[BugFix] fix warning on deepseek_v32 topk_selector.py

[sgjzfzzf]

The previous implementation of topk will report an warning as

[datetime]  [TileLang:tilelang.env:WARNING]: Loading tilelang libs from dev root: <prefix>/tilelang/build
[datetime]   [TileLang:tilelang.language.v2.builder:WARNING]: Immutable value `pos` is re-bound. If you want to modify its value, please use T.alloc_var to make it a variable!
Stack (most recent call last):
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 274, in <module>
    test_topk_selector()
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 194, in test_topk_selector
    indexes = tl_topk(input, starts, ends, topk)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 180, in tl_topk
    kernel = tl_topk_impl(topk)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 414, in __call__
    kernel = self.compile(*args, **kwargs, **tune_params)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 348, in compile
    func = self.get_tir(*args, **kwargs)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 296, in get_tir
    tir = self.func(*args, **kwargs)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 36, in tl_topk_impl
    def tl_topk_kernel(
  File "<prefix>/tilelang/tilelang/language/v2/builder.py", line 1006, in prim_func
    return impl(func) if func is not None else impl
  File "<prefix>/tilelang/tilelang/language/v2/builder.py", line 996, in impl
    ir_gen.gen(builder)(**annot)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 110, in tl_topk_kernel
    pos = T.atomic_add(s_num_input[0], 1, return_prev=True)
x  [TileLang:tilelang.language.v2.builder:WARNING]: Immutable value `pos` is re-bound. If you want to modify its value, please use T.alloc_var to make it a variable!
Stack (most recent call last):
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 274, in <module>
    test_topk_selector()
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 194, in test_topk_selector
    indexes = tl_topk(input, starts, ends, topk)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 180, in tl_topk
    kernel = tl_topk_impl(topk)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 414, in __call__
    kernel = self.compile(*args, **kwargs, **tune_params)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 348, in compile
    func = self.get_tir(*args, **kwargs)
  File "<prefix>/tilelang/tilelang/jit/__init__.py", line 296, in get_tir
    tir = self.func(*args, **kwargs)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 36, in tl_topk_impl
    def tl_topk_kernel(
  File "<prefix>/tilelang/tilelang/language/v2/builder.py", line 1006, in prim_func
    return impl(func) if func is not None else impl
  File "<prefix>/tilelang/tilelang/language/v2/builder.py", line 996, in impl
    ir_gen.gen(builder)(**annot)
  File "<prefix>/tilelang/examples/deepseek_v32/topk_selector.py", line 171, in tl_topk_kernel
    pos = T.atomic_add(s_num_input[r_idx ^ 1], 1, return_prev=True)

This PR allocates pos as a variable to avoid this warning.

Summary by CodeRabbit

• Refactor
  • Minor internal code cleanup: added an explicit local declaration with no behavioral or public API changes; no user-facing impact.

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[github-actions]

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[coderabbitai]

📝 Walkthrough

Walkthrough

Introduces an explicit local integer allocation pos (via T.alloc_var(T.int32)) in tl_topk_kernel, declared before the l_new_topk initialization; no other functional changes.

Changes

Cohort / File(s)	Summary
Variable Declaration examples/deepseek_v32/topk_selector.py	Added explicit local allocation for pos (T.alloc_var(T.int32)) placed before l_new_topk initialization; no other code logic altered

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

🐰 I hopped in to tidy the spot,
A tiny nest where pos can plot,
Declared with care, no longer stray,
Now variables rest in order, yay! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 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 (2 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 main change: fixing a warning in the deepseek_v32 topk_selector.py file.

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✨ Finishing touches

• 📝 Generate docstrings

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