[BugFix] Fix unsafe visit else case under WarpSpecializationScope

[SiriusNEO]

Fix #1698

Summary by CodeRabbit

• Bug Fixes
  • Enhanced safety by adding proper validation checks in edge case handling to prevent potential runtime errors.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[github-actions]

👋 Hi! Thank you for contributing to the TileLang project.

Please remember to run pre-commit run --all-files in the root directory of the project to ensure your changes are properly linted and formatted. This will help ensure your contribution passes the format check.

We appreciate you taking this step! Our team will review your contribution, and we look forward to your awesome work! 🚀

[coderabbitai]

📝 Walkthrough

Walkthrough

A defensive guard is added to the kWarpSpecializationScope handling in the shared memory allocation merge transform, checking whether an optional else_case exists before attempting to access it, preventing unsafe optional value dereference.

Changes

Cohort / File(s)	Summary
Warp Specialization Else Case Guard src/transform/merge_shared_memory_allocations.cc	Added conditional check for else_case existence before visiting it in kWarpSpecializationScope handling; prevents unsafe access to optional value

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A rabbit found an optional gone astray,
Without a guard, it crashed the day,
Now with a check before we poke,
The code runs strong—no broken spoke! 🌟

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the bug fix: guarding unsafe optional access to else_case in WarpSpecializationScope handling, which directly addresses the RuntimeError reported in the linked issue.
Linked Issues check	✅ Passed	The code change directly fixes the root cause of issue #1698 by adding a safety guard (checking if else_case is defined) before accessing it, preventing the 'Back optional access' RuntimeError during the MergeSharedMemoryAllocations pass.
Out of Scope Changes check	✅ Passed	The change is narrowly scoped to fix the specific unsafe optional access bug in WarpSpecializationScope handling, with no extraneous modifications.

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

✨ Finishing touches

• 📝 Generate docstrings

---

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.}