Added custom Ast classes for Goto and Label statements that track the reference count of a label.

Added an Ast transform to remove dead labels.  (first Ast transform in program, I expect many more to come.  Some stuff should be rewritten to use these explicit transforms)

Decompiler.csproj

@@ -37,6 +37,9 @@
   <ItemGroup>
     <Folder Include="src" />
     <Folder Include="src\ControlFlow" />
+    <Folder Include="src\MyAst" />
+    <Folder Include="src\Transforms" />
+    <Folder Include="src\Transforms\Ast" />
     <Compile Include="src\AssemblyInfo.cs" />
     <Compile Include="src\AstBuilder.cs" />
     <Compile Include="src\AstMetodBodyBuilder.cs" />
@@ -52,11 +55,14 @@
     <Compile Include="src\ControlFlow\Node-Structure.cs" />
     <Compile Include="src\MainForm.cs" />
     <Compile Include="src\MainForm.Designer.cs" />
+    <Compile Include="src\MyAst\MyGotoStatement.cs" />
+    <Compile Include="src\MyAst\MyLabelStatement.cs" />
     <Compile Include="src\Options.cs" />
     <Compile Include="src\Program.cs" />
     <Compile Include="src\ByteCode.StackAnalysis.cs" />
     <Compile Include="src\StackExpression.cs" />
     <Compile Include="src\StackExpressionCollection.cs" />
+    <Compile Include="src\Transforms\Ast\RemoveDeadLabels.cs" />
     <Compile Include="src\Util.cs" />
     <EmbeddedResource Include="src\MainForm.resx">
       <DependentUpon>MainForm.cs</DependentUpon>

src/AstMetodBodyBuilder.cs

@@ -50,6 +50,8 @@ namespace Decompiler
 			
 			astBlock.Children.AddRange(TransformNodes(bodyGraph.Childs));
 			
+			astBlock.AcceptVisitor(new Transforms.Ast.RemoveDeadLabels(), null);
+			
 			return astBlock;
 		}
 		
@@ -68,7 +70,7 @@ namespace Decompiler
 				yield return MakeComment("// " + node.Description);
 			}
 			
-			yield return new Ast.LabelStatement(node.Label);
+			yield return new Ast.MyLabelStatement(node.Label);
 			
 			if (node is BasicBlock) {
 				foreach(StackExpression expr in ((BasicBlock)node).Body) {
@@ -77,7 +79,7 @@ namespace Decompiler
 				Node fallThroughNode = ((BasicBlock)node).FallThroughBasicBlock;
 				// If there is default branch and it is not the following node
 				if (fallThroughNode != null && fallThroughNode != node.NextNode) {
-					yield return MakeBranchCommand(node, fallThroughNode);
+					yield return Ast.MyGotoStatement.Create(node, fallThroughNode);
 				}
 			} else if (node is AcyclicGraph) {
 				Ast.BlockStatement blockStatement = new Ast.BlockStatement();
@@ -98,7 +100,7 @@ namespace Decompiler
 				}
 			} else if (node is ConditionalNode) {
 				ConditionalNode conditionalNode = (ConditionalNode)node;
-				yield return new Ast.LabelStatement(conditionalNode.Condition.Label);
+				yield return new Ast.MyLabelStatement(conditionalNode.Condition.Label);
 				Ast.Statement lastStatement = null;
 				foreach(StackExpression expr in conditionalNode.Condition.Body) {
 					lastStatement = TransformExpression(expr);
@@ -112,7 +114,7 @@ namespace Decompiler
 				
 				Ast.BlockStatement trueBlock = new Ast.BlockStatement();
 				// The block entry code
-				trueBlock.Children.Add(MakeBranchCommand(node, conditionalNode.Condition.FallThroughBasicBlock));
+				trueBlock.Children.Add(Ast.MyGotoStatement.Create(node, conditionalNode.Condition.FallThroughBasicBlock));
 				// Sugested content
 				trueBlock.Children.AddRange(TransformNode(conditionalNode.TrueBody));
 				ifElseStmt.TrueStatement.Add(trueBlock);
@@ -184,23 +186,6 @@ namespace Decompiler
 			return MakeCodeDomExpression(methodDef, expr.LastByteCode, allArgs.ToArray());
 		}
 		
-		static Ast.Statement MakeBranchCommand(Node node, Node targetNode)
-		{
-			// Propagate target up to the top most scope
-			while (targetNode.Parent != null && targetNode.Parent.HeadChild == targetNode) {
-				targetNode = targetNode.Parent;
-			}
-			// If branches to the start of encapsulating loop
-			if (node.Parent is Loop && targetNode == node.Parent) {
-				return new Ast.ContinueStatement();
-			}
-			// If branches outside the encapsulating loop
-			if (node.Parent is Loop && targetNode == node.Parent.NextNode) {
-				return new Ast.BreakStatement();
-			}
-			return new Ast.GotoStatement(targetNode.Label);
-		}
-		
 		static object MakeCodeDomExpression(MethodDefinition methodDef, ByteCode byteCode, params Ast.Expression[] args)
 		{
 			OpCode opCode = byteCode.OpCode;
@@ -213,7 +198,7 @@ namespace Decompiler
 			
 			Ast.Statement branchCommand = null;
 			if (operand is ByteCode) {
-				branchCommand = MakeBranchCommand(byteCode.Expression.BasicBlock, ((ByteCode)operand).Expression.BasicBlock);
+				branchCommand = Ast.MyGotoStatement.Create(byteCode.Expression.BasicBlock, ((ByteCode)operand).Expression.BasicBlock);
 			}
 			
 			switch(opCode.Code) {

src/ControlFlow/Node-Structure.cs

@@ -9,6 +9,7 @@ namespace Decompiler.ControlFlow
 		public static int NextNodeID = 1;
 		
 		int id;
+		NodeLabel label;
 		Node parent;
 		NodeCollection childs = new NodeCollection();
 		
@@ -21,6 +22,10 @@ namespace Decompiler.ControlFlow
 			get { return id; }
 		}
 		
+		public NodeLabel Label {
+			get { return label; }
+		}
+		
 		public Node Parent {
 			get { return parent; }
 		}
@@ -137,12 +142,6 @@ namespace Decompiler.ControlFlow
 			}
 		}
 		
-		public string Label {
-			get {
-				return this.GetType().Name + "_" + ID;
-			}
-		}
-		
 		public string Description {
 			get {
 				return ToString();
@@ -152,6 +151,7 @@ namespace Decompiler.ControlFlow
 		protected Node()
 		{
 			this.id = NextNodeID++;
+			this.label = new NodeLabel(this.GetType().Name + "_" + ID);
 			this.Childs.Added += delegate(object sender, NodeEventArgs e) {
 				if (e.Node.Parent != null) {
 					throw new Exception("Node is already assigned to other parent");
@@ -230,4 +230,24 @@ namespace Decompiler.ControlFlow
 			return sb.ToString();
 		}
 	}
+	
+	public class NodeLabel
+	{
+		string label;
+		int referenceCount = 0;
+		
+		public string Label {
+			get { return label; }
+		}
+		
+		public int ReferenceCount {
+			get { return referenceCount; }
+			set { referenceCount = value; }
+		}
+		
+		public NodeLabel(string label)
+		{
+			this.label = label;
+		}
+	}
 }

src/MyAst/MyGotoStatement.cs

@@ -0,0 +1,40 @@
+using System;
+
+using Ast = ICSharpCode.NRefactory.Ast;
+using Decompiler.ControlFlow;
+
+namespace ICSharpCode.NRefactory.Ast
+{
+	public class MyGotoStatement: Ast.GotoStatement
+	{
+		NodeLabel nodeLabel;
+		
+		public NodeLabel NodeLabel {
+			get { return nodeLabel; }
+		}
+		
+		public MyGotoStatement(NodeLabel nodeLabel): base(nodeLabel.Label)
+		{
+			this.nodeLabel = nodeLabel;
+			
+			this.nodeLabel.ReferenceCount++;
+		}
+		
+		public static Ast.Statement Create(Node contextNode, Node targetNode)
+		{
+			// Propagate target up to the top most scope
+			while (targetNode.Parent != null && targetNode.Parent.HeadChild == targetNode) {
+				targetNode = targetNode.Parent;
+			}
+			// If branches to the start of encapsulating loop
+			if (contextNode.Parent is Loop && targetNode == contextNode.Parent) {
+				return new Ast.ContinueStatement();
+			}
+			// If branches outside the encapsulating loop
+			if (contextNode.Parent is Loop && targetNode == contextNode.Parent.NextNode) {
+				return new Ast.BreakStatement();
+			}
+			return new Ast.MyGotoStatement(targetNode.Label);
+		}
+	}
+}

src/MyAst/MyLabelStatement.cs

@@ -0,0 +1,21 @@
+using System;
+
+using Ast = ICSharpCode.NRefactory.Ast;
+using Decompiler.ControlFlow;
+
+namespace ICSharpCode.NRefactory.Ast
+{
+	public class MyLabelStatement: Ast.LabelStatement
+	{
+		NodeLabel nodeLabel;
+		
+		public NodeLabel NodeLabel {
+			get { return nodeLabel; }
+		}
+		
+		public MyLabelStatement(NodeLabel nodeLabel): base(nodeLabel.Label)
+		{
+			this.nodeLabel = nodeLabel;
+		}
+	}
+}

src/Transforms/Ast/RemoveDeadLabels.cs

@@ -0,0 +1,19 @@
+using System;
+
+using ICSharpCode.NRefactory.Ast;
+using ICSharpCode.NRefactory.Visitors;
+
+namespace Decompiler.Transforms.Ast
+{
+	public class RemoveDeadLabels: AbstractAstTransformer
+	{
+		public override object VisitLabelStatement(LabelStatement labelStatement, object data)
+		{
+			MyLabelStatement myLabel = (MyLabelStatement)labelStatement;
+			if (myLabel.NodeLabel.ReferenceCount == 0) {
+				RemoveCurrentNode();
+			}
+			return null;
+		}
+	}
+}