[all-commits] [llvm/llvm-project] 95ce3c: [RISCV] Be more aggressive about shrinking constan...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 95ce3c23c2597c882aa01fa31c70e3d5413a9c6e
      https://github.com/llvm/llvm-project/commit/95ce3c23c2597c882aa01fa31c70e3d5413a9c6e
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2023-09-25 (Mon, 25 Sep 2023)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/rvv/active_lane_mask.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-extract.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-buildvec.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-int-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-reverse.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-rotate.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-stepvector.ll
    M llvm/test/CodeGen/RISCV/srem-seteq-illegal-types.ll
    M llvm/test/CodeGen/RISCV/urem-seteq-illegal-types.ll

  Log Message:
  -----------
  [RISCV] Be more aggressive about shrinking constant build_vector etype (#67175)

If LMUL is more than m1, we can be more aggressive about narrowing the
build_vector via a vsext if legal. If the narrow build_vector gets
lowered as a load, while both are linear in lmul, load uops are
generally more expensive than extend uops. If the narrow build_vector
gets lowered via dominant values, that work is linear in both #unique
elements and LMUL. So provided the number of unique values > 2, this is
a net win in work performed.