Returns uint64_t to simplify callers. The goal is eventually replace
getValueType with this query, which should return the known minimum
reference-able size, as provided (instead of a Type) during create.
Additionally the common isSized query would be replaced with an
isExactKnownSize query to test if that size is an exact definition.
This PR introduces `amdgpu-lower-exec-sync` pass which specifically
lowers named-barrier LDS globals introduced by #114550 .
Changes include:
- Moving the logic of lowering named-barrier LDS globals from
`amdgpu-lower-module-lds` pass to this new pass.
- This PR adds the pass to pipeline, remove the existing lowering logic for
named-barrier LDS in `amdgpu-lower-module-lds`
See #161827 for discussion on this topic.