Add check for negative index in cpu kernel op_index

[Sebastian-Larsson]

Fast path cannot be taken when the index is negative in op_index. It results in a failure in check_fast_path_args. Add a check to check_fast_path_conditions for negative index and return false if one is encountered.

cc @freddan80 @per @zingo @oscarandersson8218 @digantdesai

[pytorch-bot]

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❌ 9 New Failures, 2 Pending, 4 Unrelated Failures

As of commit b2d4503 with merge base de56c81 ():

NEW FAILURES - The following jobs have failed:

• Apple / build-demo-ios / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 65
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 8bb58912dee40c0f4b73f940c5ac87731203130da9e56c9d4fd359aeba154602 /exec failed with exit code 1
• pull / unittest-nxp-neutron / linux-job (gh)
  RuntimeError: Command docker exec -t 7d683f56f4e164381b1e5a7d059e13a83a1bdd3ff957549a53b00789d29db19a /exec failed with exit code 1
• Test CUDA Builds / export-gemma3-cuda-non-quantized / linux-job (gh)
  RuntimeError: Command docker exec -t 2f152424be0018a19ddc48299c4b542c70123d71c535bd1e4ba1ff5494f40f02 /exec failed with exit code 2
• Test CUDA Builds / export-gemma3-cuda-quantized-int4-tile-packed / linux-job (gh)
  RuntimeError: Command docker exec -t 1f9970702a55030b533cd50deb1939bf253f7bc778009bac1ccc7557d64e0d58 /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-non-quantized / linux-job (gh)
  RuntimeError: Command docker exec -t 045e4a838597a0ebba2d9eb6fe626c3621c9ca72c26389acaadb07e117b5eb61 /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-quantized-int4-tile-packed / linux-job (gh)
  RuntimeError: Command docker exec -t eadeb3f9f934f64b4b549a1f43e565ec846caf6ee55289b53fb8e5ac1dd6ec8a /exec failed with exit code 2
• Test CUDA Builds / export-voxtral-cuda-quantized-int4-weight-only / linux-job (gh)
  RuntimeError: Command docker exec -t db2415019ba635cdab3c5e27ac39ae8279c6a92b27d90f4776671af112c07b6f /exec failed with exit code 2
• Test Metal Backend / export-voxtral-metal-artifact / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 2

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / unittest / linux / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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

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

• pull / unittest / macos / macos-job (gh) (trunk failure)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model
• pull / unittest-editable / linux / linux-job (gh) (trunk failure)
• trunk / unittest-release / linux / linux-job (gh) (trunk failure)

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[swolchok]

looks fine; inline comments are for your consideration and not blocking. However, please also add a test for this behavior (and feel free to @ me for re-review to avoid extra delay).

[Sebastian-Larsson]

Changed to your suggestions and added tests @swolchok

[swolchok]

I would prefer to see a templated test, but it's probably not worth blocking on

[swolchok]

looks like we have a bunch of infra failures and known flakes in CI. merging.