Implement TypedReference in CoreRT (#3000)

This is basically three things:

1. `ByReference<T>` support
2. General support infra in the type system for Byref-like types (to be
reused for e.g. `Span<T>`).
3. TypedReference

Fixes #367.

3 files changed, 80 insertions, 0 deletions

diff --git a/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/InstanceFieldLayout.cs b/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/InstanceFieldLayout.cs
index 827f9f478..912d7e778 100644
--- a/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/InstanceFieldLayout.cs
+++ b/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/InstanceFieldLayout.cs
@@ -146,3 +146,31 @@ namespace Sequential
     }
 }
 
+namespace IsByRefLike
+{
+    public struct ByRefLikeStruct
+    {
+        ByReference<object> ByRef;
+    }
+
+    public struct ComposedStruct
+    {
+        ByRefLikeStruct ByRefLike;
+    }
+
+    public struct NotByRefLike
+    {
+        int X;
+    }
+
+    public class Invalid
+    {
+        ByReference<int> ByRef;
+    }
+
+    public class ComposedInvalid
+    {
+        ByRefLikeStruct ByRefLike;
+    }
+}
+
diff --git a/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/Platform.cs b/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/Platform.cs
index 7f2a8e258..b15af240e 100644
--- a/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/Platform.cs
+++ b/src/ILCompiler.TypeSystem/tests/CoreTestAssembly/Platform.cs
@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 #pragma warning disable 649
+#pragma warning disable 169
 
 namespace System
 {
@@ -65,6 +66,14 @@ namespace System
     public class Array<T> : Array, System.Collections.Generic.IList<T> { }
 
     public class Exception { }
+
+    public struct TypedReference
+    {
+        private readonly ByReference<byte> _value;
+        private readonly RuntimeTypeHandle _typeHandle;
+    }
+
+    public struct ByReference<T> { }
 }
 
 namespace System.Collections
diff --git a/src/ILCompiler.TypeSystem/tests/InstanceFieldLayoutTests.cs b/src/ILCompiler.TypeSystem/tests/InstanceFieldLayoutTests.cs
index 67d7f82fb..ef65ceb5d 100644
--- a/src/ILCompiler.TypeSystem/tests/InstanceFieldLayoutTests.cs
+++ b/src/ILCompiler.TypeSystem/tests/InstanceFieldLayoutTests.cs
@@ -299,5 +299,48 @@ namespace TypeSystemTests
             type = _testModule.GetType("ContainsGCPointers", "ClassHasArrayOfClassType");
             Assert.True(type.ContainsGCPointers);
         }
+
+        [Fact]
+        public void TestByRefLikeTypes()
+        {
+            {
+                DefType type = _context.GetWellKnownType(WellKnownType.TypedReference);
+                Assert.True(type.IsByRefLike);
+            }
+
+            {
+                DefType type = _context.GetWellKnownType(WellKnownType.ByReferenceOfT);
+                Assert.True(type.IsByRefLike);
+            }
+
+            {
+                DefType type = _testModule.GetType("IsByRefLike", "ByRefLikeStruct");
+                Assert.True(type.IsByRefLike);
+            }
+
+            {
+                DefType type = _testModule.GetType("IsByRefLike", "ComposedStruct");
+                Assert.True(type.IsByRefLike);
+            }
+
+            {
+                DefType type = _testModule.GetType("IsByRefLike", "NotByRefLike");
+                Assert.False(type.IsByRefLike);
+            }
+        }
+
+        [Fact]
+        public void TestInvalidByRefLikeTypes()
+        {
+            {
+                DefType type = _testModule.GetType("IsByRefLike", "Invalid");
+                Assert.Throws<TypeSystemException.TypeLoadException>(() => type.ComputeInstanceLayout(InstanceLayoutKind.TypeAndFields));
+            }
+
+            {
+                DefType type = _testModule.GetType("IsByRefLike", "ComposedInvalid");
+                Assert.Throws<TypeSystemException.TypeLoadException>(() => type.ComputeInstanceLayout(InstanceLayoutKind.TypeAndFields));
+            }
+        }
     }
 }