[llvm] [SROA] Unfold gep of index select (PR #80983)

[Artem Belevich via llvm-commits]

Artem-B wrote:

We've got a fix race condition. :-) 

My WIP patch to address the same issue: https://github.com/llvm/llvm-project/commit/8ef25d66917035644395c122fe0930b3994cd353
It needs more tests and a knob to control how many select(const) indexes we may want to expand. 

Do we expect all/most GEPs to end up being untyped GEPs with a single index? Or will there still be a benefit to letting SROA expand gep(multiple select-of-const indexes) into individual GEPs? 


https://github.com/llvm/llvm-project/pull/80983