[all-commits] [llvm/llvm-project] b9181c: NFC Pre-commit of rerunning checks on partial-redu...

[Sander de Smalen via All-commits]

  Branch: refs/heads/users/sdesmalen-arm/lv-mitigate-regressions-cost-tweaks
  Home:   https://github.com/llvm/llvm-project
  Commit: b9181c5e8f833986ff2228f6d2d559fbc410d6b5
      https://github.com/llvm/llvm-project/commit/b9181c5e8f833986ff2228f6d2d559fbc410d6b5
  Author: Sander de Smalen <sander.desmalen at arm.com>
  Date:   2026-03-12 (Thu, 12 Mar 2026)

  Changed paths:
    M llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll

  Log Message:
  -----------
  NFC Pre-commit of rerunning checks on partial-reduced-chained.ll


  Commit: 3d044c3fb6847945d9b617aa705c5bb241ecf265
      https://github.com/llvm/llvm-project/commit/3d044c3fb6847945d9b617aa705c5bb241ecf265
  Author: Sander de Smalen <sander.desmalen at arm.com>
  Date:   2026-03-12 (Thu, 12 Mar 2026)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-add-sdot-i16-i32.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-fdot-product.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-sub-sdot.ll

  Log Message:
  -----------
  Various changes to the cost-model.

This has a number of changes to the partial reduction cost-model:

* Implement the fact that *MLALB/T instructions can be used for
  16-bit -> 32-bit partial reductions (or *MLAL/MLAL2 for NEON).

* Fixes the cost of reductions that don't have specific lowering,
  rather than returning a random number, we now return the cost of
  expanding the partial reduction in ISel.

  For sub-reductions we scale the cost to make them slightly cheaper,
  so that they're still candidates for forming cdot operations.

* Reduce the cost of FP reductions, which are currently prohibitively
  expensive.


Compare: https://github.com/llvm/llvm-project/compare/2d28452ba2d7...3d044c3fb684

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