DXIL requires GEP chains to point to a global variable that's a flat
array of primitive types. If we're converting deref chains to GEP
chains, we're effectively in a logical address space, which means
we can do things like change sizes of variables, since we know
they won't alias with anything else. If they could alias, we'd be
lowering them to an explicit I/O op instead. That means we can
start disabling some of the low-bit-size lowering.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23173>
Jesse Natalie
572e02a3b7