Add feature to the MethodBodyDisassembler that shows sequence points from PDB in disassembled IL.

ICSharpCode.Decompiler.Tests/Helpers/Tester.cs

@@ -111,7 +111,8 @@ namespace ICSharpCode.Decompiler.Tests.Helpers
 				using (var writer = new StreamWriter(outputFile)) {
 					module.Name = Path.GetFileNameWithoutExtension(outputFile);
 					var output = new PlainTextOutput(writer);
-					ReflectionDisassembler rd = new ReflectionDisassembler(output, false, CancellationToken.None);
+					ReflectionDisassembler rd = new ReflectionDisassembler(output, CancellationToken.None);
+					rd.DetectControlStructure = false;
 					rd.WriteAssemblyReferences(module);
 					if (module.Assembly != null)
 						rd.WriteAssemblyHeader(module.Assembly);

ICSharpCode.Decompiler/Disassembler/MethodBodyDisassembler.cs

@@ -21,6 +21,7 @@ using System.Collections.Generic;
 using System.Threading;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
+using Mono.Collections.Generic;
 
 namespace ICSharpCode.Decompiler.Disassembler
 {
@@ -30,15 +31,24 @@ namespace ICSharpCode.Decompiler.Disassembler
 	public class MethodBodyDisassembler
 	{
 		readonly ITextOutput output;
-		readonly bool detectControlStructure;
 		readonly CancellationToken cancellationToken;
 
-		public MethodBodyDisassembler(ITextOutput output, bool detectControlStructure, CancellationToken cancellationToken)
+		/// <summary>
+		/// Show .try/finally as blocks in IL code; indent loops.
+		/// </summary>
+		public bool DetectControlStructure { get; set; } = true;
+
+		/// <summary>
+		/// Show sequence points if debug information is loaded in Cecil.
+		/// </summary>
+		public bool ShowSequencePoints { get; set; }
+
+		Collection<SequencePoint> sequencePoints;
+		int nextSequencePointIndex;
+
+		public MethodBodyDisassembler(ITextOutput output, CancellationToken cancellationToken)
 		{
-			if (output == null)
-				throw new ArgumentNullException(nameof(output));
-			this.output = output;
-			this.detectControlStructure = detectControlStructure;
+			this.output = output ?? throw new ArgumentNullException(nameof(output));
 			this.cancellationToken = cancellationToken;
 		}
 
@@ -55,7 +65,9 @@ namespace ICSharpCode.Decompiler.Disassembler
 			DisassembleLocalsBlock(body);
 			output.WriteLine();
 
-			if (detectControlStructure && body.Instructions.Count > 0) {
+			sequencePoints = method.DebugInformation?.SequencePoints;
+			nextSequencePointIndex = 0;
+			if (DetectControlStructure && body.Instructions.Count > 0) {
 				Instruction inst = body.Instructions[0];
 				HashSet<int> branchTargets = GetBranchTargets(body.Instructions);
 				WriteStructureBody(new ILStructure(body), branchTargets, ref inst, method.Body.CodeSize);
@@ -66,6 +78,7 @@ namespace ICSharpCode.Decompiler.Disassembler
 				}
 				WriteExceptionHandlers(body);
 			}
+			sequencePoints = null;
 		}
 
 		private void DisassembleLocalsBlock(MethodBody body)
@@ -215,6 +228,21 @@ namespace ICSharpCode.Decompiler.Disassembler
 
 		protected virtual void WriteInstruction(ITextOutput output, Instruction instruction)
 		{
+			if (ShowSequencePoints && nextSequencePointIndex < sequencePoints?.Count) {
+				SequencePoint sp = sequencePoints[nextSequencePointIndex];
+				if (sp.Offset <= instruction.Offset) {
+					output.Write("// sequence point: ");
+					if (sp.Offset != instruction.Offset) {
+						output.Write("!! at " + DisassemblerHelpers.OffsetToString(sp.Offset) + " !!");
+					}
+					if (sp.IsHidden) {
+						output.WriteLine("hidden");
+					} else {
+						output.WriteLine($"(line {sp.StartLine}, col {sp.StartColumn}) to (line {sp.EndLine}, col {sp.EndColumn}) in {sp.Document?.Url}");
+					}
+					nextSequencePointIndex++;
+				}
+			}
 			instruction.WriteTo(output);
 		}
 	}

ICSharpCode.Decompiler/Disassembler/ReflectionDisassembler.cs

@@ -35,8 +35,18 @@ namespace ICSharpCode.Decompiler.Disassembler
 		MethodBodyDisassembler methodBodyDisassembler;
 		MemberReference currentMember;
 
-		public ReflectionDisassembler(ITextOutput output, bool detectControlStructure, CancellationToken cancellationToken)
-			: this(output, new MethodBodyDisassembler(output, detectControlStructure, cancellationToken), cancellationToken)
+		public bool DetectControlStructure {
+			get => methodBodyDisassembler.DetectControlStructure;
+			set => methodBodyDisassembler.DetectControlStructure = value;
+		}
+
+		public bool ShowSequencePoints {
+			get => methodBodyDisassembler.ShowSequencePoints;
+			set => methodBodyDisassembler.ShowSequencePoints = value;
+		}
+
+		public ReflectionDisassembler(ITextOutput output, CancellationToken cancellationToken)
+			: this(output, new MethodBodyDisassembler(output, cancellationToken), cancellationToken)
 		{
 		}
 

ICSharpCode.Decompiler/IL/ILReader.cs

@@ -304,7 +304,8 @@ namespace ICSharpCode.Decompiler.IL
 				inst.WriteTo(output, new ILAstWritingOptions());
 				output.WriteLine();
 			}
-			new Disassembler.MethodBodyDisassembler(output, false, cancellationToken).WriteExceptionHandlers(body);
+			new Disassembler.MethodBodyDisassembler(output, cancellationToken) { DetectControlStructure = false }
+				.WriteExceptionHandlers(body);
 		}
 
 		/// <summary>

ILSpy/Languages/CSharpILMixedLanguage.cs

@@ -28,7 +28,10 @@ namespace ICSharpCode.ILSpy
 		protected override ReflectionDisassembler CreateDisassembler(ITextOutput output, DecompilationOptions options)
 		{
 			return new ReflectionDisassembler(output, 
-				new MixedMethodBodyDisassembler(output, detectControlStructure, options),
+				new MixedMethodBodyDisassembler(output, options) {
+					DetectControlStructure = detectControlStructure,
+					ShowSequencePoints = true
+				},
 				options.CancellationToken);
 		}
 
@@ -55,8 +58,8 @@ namespace ICSharpCode.ILSpy
 			// lines of raw c# source code
 			string[] codeLines;
 
-			public MixedMethodBodyDisassembler(ITextOutput output, bool detectControlStructure, DecompilationOptions options)
-				: base(output, detectControlStructure, options.CancellationToken)
+			public MixedMethodBodyDisassembler(ITextOutput output, DecompilationOptions options)
+				: base(output, options.CancellationToken)
 			{
 				this.options = options;
 			}
@@ -102,7 +105,7 @@ namespace ICSharpCode.ILSpy
 					} else {
 						output.Write("// ");
 						highlightingOutput?.BeginSpan(gray);
-						output.WriteLine("(hidden sequence point)");
+						output.WriteLine("(no C# code)");
 						highlightingOutput?.EndSpan();
 					}
 				}

ILSpy/Languages/ILAstLanguage.cs

@@ -77,7 +77,7 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileMethod(MethodDefinition method, ITextOutput output, DecompilationOptions options)
 		{
 			base.DecompileMethod(method, output, options);
-			new ReflectionDisassembler(output, false, options.CancellationToken).DisassembleMethodHeader(method);
+			new ReflectionDisassembler(output, options.CancellationToken).DisassembleMethodHeader(method);
 			output.WriteLine();
 			output.WriteLine();
 		}

ILSpy/Languages/ILLanguage.cs

@@ -46,7 +46,10 @@ namespace ICSharpCode.ILSpy
 		
 		protected virtual ReflectionDisassembler CreateDisassembler(ITextOutput output, DecompilationOptions options)
 		{
-			return new ReflectionDisassembler(output, detectControlStructure, options.CancellationToken);
+			return new ReflectionDisassembler(output, options.CancellationToken) {
+				DetectControlStructure = detectControlStructure,
+				ShowSequencePoints = true
+			};
 		}
 
 		public override void DecompileMethod(MethodDefinition method, ITextOutput output, DecompilationOptions options)