[all-commits] [llvm/llvm-project] 07a31a: [X86] EltsFromConsecutiveLoads - recognise reverse...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 07a31adf287ca4d338232c6d79fe108a191007b4
      https://github.com/llvm/llvm-project/commit/07a31adf287ca4d338232c6d79fe108a191007b4
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2025-11-20 (Thu, 20 Nov 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/bitcnt-big-integer.ll
    M llvm/test/CodeGen/X86/build-vector-256.ll
    M llvm/test/CodeGen/X86/chain_order.ll
    M llvm/test/CodeGen/X86/merge-consecutive-loads-128.ll
    M llvm/test/CodeGen/X86/merge-consecutive-loads-256.ll
    M llvm/test/CodeGen/X86/merge-consecutive-loads-512.ll

  Log Message:
  -----------
  [X86] EltsFromConsecutiveLoads - recognise reverse load patterns. (#168706)

See if we can create a vector load from the src elements in reverse and
then shuffle these back into place.

SLP will (usually) catch this in the middle-end, but there are a few
BUILD_VECTOR scalarizations etc. that appear during DAG legalization.

I did start looking at a more general permute fold, but I haven't found
any good test examples for this yet - happy to take another look if
somebody has examples.



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