[llvm] [polly] [SimpleLoopUnswitch] Don't use BlockFrequencyInfo to skip cold loops (PR #159522)

[Luke Lau via llvm-commits]

lukel97 wrote:

> Isn't this a larger problem though - downstream function passes such as BB layout will also be affected by incorrect BFI. I'm unclear why disabling use of BFI in this particular pass is the right approach to this issue.

Incorrect BFI leaking through to function passes was fixed in #157888 (wasn't exactly the easiest thing to debug 😅). AFAIK SimpleLoopUnswitch is now the last user of lossy BFI.

https://github.com/llvm/llvm-project/pull/159522