[PATCH] D58965: [DAGCombiner] Enable UADDO/USUBO vector combine support

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2463
   // If Y + 1 cannot overflow.
   if (N1.getOpcode() == ISD::ADDCARRY && isNullConstant(N1.getOperand(1))) {
     SDValue Y = N1.getOperand(0);
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RKSimon wrote:
> nikic wrote:
> > Should this also become isNullorNullSplat? (Does ADDCARRY support vectors?)
> AFAICT we don't have ISD::ADDCARRY/SUBCARRY support for vectors - it might be safest to just early-out from visitUADDOLike if VT.isVector()?
Bailing out early on isVector() sounds reasonable. The code should be safe as-is, but that would make it more obvious that this transform doesn't apply to vectors.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D58965/new/

https://reviews.llvm.org/D58965