Fix --use-flash-attention ignored when xformers installed.

[comfyanonymous]

No description provided.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: a7411185-c757-40ff-b4da-a73d24d7759a

📥 Commits

Reviewing files that changed from the base of the PR and between 0af1230 and 62396b5.

📒 Files selected for processing (1)

• comfy/ldm/modules/attention.py

---

📝 Walkthrough

Walkthrough

This PR reorders the conditional logic in the optimized_attention function within the attention module. The change modifies the backend selection sequence to prioritize Flash Attention over xFormers when both backends are available and enabled. Previously, xFormers was evaluated first in the conditional chain; now Flash Attention is checked first, altering which backend is selected when both conditions are true.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	No description was provided by the author, making it impossible to assess whether any description relates to the changeset.	Add a pull request description explaining the issue being fixed, the solution, and any testing performed.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: reordering backend selection logic to prioritize Flash Attention over xFormers.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}