[llvm] [GISel][AArch64][AMDGPU][RISCV] Canonicalize (sub X, C) -> (add X, -C) (PR #114309)

[Madhur Amilkanthwar via llvm-commits]

madhur13490 wrote:

Hi @topperc 
We have CI internally which tracks number of fallbacks in SPEC 2017 benchmark and we see a massive uptick in the number of fallbacks in `gcc_r` benchmark between 4th Nov and 5th Nov. We compile SPEC 2017 for AArch64 with and without SVE. In NOSVE case, the number of fallbacks went from 8 to 28. 

Unfortunately, our CI doesn't have the capability to bisect to a change but I took a quick look on `git log` and I see this is the only relevant patch which could have caused the uptick. 

Is this expected? If you have access to SPEC, can you please try compiling before and after your patch by passing "+nosve"?

https://github.com/llvm/llvm-project/pull/114309