llvm-project

4e5e65e5 - [VPlan] Only compute reg pressure if considered. NFCI (#156923)

[VPlan] Only compute reg pressure if considered. NFCI (#156923) In #149056 VF pruning was changed so that it only pruned VFs that stemmed from MaxBandwidth being enabled. However we always compute register pressure regardless of whether or not max bandwidth is permitted for any VFs (via `MaxPermissibleVFWithoutMaxBW`). This skips the computation if not needed and renames the method for clarity. The diff in reg-usage.ll is due to the scalable VPlan not actually having any maxbandwidth VFs, so I've changed it to check the fixed-length VF instead, which is affected by maxbandwidth.