[llvm] [SDag] Fold saddo[_carry] with bitwise-not argument to ssubo[_carry] (PR #66571)

[Nikita Popov via llvm-commits]

nikic wrote:

I think this is just a proof artifact. In terms of actual SDAG nodes, we aren't increasing use counts, so freeze should not be necessary.

https://github.com/llvm/llvm-project/pull/66571