[PATCH] D43876: [LoopUnroll] Peel off iterations if it makes conditions true/false.

[Florian Hahn via Phabricator via llvm-commits]

fhahn updated this revision to Diff 136540.
fhahn added a comment.

Update to use SCEV. It now uses a rather simple approach: evaluate AddRec at the DesiredPeelCount and then try to add the recurrence step until the predicate is not known any longer. We could probably compute the number of iterations directly, but I could not find any existing function in SCEV that would handle all predicates. But we only loop for MaxPeelCount iterations at max, and MaxPeelCount should be low.


https://reviews.llvm.org/D43876

Files:
  include/llvm/Transforms/Utils/UnrollLoop.h
  lib/Transforms/Scalar/LoopUnrollPass.cpp
  lib/Transforms/Utils/LoopUnrollPeel.cpp
  test/Transforms/LoopUnroll/peel-loop-conditions.ll

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