[llvm] [InstCombine] Fold -X / -Y -> X / Y (PR #88422)

[Nikita Popov via llvm-commits]

nikic wrote:

> Alive Proofs:
> 
> https://alive2.llvm.org/ce/z/zLMokH https://alive2.llvm.org/ce/z/xviNg3 https://alive2.llvm.org/ce/z/4rdGvf https://alive2.llvm.org/ce/z/LDqsa_

Can you please clean up the proofs? The second link looks completely unrelated, and the other ones look related but non-obvious -- I would expect something simple like sub on just the divisor plus either an assume on the dividend or divisor.

https://github.com/llvm/llvm-project/pull/88422