Add RemoveDeadCode option

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -29,7 +29,7 @@ namespace ICSharpCode.Decompiler
 	public class DecompilerSettings : INotifyPropertyChanged
 	{
 		bool anonymousMethods = true;
-		
+
 		/// <summary>
 		/// Decompile anonymous methods/lambdas.
 		/// </summary>
@@ -59,7 +59,7 @@ namespace ICSharpCode.Decompiler
 		}
 
 		bool expressionTrees = true;
-		
+
 		/// <summary>
 		/// Decompile expression trees.
 		/// </summary>
@@ -72,9 +72,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool yieldReturn = true;
-		
+
 		/// <summary>
 		/// Decompile enumerators.
 		/// </summary>
@@ -87,9 +87,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool asyncAwait = true;
-		
+
 		/// <summary>
 		/// Decompile async methods.
 		/// </summary>
@@ -134,7 +134,7 @@ namespace ICSharpCode.Decompiler
 		}
 
 		bool automaticProperties = true;
-		
+
 		/// <summary>
 		/// Decompile automatic properties
 		/// </summary>
@@ -147,9 +147,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool automaticEvents = true;
-		
+
 		/// <summary>
 		/// Decompile automatic events
 		/// </summary>
@@ -162,9 +162,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool usingStatement = true;
-		
+
 		/// <summary>
 		/// Decompile using statements.
 		/// </summary>
@@ -177,9 +177,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool forEachStatement = true;
-		
+
 		/// <summary>
 		/// Decompile foreach statements.
 		/// </summary>
@@ -192,9 +192,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool lockStatement = true;
-		
+
 		/// <summary>
 		/// Decompile lock statements.
 		/// </summary>
@@ -207,9 +207,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool switchStatementOnString = true;
-		
+
 		public bool SwitchStatementOnString {
 			get { return switchStatementOnString; }
 			set {
@@ -219,9 +219,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool usingDeclarations = true;
-		
+
 		public bool UsingDeclarations {
 			get { return usingDeclarations; }
 			set {
@@ -231,9 +231,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool queryExpressions = true;
-		
+
 		public bool QueryExpressions {
 			get { return queryExpressions; }
 			set {
@@ -262,7 +262,7 @@ namespace ICSharpCode.Decompiler
 		}
 
 		bool fullyQualifyAmbiguousTypeNames = true;
-		
+
 		public bool FullyQualifyAmbiguousTypeNames {
 			get { return fullyQualifyAmbiguousTypeNames; }
 			set {
@@ -272,9 +272,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool useDebugSymbols = true;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to use variable names from debug symbols, if available.
 		/// </summary>
@@ -287,9 +287,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool objectCollectionInitializers = true;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to use C# 3.0 object/collection initializers
 		/// </summary>
@@ -302,9 +302,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool showXmlDocumentation = true;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to include XML documentation comments in the decompiled code
 		/// </summary>
@@ -319,7 +319,7 @@ namespace ICSharpCode.Decompiler
 		}
 
 		bool foldBraces = false;
-		
+
 		public bool FoldBraces {
 			get { return foldBraces; }
 			set {
@@ -329,10 +329,10 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		#region Options to aid VB decompilation
 		bool introduceIncrementAndDecrement = true;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to use increment and decrement operators
 		/// </summary>
@@ -345,9 +345,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool makeAssignmentExpressions = true;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to use assignment expressions such as in while ((count = Do()) != 0) ;
 		/// </summary>
@@ -360,9 +360,9 @@ namespace ICSharpCode.Decompiler
 				}
 			}
 		}
-		
+
 		bool alwaysGenerateExceptionVariableForCatchBlocks = false;
-		
+
 		/// <summary>
 		/// Gets/Sets whether to always generate exception variables in catch blocks
 		/// </summary>
@@ -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;
@@ -419,7 +433,7 @@ namespace ICSharpCode.Decompiler
 		#endregion
 
 		CSharpFormattingOptions csharpFormattingOptions;
-		
+
 		public CSharpFormattingOptions CSharpFormattingOptions {
 			get {
 				if (csharpFormattingOptions == null) {
@@ -440,14 +454,14 @@ namespace ICSharpCode.Decompiler
 		}
 
 		public event PropertyChangedEventHandler PropertyChanged;
-		
+
 		protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
 		{
 			if (PropertyChanged != null) {
 				PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
 			}
 		}
-		
+
 		public DecompilerSettings Clone()
 		{
 			DecompilerSettings settings = (DecompilerSettings)MemberwiseClone();

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>