[llvm] [InstCombine] Pull unary shuffles through fneg/fabs (PR #144933)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

> Once this goes in, we should remember to make the analogous change for the shuffle-like intrinsics - i.e. reverse and vp.reverse.

If anyone has any ideas on how we could implement a PatternMatch::m_ShuffleLike matcher (and corresponding Builder.CreateShuffleLike) to handle shuffles and some/all of the shuffle-like intrinsics I'd love to hear them!

https://github.com/llvm/llvm-project/pull/144933