Add hidden sequence points for unmapped code.

ICSharpCode.Decompiler/CSharp/SequencePointBuilder.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.IL;
@@ -131,8 +132,12 @@ namespace ICSharpCode.Decompiler.CSharp
 		void EndSequencePoint(TextLocation startLocation, TextLocation endLocation)
 		{
 			if (current.Intervals.Count > 0 && current.Function != null) {
+				// use LongSet to deduplicate and merge the intervals
+				var longSet = new LongSet(current.Intervals.Select(i => new LongInterval(i.Start, i.End)));
+				Debug.Assert(!longSet.IsEmpty);
 				sequencePoints.Add((current.Function, new SequencePoint {
-					Offset = current.Intervals.Select(i => i.Start).Min(),
+					Offset = (int)longSet.Intervals[0].Start,
+					EndOffset = (int)longSet.Intervals[0].End,
 					StartLine = startLocation.Line,
 					StartColumn = startLocation.Column,
 					EndLine = endLocation.Line,
@@ -183,8 +188,24 @@ namespace ICSharpCode.Decompiler.CSharp
 				}
 				list.Add(sequencePoint);
 			}
-			foreach (var list in dict.Values) {
+			foreach (var (function, list) in dict.ToList()) {
-				list.Sort((a, b) => a.Offset.CompareTo(b.Offset));
+				// For each function, sort sequence points
+				// and insert hidden sequence points in the gaps.
+				var newList = new List<SequencePoint>();
+				int pos = 0;
+				foreach (var sequencePoint in list.OrderBy(sp => sp.Offset)) {
+					Debug.Assert(sequencePoint.Offset >= pos);
+					if (sequencePoint.Offset > pos) {
+						var hidden = new SequencePoint();
+						hidden.Offset = pos;
+						hidden.EndOffset = sequencePoint.Offset;
+						hidden.SetHidden();
+						newList.Add(hidden);
+					}
+					newList.Add(sequencePoint);
+					pos = sequencePoint.EndOffset;
+				}
+				dict[function] = newList;
 			}
 			return dict;
 		}

ICSharpCode.Decompiler/IL/SequencePoint.cs

@@ -10,10 +10,20 @@ namespace ICSharpCode.Decompiler.IL
 	public struct SequencePoint
 	{
 		/// <summary>
-		/// IL offset.
+		/// IL start offset.
 		/// </summary>
 		public int Offset { get; set; }
 
+		/// <summary>
+		/// IL end offset.
+		/// </summary>
+		/// <remarks>
+		/// This does not get stored in debug information;
+		/// it is used internally to create hidden sequence points
+		/// for the IL fragments not covered by any sequence point.
+		/// </remarks>
+		public int EndOffset { get; set; }
+
 		public int StartLine { get; set; }
 		public int StartColumn { get; set; }
 		public int EndLine { get; set; }
@@ -22,5 +32,10 @@ namespace ICSharpCode.Decompiler.IL
 		public bool IsHidden {
 			get { return StartLine == 0xfeefee && StartLine == EndLine; }
 		}
+
+		internal void SetHidden()
+		{
+			StartLine = EndLine = 0xfeefee;
+		}
 	}
 }

ILSpy/Languages/CSharpILMixedLanguage.cs

@@ -82,9 +82,10 @@ namespace ICSharpCode.ILSpy
 				int index = sequencePoints.BinarySearch(instruction.Offset, seq => seq.Offset);
 				if (index >= 0) {
 					var info = sequencePoints[index];
+					var highlightingOutput = output as ISmartTextOutput;
 					if (!info.IsHidden) {
 						for (int line = info.StartLine; line <= info.EndLine; line++) {
-							if (output is ISmartTextOutput highlightingOutput) {
+							if (highlightingOutput != null) {
 								string text = codeLines[line - 1];
 								int startColumn = 1;
 								int endColumn = text.Length + 1;
@@ -97,25 +98,28 @@ namespace ICSharpCode.ILSpy
 								WriteCommentLine(output, codeLines[line - 1]);
 						}
 					} else {
-						WriteCommentLine(output, "no code");
+						output.Write("// ");
+						highlightingOutput?.BeginSpan(gray);
+						output.WriteLine("(hidden sequence point)");
+						highlightingOutput?.EndSpan();
 					}
 				}
 				base.WriteInstruction(output, instruction);
 			}
 
 			HighlightingColor gray = new HighlightingColor { Foreground = new SimpleHighlightingBrush(Colors.DarkGray) };
-			HighlightingColor black = new HighlightingColor { Foreground = new SimpleHighlightingBrush(Colors.Black) };
 
 			void WriteHighlightedCommentLine(ISmartTextOutput output, string text, int startColumn, int endColumn, bool isSingleLine)
 			{
+				output.Write("// ");
 				output.BeginSpan(gray);
 				if (isSingleLine)
-					output.Write("// " + text.Substring(0, startColumn).TrimStart());
+					output.Write(text.Substring(0, startColumn).TrimStart());
 				else
-					output.Write("// " + text.Substring(0, startColumn));
+					output.Write(text.Substring(0, startColumn));
-				output.BeginSpan(black);
-				output.Write(text.Substring(startColumn, endColumn - startColumn));
 				output.EndSpan();
+				output.Write(text.Substring(startColumn, endColumn - startColumn));
+				output.BeginSpan(gray);
 				output.Write(text.Substring(endColumn));
 				output.EndSpan();
 				output.WriteLine();