Remove DetectedLoop

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -414,11 +414,12 @@ namespace ICSharpCode.Decompiler.CSharp
 			// If there's an extra leave inside the block, extract it into optionalReturnAfterLoop.
 			var loopContainer = UnwrapNestedContainerIfPossible(container, out var optionalReturnAfterLoop);
 			// Detect whether we're dealing with a while loop with multiple embedded statements.
-			var loop = DetectedLoop.DetectLoop(loopContainer);
-			if (loop.Kind != LoopKind.While || !(loop.Body is Block body))
+			if (loopContainer.Kind != ContainerKind.While)
+				return null;
+			if (!loopContainer.MatchConditionBlock(loopContainer.EntryPoint, out var conditionInst, out var body))
 				return null;
 			// The loop condition must be a call to enumerator.MoveNext()
-			var condition = exprBuilder.TranslateCondition(loop.Conditions.Single());
+			var condition = exprBuilder.TranslateCondition(conditionInst);
 			var m2 = moveNextConditionPattern.Match(condition.Expression);
 			if (!m2.Success)
 				return null;
@@ -427,8 +428,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			if (enumeratorVar2 != enumeratorVar)
 				return null;
 			// Detect which foreach-variable transformation is necessary/possible.
-			var transformation = DetectGetCurrentTransformation(container, body, enumeratorVar, condition.ILInstructions.Single(),
-																out var singleGetter, out var foreachVariable);
+			var transformation = DetectGetCurrentTransformation(container, body, enumeratorVar, conditionInst, out var singleGetter, out var foreachVariable);
 			if (transformation == RequiredGetCurrentTransformation.NoForeach)
 				return null;
 			// The existing foreach variable, if found, can only be used in the loop container.
@@ -494,7 +494,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			};
 			// Add the variable annotation for highlighting (TokenTextWriter expects it directly on the ForeachStatement).
 			foreachStmt.AddAnnotation(new ILVariableResolveResult(foreachVariable, foreachVariable.Type));
-			foreachStmt.AddAnnotation(new ForeachAnnotation(inst.ResourceExpression, loop.Conditions.Single(), singleGetter));
+			foreachStmt.AddAnnotation(new ForeachAnnotation(inst.ResourceExpression, conditionInst, singleGetter));
 			// If there was an optional return statement, return it as well.
 			if (optionalReturnAfterLoop != null) {
 				return new BlockStatement {

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -300,7 +300,6 @@
     <Compile Include="IL\Instructions\ThreeValuedLogicInstructions.cs" />
     <Compile Include="IL\Patterns\AnyNode.cs" />
     <Compile Include="IL\ControlFlow\YieldReturnDecompiler.cs" />
-    <Compile Include="IL\DetectedLoop.cs" />
     <Compile Include="IL\Transforms\AssignVariableNames.cs" />
     <Compile Include="IL\Transforms\DetectCatchWhenConditionBlocks.cs" />
     <Compile Include="IL\Transforms\LockTransform.cs" />

ICSharpCode.Decompiler/IL/DetectedLoop.cs

@@ -1,159 +0,0 @@
-// Copyright (c) 2017 Siegfried Pammer
-// 
-// 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.Collections.Generic;
-using System.Linq;
-using ICSharpCode.Decompiler.Util;
-
-namespace ICSharpCode.Decompiler.IL
-{
-	public enum LoopKind { None, While, DoWhile, For }
-
-	public class DetectedLoop
-	{
-		public BlockContainer Container { get; }
-		public LoopKind Kind { get; private set; }
-		public ILInstruction[] Conditions { get; private set; }
-		public Block IncrementBlock { get; private set; }
-		public Block ContinueJumpTarget { get; private set; } // jumps to this block are "continue;" jumps
-		public ILInstruction Body { get; private set; }       // null in case of DoWhile
-		public Block[] AdditionalBlocks { get; private set; } // blocks to be merged into the loop body
-		public ILVariable IncrementTarget { get; private set; } // null, except in case of For
-
-		private DetectedLoop(BlockContainer container)
-		{
-			this.Container = container;
-		}
-
-		/// <summary>
-		/// Gets whether the statement is 'simple' (usable as for loop iterator):
-		/// Currently we only accept calls and assignments.
-		/// </summary>
-		private static bool IsSimpleStatement(ILInstruction inst)
-		{
-			switch (inst.OpCode) {
-				case OpCode.Call:
-				case OpCode.CallVirt:
-				case OpCode.NewObj:
-				case OpCode.StLoc:
-				case OpCode.StObj:
-				case OpCode.CompoundAssignmentInstruction:
-					return true;
-				default:
-					return false;
-			}
-		}
-
-		public static DetectedLoop DetectLoop(BlockContainer container)
-		{
-			return new DetectedLoop(container).DetectLoopInternal();
-		}
-
-		private static Block FindDoWhileConditionBlock(BlockContainer container, List<ILInstruction> conditions)
-		{
-			foreach (var b in container.Blocks) {
-				if (b.Instructions.Last().MatchBranch(container.EntryPoint)) {
-					// potentially the do-while-condition block
-					int i = b.Instructions.Count - 2;
-					while (i >= 0 && b.Instructions[i] is IfInstruction ifInst
-						&& ifInst.TrueInst.MatchLeave(container) && ifInst.FalseInst.MatchNop()) {
-						conditions.Add(ifInst.Condition);
-						i--;
-					}
-					if (i == -1 && conditions.Any()) {
-						return b;
-					}
-				}
-			}
-			return null;
-		}
-
-		private DetectedLoop DetectLoopInternal()
-		{
-			if (Container.EntryPoint.IncomingEdgeCount <= 1) {
-				Kind = LoopKind.None;
-				return this;
-			}
-			Kind = LoopKind.While;
-			ContinueJumpTarget = Container.EntryPoint;
-			if (Container.EntryPoint.Instructions.Count == 2
-				&& Container.EntryPoint.Instructions[0].MatchIfInstruction(out var conditionInst, out var trueInst)
-				&& Container.EntryPoint.Instructions[1].MatchLeave(Container)) {
-				// detected while(condition)-loop or for-loop
-				// we have to check if there's an increment block before converting the loop body using ConvertAsBlock(trueInst)
-				// and set the continueJumpTarget to correctly convert 'br incrementBlock' instructions to continue; 
-				IncrementBlock = null;
-				if (Container.EntryPoint.IncomingEdgeCount == 2) {
-					IncrementBlock = Container.Blocks.SingleOrDefault(
-						b => b.Instructions.Last().MatchBranch(Container.EntryPoint)
-							 && b.Instructions.SkipLast(1).All(IsSimpleStatement));
-					if (IncrementBlock != null)
-						ContinueJumpTarget = IncrementBlock;
-				}
-				Conditions = new[] { conditionInst };
-				Body = trueInst;
-				if (IncrementBlock != null) {
-					// for-loop
-					Kind = LoopKind.For;
-					if (IncrementBlock.Instructions[0] is StLoc increment)
-						IncrementTarget = increment.Variable;
-					AdditionalBlocks = Container.Blocks.Skip(1).Where(b => b != IncrementBlock).ToArray();
-					return this;
-				} else if (trueInst is Block block) {
-					var last = block.Instructions.LastOrDefault();
-					var secondToLast = block.Instructions.SecondToLastOrDefault();
-					if (last != null && secondToLast != null && last.MatchBranch(Container.EntryPoint) &&
-						MatchIncrement(secondToLast, out var variable) && conditionInst.Children.Any(c => c.MatchLdLoc(variable))) {
-						Kind = LoopKind.For;
-						IncrementTarget = variable;
-						AdditionalBlocks = Container.Blocks.Skip(1).ToArray();
-						return this;
-					}
-				}
-				AdditionalBlocks = Container.Blocks.Skip(1).ToArray();
-			} else {
-				// do-while or while(true)-loop
-				if (Container.EntryPoint.IncomingEdgeCount == 2) {
-					var conditions = new List<ILInstruction>();
-					Block conditionBlock = FindDoWhileConditionBlock(Container, conditions);
-					if (conditionBlock != null) {
-						Kind = LoopKind.DoWhile;
-						ContinueJumpTarget = conditionBlock;
-						Body = null;
-						Conditions = conditions.ToArray();
-						AdditionalBlocks = Container.Blocks.Where(b => b != conditionBlock).ToArray();
-					}
-				}
-			}
-			return this;
-		}
-
-		static bool MatchIncrement(ILInstruction inst, out ILVariable variable)
-		{
-			if (!inst.MatchStLoc(out variable, out var value))
-				return false;
-			if (!value.MatchBinaryNumericInstruction(BinaryNumericOperator.Add, out var left, out var right)) {
-				if (value is CompoundAssignmentInstruction cai) {
-					left = cai.Target;
-				} else return false;
-			}
-			return left.MatchLdLoc(variable);
-		}
-	}
-}

ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs

@@ -156,10 +156,11 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			var loopCounters = new HashSet<ILVariable>();
 			
 			foreach (BlockContainer possibleLoop in function.Descendants.OfType<BlockContainer>()) {
-				if (possibleLoop.EntryPoint.IncomingEdgeCount == 1) continue;
-				var loop = DetectedLoop.DetectLoop(possibleLoop);
-				if (loop.Kind != LoopKind.For || loop.IncrementTarget == null) continue;
-				loopCounters.Add(loop.IncrementTarget);
+				if (possibleLoop.Kind != ContainerKind.For) continue;
+				foreach (var inst in possibleLoop.Blocks.Last().Instructions) {
+					if (HighLevelLoopTransform.MatchIncrement(inst, out var variable))
+						loopCounters.Add(variable);
+				}
 			}
 
 			return loopCounters;

ICSharpCode.Decompiler/IL/Transforms/HighLevelLoopTransform.cs

@@ -167,7 +167,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			return true;
 		}
 
-		static bool MatchIncrement(ILInstruction inst, out ILVariable variable)
+		public static bool MatchIncrement(ILInstruction inst, out ILVariable variable)
 		{
 			if (!inst.MatchStLoc(out variable, out var value))
 				return false;