[PATCH] D100698: [X86][CostModel] X86TTIImpl::getShuffleCost(): subvector insertions are cheap

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
lebedev.ri added reviewers: RKSimon, ABataev.
lebedev.ri added a project: LLVM.
Herald added subscribers: pengfei, hiraditya.
lebedev.ri requested review of this revision.

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 <https://reviews.llvm.org/D100684>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D100698

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

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