[PATCH] D73947: [ARM][MVE] LowOverheadLoops: DCE on the iteration count setup expression

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer created this revision.
SjoerdMeijer added reviewers: samparker, dmgreen.
Herald added subscribers: hiraditya, kristof.beyls.
Herald added a project: LLVM.

Once we have created a tail-predicated hardware-loop, and thus know the number of elements that are processed, we want to clean-up the iteration count expression of that loop. In D73682 <https://reviews.llvm.org/D73682>, we bailed the analysis on conditionally executed instructions. This adds support for IT-blocks, so that we can handle these cases again. The restriction is that we only support IT blocks containing 1 statement, but that seems to cover most cases and forms of the iteration count expression.


https://reviews.llvm.org/D73947

Files:
  llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp
  llvm/test/CodeGen/Thumb2/LowOverheadLoops/dont-ignore-vctp.mir
  llvm/test/CodeGen/Thumb2/LowOverheadLoops/it-block-itercount.mir

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