Improve control flow decompilation with some compilers

Add a ControlFlowSimplification step after SplitVariables
Enable dead code removal in some unit tests

ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs

@@ -106,7 +106,8 @@ namespace ICSharpCode.Decompiler.Tests
 		public void ExceptionHandling([ValueSource("defaultOptions")] CSharpCompilerOptions cscOptions)
 		{
 			RunForLibrary(cscOptions: cscOptions, decompilerSettings: new DecompilerSettings {
-				NullPropagation = false
+				NullPropagation = false,
+				RemoveDeadCode = !cscOptions.HasFlag(CSharpCompilerOptions.UseRoslyn)
 			});
 		}
 
@@ -161,7 +162,9 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public void Loops([ValueSource("defaultOptionsWithMcs")] CSharpCompilerOptions cscOptions)
 		{
-			RunForLibrary(cscOptions: cscOptions);
+			RunForLibrary(cscOptions: cscOptions, decompilerSettings: new DecompilerSettings {
+				RemoveDeadCode = !cscOptions.HasFlag(CSharpCompilerOptions.Optimize)
+			});
 		}
 
 		[Test]

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -87,6 +87,7 @@ namespace ICSharpCode.Decompiler.CSharp
 				// is already collapsed into stloc(V, ...).
 				new RemoveDeadVariableInit(),
 				new SplitVariables(), // split variables once again, because the stobj(ldloca V, ...) may open up new replacements
+				new ControlFlowSimplification(), //split variables may enable new branch to leave inlining
 				new DynamicCallSiteTransform(),
 				new SwitchDetection(),
 				new SwitchOnStringTransform(),