[PATCH] D151390: [RISCV] Don't reduce vslidedown's VL in rotations

[Luke Lau via Phabricator via llvm-commits]

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Even though we only need to write to the bottom NumElts - Rotation
elements for the vslidedown.vi, we can save an extra vsetivli toggle if
we just keep the wide VL.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D151390

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/fixed-vector-shuffle-reverse.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-shuffles.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll
  llvm/test/CodeGen/RISCV/rvv/shuffle-reverse.ll

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