[llvm] [AMDGPU] Waterfall loop codegen improvement in SIInstrInfo (PR #192415)

[Jay Foad via llvm-commits]

jayfoad wrote:

> I have just pushed a tentative fix: add `_term` versions of `V_CMPX_EQ_*` Machine IR instructions and use them in the current PR.

Maybe we don't even need non-terminator versions of V_CMPX instructions, since they always write to EXEC?

https://github.com/llvm/llvm-project/pull/192415