[PATCH] D123163: [TLI] `TargetLowering::SimplifyDemandedVectorElts()`: narrowing bitcast: fill known zero elts from known src bits

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:2754-2759
         APInt SrcDemandedBits = APInt::getZero(SrcEltSizeInBits);
         for (unsigned i = 0; i != NumElts; ++i)
           if (DemandedElts[i]) {
             unsigned Ofs = (i % Scale) * EltSizeInBits;
             SrcDemandedBits.setBits(Ofs, Ofs + EltSizeInBits);
           }
----------------
`SrcDemandedBits` was just synthesized from the `DemandedElts`, so i don't see any need in checking the former?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123163/new/

https://reviews.llvm.org/D123163