Refactor ArrayInitializers into a general peephole-transformation step.

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -93,6 +93,7 @@
     <Compile Include="ILAst\ILCodes.cs" />
     <Compile Include="ILAst\ILInlining.cs" />
     <Compile Include="ILAst\Pattern.cs" />
+    <Compile Include="ILAst\PeepholeTransform.cs" />
     <Compile Include="ILAst\TypeAnalysis.cs" />
     <Compile Include="ITextOutput.cs" />
     <Compile Include="PlainTextOutput.cs" />

ICSharpCode.Decompiler/ILAst/ArrayInitializers.cs

@@ -12,62 +12,52 @@ namespace Decompiler
 	/// <summary>
 	/// IL AST transformation that introduces array initializers.
 	/// </summary>
-	public class ArrayInitializers
+	public static class ArrayInitializers
 	{
-		public static void Transform(ILBlock method)
+		public static PeepholeTransform Transform(ILBlock method)
 		{
-			// TODO: move this somewhere else
-			// Eliminate 'dups':
-			foreach (ILExpression expr in method.GetSelfAndChildrenRecursive<ILExpression>()) {
-				for (int i = 0; i < expr.Arguments.Count; i++) {
-					if (expr.Arguments[i].Code == ILCode.Dup)
-						expr.Arguments[i] = expr.Arguments[i].Arguments[0];
-				}
-			}
-			
 			var newArrPattern = new StoreToVariable(new ILExpression(ILCode.Newarr, ILExpression.AnyOperand, new ILExpression(ILCode.Ldc_I4, ILExpression.AnyOperand)));
 			var arg1 = new StoreToVariable(new LoadFromVariable(newArrPattern)) { MustBeGenerated = true };
 			var arg2 = new StoreToVariable(new LoadFromVariable(newArrPattern)) { MustBeGenerated = true };
 			var initializeArrayPattern = new ILCall(
 				"System.Runtime.CompilerServices.RuntimeHelpers", "InitializeArray",
 				new LoadFromVariable(arg1), new ILExpression(ILCode.Ldtoken, ILExpression.AnyOperand));
-			foreach (ILBlock block in method.GetSelfAndChildrenRecursive<ILBlock>()) {
-				for (int i = block.Body.Count - 1; i >= 0; i--) {
-					if (!newArrPattern.Match(block.Body[i]))
-						continue;
-					ILExpression newArrInst = ((ILExpression)block.Body[i]).Arguments[0];
-					int arrayLength = (int)newArrInst.Arguments[0].Operand;
-					if (arrayLength == 0)
-						continue;
-					if (arg1.Match(block.Body.ElementAtOrDefault(i + 1)) && arg2.Match(block.Body.ElementAtOrDefault(i + 2))) {
-						if (initializeArrayPattern.Match(block.Body.ElementAtOrDefault(i + 3))) {
-							if (HandleStaticallyInitializedArray(arg2, block, i, newArrInst, arrayLength)) {
-								i -= ILInlining.InlineInto(block, i + 1, method) - 1;
-							}
-							continue;
+			
+			return delegate(ILBlock block, ref int i) {
+				if (!newArrPattern.Match(block.Body[i]))
+					return;
+				ILExpression newArrInst = ((ILExpression)block.Body[i]).Arguments[0];
+				int arrayLength = (int)newArrInst.Arguments[0].Operand;
+				if (arrayLength == 0)
+					return;
+				if (arg1.Match(block.Body.ElementAtOrDefault(i + 1)) && arg2.Match(block.Body.ElementAtOrDefault(i + 2))) {
+					if (initializeArrayPattern.Match(block.Body.ElementAtOrDefault(i + 3))) {
+						if (HandleStaticallyInitializedArray(arg2, block, i, newArrInst, arrayLength)) {
+							i -= ILInlining.InlineInto(block, i + 1, method) - 1;
 						}
-					}
-					if (i + 1 + arrayLength > block.Body.Count)
-						continue;
-					List<ILExpression> operands = new List<ILExpression>();
-					for (int j = 0; j < arrayLength; j++) {
-						ILExpression expr = block.Body[i + 1 + j] as ILExpression;
-						if (expr == null || !IsStoreToArray(expr.Code))
-							break;
-						if (!(expr.Arguments[0].Code == ILCode.Ldloc && expr.Arguments[0].Operand == newArrPattern.LastVariable))
-							break;
-						if (!(expr.Arguments[1].Code == ILCode.Ldc_I4 && (int)expr.Arguments[1].Operand == j))
-							break;
-						operands.Add(expr.Arguments[2]);
-					}
-					if (operands.Count == arrayLength) {
-						((ILExpression)block.Body[i]).Arguments[0] = new ILExpression(
-							ILCode.InitArray, newArrInst.Operand, operands.ToArray());
-						block.Body.RemoveRange(i + 1, arrayLength);
-						i -= ILInlining.InlineInto(block, i + 1, method) - 1;
+						return;
 					}
 				}
-			}
+				if (i + 1 + arrayLength > block.Body.Count)
+					return;
+				List<ILExpression> operands = new List<ILExpression>();
+				for (int j = 0; j < arrayLength; j++) {
+					ILExpression expr = block.Body[i + 1 + j] as ILExpression;
+					if (expr == null || !IsStoreToArray(expr.Code))
+						break;
+					if (!(expr.Arguments[0].Code == ILCode.Ldloc && expr.Arguments[0].Operand == newArrPattern.LastVariable))
+						break;
+					if (!(expr.Arguments[1].Code == ILCode.Ldc_I4 && (int)expr.Arguments[1].Operand == j))
+						break;
+					operands.Add(expr.Arguments[2]);
+				}
+				if (operands.Count == arrayLength) {
+					((ILExpression)block.Body[i]).Arguments[0] = new ILExpression(
+						ILCode.InitArray, newArrInst.Operand, operands.ToArray());
+					block.Body.RemoveRange(i + 1, arrayLength);
+					i -= ILInlining.InlineInto(block, i + 1, method) - 1;
+				}
+			};
 		}
 		
 		static bool IsStoreToArray(ILCode code)

ICSharpCode.Decompiler/ILAst/ILAstOptimizer.cs

@@ -19,7 +19,7 @@ namespace Decompiler.ControlFlow
 		GotoRemoval,
 		DuplicateReturns,
 		FlattenIfStatements,
-		HandleArrayInitializers,
+		PeepholeTransforms,
 		TypeInference,
 		None
 	}
@@ -76,8 +76,8 @@ namespace Decompiler.ControlFlow
 			if (abortBeforeStep == ILAstOptimizationStep.FlattenIfStatements) return;
 			FlattenIfStatements(method);
 			
-			if (abortBeforeStep == ILAstOptimizationStep.HandleArrayInitializers) return;
-			ArrayInitializers.Transform(method);
+			if (abortBeforeStep == ILAstOptimizationStep.PeepholeTransforms) return;
+			PeepholeTransforms.Run(context, method);
 			
 			if (abortBeforeStep == ILAstOptimizationStep.TypeInference) return;
 			TypeAnalysis.Run(context, method);
@@ -562,9 +562,9 @@ namespace Decompiler.ControlFlow
 								DefaultGoto = block.FallthoughGoto
 							};
 							result.Add(new ILBasicBlock() {
-								EntryLabel = block.EntryLabel,  // Keep the entry label
-								Body = { ilSwitch }
-							});
+							           	EntryLabel = block.EntryLabel,  // Keep the entry label
+							           	Body = { ilSwitch }
+							           });
 
 							// Remove the item so that it is not picked up as content
 							if (!scope.Remove(node))

ICSharpCode.Decompiler/ILAst/PeepholeTransform.cs

@@ -0,0 +1,44 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+using System.Linq;
+using ICSharpCode.NRefactory.Utils;
+
+namespace Decompiler
+{
+	public delegate void PeepholeTransform(ILBlock block, ref int i);
+	
+	/// <summary>
+	/// Handles peephole transformations on the ILAst.
+	/// </summary>
+	public static class PeepholeTransforms
+	{
+		public static void Run(DecompilerContext context, ILBlock method)
+		{
+			// TODO: move this somewhere else
+			// Eliminate 'dups':
+			foreach (ILExpression expr in method.GetSelfAndChildrenRecursive<ILExpression>()) {
+				for (int i = 0; i < expr.Arguments.Count; i++) {
+					if (expr.Arguments[i].Code == ILCode.Dup)
+						expr.Arguments[i] = expr.Arguments[i].Arguments[0];
+				}
+			}
+			
+			PeepholeTransform[] transforms = {
+				ArrayInitializers.Transform(method)
+			};
+			// Traverse in post order so that nested blocks are transformed first. This is required so that
+			// patterns on the parent block can assume that all nested blocks are already transformed.
+			foreach (var block in TreeTraversal.PostOrder<ILNode>(method, c => c != null ? c.GetChildren() : null).OfType<ILBlock>()) {
+				// go through the instructions in reverse so that
+				for (int i = block.Body.Count - 1; i >= 0; i--) {
+					context.CancellationToken.ThrowIfCancellationRequested();
+					foreach (var t in transforms) {
+						t(block, ref i);
+					}
+				}
+			}
+		}
+	}
+}