[PATCH] D155101: [RISCV] Fold ops into vmv.v.v as vmerge with all-ones mask

[Luke Lau via Phabricator via llvm-commits]

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A vmv.v.v shares the same encoding as a vmerge that isn't masked, so we can
also fold it into its operands if we treat it as a vmerge with an all-ones
mask.  We take care here not to actually transform the existing vmv into a
vmerge, otherwise things like True.hasOneUse() become inaccurate. Instead this
just returns an equivalent list of operands.
This is an alternative to D153351 <https://reviews.llvm.org/D153351>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155101

Files:
  llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
  llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll
  llvm/test/CodeGen/RISCV/rvv/extract-subvector.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert-subvector-shuffle.ll

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