[clang] [llvm] [AMDGPU] Emit a waitcnt instruction after each memory instruction (PR #79236)

[Pierre van Houtryve via cfe-commits]

https://github.com/Pierre-vh commented:

I also agree with Jay, can't this go in InsertWaitCnt? Why does it have to go in SIMemoryLegalizer instead?

If it has to stay here, fine, but is it possible to merge some code with SIInsertWaitCnt in a common helper somewhere?

https://github.com/llvm/llvm-project/pull/79236