[PATCH] D54223: [SimpleLoopUnswitch] adding cost multiplier to cap exponential unswitch with

[Fedor Sergeev via Phabricator via llvm-commits]

fedor.sergeev planned changes to this revision.
fedor.sergeev added a comment.

Discovered a tricky testcase with 16-way switch and nested exiting branches which manages to skip the multiplier introduced here and still lead to exponential explosion.
Definitely need to check if exiting branch dominates the latch before skipping its multiplier calculation.
Also the testcase shows that we really need to go further calculating costs per candidate and using that in calculation of exponential-explosion threshold, just as Chandler asked to.

Will do an update to a multiplier skipping check here.
Other changes will go as a follow up (hopefully, soon  :-/ ).


Repository:
  rL LLVM

https://reviews.llvm.org/D54223