ControlFlowGraphBuilder bugfix: "try { try {} finally {} } catch {}"

ICSharpCode.Decompiler/Disassembler/MethodBodyDisassembler.cs

@@ -136,7 +136,7 @@ namespace ICSharpCode.Decompiler.Disassembler
 				}
 				output.Indent();
 			}
-			foreach (var node in s.Nodes.Concat(s.Children.Select(c => c.EntryPoint)).OrderBy(n => n.BlockIndex)) {
+			foreach (var node in s.Nodes.Concat(from c in s.Children select c.EntryPoint).OrderBy(c => c.Offset)) {
 				if (s.Nodes.Contains(node)) {
 					foreach (var inst in node.Instructions) {
 						inst.WriteTo(output);

ICSharpCode.Decompiler/FlowAnalysis/ControlFlowEdge.cs

@@ -39,10 +39,6 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		/// </summary>
 		LeaveTry,
 		/// <summary>
-		/// Jump from one catch block to its sibling (e.g. in "try {} catch (A) {} catch (B) {}")
-		/// </summary>
-		MutualProtection,
-		/// <summary>
 		/// Jump at endfinally (to any of the potential leave targets).
 		/// For any leave-instruction, control flow enters the finally block - the edge to the leave target (LeaveTry) is not a real control flow edge.
 		/// EndFinally edges are inserted at the end of the finally block, jumping to any of the targets of the leave instruction.

ICSharpCode.Decompiler/FlowAnalysis/ControlFlowGraph.cs

@@ -71,6 +71,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 						case JumpType.Normal:
 							break;
 						case JumpType.LeaveTry:
+						case JumpType.EndFinally:
 							e.color = "red";
 							break;
 						default:

ICSharpCode.Decompiler/FlowAnalysis/ControlFlowGraphBuilder.cs

@@ -55,11 +55,11 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			offsets = methodBody.Instructions.Select(i => i.Offset).ToArray();
 			hasIncomingJumps = new bool[methodBody.Instructions.Count];
 			
-			entryPoint = new ControlFlowNode(0, ControlFlowNodeType.EntryPoint);
+			entryPoint = new ControlFlowNode(0, 0, ControlFlowNodeType.EntryPoint);
 			nodes.Add(entryPoint);
-			regularExit = new ControlFlowNode(1, ControlFlowNodeType.RegularExit);
+			regularExit = new ControlFlowNode(1, -1, ControlFlowNodeType.RegularExit);
 			nodes.Add(regularExit);
-			exceptionalExit = new ControlFlowNode(2, ControlFlowNodeType.ExceptionalExit);
+			exceptionalExit = new ControlFlowNode(2, -1, ControlFlowNodeType.ExceptionalExit);
 			nodes.Add(exceptionalExit);
 			Debug.Assert(nodes.Count == 3);
 		}
@@ -140,7 +140,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 					throw new NotSupportedException();
 				ControlFlowNode endFinallyOrFaultNode = null;
 				if (handler.HandlerType == ExceptionHandlerType.Finally || handler.HandlerType == ExceptionHandlerType.Fault) {
-					endFinallyOrFaultNode = new ControlFlowNode(nodes.Count, ControlFlowNodeType.EndFinallyOrFault);
+					endFinallyOrFaultNode = new ControlFlowNode(nodes.Count, handler.HandlerEnd.Offset, ControlFlowNodeType.EndFinallyOrFault);
 					nodes.Add(endFinallyOrFaultNode);
 				}
 				nodes.Add(new ControlFlowNode(nodes.Count, handler, endFinallyOrFaultNode));
@@ -206,28 +206,15 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 					if (node.EndFinallyOrFaultNode != null) {
 						// For Fault and Finally blocks, create edge from "EndFinally" to next exception handler.
 						// This represents the exception bubbling up after finally block was executed.
-						CreateEdge(node.EndFinallyOrFaultNode, FindInnermostExceptionHandlerNode(node.ExceptionHandler.HandlerEnd.Offset), JumpType.JumpToExceptionHandler);
+						CreateEdge(node.EndFinallyOrFaultNode, FindParentExceptionHandlerNode(node), JumpType.JumpToExceptionHandler);
 					} else {
 						// For Catch blocks, create edge from "CatchHandler" block (at beginning) to next exception handler.
 						// This represents the exception bubbling up because it did not match the type of the catch block.
-						CreateEdge(node, FindInnermostExceptionHandlerNode(node.ExceptionHandler.HandlerStart.Offset), JumpType.JumpToExceptionHandler);
+						CreateEdge(node, FindParentExceptionHandlerNode(node), JumpType.JumpToExceptionHandler);
 					}
 					CreateEdge(node, node.ExceptionHandler.HandlerStart, JumpType.Normal);
 				}
 			}
-			
-			// now create edges between catch handlers that mutually protect
-			for (int i = 0; i < methodBody.ExceptionHandlers.Count; i++) {
-				ExceptionHandler first = methodBody.ExceptionHandlers[i];
-				if (first.HandlerType == ExceptionHandlerType.Catch) {
-					for (int j = i + 1; j < methodBody.ExceptionHandlers.Count; j++) {
-						ExceptionHandler second = methodBody.ExceptionHandlers[j];
-						if (second.HandlerType == ExceptionHandlerType.Catch && second.TryStart == first.TryStart && second.TryEnd == first.TryEnd) {
-							CreateEdge(nodes.Single(n => n.ExceptionHandler == first), nodes.Single(n => n.ExceptionHandler == second), JumpType.MutualProtection);
-						}
-					}
-				}
-			}
 		}
 		
 		ExceptionHandler FindInnermostExceptionHandler(int instructionOffsetInTryBlock)
@@ -260,6 +247,19 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			}
 			return exceptionalExit;
 		}
+		
+		ControlFlowNode FindParentExceptionHandlerNode(ControlFlowNode exceptionHandler)
+		{
+			Debug.Assert(exceptionHandler.NodeType == ControlFlowNodeType.CatchHandler
+			             || exceptionHandler.NodeType == ControlFlowNodeType.FinallyOrFaultHandler);
+			int offset = exceptionHandler.ExceptionHandler.TryStart.Offset;
+			for (int i = exceptionHandler.BlockIndex + 1; i < nodes.Count; i++) {
+				ExceptionHandler h = nodes[i].ExceptionHandler;
+				if (h != null && h.TryStart.Offset <= offset && offset < h.TryEnd.Offset)
+					return nodes[i];
+			}
+			return exceptionalExit;
+		}
 		#endregion
 		
 		#region Step 5a: replace LeaveTry edges with EndFinally edges

ICSharpCode.Decompiler/FlowAnalysis/ControlFlowNode.cs

@@ -77,6 +77,11 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		/// </summary>
 		public readonly int BlockIndex;
 		
+		/// <summary>
+		/// Gets the IL offset of this node.
+		/// </summary>
+		public readonly int Offset;
+		
 		/// <summary>
 		/// Type of the node.
 		/// </summary>
@@ -94,6 +99,13 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		/// </summary>
 		public bool Visited;
 		
+		/// <summary>
+		/// Gets whether this node is reachable. Requires that dominance is computed!
+		/// </summary>
+		public bool IsReachable {
+			get { return ImmediateDominator != null || NodeType == ControlFlowNodeType.EntryPoint; }
+		}
+		
 		/// <summary>
 		/// Signalizes that this node is a copy of another node.
 		/// </summary>
@@ -146,9 +158,10 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		/// </summary>
 		public readonly List<ControlFlowEdge> Outgoing = new List<ControlFlowEdge>();
 		
-		internal ControlFlowNode(int blockIndex, ControlFlowNodeType nodeType)
+		internal ControlFlowNode(int blockIndex, int offset, ControlFlowNodeType nodeType)
 		{
 			this.BlockIndex = blockIndex;
+			this.Offset = offset;
 			this.NodeType = nodeType;
 		}
 		
@@ -162,6 +175,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			this.NodeType = ControlFlowNodeType.Normal;
 			this.Start = start;
 			this.End = end;
+			this.Offset = start.Offset;
 		}
 		
 		internal ControlFlowNode(int blockIndex, ExceptionHandler exceptionHandler, ControlFlowNode endFinallyOrFaultNode)
@@ -171,6 +185,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			this.ExceptionHandler = exceptionHandler;
 			this.EndFinallyOrFaultNode = endFinallyOrFaultNode;
 			Debug.Assert((exceptionHandler.HandlerType == ExceptionHandlerType.Finally || exceptionHandler.HandlerType == ExceptionHandlerType.Fault) == (endFinallyOrFaultNode != null));
+			this.Offset = exceptionHandler.HandlerStart.Offset;
 		}
 		
 		/// <summary>

ICSharpCode.Decompiler/FlowAnalysis/ControlStructureDetector.cs

@@ -18,9 +18,9 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
-
 using Mono.Cecil.Cil;
 
 namespace ICSharpCode.Decompiler.FlowAnalysis
@@ -59,15 +59,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 				current.Children.Add(tryBlock);
 				
 				if (eh.FilterStart != null) {
-					var filterNodes = FindNodes(current, eh.FilterStart, eh.FilterEnd);
+					throw new NotSupportedException();
-					current.Nodes.ExceptWith(filterNodes);
-					ControlStructure filterBlock = new ControlStructure(
-						filterNodes,
-						g.Nodes.Single(n => n.Start == eh.HandlerStart),
-						ControlStructureType.Filter);
-					filterBlock.ExceptionHandler = eh;
-					MoveControlStructures(current, filterBlock, eh.FilterStart, eh.FilterEnd);
-					current.Children.Add(filterBlock);
 				}
 				
 				var handlerNodes = FindNodes(current, eh.HandlerStart, eh.HandlerEnd);
@@ -77,9 +69,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 					handlerNodes.Add(handlerNode.EndFinallyOrFaultNode);
 				current.Nodes.ExceptWith(handlerNodes);
 				ControlStructure handlerBlock = new ControlStructure(
-					handlerNodes,
+					handlerNodes, handlerNode, ControlStructureType.Handler);
-					g.Nodes.Single(n => n.Start == eh.HandlerStart),
-					ControlStructureType.Handler);
 				handlerBlock.ExceptionHandler = eh;
 				MoveControlStructures(current, handlerBlock, eh.HandlerStart, eh.HandlerEnd);
 				current.Children.Add(handlerBlock);
@@ -95,7 +85,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			int start = startInst.Offset;
 			int end = endInst.Offset;
 			foreach (var node in current.Nodes.ToArray()) {
-				if (node.Start != null && node.Start.Offset >= start && node.Start.Offset < end) {
+				if (node.Start != null && start <= node.Start.Offset && node.Start.Offset < end) {
 					result.Add(node);
 				}
 			}
@@ -106,7 +96,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		{
 			for (int i = 0; i < current.Children.Count; i++) {
 				var child = current.Children[i];
-				if (child.EntryPoint.Start.Offset >= startInst.Offset && child.EntryPoint.Start.Offset <= endInst.Offset) {
+				if (startInst.Offset <= child.EntryPoint.Offset && child.EntryPoint.Offset < endInst.Offset) {
 					current.Children.RemoveAt(i--);
 					target.Children.Add(child);
 					target.AllNodes.UnionWith(child.AllNodes);
@@ -128,6 +118,8 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		
 		static void DetectLoops(ControlFlowGraph g, ControlStructure current, CancellationToken cancellationToken)
 		{
+			if (!current.EntryPoint.IsReachable)
+				return;
 			g.ResetVisited();
 			cancellationToken.ThrowIfCancellationRequested();
 			FindLoops(current, current.EntryPoint);
@@ -238,6 +230,8 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		
 		public ControlStructure(HashSet<ControlFlowNode> nodes, ControlFlowNode entryPoint, ControlStructureType type)
 		{
+			if (nodes == null)
+				throw new ArgumentNullException("nodes");
 			this.Nodes = nodes;
 			this.EntryPoint = entryPoint;
 			this.Type = type;

ICSharpCode.Decompiler/FlowAnalysis/SsaFormBuilder.cs

@@ -163,7 +163,6 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 							throw new NotSupportedException("stacksize must be 0 in endfinally edge");
 						newStackSize = 0;
 						break;
-					case JumpType.MutualProtection:
 					case JumpType.JumpToExceptionHandler:
 						switch (edge.Target.NodeType) {
 							case ControlFlowNodeType.FinallyOrFaultHandler: