[PATCH] D138265: [PowerPC] move ctrloop pass before tail duplication

[ChenZheng via Phabricator via llvm-commits]

shchenz created this revision.
shchenz added reviewers: lkail, PowerPC.
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Tail duplication may modify the loop to a "non-canonical" form that CTR Loop pass can not
recognize. We fixed one issue in D135846 <https://reviews.llvm.org/D135846>. And we found in some other case, the loop is 
changed to irreducible form. It is hard to fix this case in CTR loop pass, instead we reorder the
CTR loop pass before tail duplication pass and just after final-isel pass to avoid any unexpected
change to the loop form.

This patch:
1: reverted the change in d135846
2: move the ctrloop pass before tail duplication


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138265

Files:
  llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
  llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
  llvm/test/CodeGen/PowerPC/O3-pipeline.ll
  llvm/test/CodeGen/PowerPC/ctrloop-header-multiple-preds.mir

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