[NativeAOT] Prototype guarded incremental compilation

src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.cs

@@ -87,6 +87,8 @@ protected override ModuleData CreateValueFromKey(string key)
 
         private readonly SharedGenericsMode _genericsMode;
 
+        internal SharedGenericsMode SharedGenericsMode => _genericsMode;
+
         public IReadOnlyDictionary<string, string> InputFilePaths
         {
             get;

src/coreclr/tools/Common/Compiler/ObjectWriter/CoffObjectWriter.cs

@@ -62,8 +62,18 @@ protected sealed record SectionDefinition(CoffSectionHeader Header, Stream Strea
         private static readonly ObjectNodeSection DebugTypesSection = new ObjectNodeSection(".debug$T", SectionType.ReadOnly);
         private static readonly ObjectNodeSection DebugSymbolSection = new ObjectNodeSection(".debug$S", SectionType.ReadOnly);
 
-        public CoffObjectWriter(NodeFactory factory, ObjectWritingOptions options, OutputInfoBuilder outputInfoBuilder = null)
-            : base(factory, options, outputInfoBuilder)
+        public CoffObjectWriter(
+            NodeFactory factory,
+            ObjectWritingOptions options,
+            OutputInfoBuilder outputInfoBuilder = null,
+            Action<object, int, long, object, bool> recordIncrementalNode = null,
+            Action<Func<int, long, int, long?>> completeIncrementalLayout = null)
+            : base(
+                factory,
+                options,
+                outputInfoBuilder,
+                recordIncrementalNode,
+                completeIncrementalLayout)
         {
             _machine = factory.Target.Architecture switch
             {
@@ -481,6 +491,32 @@ private protected override void EmitObjectFile(Stream outputFileStream)
             stringTable.Write(outputFileStream);
         }
 
+        private protected override bool TryGetObjectFileRange(
+            int sectionIndex,
+            long sectionOffset,
+            int size,
+            out long fileOffset)
+        {
+            fileOffset = 0;
+            if ((uint)sectionIndex >= (uint)_sections.Count ||
+                sectionOffset < 0 ||
+                size < 0)
+            {
+                return false;
+            }
+
+            CoffSectionHeader header = _sections[sectionIndex].Header;
+            if (header.PointerToRawData == 0 ||
+                sectionOffset > header.SizeOfRawData ||
+                size > header.SizeOfRawData - sectionOffset)
+            {
+                return false;
+            }
+
+            fileOffset = checked(header.PointerToRawData + sectionOffset);
+            return true;
+        }
+
         protected struct CoffHeader
         {
             public Machine Machine { get; set; }

src/coreclr/tools/Common/Compiler/ObjectWriter/ObjectWriter.cs

@@ -32,6 +32,8 @@ private protected sealed record ChecksumsToCalculate(int SectionIndex, long Offs
         private protected readonly NodeFactory _nodeFactory;
         private protected readonly ObjectWritingOptions _options;
         private protected readonly OutputInfoBuilder _outputInfoBuilder;
+        private readonly Action<object, int, long, object, bool> _recordIncrementalNode;
+        private readonly Action<Func<int, long, int, long?>> _completeIncrementalLayout;
         private readonly bool _isSingleFileCompilation;
         protected readonly Utf8StringBuilder _utf8StringBuilder = new();
 
@@ -48,11 +50,18 @@ private protected sealed record ChecksumsToCalculate(int SectionIndex, long Offs
         // Symbol table
         private readonly Dictionary<Utf8String, SymbolDefinition> _definedSymbols = new();
 
-        private protected ObjectWriter(NodeFactory factory, ObjectWritingOptions options, OutputInfoBuilder outputInfoBuilder = null)
+        private protected ObjectWriter(
+            NodeFactory factory,
+            ObjectWritingOptions options,
+            OutputInfoBuilder outputInfoBuilder = null,
+            Action<object, int, long, object, bool> recordIncrementalNode = null,
+            Action<Func<int, long, int, long?>> completeIncrementalLayout = null)
         {
             _nodeFactory = factory;
             _options = options;
             _outputInfoBuilder = outputInfoBuilder;
+            _recordIncrementalNode = recordIncrementalNode;
+            _completeIncrementalLayout = completeIncrementalLayout;
             _isSingleFileCompilation = _nodeFactory.CompilationModuleGroup.IsSingleFileCompilation;
 
             // Padding byte for code sections (NOP for x86/x64)
@@ -81,6 +90,16 @@ private protected ObjectWriter(NodeFactory factory, ObjectWritingOptions options
         /// </remarks>
         private protected virtual ObjectNodeSection GetEmitSection(ObjectNodeSection section) => section;
 
+        private protected virtual bool TryGetObjectFileRange(
+            int sectionIndex,
+            long sectionOffset,
+            int size,
+            out long fileOffset)
+        {
+            fileOffset = 0;
+            return false;
+        }
+
         private protected SectionWriter GetOrCreateSection(ObjectNodeSection section)
             => GetOrCreateSection(section, default, default);
 
@@ -399,7 +418,8 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
                 }
 
                 ObjectNodeSection section = node.GetSection(_nodeFactory);
-                SectionWriter sectionWriter = ShouldShareSymbol(node, section) ?
+                bool isComdat = ShouldShareSymbol(node, section);
+                SectionWriter sectionWriter = isComdat ?
                     GetOrCreateSection(section, currentSymbolName, currentSymbolName) :
                     GetOrCreateSection(section);
 
@@ -408,6 +428,13 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
                     sectionWriter.EmitAlignment(nodeContents.Alignment);
                 }
 
+                _recordIncrementalNode?.Invoke(
+                    node,
+                    sectionWriter.SectionIndex,
+                    sectionWriter.Position,
+                    nodeContents,
+                    isComdat);
+
                 bool isMethod = node is IPCodeSymbolNode;
                 long thumbBit = _nodeFactory.Target.Architecture == TargetArchitecture.ARM && isMethod ? 1 : 0;
 
@@ -615,6 +642,12 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
                     _outputInfoBuilder.AddSection(outputSection);
                 }
             }
+
+            _completeIncrementalLayout?.Invoke(
+                (int sectionIndex, long sectionOffset, int size) =>
+                    TryGetObjectFileRange(sectionIndex, sectionOffset, size, out long fileOffset) ?
+                        fileOffset :
+                        null);
         }
 
         private protected virtual void RecordMethodDeclaration(INodeWithTypeSignature node)

src/coreclr/tools/aot/ILCompiler.Compiler.Tests/ILCompiler.Compiler.Tests.csproj

@@ -42,6 +42,7 @@
   <ItemGroup>
     <Compile Include="DependencyGraphTests.cs" />
     <Compile Include="DevirtualizationTests.cs" />
+    <Compile Include="IncrementalCompilationTests.cs" />
     <Compile Include="SwiftLoweringTests.cs" />
   </ItemGroup>
 </Project>