[all-commits] [llvm/llvm-project] 079c96: [RISCV] Form vmv.s.f/x from single element splats ...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 079c968eb95aa2c84444d0e5d5564d575b93c909
      https://github.com/llvm/llvm-project/commit/079c968eb95aa2c84444d0e5d5564d575b93c909
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2023-08-30 (Wed, 30 Aug 2023)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td
    M llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-bitcast.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-deinterleave-load.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-extract-i1.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-bitcast.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-interleave.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-shuffles.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert-i1.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-buildvec.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-interleave.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-splat.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-interleaved-access-zve32x.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-interleaved-access.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-mask-buildvec.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-mask-splat.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-int-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-select-int.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-transpose.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store-asm.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vand-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfcmp-constrained-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfcmps-constrained-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vfwmacc.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vitofp-constrained-sdnode.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vrol.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vror.ll
    M llvm/test/CodeGen/RISCV/rvv/shuffle-reverse.ll
    M llvm/test/CodeGen/RISCV/rvv/vector-deinterleave-fixed.ll
    M llvm/test/CodeGen/RISCV/srem-seteq-illegal-types.ll

  Log Message:
  -----------
  [RISCV] Form vmv.s.f/x from single element splats via DAG combine

This re-implements the special casing we had in lowerScalarSplat as a DAG combine. As can be seen in the tests, this ends up triggering in a bunch more cases.

The semantically interesting bit of this change is the use of the implicit truncate semantics for when XLEN > SEW. We'd already been doing this for vmv.v.x, but this change extends e.g. the constant matching to make the same assumption about vmv.s.x. Per my reading of the specification, this should be fine, and if anything, is more obviously true of vmv.s.x than vmv.v.x.

Differential Revision: https://reviews.llvm.org/D158874