Move PatternMatchingTransform after LoopDetection.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/PatternMatching.cs

@@ -212,6 +212,25 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			}
 		}
 
+		public static void NotTypePatternBecauseVarIsNotDefAssignedInCaseOfFallthrough(object x)
+		{
+#if OPT
+			string obj = x as string;
+			if (obj == null)
+			{
+				Console.WriteLine("pattern doesn't match");
+			}
+			Console.WriteLine(obj == null);
+#else
+			string text = x as string;
+			if (text == null)
+			{
+				Console.WriteLine("pattern doesn't match");
+			}
+			Console.WriteLine(text == null);
+#endif
+		}
+
 		private bool F()
 		{
 			return true;

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -103,7 +103,6 @@ namespace ICSharpCode.Decompiler.CSharp
 				new RemoveDeadVariableInit(),
 				new ControlFlowSimplification(), //split variables may enable new branch to leave inlining
 				new DynamicCallSiteTransform(),
-				new PatternMatchingTransform(),
 				new SwitchDetection(),
 				new SwitchOnStringTransform(),
 				new SwitchOnNullableTransform(),
@@ -121,6 +120,7 @@ namespace ICSharpCode.Decompiler.CSharp
 				},
 				// re-run DetectExitPoints after loop detection
 				new DetectExitPoints(),
+				new PatternMatchingTransform(), // must run after LoopDetection and before ConditionDetection
 				new BlockILTransform { // per-block transforms
 					PostOrderTransforms = {
 						new ConditionDetection(),

ICSharpCode.Decompiler/IL/Transforms/PatternMatchingTransform.cs

@@ -193,6 +193,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 			if (targetBlock.Parent != container)
 				return false;
+			if (targetBlock.IncomingEdgeCount != 1)
+				return false;
 			cfg ??= new ControlFlowGraph(container, context.CancellationToken);
 			var targetBlockNode = cfg.GetNode(targetBlock);
 			var uses = v.LoadInstructions.Concat<ILInstruction>(v.AddressInstructions)