JIT: Inliner direct substitution of return buffers can reorder side effects

[jakobbotsch]

The following program throws DivideByZeroException when optimizing and NullReferenceException otherwise. The correct exception is DivideByZeroException.

using System;
using System.Runtime.CompilerServices;

public unsafe class Program
{
    public static void Main()
    {
        Foo(null, 0);
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static void Foo(C c, int x)
    {
        c.G = Test(1 / x);
    }

    public static Guid Test(int x)
    {
        return new Guid(x, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
    }

    class C
    {
        public Guid G;
    }
}

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[SingleAccretion]

Also linking #77650.

[jakobbotsch]

Ah, thanks! I'm going to close #77650 as the duplicate here since I already added a test pointing to this issue in #112010.

[jakobbotsch]

Actually given that there is already discussion in that issue I will just rename the test.

Duplicate of #77650

[jakobbotsch]

Maybe not :-) Looks like these are different issues. Probably #77650 and #72323 are actually the same issue

[jakobbotsch]

I will close this as a duplicate of #77650. It's hard to come up with a test case that fails because of the inliner substitution.