[CI ONLY] [NativeAOT] ObjWriter in C#

src/coreclr/tools/Common/Compiler/DependencyAnalysis/ObjectNodeSection.cs

@@ -9,6 +9,7 @@ public enum SectionType
         Writeable,
         Executable,
         Uninitialized,
+        Debug,
     }
 
     /// <summary>

src/coreclr/tools/Common/Compiler/DependencyAnalysis/Relocation.cs

@@ -23,6 +23,7 @@ public enum RelocType
                                                        // This is a special NGEN-specific relocation type
                                                        // for relative pointer (used to make NGen relocation
                                                        // section smaller)
+        IMAGE_REL_SECTION                    = 0x79,   // 16 bit section index containing target
 
         IMAGE_REL_BASED_ARM64_PAGEBASE_REL21 = 0x81,   // ADRP
         IMAGE_REL_BASED_ARM64_PAGEOFFSET_12A = 0x82,   // ADD/ADDS (immediate) with zero shift, for page offset

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/ObjectWriter/CodeView/CodeViewFileTableBuilder.cs

@@ -0,0 +1,67 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Buffers;
+using System.Buffers.Binary;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Text;
+
+using static ILCompiler.ObjectWriter.CodeViewNative;
+
+namespace ILCompiler.ObjectWriter
+{
+    internal sealed class CodeViewFileTableBuilder
+    {
+        private MemoryStream _stringTableWriter = new();
+        private MemoryStream _fileTableWriter = new();
+        private Dictionary<string, uint> _fileNameToIndex = new();
+
+        public CodeViewFileTableBuilder()
+        {
+            // Insert empty entry at the beginning of string table
+            _stringTableWriter.Write(stackalloc byte[2]);
+        }
+
+        public uint GetFileIndex(string fileName)
+        {
+            if (fileName == "")
+            {
+                fileName = "<stdin>";
+            }
+
+            if (_fileNameToIndex.TryGetValue(fileName, out uint fileIndex))
+            {
+                return fileIndex;
+            }
+            else
+            {
+                uint stringTableIndex = (uint)_stringTableWriter.Position;
+                _stringTableWriter.Write(Encoding.UTF8.GetBytes(fileName));
+                _stringTableWriter.WriteByte(0);
+
+                uint fileTableIndex = (uint)_fileTableWriter.Position;
+                Span<byte> fileTableEntry = stackalloc byte[sizeof(uint) + sizeof(uint)];
+                BinaryPrimitives.WriteUInt32LittleEndian(fileTableEntry, stringTableIndex);
+                BinaryPrimitives.WriteUInt32LittleEndian(fileTableEntry.Slice(4), 0);
+                _fileTableWriter.Write(fileTableEntry);
+
+                _fileNameToIndex.Add(fileName, fileTableIndex);
+
+                return fileTableIndex;
+            }
+        }
+
+        public void Write(SectionWriter sectionWriter)
+        {
+            sectionWriter.WriteLittleEndian<uint>((uint)DebugSymbolsSubsectionType.FileChecksums);
+            sectionWriter.WriteLittleEndian<uint>((uint)_fileTableWriter.Length);
+            sectionWriter.EmitData(_fileTableWriter.GetBuffer().AsMemory(0, (int)_fileTableWriter.Length));
+            sectionWriter.WriteLittleEndian<uint>((uint)DebugSymbolsSubsectionType.StringTable);
+            sectionWriter.WriteLittleEndian<uint>((uint)_stringTableWriter.Length);
+            sectionWriter.EmitData(_stringTableWriter.GetBuffer().AsMemory(0, (int)_stringTableWriter.Length));
+        }
+    }
+}