[llvm] [MachineSink] Check predecessor/successor relationship between two basic blocks involved in critical edge splitting (PR #98540)

[via llvm-commits]

yozhu wrote:

> > > Also, please add tests.
> > 
> > 
> > See [#98477 (comment)](https://github.com/llvm/llvm-project/issues/98477#issuecomment-2223068608).
> 
> Also [#97618 (comment)](https://github.com/llvm/llvm-project/pull/97618#issuecomment-2223340466) ;)

Thanks @dtcxzyw and @alexfh :)

https://github.com/llvm/llvm-project/pull/98540