[PATCH] D79003: [DAG] Add SimplifyDemandedVectorElts binop SimplifyMultipleUseDemandedBits handling

Roman Lebedev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon May 4 04:46:18 PDT 2020


lebedev.ri added a comment.

Seems reasonable to me in general.



================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:2646-2649
     KnownUndef = getKnownUndefForVectorBinop(Op, TLO.DAG, UndefLHS, UndefRHS);
+
+    // Attempt to avoid multi-use ops if we don't need anything from them.
+    if (!DemandedElts.isAllOnesValue()) {
----------------
Just wondering, should we not demand elts that are `KnownUndef`?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79003/new/

https://reviews.llvm.org/D79003





More information about the llvm-commits mailing list