[PATCH] D123865: [LoopPeel] Allow partial unrolling for profile-based peeling

[Igor Kudrin via Phabricator via llvm-commits]

ikudrin created this revision.
ikudrin added reviewers: skatkov, anemet, davidxl, mkuper, reames, ebrevnov, Ayal.
ikudrin added a project: LLVM.
Herald added subscribers: wenlei, zzheng, hiraditya.
Herald added a project: All.
ikudrin requested review of this revision.

As for now, the loop is unrolled if the profile-based trip count is not greater than a limit, which is 7 by default; i.e. no iterations are peeled off for a loop that has the estimation of 8. The patch is based on the idea that a bit longer loop can still benefit from extracting several first iterations. The longer the loop, the lower the effect of the extraction, so if the trip count is estimated to be more than twice the threshold, the optimization is not applied.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D123865

Files:
  llvm/lib/Transforms/Utils/LoopPeel.cpp
  llvm/test/Transforms/LoopUnroll/peel-loop-conditions-pgo-2.ll
  llvm/test/Transforms/LoopUnroll/peel-loop-conditions-pgo-3.ll

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