JIT: (bug) comparing `GetType()` of two references drops the null check on a null reference

[EgorBo]

Repro

using System;
using System.Runtime.CompilerServices;

internal static class Program
{
    [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.AggressiveOptimization)]
    private static int Test(string a, string b)
    {
        if (a.GetType() != b.GetType())
            return 2;

        return 3;
    }

    private static void Main()
    {
        try
        {
            Console.WriteLine($"returned {Test(null, "text")}");
        }
        catch (NullReferenceException)
        {
            Console.WriteLine("NullReferenceException");
        }
    }
}

Expected

NullReferenceException

Actual

returned 3

a is null, so a.GetType() must throw, but the whole method body is optimized away to
return 3.

Platform

Windows x64, local Checked build of dotnet/runtime main (ef97eb5).

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