Initial support for switch statements

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -1,14 +1,14 @@
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Linq;
-using Ast = ICSharpCode.NRefactory.CSharp;
-using ICSharpCode.NRefactory.CSharp;
-using Cecil = Mono.Cecil;
-using Mono.Cecil;
-using Mono.Cecil.Cil;
-using Mono.Cecil.Rocks;
-using Decompiler.ControlFlow;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using Ast = ICSharpCode.NRefactory.CSharp;
+using ICSharpCode.NRefactory.CSharp;
+using Cecil = Mono.Cecil;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using Mono.Cecil.Rocks;
+using Decompiler.ControlFlow;
 
 namespace Decompiler
 {
@@ -167,6 +167,16 @@ namespace Decompiler
 						FalseStatement = TransformBlock(conditionalNode.FalseBlock)
 					};
 				}
+			} else if (node is ILSwitch) {
+				ILSwitch ilSwitch = (ILSwitch)node;
+				SwitchStatement switchStmt = new SwitchStatement() { Expression = (Expression)TransformExpression(ilSwitch.Condition.Arguments[0]) };
+				for (int i = 0; i < ilSwitch.CaseBlocks.Count; i++) {
+					switchStmt.AddChild(new SwitchSection() {
+					    	CaseLabels = new CaseLabel[] { new CaseLabel() { Expression = new PrimitiveExpression(i) } },
+					    	Statements = new Statement[] { TransformBlock(ilSwitch.CaseBlocks[i]) }
+					}, SwitchStatement.SwitchSectionRole);
+				}
+				yield return switchStmt;
 			} else if (node is ILTryCatchBlock) {
 				ILTryCatchBlock tryCatchNode = ((ILTryCatchBlock)node);
 				List<Ast.CatchClause> catchClauses = new List<CatchClause>();

ICSharpCode.Decompiler/ILAst/ILAstOptimizer.cs

@@ -217,18 +217,69 @@ namespace Decompiler.ControlFlow
 					ILMoveableBlock block = node.UserData as ILMoveableBlock;
 					
 					if (block != null && block.Body.Count == 3) {
+						
 						ILLabel      label      = block.Body[0] as ILLabel;
 						ILExpression condBranch = block.Body[1] as ILExpression;
 						ILExpression statBranch = block.Body[2] as ILExpression;
 						
+						// Switch
+						if (label != null &&  
+						    condBranch != null && condBranch.Operand is ILLabel[] && condBranch.Arguments.Count > 0 &&
+						    statBranch != null && statBranch.Operand is ILLabel   && statBranch.Arguments.Count == 0)
+						{
+							ILSwitch ilSwitch = new ILSwitch() { Condition = condBranch };
+							
+							// Replace the two branches with a conditional structure - this preserves the node label
+							block.Body.Remove(condBranch);
+							block.Body.Remove(statBranch);
+							block.Body.Add(ilSwitch);
+							
+							ControlFlowNode statTarget = null;
+							labelToCfNode.TryGetValue((ILLabel)statBranch.Operand, out statTarget);
+							
+							// Pull in the conditional code
+							HashSet<ControlFlowNode> frontiers = new HashSet<ControlFlowNode>();
+							
+							if (statTarget != null)
+								frontiers.UnionWith(statTarget.DominanceFrontier);
+							
+							foreach(ILLabel condLabel in (ILLabel[])condBranch.Operand) {
+								ControlFlowNode condTarget = null;
+								labelToCfNode.TryGetValue(condLabel, out condTarget);
+								
+								if (condTarget != null)
+									frontiers.UnionWith(condTarget.DominanceFrontier);
+							}
+							
+							foreach(ILLabel condLabel in (ILLabel[])condBranch.Operand) {
+								ControlFlowNode condTarget = null;
+								labelToCfNode.TryGetValue(condLabel, out condTarget);
+								
+								ILBlock caseBlock = new ILBlock() { EntryPoint = condLabel };
+								if (condTarget != null && !frontiers.Contains(condTarget)) {
+									HashSet<ControlFlowNode> content = FindDominatedNodes(nodes, condTarget);
+									nodes.ExceptWith(content);
+									caseBlock.Body.AddRange(FindConditions(content, condTarget));
+								}
+								ilSwitch.CaseBlocks.Add(caseBlock);
+							}
+							
+							// The labels will not be used - kill them
+							condBranch.Operand = null;
+							
+							result.Add(block);
+							nodes.Remove(node);
+						}
+						
+						// Two-way branch
 						if (label != null &&  
 						    condBranch != null && condBranch.Operand is ILLabel && condBranch.Arguments.Count > 0 &&
 						    statBranch != null && statBranch.Operand is ILLabel && statBranch.Arguments.Count == 0)
 						{
-							ControlFlowNode condTarget = null;
 							ControlFlowNode statTarget = null;
-							labelToCfNode.TryGetValue((ILLabel)condBranch.Operand, out condTarget);
 							labelToCfNode.TryGetValue((ILLabel)statBranch.Operand, out statTarget);
+							ControlFlowNode condTarget = null;
+							labelToCfNode.TryGetValue((ILLabel)condBranch.Operand, out condTarget);
 							
 							ILCondition condition = new ILCondition() {
 							    Condition  = condBranch,
@@ -236,21 +287,17 @@ namespace Decompiler.ControlFlow
 							    FalseBlock = new ILBlock() { EntryPoint = (ILLabel)statBranch.Operand }
 							};
 							
-							// The label will not be used - kill it
-							condBranch.Operand = null;
-							
-							// Replace the two branches with a conditional structure
+							// Replace the two branches with a conditional structure - this preserves the node label
 							block.Body.Remove(condBranch);
 							block.Body.Remove(statBranch);
 							block.Body.Add(condition);
-							result.Add(block);
 							
 							// Pull in the conditional code
 							HashSet<ControlFlowNode> frontiers = new HashSet<ControlFlowNode>();
-							if (condTarget != null)
-								frontiers.UnionWith(condTarget.DominanceFrontier);
 							if (statTarget != null)
 								frontiers.UnionWith(statTarget.DominanceFrontier);
+							if (condTarget != null)
+								frontiers.UnionWith(condTarget.DominanceFrontier);
 							
 							if (condTarget != null && !frontiers.Contains(condTarget)) {
 								HashSet<ControlFlowNode> content = FindDominatedNodes(nodes, condTarget);
@@ -263,6 +310,10 @@ namespace Decompiler.ControlFlow
 								condition.FalseBlock.Body.AddRange(FindConditions(content, statTarget));
 							}
 							
+							// The label will not be used - kill it
+							condBranch.Operand = null;
+							
+							result.Add(block);
 							nodes.Remove(node);
 						}
 					}

ICSharpCode.Decompiler/ILAst/ILAstTypes.cs

@@ -1,11 +1,11 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Decompiler.ControlFlow;
-using Mono.Cecil;
-using Mono.Cecil.Cil;
-using Cecil = Mono.Cecil;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Decompiler.ControlFlow;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using Cecil = Mono.Cecil;
 
 namespace Decompiler
 {
@@ -48,6 +48,7 @@ namespace Decompiler
 	
 	public class ILBlock: ILNode
 	{
+		// TODO: This should really be a goto, not a label
 		public ILLabel EntryPoint;
 		
 		public List<ILNode> Body;
@@ -124,8 +125,8 @@ namespace Decompiler
 		public int From;
 		public int To;   // Exlusive
 		
-		public override string ToString()
-		{
+		public override string ToString()
+		{
 			return string.Format("{0}-{1}", From, To);
 		}
 	}
@@ -226,4 +227,18 @@ namespace Decompiler
 			yield return FalseBlock;
 		}
 	}
+	
+	public class ILSwitch: ILNode
+	{
+		public ILExpression Condition;
+		public List<ILBlock> CaseBlocks = new List<ILBlock>();
+		
+		public override IEnumerable<ILNode> GetChildren()
+		{
+			yield return Condition;
+			foreach (ILBlock caseBlock in this.CaseBlocks) {
+				yield return caseBlock;
+			}
+		}
+	}
 }