[llvm] [AMDGPU] Add SSA-form memory clause pass (AMDGPUFormSSAMemoryClauses) (PR #209656)

[Jun Wang via llvm-commits]

jwanggit86 wrote:

> This PR duplicates roughly 430 lines from SIFormMemoryClauses.cpp verbatim. Since the old and new passes are expected to coexist for quite some time, have you considered sharing the core implementation and making each pass just a thin wrapper around the SSA-specific differences, such as clearing isSSA and processing PHIs? That would save us from having to keep two copies in sync.

The common implementation is now in a separate file. 

https://github.com/llvm/llvm-project/pull/209656