[clang] [clang] Better bitfield access units (PR #65742)

[Nathan Sidwell via cfe-commits]

urnathan wrote:

> Note that changing the memory accesses performed by clang (load or store) _is_ an ABI change at IR level because of UB.

Could you clarify why UB is a consideration here?


https://github.com/llvm/llvm-project/pull/65742