[llvm] [AArch64] Transform add(x, abs(y)) -> saba(x, y, 0) (PR #156615)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Nice, I'm surprised this is the first use of SDPatternMatch.

Do we need the new combine / node, or could this be done with a tablegen pattern directly?

https://github.com/llvm/llvm-project/pull/156615