From a19c46430f61cbefd7024dd9c2aace8e48121e7a Mon Sep 17 00:00:00 2001
From: User <User@DESKTOP-8CP4L96>
Date: Mon, 5 May 2025 04:28:11 +0300
Subject: [PATCH 1/2] Fix instance size emission in ILCompiler to handle
 indeterminate sizes

---
 .../Compiler/UserDefinedTypeDescriptor.cs                   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
index 26d008f8377fee..e39ec99b00ae3c 100644
--- a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
+++ b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
@@ -732,11 +732,11 @@ private uint GetClassTypeIndex(TypeDesc type, bool needsCompleteType)
                 statics[i] = staticsDescs[i];
             }
 
-            LayoutInt elementSize = defType.GetElementSize();
-            int elementSizeEmit = elementSize.IsIndeterminate ? 0xBAAD : elementSize.AsInt;
+            LayoutInt instanceSize = defType.InstanceByteCount;
+            int instanceSizeEmit = instanceSize.IsIndeterminate ? 0xBAAD : instanceSize.AsInt;
             ClassFieldsTypeDescriptor fieldsDescriptor = new ClassFieldsTypeDescriptor
             {
-                Size = (ulong)elementSizeEmit,
+                Size = (ulong)instanceSizeEmit,
                 FieldsCount = fieldsDescs.Count,
             };
 

From ec8c1cc77ad4b911a8d9831592be7c9c4926fe77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Strehovsk=C3=BD?=
 <MichalStrehovsky@users.noreply.github.com>
Date: Tue, 6 May 2025 13:37:17 -0700
Subject: [PATCH 2/2] Update
 src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs

---
 .../ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
index e39ec99b00ae3c..6decba09f41ca9 100644
--- a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
+++ b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UserDefinedTypeDescriptor.cs
@@ -732,7 +732,7 @@ private uint GetClassTypeIndex(TypeDesc type, bool needsCompleteType)
                 statics[i] = staticsDescs[i];
             }
 
-            LayoutInt instanceSize = defType.InstanceByteCount;
+            LayoutInt instanceSize = defType.IsValueType ? defType.InstanceFieldSize : defType.InstanceByteCount;
             int instanceSizeEmit = instanceSize.IsIndeterminate ? 0xBAAD : instanceSize.AsInt;
             ClassFieldsTypeDescriptor fieldsDescriptor = new ClassFieldsTypeDescriptor
             {