[PATCH] D86303: [ARM][MVE] Tail-predication: remove the BTC + 1 overflow checks

[Sjoerd Meijer via Phabricator via llvm-commits]

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

Adapt tail-predication to the new semantics of get.active.lane.mask as proposed in D86147 <https://reviews.llvm.org/D86147>. This means that:

- we can remove  BTC + 1 overflow checks because now the loop tripcount is passed in to the intrinsic,
- we can immediately use that value to setup a counter for the number of elements processed by the loop and don't need to materialize BTC + 1.

I have only updated 1 test-case, but all the others need updating to. which I still need to do. But I am already uploading this as the last patch of a series of patches to adapt to the new semantics; I have run test and numbers with all of them, and everything looks okay and there has been no surprises, which is what I wanted to check.


https://reviews.llvm.org/D86303

Files:
  llvm/lib/Target/ARM/MVETailPredication.cpp
  llvm/test/CodeGen/Thumb2/LowOverheadLoops/basic-tail-pred.ll

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