[all-commits] [llvm/llvm-project] 4c2348: [TargetLowering] Split CTTZ_ELTS when its step vec...

[Akash Agrawal via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4c2348902c68ae2b095317e34ff0b4fdcc571042
      https://github.com/llvm/llvm-project/commit/4c2348902c68ae2b095317e34ff0b4fdcc571042
  Author: Akash Agrawal <akashag at qti.qualcomm.com>
  Date:   2026-06-01 (Mon, 01 Jun 2026)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    A llvm/test/CodeGen/Hexagon/autohvx/cttz-elts-split.ll

  Log Message:
  -----------
  [TargetLowering] Split CTTZ_ELTS when its step vector requires splitting (#197623)

Follow-up to #190914: getLegalMaskAndStepVector() returns an empty
StepVec to signal that the operation should be split. Only
expandVectorFindLastActive handled this; expandCttzElts crashed by
dereferencing the null SDValue during vector op legalization. Apply the
same split-and-recurse strategy, preferring the low half since CTTZ_ELTS
finds the first active lane.

Assisted-by: Anthropic::claude-4.6



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