ILInstruction.Clone()

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -41,6 +41,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		readonly DecompilerTypeSystem typeSystem;
 
 		List<IILTransform> ilTransforms = new List<IILTransform> {
+			new OptimizingTransform(),
 			new LoopDetection(),
 			new TransformingVisitor(),
 			new TransformStackIntoVariables()
@@ -101,9 +102,11 @@ namespace ICSharpCode.Decompiler.CSharp
 		
 		void RunTransforms(AstNode rootNode, ITypeResolveContext decompilationContext)
 		{
-			var context = new TransformContext(typeSystem, decompilationContext);
+			var context = new TransformContext(typeSystem, decompilationContext, CancellationToken);
-			foreach (var transform in astTransforms)
+			foreach (var transform in astTransforms) {
+				CancellationToken.ThrowIfCancellationRequested();
 				transform.Run(rootNode, context);
+			}
 			rootNode.AcceptVisitor(new InsertParenthesesVisitor { InsertParenthesesForReadability = true });
 		}
 		
@@ -226,8 +229,9 @@ namespace ICSharpCode.Decompiler.CSharp
 			var ilReader = new ILReader(specializingTypeSystem);
 			var function = ilReader.ReadIL(methodDefinition.Body, CancellationToken);
 			function.CheckInvariant();
-			var context = new ILTransformContext { TypeSystem = specializingTypeSystem };
+			var context = new ILTransformContext { TypeSystem = specializingTypeSystem, CancellationToken = CancellationToken };
 			foreach (var transform in ilTransforms) {
+				CancellationToken.ThrowIfCancellationRequested();
 				transform.Run(function, context);
 				function.CheckInvariant();
 			}

ICSharpCode.Decompiler/CSharp/Transforms/TransformContext.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Threading;
 using ICSharpCode.NRefactory.CSharp.Resolver;
 using ICSharpCode.NRefactory.TypeSystem;
 
@@ -28,6 +29,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 	public class TransformContext
 	{
 		public readonly DecompilerTypeSystem TypeSystem;
+		public readonly CancellationToken CancellationToken;
 		readonly ITypeResolveContext decompilationContext;
 		
 		/// <summary>
@@ -44,10 +46,11 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			get { return decompilationContext.CurrentTypeDefinition; }
 		}
 		
-		internal TransformContext(DecompilerTypeSystem typeSystem, ITypeResolveContext decompilationContext)
+		internal TransformContext(DecompilerTypeSystem typeSystem, ITypeResolveContext decompilationContext, CancellationToken cancellationToken)
 		{
 			this.TypeSystem = typeSystem;
 			this.decompilationContext = decompilationContext;
+			this.CancellationToken = cancellationToken;
 		}
 	}
 }

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -105,10 +105,10 @@
     <Compile Include="IL\IInlineContext.cs" />
     <Compile Include="IL\NRTypeExtensions.cs" />
     <Compile Include="IL\Transforms\LoopDetection.cs" />
+    <Compile Include="IL\Transforms\OptimizingTransform.cs" />
     <Compile Include="IL\Transforms\TransformingVisitor.cs" />
     <Compile Include="IL\Transforms\TransformStackIntoVariables.cs" />
     <Compile Include="IL\Transforms\TransformStackIntoVariablesState.cs" />
-    <Compile Include="IL\UnionFind.cs" />
     <Compile Include="CecilExtensions.cs" />
     <Compile Include="Disassembler\DisassemblerHelpers.cs" />
     <Compile Include="Disassembler\ILStructure.cs" />
@@ -137,9 +137,9 @@
     <Compile Include="TypeSystem\IDecompilerTypeSystem.cs" />
     <Compile Include="TypeSystem\ReferenceResolvingException.cs" />
     <Compile Include="TypeSystem\TypesHierarchyHelpers.cs" />
-    <Compile Include="Util\Argument.cs" />
     <Compile Include="Util\CollectionExtensions.cs" />
     <Compile Include="Util\Interval.cs" />
+    <Compile Include="Util\UnionFind.cs" />
     <None Include="IL\ILOpCodes.tt">
       <Generator>TextTemplatingFileGenerator</Generator>
       <LastGenOutput>ILOpCodes.cs</LastGenOutput>

ICSharpCode.Decompiler/IL/BlockBuilder.cs

@@ -32,6 +32,12 @@ namespace ICSharpCode.Decompiler.IL
 		readonly Mono.Cecil.Cil.MethodBody body;
 		readonly IDecompilerTypeSystem typeSystem;
 
+		/// <summary>
+		/// Gets/Sets whether to create extended basic blocks instead of basic blocks.
+		/// The default is <c>false</c>.
+		/// </summary>
+		public bool CreateExtendedBlocks;
+		
 		public BlockBuilder(Mono.Cecil.Cil.MethodBody body, IDecompilerTypeSystem typeSystem)
 		{
 			Debug.Assert(body != null);
@@ -145,6 +151,8 @@ namespace ICSharpCode.Decompiler.IL
 				currentBlock.Instructions.Add(inst);
 				if (inst.HasFlag(InstructionFlags.EndPointUnreachable))
 					FinalizeCurrentBlock(inst.ILRange.End, fallthrough: false);
+				else if (!CreateExtendedBlocks && inst.HasFlag(InstructionFlags.MayBranch))
+					FinalizeCurrentBlock(inst.ILRange.End, fallthrough: true);
 			}
 			FinalizeCurrentBlock(body.CodeSize, fallthrough: false);
 			containerStack.Clear();
@@ -195,42 +203,3 @@ namespace ICSharpCode.Decompiler.IL
 		}
 	}
 }
-
-
-/* Inlining logic: } else {
-						bool finished;
-						var inlinedInst = inst.Inline(InstructionFlags.None, instructionStack, out finished);
-						if (inlinedInst.HasFlag(InstructionFlags.MayBranch)) {
-							// Values currently on the stack might be used on both sides of the branch,
-							// so we can't inline them.
-							FlushInstructionStack();
-						}
-						if (inlinedInst.ResultType == StackType.Void) {
-							// We cannot directly push instructions onto the stack if they don't produce
-							// a result.
-							if (finished && instructionStack.Count > 0) {
-								// Wrap the instruction on top of the stack into an inline block,
-								// and append our void-typed instruction to the end of that block.
-								var headInst = instructionStack.Pop();
-								var block = headInst as Block ?? new Block { Instructions = { headInst } };
-								block.Instructions.Add(inlinedInst);
-								instructionStack.Push(block);
-							} else {
-								// We can't move incomplete instructions into a nested block
-								// or the instruction stack was empty
-								FlushInstructionStack();
-								currentBlock.Instructions.Add(inst);
-							}
-						} else {
-							// Instruction has a result, so we can push it on the stack normally
-							instructionStack.Push(inlinedInst);
-						}
-					}
-		private void FlushInstructionStack()
-		{
-			if (instructionStack != null && instructionStack.Count > 0) {
-				// Flush instruction stack
-				currentBlock.Instructions.AddRange(instructionStack.Reverse());
-				instructionStack.Clear();
-			}
-		}*/

ICSharpCode.Decompiler/IL/Instructions.cs

@@ -214,6 +214,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (UnaryInstruction)ShallowClone();
+			clone.Argument = this.argument.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Argument = this.argument.Inline(flagsBefore, context);
@@ -288,6 +294,13 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (BinaryInstruction)ShallowClone();
+			clone.Left = this.left.Clone();
+			clone.Right = this.right.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Right = this.right.Inline(flagsBefore | ((this.left.Flags) & ~(InstructionFlags.MayPeek | InstructionFlags.MayPop)), context);
@@ -420,6 +433,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (ILFunction)ShallowClone();
+			clone.Body = this.body.Clone();
+			return clone;
+		}
 		public override StackType ResultType { get { return StackType.O; } }
 		public override void AcceptVisitor(ILVisitor visitor)
 		{
@@ -763,6 +782,14 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (IfInstruction)ShallowClone();
+			clone.Condition = this.condition.Clone();
+			clone.TrueInst = this.trueInst.Clone();
+			clone.FalseInst = this.falseInst.Clone();
+			return clone;
+		}
 		public override void AcceptVisitor(ILVisitor visitor)
 		{
 			visitor.VisitIfInstruction(this);
@@ -841,6 +868,13 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (TryCatchHandler)ShallowClone();
+			clone.Filter = this.filter.Clone();
+			clone.Body = this.body.Clone();
+			return clone;
+		}
 		readonly ILVariable variable;
 		/// <summary>Returns the variable operand.</summary>
 		public ILVariable Variable { get { return variable; } }
@@ -1153,6 +1187,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (StLoc)ShallowClone();
+			clone.Value = this.value.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Value = this.value.Inline(flagsBefore, context);
@@ -1529,6 +1569,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (LdFld)ShallowClone();
+			clone.Target = this.target.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Target = this.target.Inline(flagsBefore, context);
@@ -1612,6 +1658,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (LdFlda)ShallowClone();
+			clone.Target = this.target.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Target = this.target.Inline(flagsBefore, context);
@@ -1701,6 +1753,13 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (StFld)ShallowClone();
+			clone.Target = this.target.Clone();
+			clone.Value = this.value.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Value = this.value.Inline(flagsBefore | ((this.target.Flags) & ~(InstructionFlags.MayPeek | InstructionFlags.MayPop)), context);
@@ -1854,6 +1913,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (StsFld)ShallowClone();
+			clone.Value = this.value.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Value = this.value.Inline(flagsBefore, context);
@@ -2001,6 +2066,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (LdObj)ShallowClone();
+			clone.Target = this.target.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Target = this.target.Inline(flagsBefore, context);
@@ -2098,6 +2169,13 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (StObj)ShallowClone();
+			clone.Target = this.target.Clone();
+			clone.Value = this.value.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Value = this.value.Inline(flagsBefore | ((this.target.Flags) & ~(InstructionFlags.MayPeek | InstructionFlags.MayPop)), context);
@@ -2429,6 +2507,12 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (LdLen)ShallowClone();
+			clone.Target = this.target.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Target = this.target.Inline(flagsBefore, context);
@@ -2513,6 +2597,13 @@ namespace ICSharpCode.Decompiler.IL
 					throw new IndexOutOfRangeException();
 			}
 		}
+		public sealed override ILInstruction Clone()
+		{
+			var clone = (LdElema)ShallowClone();
+			clone.Array = this.array.Clone();
+			clone.Index = this.index.Clone();
+			return clone;
+		}
 		internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)
 		{
 			this.Index = this.index.Inline(flagsBefore | ((this.array.Flags) & ~(InstructionFlags.MayPeek | InstructionFlags.MayPop)), context);

ICSharpCode.Decompiler/IL/Instructions.tt

@@ -528,7 +528,6 @@ namespace ICSharpCode.Decompiler.IL
 		public readonly string PropertyName;
 		public readonly string Name;
 		public bool IsArgument;
-		public bool IsOptional;
 		
 		public ChildInfo(string name)
 		{
@@ -551,15 +550,11 @@ namespace ICSharpCode.Decompiler.IL
 				opCode.ConstructorBody.Add("this." + argProp + " = " + arg + ";");
 				if (i > 0)
 					opCode.WriteArguments.Add("output.Write(\", \");");
-				if (children[i].IsOptional)
+				opCode.WriteArguments.Add("this." + arg + ".WriteTo(output);");
-					opCode.WriteArguments.Add("if (this." + arg + " != null) this." + arg + ".WriteTo(output);");
-				else
-					opCode.WriteArguments.Add("this." + arg + ".WriteTo(output);");
 				opCode.Members.Add("ILInstruction " + arg + ";");
 				opCode.Members.Add("public ILInstruction " + argProp + " {" + Environment.NewLine
 					+ "\tget { return this." + arg + "; }" + Environment.NewLine
 					+ "\tset {" + Environment.NewLine
-					+ (children[i].IsOptional ? "\t\tif (value != null)" + Environment.NewLine + "\t" : "")
 					+ "\t\t" + (children[i].IsArgument ? "ValidateArgument" : "ValidateChild") + "(value);" + Environment.NewLine
 					+ "\t\tSetChildInstruction(ref this." + arg + ", value, " + i + ");" + Environment.NewLine
 					+ "\t}" + Environment.NewLine
@@ -603,44 +598,23 @@ namespace ICSharpCode.Decompiler.IL
 			b.Append("}");
 			opCode.Members.Add(b.ToString());
 			
-			/*
 			b = new StringBuilder();
-			b.AppendLine("public override IEnumerable<ILInstruction> Children {");
+			b.AppendLine("public sealed override ILInstruction Clone()");
-			b.AppendLine("\tget {");
-			foreach (var child in children) {
-				if (child.IsOptional) {
-					b.AppendLine("\t\tif (this." + child.Name + " != null)");
-					b.Append('\t');
-				}
-				b.AppendLine("\t\tyield return this." + child.Name + ";");
-			}
-			b.AppendLine("\t}");
-			b.Append("}");
-			opCode.Members.Add(b.ToString());
-			
-			b = new StringBuilder();
-			b.AppendLine("public override void TransformChildren(ILVisitor<ILInstruction> visitor)");
 			b.AppendLine("{");
-			foreach (var child in children) {
+			b.AppendLine("\tvar clone = (" + opCode.Name + ")ShallowClone();");
-				if (child.IsOptional) {
+			for (int i = 0; i < children.Length; i++) {
-					b.AppendLine("\tif (this." + child.Name + " != null)");
+				b.AppendLine("\tclone." + children[i].PropertyName + " = this." + children[i].Name + ".Clone();");
-					b.Append('\t');
-				}
-				b.AppendLine("\tthis." + child.PropertyName + " = this." + child.Name + ".AcceptVisitor(visitor);");
 			}
+			b.AppendLine("\treturn clone;");
 			b.Append("}");
 			opCode.Members.Add(b.ToString());
-			*/
+			
 			if (generateInline) {
 				b = new StringBuilder();
 				b.AppendLine("internal sealed override ILInstruction Inline(InstructionFlags flagsBefore, IInlineContext context)");
 				b.AppendLine("{");
 				for (int i = children.Length - 1; i >= 0; i--) {
 					string arg = children[i].Name;
-					if (children[i].IsOptional) {
-						b.AppendLine("\tif (this." + arg + " != null)");
-						b.Append("\t");
-					}
 					b.Append("\tthis." + MakeName(arg) + " = this." + arg + ".Inline(flagsBefore");
 					if (i > 0) {
 						b.Append(" | ((");

ICSharpCode.Decompiler/IL/Instructions/Block.cs

@@ -95,6 +95,15 @@ namespace ICSharpCode.Decompiler.IL
 			this.FinalInstruction = new Nop();
 		}
 		
+		public override ILInstruction Clone()
+		{
+			Block clone = new Block();
+			clone.ILRange = this.ILRange;
+			clone.Instructions.AddRange(this.Instructions.Select(inst => inst.Clone()));
+			clone.FinalInstruction = this.FinalInstruction.Clone();
+			return clone;
+		}
+		
 		public override StackType ResultType {
 			get {
 				return finalInstruction.ResultType;

ICSharpCode.Decompiler/IL/Instructions/BlockContainer.cs

@@ -66,6 +66,23 @@ namespace ICSharpCode.Decompiler.IL
 			this.Blocks = new InstructionCollection<Block>(this, 0);
 		}
 
+		public override ILInstruction Clone()
+		{
+			BlockContainer clone = new BlockContainer();
+			clone.ILRange = this.ILRange;
+			clone.Blocks.AddRange(this.Blocks.Select(block => (Block)block.Clone()));
+			// Adjust branch instructions to point to the new container
+			foreach (var branch in clone.Descendants.OfType<Branch>()) {
+				if (branch.TargetBlock != null && branch.TargetBlock.Parent == this)
+					branch.TargetBlock = clone.Blocks[branch.TargetBlock.ChildIndex];
+			}
+			foreach (var leave in clone.Descendants.OfType<Leave>()) {
+				if (leave.TargetContainer == this)
+					leave.TargetContainer = clone;
+			}
+			return clone;
+		}
+		
 		protected internal override void InstructionCollectionUpdateComplete()
 		{
 			base.InstructionCollectionUpdateComplete();

ICSharpCode.Decompiler/IL/Instructions/CallInstruction.cs

@@ -46,6 +46,17 @@ namespace ICSharpCode.Decompiler.IL
 		public readonly InstructionCollection<ILInstruction> Arguments;
 		public readonly IMethod Method;
 		
+		/// <summary>
+		/// Gets/Sets whether the call has the 'tail.' prefix.
+		/// </summary>
+		public bool IsTail;
+
+		/// <summary>
+		/// Gets/Sets the type specified in the 'constrained.' prefix.
+		/// Returns null if no 'constrained.' prefix exists for this call.
+		/// </summary>
+		public IType ConstrainedTo;
+
 		protected CallInstruction(OpCode opCode, IMethod method) : base(opCode)
 		{
 			Debug.Assert(method != null);
@@ -53,6 +64,16 @@ namespace ICSharpCode.Decompiler.IL
 			this.Arguments = new InstructionCollection<ILInstruction>(this, 0);
 		}
 		
+		public sealed override ILInstruction Clone()
+		{
+			var clone = Create(this.OpCode, this.Method);
+			clone.Arguments.AddRange(this.Arguments.Select(arg => arg.Clone()));
+			clone.ILRange = this.ILRange;
+			clone.IsTail = this.IsTail;
+			clone.ConstrainedTo = this.ConstrainedTo;
+			return clone;
+		}
+		
 		public override StackType ResultType {
 			get {
 				if (OpCode == OpCode.NewObj)
@@ -62,17 +83,17 @@ namespace ICSharpCode.Decompiler.IL
 			}
 		}
 		
-		protected override int GetChildCount()
+		protected sealed override int GetChildCount()
 		{
 			return Arguments.Count;
 		}
 		
-		protected override ILInstruction GetChild(int index)
+		protected sealed override ILInstruction GetChild(int index)
 		{
 			return Arguments[index];
 		}
 		
-		protected override void SetChild(int index, ILInstruction value)
+		protected sealed override void SetChild(int index, ILInstruction value)
 		{
 			Arguments[index] = value;
 		}
@@ -85,17 +106,6 @@ namespace ICSharpCode.Decompiler.IL
 			return flags;
 		}
 		
-		/// <summary>
-		/// Gets/Sets whether the call has the 'tail.' prefix.
-		/// </summary>
-		public bool IsTail;
-
-		/// <summary>
-		/// Gets/Sets the type specified in the 'constrained.' prefix.
-		/// Returns null if no 'constrained.' prefix exists for this call.
-		/// </summary>
-		public IType ConstrainedTo;
-
 		public override void WriteTo(ITextOutput output)
 		{
 			if (ConstrainedTo != null) {

ICSharpCode.Decompiler/IL/Instructions/ILInstruction.cs

@@ -465,5 +465,29 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			InvalidateFlags();
 		}
+		
+		/// <summary>
+		/// Creates a deep clone of the ILInstruction.
+		/// </summary>
+		public abstract ILInstruction Clone();
+		
+		/// <summary>
+		/// Creates a shallow clone of the ILInstruction.
+		/// </summary>
+		/// <remarks>
+		/// Like MemberwiseClone(), except that the new instruction starts as disconnected.
+		/// </remarks>
+		protected ILInstruction ShallowClone()
+		{
+			ILInstruction inst = (ILInstruction)MemberwiseClone();
+			// reset refCount and parent so that the cloned instruction starts as disconnected
+			inst.refCount = 0;
+			inst.parent = null;
+			inst.flags = invalidFlags;
+			#if DEBUG
+			inst.activeEnumerators = 0;
+			#endif
+			return inst;
+		}
 	}
 }

ICSharpCode.Decompiler/IL/Instructions/Return.cs

@@ -31,7 +31,7 @@ namespace ICSharpCode.Decompiler.IL
 		/// </summary>
 		public ILInstruction ReturnValue {
 			get { return returnValue; }
-			set { 
+			set {
 				if (value != null)
 					ValidateArgument(value);
 				SetChildInstruction(ref returnValue, value, 0);
@@ -47,6 +47,14 @@ namespace ICSharpCode.Decompiler.IL
 			this.ReturnValue = argument;
 		}
 		
+		public override ILInstruction Clone()
+		{
+			Return clone = (Return)ShallowClone();
+			if (returnValue != null)
+				clone.ReturnValue = returnValue.Clone();
+			return clone;
+		}
+		
 		protected override InstructionFlags ComputeFlags()
 		{
 			InstructionFlags flags = InstructionFlags.MayBranch | InstructionFlags.EndPointUnreachable;

ICSharpCode.Decompiler/IL/Instructions/SimpleInstruction.cs

@@ -39,21 +39,26 @@ namespace ICSharpCode.Decompiler.IL
 			output.Write(OpCode);
 		}
 		
-		protected override int GetChildCount()
+		protected sealed override int GetChildCount()
 		{
 			return 0;
 		}
 		
-		protected override ILInstruction GetChild(int index)
+		protected sealed override ILInstruction GetChild(int index)
 		{
 			throw new IndexOutOfRangeException();
 		}
 		
-		protected override void SetChild(int index, ILInstruction value)
+		protected sealed override void SetChild(int index, ILInstruction value)
 		{
 			throw new IndexOutOfRangeException();
 		}
 		
+		public sealed override ILInstruction Clone()
+		{
+			return ShallowClone();
+		}
+		
 		protected override InstructionFlags ComputeFlags()
 		{
 			return InstructionFlags.None;

ICSharpCode.Decompiler/IL/Instructions/TryInstruction.cs

@@ -19,6 +19,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 
 namespace ICSharpCode.Decompiler.IL
 {
@@ -64,6 +65,14 @@ namespace ICSharpCode.Decompiler.IL
 			this.Handlers = new InstructionCollection<TryCatchHandler>(this, 1);
 		}
 		
+		public override ILInstruction Clone()
+		{
+			var clone = new TryCatch(TryBlock.Clone());
+			clone.ILRange = this.ILRange;
+			clone.Handlers.AddRange(this.Handlers.Select(h => (TryCatchHandler)h.Clone()));
+			return clone;
+		}
+		
 		public override void WriteTo(ITextOutput output)
 		{
 			output.Write(".try ");
@@ -197,6 +206,13 @@ namespace ICSharpCode.Decompiler.IL
 			}
 		}
 		
+		public override ILInstruction Clone()
+		{
+			return new TryFinally(TryBlock.Clone(), finallyBlock.Clone()) {
+				ILRange = this.ILRange
+			};
+		}
+		
 		public override void WriteTo(ITextOutput output)
 		{
 			output.Write(".try ");
@@ -270,6 +286,13 @@ namespace ICSharpCode.Decompiler.IL
 			}
 		}
 		
+		public override ILInstruction Clone()
+		{
+			return new TryFault(TryBlock.Clone(), faultBlock.Clone()) {
+				ILRange = this.ILRange
+			};
+		}
+		
 		public override void WriteTo(ITextOutput output)
 		{
 			output.Write(".try ");

ICSharpCode.Decompiler/IL/Transforms/LoopDetection.cs

@@ -26,12 +26,15 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 	/// <summary>
 	/// Detect loops in IL AST.
 	/// </summary>
+	/// <remarks>
+	/// Transform ordering:
+	/// * LoopDetection should run before other control flow structures are detected.
+	/// * Blocks should be basic blocks (not extended basic blocks) so that the natural loops
+	/// don't include more instructions than strictly necessary.
+	/// * (depending on future loop detection improvements:) Loop detection should run after the 'return block' is duplicated.
+	/// </remarks>
 	public class LoopDetection : IILTransform
 	{
-		// Transform ordering:
-		// LoopDetection should run before other control flow structures are detected.
-		// It should run after the 'return block' is duplicated.
-		
 		#region Construct Control Flow Graph
 		/// <summary>
 		/// Constructs a control flow graph for the blocks in the given block container.

ICSharpCode.Decompiler/IL/Transforms/OptimizingTransform.cs

@@ -0,0 +1,53 @@
+// Copyright (c) 2014 Daniel Grunwald
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+using System;
+using System.Linq;
+
+namespace ICSharpCode.Decompiler.IL.Transforms
+{
+	/// <summary>
+	/// This transform 'optimizes' the IL code: it replaces constructs that
+	/// are generated by the C# compiler in debug mode with shorter constructs
+	/// that are more straightforward to analyze.
+	/// </summary>
+	/// <remarks>
+	/// The optimizations performed are:
+	/// * 'nop' instructions are removed
+	/// * TODO branches that lead to a 'return block' are replaced with a return instruction
+	/// </remarks>
+	public class OptimizingTransform : IILTransform
+	{
+		public void Run(ILFunction function, ILTransformContext context)
+		{
+			foreach (var block in function.Descendants.OfType<Block>()) {
+				// Remove 'nop' instructions
+				block.Instructions.RemoveAll(inst => inst.OpCode == OpCode.Nop);
+				/* TODO we might need this for the 'return block' optimization
+				// Ensure return blocks are inlined:
+				if (block.Instructions.Count == 2 && block.Instructions[1].OpCode == OpCode.Return) {
+					Return ret = (Return)block.Instructions[1];
+					if (ret.ReturnValue != null && ret.ReturnValue.OpCode == OpCode.Pop && block.Instructions[0].ResultType != StackType.Void) {
+						ret.ReturnValue = block.Instructions[0];
+						block.Instructions.RemoveAt(0);
+					}
+				}
+				*/
+			}
+		}
+	}
+}

ICSharpCode.Decompiler/Output/PlainTextOutput.cs

@@ -97,12 +97,12 @@ namespace ICSharpCode.Decompiler
 			column = 1;
 		}
 		
-		public void WriteDefinition(string text, object definition, bool isLocal)
+		public void WriteDefinition(string text, object definition, bool isLocal = true)
 		{
 			Write(text);
 		}
 		
-		public void WriteReference(string text, object reference, bool isLocal)
+		public void WriteReference(string text, object reference, bool isLocal = false)
 		{
 			Write(text);
 		}

ICSharpCode.Decompiler/Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -102,13 +102,13 @@
     <Compile Include="Helpers\TypeSystemHelper.cs" />
     <Compile Include="ILTransforms\InliningTests.cs" />
     <Compile Include="Loops.cs" />
-    <Compile Include="LongSetTests.cs" />
     <Compile Include="StackToVariablesTests.cs" />
     <Compile Include="TestCases\CompoundAssignment.cs" />
     <Compile Include="TestCases\ControlFlow.cs" />
     <Compile Include="TestCases\HelloWorld.cs" />
     <Compile Include="TestCases\PropertiesAndEvents.cs" />
     <Compile Include="TestRunner.cs" />
+    <Compile Include="Util\LongSetTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />

ICSharpCode.Decompiler/Util/Argument.cs

@@ -1,15 +0,0 @@
-using System;
-using ICSharpCode.Decompiler.IL;
-
-namespace ICSharpCode.Decompiler
-{
-	static class Argument
-	{
-		public static T NotNull<T>(T value, string paramName)
-		{
-			if (value == null)
-				throw new ArgumentNullException(paramName);
-			return value;
-		}
-	}
-}

ICSharpCode.Decompiler/Util/UnionFind.cs

@@ -20,8 +20,11 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-namespace ICSharpCode.Decompiler.IL
+namespace ICSharpCode.Decompiler
 {
+	/// <summary>
+	/// Union-Find data structure.
+	/// </summary>
 	public class UnionFind<T>
 	{
 		Dictionary<T, Node> mapping;

ILSpy/Languages/CSharpLanguage.cs

@@ -44,33 +44,34 @@ namespace ICSharpCode.ILSpy
 	{
 		string name = "C#";
 		bool showAllMembers = false;
-		//Predicate<IAstTransform> transformAbortCondition = null;
+		int transformCount = int.MaxValue;
 
 		public CSharpLanguage()
 		{
 		}
 
 		#if DEBUG
-		/*
 		internal static IEnumerable<CSharpLanguage> GetDebugLanguages()
 		{
-			DecompilerContext context = new DecompilerContext(ModuleDefinition.CreateModule("dummy", ModuleKind.Dll));
+			//DecompilerContext context = new DecompilerContext(ModuleDefinition.CreateModule("dummy", ModuleKind.Dll));
+			var decompiler = new CSharpDecompiler(ModuleDefinition.CreateModule("Dummy", ModuleKind.Dll));
 			string lastTransformName = "no transforms";
-			foreach (Type _transformType in TransformationPipeline.CreatePipeline(context).Select(v => v.GetType()).Distinct()) {
+			int transformCount = 0;
-				Type transformType = _transformType; // copy for lambda
+			foreach (var transform in decompiler.AstTransforms) {
+				Type transformType = transform.GetType(); // copy for lambda
 				yield return new CSharpLanguage {
-					transformAbortCondition = v => transformType.IsInstanceOfType(v),
+					transformCount = transformCount,
 					name = "C# - " + lastTransformName,
 					showAllMembers = true
 				};
 				lastTransformName = "after " + transformType.Name;
+				transformCount++;
 			}
 			yield return new CSharpLanguage {
 				name = "C# - " + lastTransformName,
 				showAllMembers = true
 			};
 		}
-		*/
 		#endif
 
 		public override string Name
@@ -92,6 +93,8 @@ namespace ICSharpCode.ILSpy
 		{
 			WriteCommentLine(output, TypeToString(method.DeclaringType, includeNamespace: true));
 			CSharpDecompiler decompiler = new CSharpDecompiler(method.Module);
+			while (decompiler.AstTransforms.Count > transformCount)
+				decompiler.AstTransforms.RemoveAt(decompiler.AstTransforms.Count - 1);
 			output.WriteLine(decompiler.Decompile(method).ToString());
 			/*
 			AstBuilder codeDomBuilder = CreateAstBuilder(options, currentType: method.DeclaringType, isSingleMember: true);

ILSpy/Languages/Languages.cs

@@ -42,7 +42,7 @@ namespace ICSharpCode.ILSpy
 			languages.AddRange(composition.GetExportedValues<Language>());
 			#if DEBUG
 			languages.AddRange(ILAstLanguage.GetDebugLanguages());
-			//languages.AddRange(CSharpLanguage.GetDebugLanguages());
+			languages.AddRange(CSharpLanguage.GetDebugLanguages());
 			#endif
 			allLanguages = languages.AsReadOnly();
 		}

ILSpy/MainWindow.xaml.cs

@@ -541,6 +541,9 @@ namespace ICSharpCode.ILSpy
 					break;
 				bestMatch = node;
 				node.EnsureLazyChildren();
+				var ilSpyTreeNode = node as ILSpyTreeNode;
+				if (ilSpyTreeNode != null)
+					ilSpyTreeNode.EnsureChildrenFiltered();
 				node = node.Children.FirstOrDefault(c => c.ToString() == element);
 			}
 			if (returnBestMatch)

ILSpy/TreeNodes/ILSpyTreeNode.cs

@@ -157,7 +157,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			EnsureChildrenFiltered();
 		}
 
-		void EnsureChildrenFiltered()
+		internal void EnsureChildrenFiltered()
 		{
 			EnsureLazyChildren();
 			if (childrenNeedFiltering) {