[all-commits] [llvm/llvm-project] df9597: [X86][CostModel] X86TTIImpl::getShuffleCost(): sub...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: df9597cf5a68477058e05028aa91c4eafc4ebcdd
      https://github.com/llvm/llvm-project/commit/df9597cf5a68477058e05028aa91c4eafc4ebcdd
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-04-19 (Mon, 19 Apr 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/X86/masked-intrinsic-cost-inseltpoison.ll
    M llvm/test/Analysis/CostModel/X86/masked-intrinsic-cost.ll
    M llvm/test/Transforms/LoopVectorize/X86/gather_scatter.ll

  Log Message:
  -----------
  [X86][CostModel] X86TTIImpl::getShuffleCost(): subvector insertions are cheap

This is similar to the subvector extractions,
except that the 0'th subvector isn't free to insert,
because we generally don't know whether or not
the upper elements need to be preserved:
https://godbolt.org/z/rsxP5W4sW

This is needed to avoid regressions in D100684

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D100698