Implement support for copy constructors when marshalling in IJW (#22805)

Fixes #22219.

I decided to try simplifying the code when bringing this feature over from .NET Framework. The .NETFX x86 implementation of this marshaler adds a lot of extra code-paths, and intercepts the calling stub to enable it to exactly replicate the behavior of what would be the native code by copy-constructing an object in-place where it goes on the stack for the native call.

Instead of adding all of that extra goo, I decided to keep the implementation much more similar to the non-x86 implementation from .NETFX. Instead of intercepting the call and adding bookkeeping helper stubs, the marshaler just copies to a local in the IL stub, just like non-x86. When calling the native function, it just loads the local onto the IL stack and calls the native function as a normal function. There is a difference there, but I cannot think of a way that the difference is observable to the user.

The non-x86 implementation is identical to the .NETFX implementation.

1 files changed, 32 insertions, 0 deletions

diff --git a/src/vm/ilmarshalers.h b/src/vm/ilmarshalers.h
index 99a3d8f8d6..c892ae66a9 100644
--- a/src/vm/ilmarshalers.h
+++ b/src/vm/ilmarshalers.h
@@ -2725,8 +2725,40 @@ protected:
     virtual void EmitConvertContentsNativeToCLR(ILCodeStream* pslILEmit);
 };
 
+class ILBlittableValueClassWithCopyCtorMarshaler : public ILMarshaler
+{
+public:
+    enum
+    {
+        c_fInOnly               = TRUE,
+        c_nativeSize            = VARIABLESIZE,
+        c_CLRSize               = sizeof(OBJECTREF),
+    };
 
+    LocalDesc GetManagedType()
+    {
+        LIMITED_METHOD_CONTRACT;
+        return LocalDesc();
+    }
 
+    LocalDesc GetNativeType()
+    {
+        LIMITED_METHOD_CONTRACT;
+        return LocalDesc();
+    }
+
+    static MarshalerOverrideStatus ArgumentOverride(NDirectStubLinker* psl,
+                                            BOOL               byref,
+                                            BOOL               fin,
+                                            BOOL               fout,
+                                            BOOL               fManagedToNative,
+                                            OverrideProcArgs*  pargs,
+                                            UINT*              pResID,
+                                            UINT               argidx,
+                                            UINT               nativeStackOffset);
+
+
+};
 
 class ILArgIteratorMarshaler : public ILMarshaler
 {