[llvm] [AMDGPU] Handle lowering addrspace casts from LDS to FLAT address in amdgpu-sw-lower-lds. (PR #121214)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Since, infer-address-space pass is not run prior to this pass at -O0, load/stores that were supposed to be on lds ptrs are now on flat ptrs with extra addrspacecasts from lds to flat ptr being added.
> 

Loads and stores aren't "supposed" to be" in any particular address space. The pass needs to function independently of context. The description and justification should not be based around -O0 or whatever infer address space happens to do.

It's not clear to me from the description what the symptoms of not handling this cast before are. Was it a fatal error? 


https://github.com/llvm/llvm-project/pull/121214