[all-commits] [llvm/llvm-project] 2023a2: [RISCV] Move V0 to the end of register allocation ...

[Wang Pengcheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2023a230d122d6971c5ff90615c128e7e711b08f
      https://github.com/llvm/llvm-project/commit/2023a230d122d6971c5ff90615c128e7e711b08f
  Author: Wang Pengcheng <wangpengcheng.pp at bytedance.com>
  Date:   2024-03-01 (Fri, 01 Mar 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVRegisterInfo.td
    M llvm/test/CodeGen/RISCV/pr69586.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vector-i8-index-cornercase.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-abs-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-ctpop-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fmaximum-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fmaximum.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fminimum-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fminimum.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-interleaved-access.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-nearbyint-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-fp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-setcc-fp-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-setcc-int-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-concat.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-trunc-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vadd-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vcopysign-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfma-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfmax-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfmin-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfmuladd-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmax-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmaxu-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vmin-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vminu-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vpgather.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsadd-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vsaddu-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssub-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vssubu-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fmaximum-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/fmaximum-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fminimum-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/fminimum-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/mscatter-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/nearbyint-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/setcc-fp-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/setcc-int-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vcopysign-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vector-interleave-store.ll
    M llvm/test/CodeGen/RISCV/rvv/vfadd-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfdiv-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfmadd-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/vfmax-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfmin-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfmul-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfmuladd-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfnmadd-constrained-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/vfnmsub-constrained-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/vfptrunc-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfsub-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfwmacc-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfwnmacc-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vfwnmsac-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vpmerge-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/vreductions-fp-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vselect-fp.ll
    M llvm/test/CodeGen/RISCV/rvv/vsitofp-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vtrunc-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vuitofp-vp.ll

  Log Message:
  -----------
  [RISCV] Move V0 to the end of register allocation order (#82967)

According to

https://riscv-optimization-guide-riseproject-c94355ae3e6872252baa952524.gitlab.io/riscv-optimization-guide.html:

> The v0 register defined by the RISC-V vector extension is special in
> that it can be used both as a general purpose vector register and also
> as a mask register. As a preference, use registers other than v0 for
> non-mask values. Otherwise data will have to be moved out of v0 when a
> mask is required in an operation. v0 may be used when all other
> registers are in use, and using v0 would avoid spilling register state
> to memory.

And using V0 register may stall masking pipeline and stop chaining
for some microarchitectures.

So we should try to not use V0 and register groups contained it as
much as possible. We achieve this via moving V0 to the end of RA
order.



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