[all-commits] [llvm/llvm-project] 1540ed: [AArch64] Neoverse V2 FeatureDisableLatencySchedHe...

[Sjoerd Meijer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1540ed52eeb25d6cf8142c1071d85a50f5c167b1
      https://github.com/llvm/llvm-project/commit/1540ed52eeb25d6cf8142c1071d85a50f5c167b1
  Author: Sjoerd Meijer <smeijer at nvidia.com>
  Date:   2025-06-06 (Fri, 06 Jun 2025)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64Processors.td

  Log Message:
  -----------
  [AArch64] Neoverse V2 FeatureDisableLatencySchedHeuristic (#140897)

This adds FeatureDisableLatencySchedHeuristic to the Neoverse V2 core
tuning description. This gives us a 20% improvement on a key workload,
some other minor improvements here and there, and no real regressions;
nothing outside the noise levels.

Earlier attempts to solve this problems included disabling the MI
scheduler entirely (#127784), and #139557 was about a heuristic to not
schedule hand-written vector code. This solution is preferred because it
avoids another heuristic and achieves what we want, and for what is
worth, there is a lot of precedent for setting this feature.

Thanks to:
- Ricardo Jesus for pointing out this subtarget feature, and
- Cameron McInally for the extensive performance testing.



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