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@jikechao jikechao commented Nov 7, 2025

Adds support for integer inputs in topi.log and topi.log2 by automatically converting them to float32, aligning with NumPy's implicit float promotion behavior.

Fix #18425

Convert integer inputs to float32 for log and log2 functions.
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Summary of Changes

Hello @jikechao, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the topi.log and topi.log2 functions by introducing robust support for integer tensor inputs. Previously, these functions might have encountered issues or produced unexpected results when given integer types. With this update, any integer input will be automatically promoted to float32 before the logarithmic calculation, ensuring consistent and predictable behavior that mirrors NumPy's approach to such operations. This resolves a reported issue and improves the overall reliability of these mathematical functions within TVM.

Highlights

  • Integer Input Support: The topi.log and topi.log2 functions now accept integer inputs, automatically casting them to float32 before performing the logarithmic computation.
  • NumPy Alignment: This change aligns the behavior of topi.log and topi.log2 with NumPy's implicit float promotion, ensuring consistent handling of integer inputs.
  • Tag Scope Refinement: The tag.ELEMWISE scope for log and log2 functions has been moved from a decorator to an argument directly within the te.compute call.
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Code Review

This pull request adds support for integer inputs to topi.log and topi.log2 by casting them to float32, which is a good improvement for usability and consistency with libraries like NumPy. The implementation correctly moves the elemwise tag from a decorator to the final te.compute call, which is good practice for avoiding issues with nested tag scopes. My review includes suggestions to also tag the intermediate cast operations as elemwise to ensure they can be fused by the scheduler, which is important for performance.

"""
return te.compute(x.shape, lambda *i: te.log(x(*i)))
if x.dtype.startswith("int"):
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"))
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medium

The intermediate te.compute for casting should be tagged as elemwise to allow for operator fusion. Without this tag, the cast operation might not be inlined, potentially leading to suboptimal performance.

Suggested change
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"))
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"), tag=tag.ELEMWISE)

"""
return te.compute(x.shape, lambda *i: te.log2(x(*i)))
if x.dtype.startswith("int"):
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"))
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medium

Similar to the log function, the intermediate te.compute for casting here should be tagged as elemwise to enable operator fusion. This ensures that the cast can be inlined by the scheduler.

Suggested change
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"))
x = te.compute(x.shape, lambda *i: x(*i).astype("float32"), tag=tag.ELEMWISE)

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jikechao commented Nov 7, 2025

cc @tqchen @Hzfengsy @tlopex

@tlopex tlopex self-assigned this Nov 7, 2025
@MasterJH5574 MasterJH5574 merged commit d013dad into apache:main Nov 12, 2025
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Successfully merging this pull request may close these issues.

[Bug] Cannot find intrinsic declaration, possible type mismatch: llvm.log2

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