[all-commits] [llvm/llvm-project] 9a2d4d: [SelectionDAG][AArch64] Legalize power of 2 vector...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9a2d4d176ad290eb556f27a990880acad99cc163
      https://github.com/llvm/llvm-project/commit/9a2d4d176ad290eb556f27a990880acad99cc163
  Author: Luke Lau <luke at igalia.com>
  Date:   2025-06-03 (Tue, 03 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/sve-vector-deinterleave.ll
    M llvm/test/CodeGen/AArch64/sve-vector-interleave.ll

  Log Message:
  -----------
  [SelectionDAG][AArch64] Legalize power of 2 vector.[de]interleaveN (#141513)

After https://github.com/llvm/llvm-project/pull/139893, we now have
[de]interleave intrinsics for factors 2-8 inclusive, with the plan to
eventually get the loop vectorizer to emit a single intrinsic for these
factors instead of recursively deinterleaving (to support scalable
non-power-of-2 factors and to remove the complexity in the interleaved
access pass).

AArch64 currently supports scalable interleaved groups of factors 2 and
4 from the loop vectorizer. For factor 4 this is currently emitted as a
series of recursive [de]interleaves, and normally converted to a target
intrinsic in the interleaved access pass.

However if for some reason the interleaved access pass doesn't catch it,
the [de]interleave4 intrinsic will need to be lowered by the backend.

This patch legalizes the node and any other power-of-2 factor to smaller
factors, so if a target can lower [de]interleave2 it should be able to
handle this without crashing.

Factor 3 will probably be more complicated to lower so I've left it out
for now. We can disable it in the AArch64 cost model when implementing
the loop vectorizer changes.



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