[all-commits] [llvm/llvm-project] 9df592: [AArch64] Fold away zext of extract of uzp. (#107367)

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9df592fb806b77d5fb0c7a9d5c9057d1626587e3
      https://github.com/llvm/llvm-project/commit/9df592fb806b77d5fb0c7a9d5c9057d1626587e3
  Author: David Green <david.green at arm.com>
  Date:   2024-09-05 (Thu, 05 Sep 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/zext-shuffle.ll

  Log Message:
  -----------
  [AArch64] Fold away zext of extract of uzp. (#107367)

Similar to #107201, this comes up from the lowering of zext of
deinterleaving shuffles. Patterns such as ext(extract_subvector(uzp(a,
b))) can be converted to a simple and to perform the extract/zext from a
uzp1. Uzp2 can be handled with an extra shift, and due to the existing
legalization we could have and / shift between which can be combined in.

Mostly this reduces instruction count or increases the amount of
parallelism in the sequence.



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