Improve cancellation.

ICSharpCode.Decompiler/IL/BlockBuilder.cs

@@ -21,6 +21,7 @@ using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using System.Threading;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.Util;
 
@@ -107,13 +108,14 @@ namespace ICSharpCode.Decompiler.IL
 		Block currentBlock;
 		Stack<BlockContainer> containerStack = new Stack<BlockContainer>();
 		
-		public void CreateBlocks(BlockContainer mainContainer, List<ILInstruction> instructions, BitArray incomingBranches)
+		public void CreateBlocks(BlockContainer mainContainer, List<ILInstruction> instructions, BitArray incomingBranches, CancellationToken cancellationToken)
 		{
 			CreateContainerStructure();
 			mainContainer.ILRange = new Interval(0, body.CodeSize);
 			currentContainer = mainContainer;
 
 			foreach (var inst in instructions) {
+				cancellationToken.ThrowIfCancellationRequested();
 				int start = inst.ILRange.Start;
 				if (currentBlock == null || incomingBranches[start]) {
 					// Finish up the previous block
@@ -153,7 +155,7 @@ namespace ICSharpCode.Decompiler.IL
 			}
 			FinalizeCurrentBlock(body.CodeSize, fallthrough: false);
 			containerStack.Clear();
-			ConnectBranches(mainContainer);
+			ConnectBranches(mainContainer, cancellationToken);
 		}
 
 		private void FinalizeCurrentBlock(int currentILOffset, bool fallthrough)
@@ -166,10 +168,11 @@ namespace ICSharpCode.Decompiler.IL
 			currentBlock = null;
 		}
 
-		void ConnectBranches(ILInstruction inst)
+		void ConnectBranches(ILInstruction inst, CancellationToken cancellationToken)
 		{
 			switch (inst) {
 				case Branch branch:
+					cancellationToken.ThrowIfCancellationRequested();
 					Debug.Assert(branch.TargetBlock == null);
 					branch.TargetBlock = FindBranchTarget(branch.TargetILOffset);
 					break;
@@ -184,7 +187,8 @@ namespace ICSharpCode.Decompiler.IL
 				case BlockContainer container:
 					containerStack.Push(container);
 					foreach (var block in container.Blocks) {
-						ConnectBranches(block);
+						cancellationToken.ThrowIfCancellationRequested();
+						ConnectBranches(block, cancellationToken);
 						if (block.Instructions.Count == 0 || !block.Instructions.Last().HasFlag(InstructionFlags.EndPointUnreachable)) {
 							block.Instructions.Add(new InvalidBranch("Unexpected end of block"));
 						}
@@ -193,7 +197,7 @@ namespace ICSharpCode.Decompiler.IL
 					break;
 				default:
 					foreach (var child in inst.Children)
-						ConnectBranches(child);
+						ConnectBranches(child, cancellationToken);
 					break;
 			}
 		}

ICSharpCode.Decompiler/IL/ILReader.cs

@@ -306,7 +306,7 @@ namespace ICSharpCode.Decompiler.IL
 			Init(body);
 			ReadInstructions(cancellationToken);
 			var blockBuilder = new BlockBuilder(body, typeSystem, variableByExceptionHandler);
-			blockBuilder.CreateBlocks(mainContainer, instructionBuilder, isBranchTarget);
+			blockBuilder.CreateBlocks(mainContainer, instructionBuilder, isBranchTarget, cancellationToken);
 			var function = new ILFunction(body.Method, mainContainer);
 			CollectionExtensions.AddRange(function.Variables, parameterVariables);
 			CollectionExtensions.AddRange(function.Variables, localVariables);

ICSharpCode.Decompiler/IL/Transforms/LoopingTransform.cs

@@ -40,11 +40,12 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				throw new InvalidOperationException("LoopingBlockTransform already running. Transforms (and the CSharpDecompiler) are neither neither thread-safe nor re-entrant.");
 			running = true;
 			try {
+				int count = 1;
 				do {
 					block.ResetDirty();
 					block.RunTransforms(children, context);
 					if (block.IsDirty)
-						context.Step("Block is dirty; running another loop iteration.", block);
+						context.Step($"Block is dirty; running loop iteration #{++count}.", block);
 				} while (block.IsDirty);
 			} finally {
 				running = false;

ILSpy/Languages/ILAstLanguage.cs

@@ -156,7 +156,11 @@ namespace ICSharpCode.ILSpy
 				ILReader reader = new ILReader(typeSystem);
 				reader.UseDebugSymbols = options.DecompilerSettings.UseDebugSymbols;
 				ILFunction il = reader.ReadIL(method.Body, options.CancellationToken);
-				ILTransformContext context = new ILTransformContext { Settings = options.DecompilerSettings, TypeSystem = typeSystem };
+				ILTransformContext context = new ILTransformContext {
+					Settings = options.DecompilerSettings,
+					TypeSystem = typeSystem,
+					CancellationToken = options.CancellationToken
+				};
 				context.Stepper.StepLimit = options.StepLimit;
 				context.Stepper.IsDebug = options.IsDebug;
 				try {