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

[Hari Limaye via llvm-commits]

hazzlim wrote:

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

I was suprised too, but it does seem to be (llvm::PatternMatch is used, but not llvm::SDPatternMatch).

> Do we need the new combine / node, or could this be done with a tablegen pattern directly?
I was thinking that this couldn't be done via tablegen, because in order to transform `add(x, abs(y)) -> saba(x, y, 0)` we need to create a new operand (the zeros vector), which I wasn't sure is possible to do via a tablegen pattern. But maybe I'm wrong there?




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