[all-commits] [llvm/llvm-project] 10b48e: [InstCombine] Combine extract from get_active_lane...

[Kerry McLaughlin via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 10b48e41e7d7455a68c00ac52442f994d7c51ffe
      https://github.com/llvm/llvm-project/commit/10b48e41e7d7455a68c00ac52442f994d7c51ffe
  Author: Kerry McLaughlin <kerry.mclaughlin at arm.com>
  Date:   2026-02-27 (Fri, 27 Feb 2026)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
    M llvm/test/Transforms/InstCombine/get_active_lane_mask.ll

  Log Message:
  -----------
  [InstCombine] Combine extract from get_active_lane_mask where all lanes inactive (#183329)

When extracting a subvector from the result of a get_active_lane_mask, return
a constant zero vector if it can be proven that all lanes will be inactive.

For example, the result of the extract below will be a subvector where
every lane is inactive if X & Y are const, and `Y * VScale >= X`:
  vector.extract(get.active.lane.mask(Start, X), Y)



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