[all-commits] [llvm/llvm-project] 7ef77e: [LV] Support scalable interleave groups for factor...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7ef77eb9984d1fb537a409cf4be89560fbb681fe
      https://github.com/llvm/llvm-project/commit/7ef77eb9984d1fb537a409cf4be89560fbb681fe
  Author: Luke Lau <luke at igalia.com>
  Date:   2025-06-12 (Thu, 12 Jun 2025)

  Changed paths:
    M llvm/include/llvm/Analysis/VectorUtils.h
    M llvm/lib/Analysis/VectorUtils.cpp
    M llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/sve-interleaved-accesses.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/sve-interleaved-masked-accesses.ll
    M llvm/test/Transforms/LoopVectorize/RISCV/interleaved-accesses.ll

  Log Message:
  -----------
  [LV] Support scalable interleave groups for factors 3,5,6 and 7 (#141865)

Currently the loop vectorizer can only vectorize interleave groups for
power-of-2 factors at scalable VFs by recursively interleaving
[de]interleave2 intrinsics.

However after https://github.com/llvm/llvm-project/pull/124825 and
#139893, we now have [de]interleave intrinsics for all factors up to 8,
which is enough to support all types of segmented loads and stores on
RISC-V.

Now that the interleaved access pass has been taught to lower these in
#139373 and #141512, this patch teaches the loop vectorizer to emit
these intrinsics for factors up to 8, which enables scalable
vectorization for non-power-of-2 factors.

As far as I'm aware, no in-tree target will vectorize a scalable
interelave group above factor 8 because the maximum interleave factor is
capped at 4 on AArch64 and 8 on RISC-V, and the
`-max-interleave-group-factor` CLI option defaults to 8, so the
recursive [de]interleaving code has been removed for now.

Factors of 3 with scalable VFs are also turned off in AArch64 since
there's no lowering for [de]interleave3 just yet either.



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