[all-commits] [llvm/llvm-project] 43f296: [RISCV] Recognize VLA shift pairs from shuffle mas...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 43f2968a028fbc6b4fac5ba6d18ad9d27eb4ef76
      https://github.com/llvm/llvm-project/commit/43f2968a028fbc6b4fac5ba6d18ad9d27eb4ef76
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2025-02-20 (Thu, 20 Feb 2025)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.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-int-interleave.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-shuffles.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-interleaved-access.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-changes-length.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-deinterleave.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-exact-vlen.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-rotate.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-transpose.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shuffle-vslide1up.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-shufflevector-vnsrl.ll
    M llvm/test/CodeGen/RISCV/rvv/vector-deinterleave-fixed.ll

  Log Message:
  -----------
  [RISCV] Recognize VLA shift pairs from shuffle masks (#127710)

If we have a shuffle mask which can be represented as two slides + some
conditional masking, we can emit a VLA sequence which is at most
O(2*LMUL). This is essentially a generalization of the existing
isElementRotate, but is staged to only introduce the new match for the
moment. A follow up change will start consolidating code - see the notes
below.

A couple of notes:
1) I'm excluding bit rotates mostly to keep the diffs manageable. 
2) The existing isElementRotate logic is nearly redundant after this
   change.  However, we have some intersection between the bit rotate
   and element rotate matching.  To keep things simple, I left that in
   place for now, and will merge/cleanup in a separate change.
3) The individual asVSlideup and asVSlidedown are closely related, but
the former looks through extracts and the later changes VL. I'm leaving
these in place for now, but hope to common them up a bit as well.



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications