[RyuJIT Wasm] WasmObjectWriter Webcil Envelope Support

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

@@ -22,7 +22,15 @@ public AssemblyStubNode()
         /// </summary>
         protected virtual bool IsVisibleFromManagedCode => true;
 
-        public override ObjectNodeSection GetSection(NodeFactory factory) => ObjectNodeSection.TextSection;
+        public override ObjectNodeSection GetSection(NodeFactory factory)
+        {
+            if (factory.Target.IsWasm)
+            {
+                return ObjectNodeSection.ReadOnlyDataSection;
+            }
+
+            return ObjectNodeSection.TextSection;
+        }
 
         public override bool StaticDependenciesAreComputed => true;
 

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

@@ -94,7 +94,7 @@ public enum RelocType
     public struct Relocation
     {
         // NOTE: Keep in sync with emitwasm.cpp
-        private const int WASM_PADDED_RELOC_SIZE_32 = 5;
+        public const int WASM_PADDED_RELOC_SIZE_32 = 5;
 
         public readonly RelocType RelocType;
         public readonly int Offset;

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

@@ -9,14 +9,14 @@
 using System.Linq;
 using System.Xml.Linq;
 using ILCompiler.DependencyAnalysis;
+using ILCompiler.DependencyAnalysis.Wasm;
 using ILCompiler.DependencyAnalysisFramework;
 using Internal.Text;
 using Internal.TypeSystem;
 
 using static ILCompiler.DependencyAnalysis.ObjectNode;
 using static ILCompiler.DependencyAnalysis.RelocType;
 using ObjectData = ILCompiler.DependencyAnalysis.ObjectNode.ObjectData;
-
 using CodeDataLayout = CodeDataLayoutMode.CodeDataLayout;
 
 namespace ILCompiler.ObjectWriter
@@ -187,7 +187,7 @@ or IMAGE_REL_BASED_THUMB_BRANCH24 or IMAGE_REL_BASED_THUMB_MOV32_PCREL &&
                 definedSymbol.SectionIndex == sectionIndex)
             {
                 // Resolve the relocation to already defined symbol and write it into data
-                fixed (byte *pData = data)
+                fixed (byte* pData = data)
                 {
                     // RyuJIT generates the Thumb bit in the addend and we also get it from
                     // the symbol value. The AAELF ABI specification defines the R_ARM_THM_JUMP24
@@ -332,13 +332,13 @@ private SortedSet<Utf8String> GetUndefinedSymbols()
         {
             SortedSet<Utf8String> undefinedSymbolSet = new SortedSet<Utf8String>();
             foreach (var relocationList in _sectionIndexToRelocations)
-            foreach (var symbolicRelocation in relocationList)
-            {
-                if (!_definedSymbols.ContainsKey(symbolicRelocation.SymbolName))
+                foreach (var symbolicRelocation in relocationList)
                 {
-                    undefinedSymbolSet.Add(symbolicRelocation.SymbolName);
+                    if (!_definedSymbols.ContainsKey(symbolicRelocation.SymbolName))
+                    {
+                        undefinedSymbolSet.Add(symbolicRelocation.SymbolName);
+                    }
                 }
-            }
             return undefinedSymbolSet;
         }
 
@@ -379,11 +379,10 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
             List<ChecksumsToCalculate> checksumRelocations = [];
             foreach (DependencyNode depNode in nodes)
             {
-
                 // TODO-WASM: emit symbol ranges properly when code and data are separated
                 // Right now we still need to determine placements for some traditionally text-placed nodes,
                 // such as DebugDirectoryEntryNode and AssemblyStubNode
-                if (depNode is ISymbolRangeNode symbolRange && LayoutMode == CodeDataLayout.Unified)
+                if (depNode is ISymbolRangeNode symbolRange)
                 {
                     symbolRangeNodes.Add(symbolRange);
                     continue;
@@ -436,20 +435,11 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
                 // R2R records the thumb bit in the addend when needed, so we don't have to do it here.
                 long thumbBit = 0;
 #endif
-
                 if (node is WasmTypeNode signature)
                 {
                     RecordMethodSignature(signature);
                 }
 
-
-                if (node is AssemblyStubNode && _nodeFactory.Target.IsWasm)
-                {
-                    // TODO-Wasm: Handle AssemblyStubNode.
-                    // It is the other primary IWasmCodeNode implementation we should see for R2R. (NativeAOT will have others)
-                    continue;
-                }
-
                 if (node is INodeWithTypeSignature codeNode && _nodeFactory.Target.IsWasm)
                 {
                     Debug.Assert(codeNode.Signature != null, $"Wasm code node {codeNode.GetType()} has null signature");
@@ -573,7 +563,8 @@ public virtual void EmitObject(Stream outputFileStream, IReadOnlyCollection<Depe
                 if (startNode is null)
                 {
                     // Emit empty symbol ranges as an empty symbol at the end of the text section.
-                    var writer = GetOrCreateSection(ObjectNodeSection.TextSection);
+                    var writer = _nodeFactory.Target.IsWasm ? GetOrCreateSection(ObjectNodeSection.ReadOnlyDataSection) :
+                        GetOrCreateSection(ObjectNodeSection.TextSection);
                     writer.EmitSymbolDefinition(GetMangledName(range));
                     continue;
                 }

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

@@ -3,19 +3,56 @@
 
 using System;
 using System.Diagnostics;
+using ILCompiler.DependencyAnalysis.Wasm;
 
 // This namespace implements encodings for certain Wasm expressions (instructions)
 // which are used in the object writer.
 // For now, these instructions are only used for constructing constant expressions
 // to calculate placements for data segments based on imported globals.
 namespace ILCompiler.ObjectWriter.WasmInstructions
 {
+    // Represents a Wasm function body in the code section.
+    // Encodes as: ULEB128(0) (zero local declarations) + instructions + 0x0B end
+    public class WasmFunctionBody : IWasmEncodable
+    {
+        public readonly WasmFuncType Signature;
+        private readonly WasmInstructionGroup _body;
+
+        public WasmFunctionBody(WasmFuncType signature, WasmExpr[] instructions)
+        {
+            Signature = signature;
+            _body = new WasmInstructionGroup(instructions);
+        }
+
+        private int BodyContentSize()
+        {
+            // 1 byte for ULEB128(0) local declarations + instruction group (instructions + end opcode)
+            return 1 + _body.EncodeSize();
+        }
+
+        public int EncodeSize()
+        {
+            return BodyContentSize();
+        }
+
+        public int Encode(Span<byte> buffer)
+        {
+            int pos = 0;
+            buffer[pos++] = 0x00; // zero local declarations
+            pos += _body.Encode(buffer.Slice(pos));
+
+            return pos;
+        }
+    }
     public enum WasmExprKind
     {
+        LocalGet = 0x20,
+        GlobalGet = 0x23,
         I32Const = 0x41,
         I64Const = 0x42,
-        GlobalGet = 0x23,
         I32Add = 0x6A,
+        // Sentinel value — not directly cast to a byte; WasmMemoryInitExpr overrides Encode().
+        MemoryInit = 0xFC08,
     }
 
     public static class WasmExprKindExtensions
@@ -30,15 +67,25 @@ public static bool IsBinaryExpr(this WasmExprKind kind)
             return kind == WasmExprKind.I32Add;
         }
 
+        public static bool IsLocalVarExpr(this WasmExprKind kind)
+        {
+            return kind == WasmExprKind.LocalGet;
+        }
+
         public static bool IsGlobalVarExpr(this WasmExprKind kind)
         {
             return kind == WasmExprKind.GlobalGet;
         }
+
+        public static bool IsMemoryExpr(this WasmExprKind kind)
+        {
+            return kind == WasmExprKind.MemoryInit;
+        }
     }
 
     // Represents a group of Wasm instructions (expressions) which 
     // form a complete expression ending with the 'end' opcode.
-    class WasmInstructionGroup : IWasmEncodable
+    public class WasmInstructionGroup : IWasmEncodable
     {
         readonly WasmExpr[] _wasmExprs;
         public WasmInstructionGroup(WasmExpr[] wasmExprs)
@@ -116,6 +163,31 @@ public override int Encode(Span<byte> buffer)
         }
     }
 
+    // Represents a local variable expression (e.g., (local.get <index>))
+    class WasmLocalVarExpr : WasmExpr
+    {
+        public readonly int LocalIndex;
+        public WasmLocalVarExpr(WasmExprKind kind, int localIndex) : base(kind)
+        {
+            Debug.Assert(localIndex >= 0);
+            Debug.Assert(kind.IsLocalVarExpr());
+            LocalIndex = localIndex;
+        }
+
+        public override int Encode(Span<byte> buffer)
+        {
+            int pos = base.Encode(buffer);
+            pos += DwarfHelper.WriteULEB128(buffer.Slice(pos), (uint)LocalIndex);
+
+            return pos;
+        }
+
+        public override int EncodeSize()
+        {
+            return base.EncodeSize() + (int)DwarfHelper.SizeOfULEB128((uint)LocalIndex);
+        }
+    }
+
     // Represents a global variable expression (e.g., (global.get <index))
     class WasmGlobalVarExpr : WasmExpr
     {
@@ -151,9 +223,55 @@ public WasmBinaryExpr(WasmExprKind kind) : base(kind)
         // base class defaults are sufficient as the base class encodes just the opcode
     }
 
+    // Represents a memory.init expression.
+    // Binary encoding: 0xFC prefix + u32(8) sub-opcode + u32(dataSegmentIndex) + u32(memoryIndex)
+    class WasmMemoryInitExpr : WasmExpr
+    {
+        private const byte ExtendedPrefix = 0xFC;
+        private const uint MemoryInitSubOpcode = 8;
+
+        public readonly int DataSegmentIndex;
+        public readonly int MemoryIndex;
+
+        public WasmMemoryInitExpr(int dataSegmentIndex, int memoryIndex = 0) : base(WasmExprKind.MemoryInit)
+        {
+            Debug.Assert(dataSegmentIndex >= 0);
+            Debug.Assert(memoryIndex >= 0);
+            DataSegmentIndex = dataSegmentIndex;
+            MemoryIndex = memoryIndex;
+        }
+
+        public override int Encode(Span<byte> buffer)
+        {
+            int pos = 0;
+            buffer[pos++] = ExtendedPrefix;
+            pos += DwarfHelper.WriteULEB128(buffer.Slice(pos), MemoryInitSubOpcode);
+            pos += DwarfHelper.WriteULEB128(buffer.Slice(pos), (uint)DataSegmentIndex);
+            pos += DwarfHelper.WriteULEB128(buffer.Slice(pos), (uint)MemoryIndex);
+
+            return pos;
+        }
+
+        public override int EncodeSize()
+        {
+            return 1
+                + (int)DwarfHelper.SizeOfULEB128(MemoryInitSubOpcode)
+                + (int)DwarfHelper.SizeOfULEB128((uint)DataSegmentIndex)
+                + (int)DwarfHelper.SizeOfULEB128((uint)MemoryIndex);
+        }
+    }
+
     // ************************************************
     // Simple DSL wrapper for creating Wasm expressions
     // ************************************************
+    static class Local
+    {
+        public static WasmExpr Get(int index)
+        {
+            return new WasmLocalVarExpr(WasmExprKind.LocalGet, index);
+        }
+    }
+
     static class Global
     {
         public static WasmExpr Get(int index)
@@ -171,4 +289,12 @@ public static WasmExpr Const(long value)
 
         public static WasmExpr Add => new WasmBinaryExpr(WasmExprKind.I32Add);
     }
+
+    static class Memory
+    {
+        public static WasmExpr Init(int dataSegmentIndex, int memoryIndex = 0)
+        {
+            return new WasmMemoryInitExpr(dataSegmentIndex, memoryIndex);
+        }
+    }
 }

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

@@ -2,11 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Diagnostics;
-using System.Linq;
-using System.Collections.Generic;
 
 using ILCompiler.DependencyAnalysis.Wasm;
+using ILCompiler.ObjectWriter.WasmInstructions;
 
 namespace ILCompiler.ObjectWriter
 {
@@ -154,4 +152,31 @@ public WasmImport(string module, string name, WasmImportType import, int? index
         public int Encode(Span<byte> buffer) => Import.Encode(buffer);
         public int EncodeSize() => Import.EncodeSize();
     }
+
+    public class WasmGlobal : IWasmEncodable
+    {
+        public readonly int Index;
+        public readonly string Name;
+        private readonly WasmValueType _valueType;
+        private readonly WasmMutabilityType _mutability;
+        private readonly WasmInstructionGroup _initExpr;
+
+        public WasmGlobal(int index, string name, WasmValueType valueType, WasmMutabilityType mutability, WasmInstructionGroup initExpr)
+        {
+            Index = index;
+            Name = name;
+            _valueType = valueType;
+            _mutability = mutability;
+            _initExpr = initExpr;
+        }
+
+        public int Encode(Span<byte> buffer)
+        {
+            buffer[0] = (byte)_valueType;
+            buffer[1] = (byte)_mutability;
+            return 2 + _initExpr.Encode(buffer.Slice(2));
+        }
+
+        public int EncodeSize() => 2 + _initExpr.EncodeSize();
+    }
 }