[all-commits] [llvm/llvm-project] 294972: [RISCV] Move vmerge same mask peephole to RISCVVec...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2949720c2e55d2695682d6412d5afe45b167cb1e
      https://github.com/llvm/llvm-project/commit/2949720c2e55d2695682d6412d5afe45b167cb1e
  Author: Luke Lau <luke at igalia.com>
  Date:   2024-09-06 (Fri, 06 Sep 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
    M llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store-asm.ll
    M llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir

  Log Message:
  -----------
  [RISCV] Move vmerge same mask peephole to RISCVVectorPeephole (#106108)

We currently fold a vmerge.vvm into its true operand if the true operand
is a masked pseudo with the same mask.

We can move this over to RISCVVectorPeephole by instead splitting it up
into a smaller peephole which converts it to a vmv.v.v first. The
existing foldVMV_V_V peephole will then take care of folding it if
needed.

This is very similar to the existing all-ones mask peephole and we could
potentially do it inside of it. I opted to put it in a separate peephole
to make it easier to reason about, given that the duplication is small,
but I could be persuaded either way.



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