Traverse the dominator tree in depth-first order when finding conditions. This reduces the number of gotos produced for complex control flow.

Closes #253.

ICSharpCode.Decompiler/FlowAnalysis/ControlFlowNode.cs

@@ -280,6 +280,10 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 				writer.WriteLine();
 				Disassembler.DisassemblerHelpers.WriteTo(inst, new PlainTextOutput(writer));
 			}
+			if (UserData != null) {
+				writer.WriteLine();
+				writer.Write(UserData.ToString());
+			}
 			return writer.ToString();
 		}
 		

ICSharpCode.Decompiler/ILAst/LoopsAndConditions.cs

@@ -228,15 +228,10 @@ namespace ICSharpCode.Decompiler.ILAst
 			// Do not modify entry data
 			scope = new HashSet<ControlFlowNode>(scope);
 			
-			HashSet<ControlFlowNode> agenda  = new HashSet<ControlFlowNode>();
-			agenda.Add(entryNode);
-			while(agenda.Any()) {
-				ControlFlowNode node = agenda.First();
-				// Attempt for a good order
-				while(agenda.Contains(node.ImmediateDominator)) {
-					node = node.ImmediateDominator;
-				}
-				agenda.Remove(node);
+			Stack<ControlFlowNode> agenda  = new Stack<ControlFlowNode>();
+			agenda.Push(entryNode);
+			while(agenda.Count > 0) {
+				ControlFlowNode node = agenda.Pop();
 				
 				// Find a block that represents a simple condition
 				if (scope.Contains(node)) {
@@ -384,9 +379,9 @@ namespace ICSharpCode.Decompiler.ILAst
 					}
 				}
 
-				// Using the dominator tree should ensure we find the the widest loop first
-				foreach(var child in node.DominatorTreeChildren) {
-					agenda.Add(child);
+				// depth-first traversal of dominator tree
+				for (int i = node.DominatorTreeChildren.Count - 1; i >= 0; i--) {
+					agenda.Push(node.DominatorTreeChildren[i]);
 				}
 			}
 			

ICSharpCode.Decompiler/Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -66,6 +66,8 @@
     <Compile Include="CheckedUnchecked.cs" />
     <Compile Include="ControlFlow.cs" />
     <Compile Include="ExpressionTrees.cs" />
+    <None Include="IL\SequenceOfNestedIfs.Output.cs" />
+    <Compile Include="IL\ILTests.cs" />
     <Compile Include="LiftedOperators.cs" />
     <Compile Include="CustomShortCircuitOperators.cs" />
     <Compile Include="Helpers\CodeAssert.cs" />
@@ -78,6 +80,10 @@
     <Compile Include="UnsafeCode.cs" />
     <Compile Include="Types\S_TypeDeclarations.cs" />
     <Compile Include="YieldReturn.cs" />
+    <None Include="IL\SequenceOfNestedIfs.dll" />
+    <None Include="IL\SequenceOfNestedIfs.il" />
+    <None Include="IL\StackTests.exe" />
+    <None Include="IL\StackTests.il" />
     <None Include="packages.config" />
     <None Include="Types\S_EnumSamples.cs" />
     <None Include="CustomAttributes\S_AssemblyCustomAttribute.cs" />
@@ -118,10 +124,11 @@
       <Name>ICSharpCode.Decompiler</Name>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup />
+  <ItemGroup>
+    <Folder Include="IL" />
+  </ItemGroup>
   <ItemGroup>
     <None Include="BooleanConsumedAsInteger.il" />
-    <None Include="StackTests\StackTests.il" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.Targets" />
 </Project>

ICSharpCode.Decompiler/Tests/IL/ILTests.cs

@@ -0,0 +1,51 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.IO;
+using ICSharpCode.Decompiler.Ast;
+using ICSharpCode.Decompiler.Tests.Helpers;
+using Mono.Cecil;
+using NUnit.Framework;
+
+namespace ICSharpCode.Decompiler.Tests
+{
+	[TestFixture]
+	public class ILTests
+	{
+		const string path = "../../Tests/IL";
+		
+		[Test]
+		public void SequenceOfNestedIfs()
+		{
+			Run("SequenceOfNestedIfs.dll", "SequenceOfNestedIfs.Output.cs");
+		}
+		
+		void Run(string compiledFile, string expectedOutputFile)
+		{
+			string expectedOutput = File.ReadAllText(Path.Combine(path, expectedOutputFile));
+			var assembly = AssemblyDefinition.ReadAssembly(Path.Combine(path, compiledFile));
+			AstBuilder decompiler = new AstBuilder(new DecompilerContext(assembly.MainModule));
+			decompiler.AddAssembly(assembly);
+			new Helpers.RemoveCompilerAttribute().Run(decompiler.CompilationUnit);
+			StringWriter output = new StringWriter();
+			decompiler.GenerateCode(new PlainTextOutput(output));
+			CodeAssert.AreEqual(expectedOutput, output.ToString());
+		}
+	}
+}

ICSharpCode.Decompiler/Tests/IL/SequenceOfNestedIfs.Output.cs

@@ -0,0 +1,53 @@
+using System;
+[Serializable]
+public class Material
+{
+	public static implicit operator bool(Material m)
+	{
+		return m == null;
+	}
+}
+[Serializable]
+public class SequenceOfNestedIfs
+{
+	public bool _clear;
+	public Material _material;
+	public override bool CheckShader()
+	{
+		return false;
+	}
+	public override void CreateMaterials()
+	{
+		if (!this._clear)
+		{
+			if (!this.CheckShader())
+			{
+				return;
+			}
+			this._material = new Material();
+		}
+		if (!this._material)
+		{
+			if (!this.CheckShader())
+			{
+				return;
+			}
+			this._material = new Material();
+		}
+		if (!this._material)
+		{
+			if (!this.CheckShader())
+			{
+				return;
+			}
+			this._material = new Material();
+		}
+		if (!this._material)
+		{
+			if (this.CheckShader())
+			{
+				this._material = new Material();
+			}
+		}
+	}
+}

ICSharpCode.Decompiler/Tests/IL/SequenceOfNestedIfs.il

@@ -0,0 +1,140 @@
+// Metadata version: v2.0.50727
+.assembly extern mscorlib
+{
+  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
+  .ver 2:0:0:0
+}
+
+.assembly SequenceOfNestedIfs
+{
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
+                                                                                                             63 65 70 74 69 6F 6E 54 68 72 6F 77 73 01 )       // ceptionThrows.
+  .hash algorithm 0x00008004
+  .ver 0:0:0:0
+}
+.module SequenceOfNestedIfs
+// MVID: {DCEC8A87-5679-4EBE-89A3-51274D8B5446}
+.imagebase 0x00400000
+.file alignment 0x00000200
+.stackreserve 0x00100000
+.subsystem 0x0003       // WINDOWS_CUI
+.corflags 0x00000001    //  ILONLY
+// Image base: 0x01D60000
+
+
+// =============== CLASS MEMBERS DECLARATION ===================
+
+.class public auto ansi serializable beforefieldinit Material
+       extends [mscorlib]System.Object
+{
+  .method public hidebysig specialname rtspecialname 
+          instance void  .ctor() cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  call       instance void [mscorlib]System.Object::.ctor()
+    IL_0006:  ret
+  } // end of method Material::.ctor
+
+  .method public hidebysig specialname static 
+          bool  op_Implicit(class Material m) cil managed
+  {
+    // Code size       11 (0xb)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldnull
+    IL_0008:  ceq
+    IL_000a:  ret
+  } // end of method Material::op_Implicit
+
+} // end of class Material
+
+.class public auto ansi serializable beforefieldinit SequenceOfNestedIfs
+       extends [mscorlib]System.Object
+{
+  .field public bool _clear
+  .field public class Material _material
+  .method public hidebysig specialname rtspecialname 
+          instance void  .ctor() cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  call       instance void  [mscorlib]System.Object::.ctor()
+    IL_0006:  ret
+  } // end of method SequenceOfNestedIfs::.ctor
+
+  .method public hidebysig virtual instance bool 
+          CheckShader() cil managed
+  {
+    // Code size       2 (0x2)
+    .maxstack  8
+    IL_0000:  ldc.i4.0
+    IL_0001:  ret
+  } // end of method SequenceOfNestedIfs::CheckShader
+
+  .method public hidebysig virtual instance void 
+          CreateMaterials() cil managed
+  {
+    // Code size       168 (0xa8)
+    .maxstack  13
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld      bool SequenceOfNestedIfs::_clear
+    IL_0006:  brtrue     IL_0026
+
+    IL_000b:  ldarg.0
+    IL_000c:  callvirt   instance bool SequenceOfNestedIfs::CheckShader()
+    IL_0011:  brtrue     IL_001b
+
+    IL_0016:  br         IL_00a7
+
+    IL_001b:  ldarg.0
+    IL_001c:  newobj     instance void Material::.ctor()
+    IL_0021:  stfld      class Material SequenceOfNestedIfs::_material
+    IL_0026:  ldarg.0
+    IL_0027:  ldfld      class Material SequenceOfNestedIfs::_material
+    IL_002c:  call       bool Material::op_Implicit(class Material)
+    IL_0031:  brtrue     IL_0051
+
+    IL_0036:  ldarg.0
+    IL_0037:  callvirt   instance bool SequenceOfNestedIfs::CheckShader()
+    IL_003c:  brtrue     IL_0046
+
+    IL_0041:  br         IL_00a7
+
+    IL_0046:  ldarg.0
+    IL_0047:  newobj     instance void Material::.ctor()
+    IL_004c:  stfld      class Material SequenceOfNestedIfs::_material
+    IL_0051:  ldarg.0
+    IL_0052:  ldfld      class Material SequenceOfNestedIfs::_material
+    IL_0057:  call       bool Material::op_Implicit(class Material)
+    IL_005c:  brtrue     IL_007c
+
+    IL_0061:  ldarg.0
+    IL_0062:  callvirt   instance bool SequenceOfNestedIfs::CheckShader()
+    IL_0067:  brtrue     IL_0071
+
+    IL_006c:  br         IL_00a7
+
+    IL_0071:  ldarg.0
+    IL_0072:  newobj     instance void Material::.ctor()
+    IL_0077:  stfld      class Material SequenceOfNestedIfs::_material
+    IL_007c:  ldarg.0
+    IL_007d:  ldfld      class Material SequenceOfNestedIfs::_material
+    IL_0082:  call       bool Material::op_Implicit(class Material)
+    IL_0087:  brtrue     IL_00a7
+
+    IL_008c:  ldarg.0
+    IL_008d:  callvirt   instance bool SequenceOfNestedIfs::CheckShader()
+    IL_0092:  brtrue     IL_009c
+
+    IL_0097:  br         IL_00a7
+
+    IL_009c:  ldarg.0
+    IL_009d:  newobj     instance void Material::.ctor()
+    IL_00a2:  stfld      class Material SequenceOfNestedIfs::_material
+    IL_00a7:  ret
+  } // end of method SequenceOfNestedIfs::CreateMaterials
+
+} // end of class SequenceOfNestedIfs

NRefactory/ICSharpCode.NRefactory/Utils/GraphVizGraph.cs

@@ -22,6 +22,7 @@ using System.Diagnostics;
 using System.Globalization;
 using System.IO;
 using System.Text.RegularExpressions;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.Utils
 {
@@ -66,8 +67,11 @@ namespace ICSharpCode.NRefactory.Utils
 					name = name.Replace(c, '-');
 			string fileName = name != null ? Path.Combine(Path.GetTempPath(), name) : Path.GetTempFileName();
 			Save(fileName + ".gv");
-			Process.Start("dot", "\"" + fileName + ".gv\" -Tpng -o \"" + fileName + ".png\"").WaitForExit();
-			Process.Start(fileName + ".png");
+			new Thread(new ThreadStart(
+				delegate {
+					Process.Start("dot", "\"" + fileName + ".gv\" -Tpng -o \"" + fileName + ".png\"").WaitForExit();
+					Process.Start(fileName + ".png");
+				})).Start();
 		}
 		
 		static string Escape(string text)