Support multiple values per case block

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -122,11 +122,11 @@ namespace ICSharpCode.Decompiler.Ast
 				};
 			} 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++) {
+				SwitchStatement switchStmt = new SwitchStatement() { Expression = (Expression)TransformExpression(ilSwitch.Condition) };
+				foreach (var caseBlock in ilSwitch.CaseBlocks) {
 					SwitchSection section = new SwitchSection();
-					section.CaseLabels.Add(new CaseLabel() { Expression = new PrimitiveExpression(i) });
-					section.Statements.Add(TransformBlock(ilSwitch.CaseBlocks[i]));
+					section.CaseLabels.AddRange(caseBlock.Values.Select(i => new CaseLabel() { Expression = new PrimitiveExpression(i) }));
+					section.Statements.Add(TransformBlock(caseBlock));
 					switchStmt.SwitchSections.Add(section);
 				}
 				yield return switchStmt;

ICSharpCode.Decompiler/ILAst/GotoRemoval.cs

@@ -57,6 +57,7 @@ namespace ICSharpCode.Decompiler.ILAst
 			}
 			
 			// Remove redundant break at the end of case
+			// Remove redundant case blocks altogether
 			foreach(ILSwitch ilSwitch in method.GetSelfAndChildrenRecursive<ILSwitch>()) {
 				foreach(ILBlock ilCase in ilSwitch.CaseBlocks) {
 					int count = ilCase.Body.Count;
@@ -67,6 +68,7 @@ namespace ICSharpCode.Decompiler.ILAst
 						}
 					}
 				}
+				ilSwitch.CaseBlocks.RemoveAll(b => b.Body.Count == 1 && b.Body.Single().Match(ILCode.LoopOrSwitchBreak));
 			}
 			
 			// Remove redundant return

ICSharpCode.Decompiler/ILAst/ILAstOptimizer.cs

@@ -101,6 +101,7 @@ namespace ICSharpCode.Decompiler.ILAst
 				ILExpression expr = block.Body[i] as ILExpression;
 				if (expr != null && expr.Prefixes == null) {
 					switch(expr.Code) {
+						case ILCode.Switch:
 						case ILCode.Brtrue:
 							expr.Arguments.Single().ILRanges.AddRange(expr.ILRanges);
 							expr.ILRanges.Clear();
@@ -579,14 +580,10 @@ namespace ICSharpCode.Decompiler.ILAst
 						ILExpression condBranch = block.Body[0] as ILExpression;
 						
 						// Switch
-						if (condBranch != null && condBranch.Operand is ILLabel[] && condBranch.Arguments.Count > 0) {
+						ILLabel[] caseLabels;
+						if (condBranch.Match(ILCode.Switch, out caseLabels)) {
 							
-							ILLabel[] caseLabels = (ILLabel[])condBranch.Operand;
-							
-							// The labels will not be used - kill them
-							condBranch.Operand = null;
-							
-							ILSwitch ilSwitch = new ILSwitch() { Condition = condBranch };
+							ILSwitch ilSwitch = new ILSwitch() { Condition = condBranch.Arguments.Single() };
 							result.Add(new ILBasicBlock() {
 								EntryLabel = block.EntryLabel,  // Keep the entry label
 								Body = { ilSwitch },
@@ -611,13 +608,17 @@ namespace ICSharpCode.Decompiler.ILAst
 									frontiers.UnionWith(condTarget.DominanceFrontier);
 							}
 							
-							foreach(ILLabel condLabel in caseLabels) {
+							for (int i = 0; i < caseLabels.Length; i++) {
+								ILLabel condLabel = caseLabels[i];
+								
+								// Find or create new case block
+								ILSwitch.CaseBlock caseBlock = ilSwitch.CaseBlocks.Where(b => b.EntryGoto.Operand == condLabel).FirstOrDefault();
+								if (caseBlock == null) {
+									caseBlock = new ILSwitch.CaseBlock() { EntryGoto = new ILExpression(ILCode.Br, condLabel) };
+									ilSwitch.CaseBlocks.Add(caseBlock);
+									
 									ControlFlowNode condTarget = null;
 									labelToCfNode.TryGetValue(condLabel, out condTarget);
-								
-								ILBlock caseBlock = new ILBlock() {
-									EntryGoto = new ILExpression(ILCode.Br, condLabel)
-								};
 									if (condTarget != null && !frontiers.Contains(condTarget)) {
 										HashSet<ControlFlowNode> content = FindDominatedNodes(scope, condTarget);
 										scope.ExceptWith(content);
@@ -625,7 +626,8 @@ namespace ICSharpCode.Decompiler.ILAst
 										// Add explicit break which should not be used by default, but the goto removal might decide to use it
 										caseBlock.Body.Add(new ILBasicBlock() { Body = { new ILExpression(ILCode.LoopOrSwitchBreak, null) } });
 									}
-								ilSwitch.CaseBlocks.Add(caseBlock);
+								}
+								caseBlock.Values.Add(i);
 							}
 						}
 						

ICSharpCode.Decompiler/ILAst/ILAstTypes.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -441,8 +442,24 @@ namespace ICSharpCode.Decompiler.ILAst
 	
 	public class ILSwitch: ILNode
 	{
+		public class CaseBlock: ILBlock
+		{
+			public List<int> Values = new List<int>();
+			
+			public override void WriteTo(ITextOutput output)
+			{
+				Debug.Assert(Values.Count > 0);
+				foreach (int i in this.Values) {
+					output.WriteLine("case {0}:", i);
+				}
+				output.Indent();
+				base.WriteTo(output);
+				output.Unindent();
+			}
+		}
+		
 		public ILExpression Condition;
-		public List<ILBlock> CaseBlocks = new List<ILBlock>();
+		public List<CaseBlock> CaseBlocks = new List<CaseBlock>();
 		
 		public override IEnumerable<ILNode> GetChildren()
 		{
@@ -459,11 +476,8 @@ namespace ICSharpCode.Decompiler.ILAst
 			Condition.WriteTo(output);
 			output.WriteLine(") {");
 			output.Indent();
-			for (int i = 0; i < CaseBlocks.Count; i++) {
-				output.WriteLine("case {0}:", i);
-				output.Indent();
-				CaseBlocks[i].WriteTo(output);
-				output.Unindent();
+			foreach (CaseBlock caseBlock in this.CaseBlocks) {
+				caseBlock.WriteTo(output);
 			}
 			output.Unindent();
 			output.WriteLine("}");