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

[Teresa Johnson via llvm-commits]

teresajohnson wrote:

> Overall checking for hot/cold loops in principle makes more sense to me; i.e. no point in unswitching a loop that's never executed in a hot function.

Agree, this change isn't going to be equivalent. I'm a little unclear of the problem being solved by this PR. What is the main motivation? There's a list of benefits but I'm not sure how important they are.

> Not regressing SPEC is great, but still leaves a lot of room to regress other workloads. I don't really have any concrete suggestions at the moment; if we can't easily check for hotness of loops I guess this is fine for now and we can revisit if/when we discover regressions


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