Arm backend: Make warning statement more clear

[gggekov]

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils @Sebastian-Larsson @robell

[pytorch-bot]

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❌ 1 New Failure, 1 Cancelled Job, 3 Unrelated Failures

As of commit 921f4ea with merge base ae07d06 ():

NEW FAILURE - The following job has failed:

• trunk / test-arm-backend-vkml (test_pytest_ops_vkml) / linux-job (gh)
  RuntimeError: Command docker exec -t 443a275d14f307908557c586ae1ef59f0d8054287b09381bde94f18b5ff0fa8c /exec failed with exit code 1

CANCELLED JOB - The following job was cancelled. Please retry:

• trunk / test-models-macos-cpu (llama2, xnnpack-quantization-delegation) / macos-job (gh)

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• trunk / unittest-release / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[github-actions]

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[Copilot]

Pull request overview

Updates the Arm FVP runner script messaging to better describe performance/cycle-accuracy expectations when running Corstone FVP simulations.

Changes:

• Updates the copyright year in run_fvp.sh.
• Rewords the Corstone FVP performance/cycle-accuracy warning shown at runtime.

---

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[Copilot]

The file previously carried a 2025 copyright header; changing it to only 2026 drops the original year. Other Arm scripts in this directory use a year range when spanning multiple years (e.g., 2025-2026). Consider using a 2025-2026 range here as well to preserve the original year and match the prevailing header pattern.

Suggested change

	# Copyright 2026 Arm Limited and/or its affiliates.
	# Copyright 2025-2026 Arm Limited and/or its affiliates.

[zingo]

God catch

[Copilot]

This line no longer starts with a clear warning marker (e.g., "WARNING:") like other scripts (see run_vkml.sh). Keeping a consistent "WARNING:" prefix would make the performance caveat easier to spot in logs and align with existing messaging conventions.

Suggested change

	echo "The Corstone FVPs are cycle accurate for the NPU part, but note that the CPU performance is not cycle accurate."
	echo "WARNING: The Corstone FVPs are cycle accurate for the NPU part, but note that the CPU performance is not cycle accurate."

[zingo]

Copyright year 2025-2026, sorry for missing this in internal review.

[zingo]

Known issue
FAILED backends/arm/test/ops/test_permute.py::test_permute_vgf_quant[rank_4_large

Ok to merge with this fail.