Handle mutually nested loops/conditions

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -151,12 +151,20 @@ namespace Decompiler
 			*/
 			} else if (node is ILCondition) {
 				ILCondition conditionalNode = (ILCondition)node;
-				// Swap bodies
-				yield return new Ast.IfElseStatement {
-					Condition = new UnaryOperatorExpression(UnaryOperatorType.Not, MakeBranchCondition(conditionalNode.Condition)),
-					TrueStatement = TransformBlock(conditionalNode.FalseBlock),
-					FalseStatement = TransformBlock(conditionalNode.TrueBlock)
-				};
+				if (conditionalNode.FalseBlock.Body.Any()) {
+					// Swap bodies
+					yield return new Ast.IfElseStatement {
+						Condition = new UnaryOperatorExpression(UnaryOperatorType.Not, MakeBranchCondition(conditionalNode.Condition)),
+						TrueStatement = TransformBlock(conditionalNode.FalseBlock),
+						FalseStatement = TransformBlock(conditionalNode.TrueBlock)
+					};
+				} else {
+					yield return new Ast.IfElseStatement {
+						Condition = MakeBranchCondition(conditionalNode.Condition),
+						TrueStatement = TransformBlock(conditionalNode.TrueBlock),
+						FalseStatement = TransformBlock(conditionalNode.FalseBlock)
+					};
+				}
 			} else if (node is ILTryCatchBlock) {
 				ILTryCatchBlock tryCatchNode = ((ILTryCatchBlock)node);
 				List<Ast.CatchClause> catchClauses = new List<CatchClause>();

ICSharpCode.Decompiler/ILAst/ILAstOptimizer.cs

@@ -14,18 +14,20 @@ namespace Decompiler.ControlFlow
 		
 		public void Optimize(ILBlock method)
 		{
-			var blocks = method.GetSelfAndChildrenRecursive<ILBlock>().ToList();
+			foreach(ILBlock block in method.GetSelfAndChildrenRecursive<ILBlock>().ToList()) {
+				SplitToMovableBlocks(block);
+			}
 			
-			foreach(ILBlock block in blocks) {
+			foreach(ILBlock block in method.GetSelfAndChildrenRecursive<ILBlock>().Where(b => !(b is ILMoveableBlock)).ToList()) {
 				ControlFlowGraph graph;
-				
-				SplitToMovableBlocks(block);
-				
 				graph = BuildGraph(block.Body, block.EntryPoint);
 				graph.ComputeDominance();
 				graph.ComputeDominanceFrontier();
 				block.Body = FindLoops(new HashSet<ControlFlowNode>(graph.Nodes.Skip(3)), graph.EntryPoint);
-	
+			}
+			
+			foreach(ILBlock block in method.GetSelfAndChildrenRecursive<ILBlock>().Where(b => !(b is ILMoveableBlock)).ToList()) {
+				ControlFlowGraph graph;
 				graph = BuildGraph(block.Body, block.EntryPoint);
 				graph.ComputeDominance();
 				graph.ComputeDominanceFrontier();
@@ -153,7 +155,7 @@ namespace Decompiler.ControlFlow
 			return new ControlFlowGraph(cfNodes.ToArray());
 		}
 		
-		static List<ILNode> FindLoops(HashSet<ControlFlowNode> nodes, ControlFlowNode entryPoint)
+		List<ILNode> FindLoops(HashSet<ControlFlowNode> nodes, ControlFlowNode entryPoint)
 		{
 			List<ILNode> result = new List<ILNode>();
 			
@@ -171,7 +173,9 @@ namespace Decompiler.ControlFlow
 					
 					// Move the content into loop block
 					nodes.ExceptWith(loopContents);
-					result.Add(new ILLoop() { ContentBlock = new ILBlock(FindLoops(loopContents, node)) });
+					ILLabel entryLabel = new ILLabel() { Name = "Loop_" + (nextBlockIndex++) };
+					((ILBlock)node.UserData).Body.Insert(0, entryLabel);
+					result.Add(new ILLoop() { ContentBlock = new ILBlock(FindLoops(loopContents, node)) { EntryPoint = entryLabel } });
 				}
 
 				// Using the dominator tree should ensure we find the the widest loop first