Related to #1805.

If you have code such as:

Unsafe.SkipInit(out Vector128<short> value);
if (Sse.IsSupported)
{
    value = Vector128.Create(value);
}

The linker will trim out the initialization but not the Unsafe.SkipInit(out Vector128<short> value); as it doesn't recognize the call today.

If you try to refactor this to something such as:

Vector128<short> value;

if (Sse.IsSupported)
{
    value = Vector128.Create(value);
}
else
{
    value = default;
}

The linker trims it down to just: Vector128<short> value = default; but does not remove the local and therefore does not remove the now unused Vector128<T> type even though the only usage of value is in an initobj valuetype [System.Private.CoreLib]System.Runtime.Intrinsics.Vector1281` instruction.

The linker should likely recognize this scenario and trim the unused local.