[llvm] [AArch64][SVE] Fold ADD+CNTB to INCB and DECB (PR #118280)

[Ricardo Jesus via llvm-commits]

rj-jesus wrote:

Hi @paulwalker-arm, I'm still keen to pursue it, but I haven't found a nice way to avoid the potential MOVs that INCB/DECB may introduce due to the tied source and destination registers. I tried to sketch an alternative implementation in `AArch64MIPeepholeOpt` that would fold ADDVL to INCB iff the source register `hasOneNonDBGUse`, but I wasn't convinced that approach was sound. Do you have any ideas?

I'll try to have a loop into this again next week.

https://github.com/llvm/llvm-project/pull/118280