Add RemoveDeadCode option

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -390,6 +390,20 @@ namespace ICSharpCode.Decompiler
 
 		#endregion
 
+		#region Options to aid F# decompilation
+		bool removeDeadCode = false;
+
+		public bool RemoveDeadCode {
+			get { return removeDeadCode; }
+			set {
+				if (removeDeadCode != value) {
+					removeDeadCode = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+		#endregion
+
 		#region Assembly Load and Resolve options
 
 		bool loadInMemory = false;

ICSharpCode.Decompiler/IL/Transforms/RemoveDeadVariableInit.cs

@@ -44,22 +44,24 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			// This is necessary to remove useless stores generated by some compilers, e.g., the F# compiler.
 			// In yield return + async, the C# compiler tends to store null/default(T) to variables
 			// when the variable goes out of scope.
-			var variableQueue = new Queue<ILVariable>(function.Variables);
-			while (variableQueue.Count > 0) {
-				var v = variableQueue.Dequeue();
-				if (v.Kind != VariableKind.Local && v.Kind != VariableKind.StackSlot)
-					continue;
-				if (v.LoadCount != 0 || v.AddressCount != 0)
-					continue;
-				foreach (var stloc in v.StoreInstructions.OfType<StLoc>().ToArray()) {
-					if (stloc.Parent is Block block) {
-						if (SemanticHelper.IsPure(stloc.Value.Flags)) {
-							block.Instructions.Remove(stloc);
-						} else {
-							stloc.ReplaceWith(stloc.Value);
-						}
-						if (stloc.Value is LdLoc ldloc) {
-							variableQueue.Enqueue(ldloc.Variable);
+			if (function.IsAsync || function.IsIterator || context.Settings.RemoveDeadCode) {
+				var variableQueue = new Queue<ILVariable>(function.Variables);
+				while (variableQueue.Count > 0) {
+					var v = variableQueue.Dequeue();
+					if (v.Kind != VariableKind.Local && v.Kind != VariableKind.StackSlot)
+						continue;
+					if (v.LoadCount != 0 || v.AddressCount != 0)
+						continue;
+					foreach (var stloc in v.StoreInstructions.OfType<StLoc>().ToArray()) {
+						if (stloc.Parent is Block block) {
+							if (SemanticHelper.IsPure(stloc.Value.Flags)) {
+								block.Instructions.Remove(stloc);
+							} else {
+								stloc.ReplaceWith(stloc.Value);
+							}
+							if (stloc.Value is LdLoc ldloc) {
+								variableQueue.Enqueue(ldloc.Variable);
+							}
 						}
 					}
 				}

ILSpy/Options/DecompilerSettingsPanel.xaml

@@ -14,5 +14,6 @@
 		<CheckBox IsChecked="{Binding ShowDebugInfo}">Show info from debug symbols, if available</CheckBox>
 		<CheckBox IsChecked="{Binding ShowXmlDocumentation}">Show XML documentation in decompiled code</CheckBox>
 		<CheckBox IsChecked="{Binding FoldBraces}">Enable folding on all blocks in braces</CheckBox>
+		<CheckBox IsChecked="{Binding RemoveDeadCode}">Remove dead and side effect free code.</CheckBox>
 	</StackPanel>
 </UserControl>