From 3af8f77411689fb95816e3c5accd631186b4b635 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Rylek?= <trylek@microsoft.com>
Date: Thu, 19 Mar 2020 00:59:40 +0100
Subject: [PATCH] Add support for previously missing helper Check_FieldOffset
 (#33729)

This failure crashes Crossgen2 build of several framework assemblies
without the large version bubble. I discovered this during my work
on composite build against shared framework where we newly introduce
the notion of two separate large bubbles (app vs. framework).

Thanks

Tomas
---
 .../ReadyToRun/FieldFixupSignature.cs             |  5 +++++
 .../ReadyToRunSymbolNodeFactory.cs                | 15 +++++++++++++++
 .../JitInterface/CorInfoImpl.ReadyToRun.cs        |  5 ++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/FieldFixupSignature.cs b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/FieldFixupSignature.cs
index 32cae03ba4016..88abad8269ac0 100644
--- a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/FieldFixupSignature.cs
+++ b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/FieldFixupSignature.cs
@@ -40,6 +40,11 @@ public override ObjectData GetData(NodeFactory factory, bool relocsOnly = false)
                 EcmaModule targetModule = factory.SignatureContext.GetTargetModule(_fieldDesc);
                 SignatureContext innerContext = dataBuilder.EmitFixup(factory, _fixupKind, targetModule, factory.SignatureContext);
 
+                if (_fixupKind == ReadyToRunFixupKind.Check_FieldOffset)
+                {
+                    dataBuilder.EmitInt(_fieldDesc.Offset.AsInt);
+                }
+
                 dataBuilder.EmitFieldSignature(_fieldDesc, innerContext);
             }
 
diff --git a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs
index 735ada49e6191..30191aad4e973 100644
--- a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs
+++ b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs
@@ -80,6 +80,14 @@ private void CreateNodeCaches()
                 );
             });
 
+            _checkFieldOffsetCache = new NodeCache<FieldDesc, ISymbolNode>(key =>
+            {
+                return new PrecodeHelperImport(
+                    _codegenNodeFactory,
+                    new FieldFixupSignature(ReadyToRunFixupKind.Check_FieldOffset, key)
+                );
+            });
+
             _interfaceDispatchCells = new NodeCache<MethodAndCallSite, ISymbolNode>(cellKey =>
             {
                 return new DelayLoadHelperMethodImport(
@@ -376,6 +384,13 @@ public ISymbolNode FieldOffset(FieldDesc fieldDesc)
             return _fieldOffsetCache.GetOrAdd(fieldDesc);
         }
 
+        private NodeCache<FieldDesc, ISymbolNode> _checkFieldOffsetCache;
+
+        public ISymbolNode CheckFieldOffset(FieldDesc fieldDesc)
+        {
+            return _checkFieldOffsetCache.GetOrAdd(fieldDesc);
+        }
+
         private NodeCache<TypeDesc, ISymbolNode> _fieldBaseOffsetCache;
 
         public ISymbolNode FieldBaseOffset(TypeDesc typeDesc)
diff --git a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
index 62f8e3333a0c2..08c0b884e5c85 100644
--- a/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
+++ b/src/coreclr/src/tools/crossgen2/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
@@ -2126,7 +2126,10 @@ private void EncodeFieldBaseOffset(FieldDesc field, CORINFO_FIELD_INFO* pResult,
             {
                 if (pMT.IsValueType)
                 {
-                    throw new NotImplementedException("https://github.com/dotnet/runtime/issues/32630: ENCODE_CHECK_FIELD_OFFSET: root field check import");
+                    // ENCODE_CHECK_FIELD_OFFSET
+                    pResult->offset = 0;
+                    pResult->fieldAccessor = CORINFO_FIELD_ACCESSOR.CORINFO_FIELD_INSTANCE_WITH_BASE;
+                    pResult->fieldLookup = CreateConstLookupToSymbol(_compilation.SymbolNodeFactory.CheckFieldOffset(field));
                 }
                 else
                 {