[llvm] [LoopInterchange] Ignore the cost-model, force interchange if legal (PR #148858)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

Sorry, I spaced out and forgot to mention what I’m actually concerned about: the behavior when both `--loop-interchange-profitabilities=...` and `--loop-interchange-force=1` are specified. Which one should take precedence in this case? It depends on the implementation. Of course, I think it’s fine to explicitly document the priority between these options somewhere, but instead of providing two separate options, I’d prefer to have a single option to avoid this issue. 

Being able to specify something like `--loop-interchange-profitabilities=cache,force` is just a small bonus, and doesn’t seem very important to me.

https://github.com/llvm/llvm-project/pull/148858