[NativeAOT] Missed devirtualization opportunities due to Unsafe.As #85906
Description
In the below program we miss a devirtualization opportunity in Method due to the Unsafe.As.
IFace has a single implementor but RyuJIT doesn't even ask for it.
using System;
using System.Runtime.CompilerServices;
interface IFace
{
void Frob();
}
class Program : IFace
{
public static IFace s_inst = new Program();
public object inst;
public Program() => inst = s_inst;
public void Frob() { }
[MethodImpl(MethodImplOptions.NoInlining)]
public void Method() => Unsafe.As<IFace>(inst).Frob();
static void Main()
{
new Program().Method();
}
}I noticed this in the pattern from here as I was looking why interface dispatch is so hot (2.7% of samples spent in RhpInterfaceDispatch1 alone) in BasicMinimalApis:
Cc @EgorBo