[PATCH] D88201: [DAGCombiner] Add decomposition patterns for Mul-by-Imm.

Mon Oct 5 06:53:39 PDT 2020

RKSimon added inline comments.

================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:3602-3604
   if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
       DAG.isKnownToBeAPowerOfTwo(N1) &&
       (!VT.isVector() || Level <= AfterLegalizeVectorOps)) {
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spatel wrote:
> Independent of this patch, but if you are looking at making further changes in here...that looks strange/unnecessary. The other transforms around here are using `N1IsConst`; why is this one different?
I think because this one has been updated to support non-uniform vectors but most of others haven't, or only match scalars or uniform/splat vectors.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88201/new/

https://reviews.llvm.org/D88201