ComparisonKind.Equality && !comp.IsLifted) {
+			ILInstruction thisInst = this;
+			var compKind = ComparisonKind.Equality;
+			while (thisInst.MatchLogicNot(out var arg) && arg is Comp) {
+				thisInst = arg;
+				if (compKind == ComparisonKind.Equality)
+					compKind = ComparisonKind.Inequality;
+				else
+					compKind = ComparisonKind.Equality;
+			}
+			if (thisInst is Comp comp && comp.Kind == compKind && !comp.IsLifted) {
 				left = comp.Left;
 				right = comp.Right;
 				return true;
@@ -389,11 +394,16 @@ namespace ICSharpCode.Decompiler.IL
 		/// </summary>
 		public bool MatchCompNotEquals(out ILInstruction left, out ILInstruction right)
 		{
-			if (this.MatchLogicNot(out var arg) && arg is Comp nestedComp && nestedComp.Kind == ComparisonKind.Equality && !nestedComp.IsLifted) {
-				left = nestedComp.Left;
-				right = nestedComp.Right;
-				return true;
-			} else if (this is Comp comp && comp.Kind == ComparisonKind.Inequality && !comp.IsLifted) {
+			ILInstruction thisInst = this;
+			var compKind = ComparisonKind.Inequality;
+			while (thisInst.MatchLogicNot(out var arg) && arg is Comp) {
+				thisInst = arg;
+				if (compKind == ComparisonKind.Equality)
+					compKind = ComparisonKind.Inequality;
+				else
+					compKind = ComparisonKind.Equality;
+			}
+			if (thisInst is Comp comp && comp.Kind == compKind && !comp.IsLifted) {
 				left = comp.Left;
 				right = comp.Right;
 				return true;