[llvm] [DependenceAnalysis] Extending SIV to handle fusable loops (PR #128782)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

So, at the very least, I think it would be better to insert an assertion like `assert(Dep->getFusableLevel() == 0)` in every place where DA is used to prevent any accidents in the future.

https://github.com/llvm/llvm-project/pull/128782