[PATCH] D98413: [ARM] Revert WhileLoopStartLR to DoLoopStart

[Dave Green via Phabricator via llvm-commits]

dmgreen created this revision.
dmgreen added reviewers: SjoerdMeijer, samtebbs, samparker, efriedma, ostannard, simon_tatham.
Herald added subscribers: danielkiss, hiraditya, kristof.beyls.
dmgreen requested review of this revision.
Herald added a project: LLVM.

If a WhileLoopStartLR is reverted due to calls in the preheader, we may still be able to instead create a DoLoopStart, preserving the low overhead loop. This adds code for that, only reverting the WhileLoopStartR to a Br/Cmp, leaving the rest of the low overhead loop in place.


https://reviews.llvm.org/D98413

Files:
  llvm/lib/Target/ARM/MVETPAndVPTOptimisationsPass.cpp
  llvm/lib/Target/ARM/MVETailPredUtils.h
  llvm/test/CodeGen/Thumb2/LowOverheadLoops/while-loops.ll

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