[clang] [llvm] [mlir] [NVPTX] Add support for Shared Cluster Memory address space. (PR #135444)

[Alex MacLean via llvm-commits]

https://github.com/AlexMaclean commented:

Getting close to ready, a couple more places to update:
- NVPTXTargetTransformInfo.cpp: evaluateIsSpace
- NVPTXUsage.rst: Address Space section, add intrinsics you're modifying, such as `mapa`, to the spec

https://github.com/llvm/llvm-project/pull/135444