[NativeAOT] fix NAOT mappings (follow-up to #123333) (#123831)

Testing on #122722 revealed some issues with #123333 so I am fixing
these here.

After #123333 there remain two error cases:
1. Our IL offset is greater than the previously found offset, but lower
than the max found offset. In this case, we would like to advance the
line number in accordance with the new IL offset, which was omitted
after #123333.
2. Our IL offset is greater than the highest IL offset for which there
exists a sequence point. In this case, we want to ensure we can create a
native <-> line mapping - #123333 had left these IL offsets with a
Document of null, meaning no mappings were possible.
This fixes both of these issues.

Before:
<img width="1298" height="268" alt="Screenshot 2026-01-30 192451"
src="https://github.com/user-attachments/assets/ab46947f-ea52-4530-949b-3e36bf3b3df6"
/>
<img width="1312" height="359" alt="Screenshot 2026-01-30 192408"
src="https://github.com/user-attachments/assets/b08a8f45-0af2-484a-8392-8d12c3694361"
/>

After:
<img width="1020" height="311" alt="Screenshot 2026-01-30 190332"
src="https://github.com/user-attachments/assets/ac8bca54-6466-4436-9fac-1f6f685e7bd0"
/>
<img width="1030" height="400" alt="Screenshot 2026-01-30 190613"
src="https://github.com/user-attachments/assets/321c8160-cf06-4f43-8c36-352d2bd6908a"
/>
[foo.txt](https://github.com/user-attachments/files/24984632/foo.txt)
[foo2.txt](https://github.com/user-attachments/files/24984633/foo2.txt)
[New Compressed (zipped)
Folder.zip](https://github.com/user-attachments/files/24976959/New.Compressed.zipped.Folder.zip)

---------

Co-authored-by: Michal Strehovský <MichalStrehovsky@users.noreply.github.com>
Co-authored-by: Jan Kotas <jkotas@microsoft.com>

Author: 3 people

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/StackTraceLineNumbersNode.cs

@@ -103,14 +103,9 @@ static Vertex CreateLineNumbersBlob(NativeWriter writer, StackTraceDocumentsNode
 
                 foreach (NativeSequencePoint sequencePoint in debugInfoNode.GetNativeSequencePoints())
                 {
-                    if (currentLineNumber == sequencePoint.LineNumber && currentDocument == sequencePoint.FileName)
-                        continue;
-
                     // Make sure a zero native offset delta is not possible because we use it below
                     // to indicate an update to the current document.
-                    if (currentDocument != null && currentNativeOffset == sequencePoint.NativeOffset)
-                        continue;
-
+                    Debug.Assert(currentDocument == null || currentNativeOffset != sequencePoint.NativeOffset);
                     if (currentDocument != sequencePoint.FileName)
                     {
                         // We start with currentDocument == null, so the reader knows the first byte of the output

src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/DependencyAnalysis/MethodCodeNode.cs

@@ -260,10 +260,9 @@ public IEnumerable<NativeSequencePoint> GetNativeSequencePoints()
             if (_debugLocInfos == null)
                 yield break;
 
-            var sequencePoints = new (string Document, int LineNumber, bool IsBackedSequencePoint)[_debugLocInfos.Length * 4 /* chosen empirically */];
+            var sequencePoints = new (string Document, int LineNumber)[_debugLocInfos.Length * 4 /* chosen empirically */];
             try
             {
-                int maxOffset = 0;
                 foreach (var sequencePoint in _debugInfo.GetSequencePoints())
                 {
                     int offset = sequencePoint.Offset;
@@ -272,16 +271,15 @@ public IEnumerable<NativeSequencePoint> GetNativeSequencePoints()
                         int newLength = Math.Max(2 * sequencePoints.Length, sequencePoint.Offset + 1);
                         Array.Resize(ref sequencePoints, newLength);
                     }
-                    sequencePoints[offset] = (sequencePoint.Document, sequencePoint.LineNumber, true);
-                    maxOffset = Math.Max(maxOffset, offset);
+                    sequencePoints[offset] = (sequencePoint.Document, sequencePoint.LineNumber);
                 }
 
                 // Propagate last known document/line number forward to enable correct mapping when IL offsets decrease at higher native offsets
-                for (int i = 1; i <= maxOffset; i++)
+                for (int i = 1; i < sequencePoints.Length; i++)
                 {
                     if (sequencePoints[i].Document == null && sequencePoints[i - 1].Document != null)
                     {
-                        sequencePoints[i] = (sequencePoints[i - 1].Document, sequencePoints[i - 1].LineNumber, false);
+                        sequencePoints[i] = (sequencePoints[i - 1].Document, sequencePoints[i - 1].LineNumber);
                     }
                 }
             }
@@ -294,28 +292,26 @@ public IEnumerable<NativeSequencePoint> GetNativeSequencePoints()
             }
 
             int previousNativeOffset = -1;
-            int previousIlOffset = -1;
+            string previousDocument = null;
+            int previousLineNumber = -1;
+            // OffsetMapping is sorted in order of increasing native offset (but not necessarily by IL offset)
             foreach (var nativeMapping in _debugLocInfos)
             {
                 if (nativeMapping.NativeOffset == previousNativeOffset)
                     continue;
 
-                if (nativeMapping.ILOffset < sequencePoints.Length)
+                var sequencePoint = sequencePoints[Math.Min(nativeMapping.ILOffset, sequencePoints.Length - 1)];
+                // Emit sequence point if its line number or document differ from the previous one.
+                // See WalkILOffsetsCallback in src/coreclr/vm/debugdebugger.cpp for more details.
+                if (sequencePoint.Document != null && (sequencePoint.Document != previousDocument || sequencePoint.LineNumber != previousLineNumber))
                 {
-                    var sequencePoint = sequencePoints[nativeMapping.ILOffset];
-                    // Emit sequence point if we have it from _debugInfo or if ILOffset decreases.
-                    // This handles the case of IL offsets decreasing at higher native offsets.
-                    // See WalkILOffsetsCallback in src/coreclr/vm/debugdebugger.cpp for more details.
-                    if ((sequencePoint.IsBackedSequencePoint || nativeMapping.ILOffset < previousIlOffset) &&
-                        sequencePoint.Document != null)
-                    {
-                        yield return new NativeSequencePoint(
-                            nativeMapping.NativeOffset,
-                            sequencePoint.Document,
-                            sequencePoint.LineNumber);
-                        previousNativeOffset = nativeMapping.NativeOffset;
-                        previousIlOffset = nativeMapping.ILOffset;
-                    }
+                    yield return new NativeSequencePoint(
+                        nativeMapping.NativeOffset,
+                        sequencePoint.Document,
+                        sequencePoint.LineNumber);
+                    previousNativeOffset = nativeMapping.NativeOffset;
+                    previousDocument = sequencePoint.Document;
+                    previousLineNumber = sequencePoint.LineNumber;
                 }
             }
         }

src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs

@@ -1048,6 +1048,9 @@ private void setBoundaries(CORINFO_METHOD_STRUCT_* ftn, uint cMap, OffsetMapping
                     case (int)MappingTypes.NO_MAPPING:
                         continue;
                 }
+                // Ignore these; see WalkILOffsetsCallback in src/coreclr/vm/debugdebugger.cpp.
+                if (nativeToILInfo->source == SourceTypes.CALL_INSTRUCTION)
+                    continue;
 
                 debugLocInfos.Add(new DebugLocInfo((int)nativeToILInfo->nativeOffset, ilOffset));
             }