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

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added inline comments.


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Comment at: llvm/lib/Target/ARM/MVETailPredication.cpp:399
   uint64_t MaxMinusVW = Diff.getZExtValue();
-  uint64_t UpperboundTC = SE->getSignedRange(TC).getUpper().getZExtValue();
+  uint64_t UpperboundTC = SE->getSignedRange(TCDef).getUpper().getZExtValue();
 
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samparker wrote:
> Could you add a comment on why we're using SignedRange here? And below for the ranges and ceiling.
Hm, good catch I think. The ranges are signed because they can just be negative, but extracting the ZExt value here for that probably doesn't make any sense. I will put a fixme in for that now, because after addressing the TODO above, the: 

  // 1) TODO: Check that the TripCount (TC) belongs ...

which is addressed in D86074, revising this part here is highest on my list. 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86303/new/

https://reviews.llvm.org/D86303