[PATCH] D152496: [RISCV] Use vslidedown.vi vN, vN, 0 instead of vslideup.vi vN, vM, 0 for scalable vectors.

[Craig Topper via Phabricator via llvm-commits]

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These instructions are semantically identical in the case where the
offset is 0 with the exception that vslideup has a vector overlap
constraint and vslidedown doesn't. As a result, we can prefer the one
without register overlap constraints to improve register allocation
flexibility.

This the scalable vector version of https://reviews.llvm.org/D152298.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D152496

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/extract-subvector.ll
  llvm/test/CodeGen/RISCV/rvv/insert-subvector.ll
  llvm/test/CodeGen/RISCV/rvv/vreductions-fp-sdnode.ll

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