[llvm] [InstCombine] Fix the correctness of missing check reassoc attribute (PR #71277)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> This is hard to fix with a unified approach, and need continuous improvement, such as [PR86428](https://github.com/llvm/llvm-project/pull/86428), so close it now

I don't follow why this is being closed. What do you mean unified approach? 

https://github.com/llvm/llvm-project/pull/71277