Adding code for Endless loop types, but it's not working right now

flaub · Jan 31, 2010 · eff63f2 · eff63f2
1 parent bcb3bbf
commit eff63f2
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Showing 6 changed files with 74 additions and 27 deletions.
diff --git a/src/DotWeb.Decompiler/Core/BasicBlock.cs b/src/DotWeb.Decompiler/Core/BasicBlock.cs
@@ -22,6 +22,7 @@
 using Mono.Cecil.Cil;
 using Mono.Cecil;
 using DotWeb.Utility.Cecil;
+using System.Text;
 
 namespace DotWeb.Decompiler.Core
 {
@@ -34,6 +35,18 @@ class BasicBlock : Node
 			}
 		}
 
+		public string ToStringDetails() {
+			var sb = new StringBuilder(this.ToString());
+			sb.AppendLine();
+			foreach (var cil in this.Instructions) {
+				sb.Append("\t");
+				sb.Append(cil.DisplayString());
+				sb.AppendLine();
+			}
+			return sb.ToString();
+		}
+
+
 		public List<CodeStatement> Statements { get; private set; }
 
 		public List<Instruction> Instructions { get; private set; }

diff --git a/src/DotWeb.Decompiler/Core/ControlFlowAnalyzer.cs b/src/DotWeb.Decompiler/Core/ControlFlowAnalyzer.cs
@@ -287,9 +287,7 @@ private bool IsSuccessor(int successor, int header)
 		}
 
 		private void StructureLoops() {
-			int level = 0;
 			foreach (var graph in this.Cfg.Graphs) {
-				level++;
 				foreach (Interval interval in graph.Nodes) {
 					// Find nodes that belong to the interval (nodes from G1)
 					List<Node> nodes = new List<Node>();
@@ -350,6 +348,11 @@ private bool IsSuccessor(int successor, int header)
 				}
 			}
 
+			latchNode.LoopHead = headerNode.LoopHead;
+			if (latchNode != headerNode) {
+				loopNodes.Add(latchNode.DfsPostOrder);
+			}
+
 			ClassifyLoop(headerNode, latchNode, loopNodes);
 		}
 
@@ -359,7 +362,6 @@ private bool IsSuccessor(int successor, int header)
 			if (headerNode.Successors.Count > 1)
 				elseDfs = headerNode.ElseEdge.DfsPostOrder;
 
-			latchNode.LoopHead = headerNode.LoopHead;
 			if (latchNode.IsTwoWay) {
 				if ((headerNode.IsTwoWay) || (latchNode == headerNode)) {
 					if ((latchNode == headerNode) ||
@@ -407,7 +409,7 @@ private bool IsSuccessor(int successor, int header)
 						 * loop, so it is safer to consider it an endless loop */
 						if (node.DfsPostOrder <= headerNode.DfsPostOrder) {
 							headerNode.LoopType = LoopType.Endless;
-							// findEndlessFollow();
+							FindEndlessFollow(loopNodes, headerNode);
 							break;
 						}
 
@@ -421,7 +423,21 @@ private bool IsSuccessor(int successor, int header)
 				}
 				else {
 					headerNode.LoopType = LoopType.Endless;
-					// findEndlessFollow();
+					FindEndlessFollow(loopNodes, headerNode);
+				}
+			}
+		}
+
+		private void FindEndlessFollow(List<int> loopNodes, BasicBlock head) {
+			head.LoopFollow = int.MaxValue;
+
+			foreach (var i in loopNodes) {
+				var node = this.Cfg.DepthFirstPostOrder[i];
+				foreach (var succ in node.Successors) {
+					if (!loopNodes.Contains(succ.DfsPostOrder) &&
+						(succ.DfsPostOrder < head.LoopFollow)) {
+						head.LoopFollow = succ.DfsPostOrder;
+					}
 				}
 			}
 		}

diff --git a/src/DotWeb.Decompiler/Core/ControlFlowGraph.cs b/src/DotWeb.Decompiler/Core/ControlFlowGraph.cs
@@ -23,6 +23,7 @@
 using Mono.Cecil;
 using Mono.Cecil.Cil;
 using DotWeb.Utility.Cecil;
+using System.Diagnostics;
 
 namespace DotWeb.Decompiler.Core
 {
@@ -62,6 +63,8 @@ class ControlFlowGraph
 		private void CreateBlocks(Dictionary<int, BasicBlock> blocksByOffset) {
 			BasicBlock lastBlock = null;
 			foreach (Instruction cil in Method.Body.Instructions) {
+				Debug.Assert(cil.OpCode.FlowControl != FlowControl.Break);
+
 				if (cil.OpCode.OperandType == OperandType.InlineSwitch)
 					this.HasCases = true;
 
@@ -85,6 +88,7 @@ class ControlFlowGraph
 
 		private void Merge(BasicBlock bb) {
 			while (bb.FlowControl != FlowControl.Cond_Branch &&
+				bb.FlowControl != FlowControl.Branch &&
 				bb.FlowControl != FlowControl.Return &&
 				bb.FlowControl != FlowControl.Throw) {
 				BasicBlock next = (BasicBlock)bb.Successors.First();
@@ -132,18 +136,15 @@ class ControlFlowGraph
 
 		public override string ToString() {
 			StringBuilder sb = new StringBuilder();
-			if (Graphs != null) {
-				foreach (BasicBlock block in this.BasicGraph.Nodes) {
-					sb.AppendLine(block.ToString());
-				}
+			foreach (BasicBlock block in this.BasicGraph.Nodes) {
+				sb.AppendLine(block.ToStringDetails());
 			}
-			else {
-				int i = 0;
-				foreach (var graph in Graphs) {
-					sb.AppendFormat("Level: {0}\n", i++);
-					foreach (var interval in graph.Nodes) {
-						sb.AppendLine(interval.ToString());
-					}
+
+			int i = 0;
+			foreach (var graph in Graphs) {
+				sb.AppendFormat("Level: {0}\n", i++);
+				foreach (var interval in graph.Nodes) {
+					sb.AppendLine(interval.ToString());
 				}
 			}
 			return sb.ToString();

diff --git a/src/DotWeb.Decompiler/MethodDecompiler.cs b/src/DotWeb.Decompiler/MethodDecompiler.cs
@@ -28,10 +28,11 @@ namespace DotWeb.Decompiler
 	public static class MethodDecompiler
 	{
 		public static CodeMethodMember Parse(TypeSystem typeHierarchy, MethodDefinition method) {
-			Console.WriteLine(method);
-
 			var cfg = new ControlFlowGraph(typeHierarchy, method);
+#if DEBUG
+			Console.WriteLine(method);
 			Console.WriteLine(cfg);
+#endif
 
 			var cfa = new ControlFlowAnalyzer(cfg);
 			cfa.Structure();

diff --git a/test/DotWeb.Translator.Test/IntervalTests.cs b/test/DotWeb.Translator.Test/IntervalTests.cs
@@ -171,6 +171,20 @@ class GraphBuilder
 			builder.Test("L1, i1, n1, n2, n3");
 		}
 
+		[Test]
+		public void WhileBreak() {
+			var builder = new GraphBuilder(4);
+			builder.Connect(1, 2);
+			builder.Connect(2, 3);
+			builder.Connect(3, 2);
+			builder.Connect(2, 4);
+			builder.Test(
+				"L1, i1, n1", 
+				"L1, i2, n2, n3, n4", 
+				"L2, i1, n1, n2, n3, n4"
+			);
+		}
+
 		[Test]
 		public void DragonBook() {
 			// Taken from the Dragon book, Page 661, Example 10.30, Fig. 10.45

diff --git a/test/DotWeb.Translator.Test/Script/Loops.cs b/test/DotWeb.Translator.Test/Script/Loops.cs
@@ -42,11 +42,12 @@ class Loops
 		public void BreakInWhile(int a) {
 			while (a < 100) {
 				if (a == 12) {
-					Console.WriteLine(a);
+					Console.WriteLine("break");
 					break;
 				}
-				else
-					Console.WriteLine(a);
+				else {
+					Console.WriteLine("else");
+				}
 
 				a--;
 			}
@@ -56,27 +57,28 @@ class Loops
 		public void WhileBreak() {
 			int i = 0;
 			while (true) {
+				i = 20;
 				if (i == 10) {
-					Console.WriteLine(i);
+					Console.WriteLine("break");
 					break;
 				}
-				Console.WriteLine(i);
+				Console.WriteLine("loop");
 				i++;
 			}
-			Console.WriteLine(i);
+			Console.WriteLine("exit");
 		}
 
 		public void WhileCondBreak() {
 			int i = 0;
 			while (i < 9) {
 				if (i == 10) {
-					Console.WriteLine(i);
+					Console.WriteLine("break");
 					break;
 				}
-				Console.WriteLine(i);
+				Console.WriteLine("loop");
 				i++;
 			}
-			Console.WriteLine(i);
+			Console.WriteLine("exit");
 		}
 	}
 }