[Fix] Handle empty variable name in NameSupply::FreshName

[MasterJH5574]

Map empty names to "v" to prevent codegen from producing GPU code with empty variable names that fail compilation. Also fix add_prefix_to_name to use the (possibly remapped) unique_name instead of the original name.

[gemini-code-assist]

Summary of Changes

Hello @MasterJH5574, 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 addresses a critical issue where empty variable names could be generated, leading to compilation failures in GPU code. It introduces a robust mechanism to default empty names to 'v' and corrects the logic for applying prefixes to these names. A new test case has been added to validate this behavior, ensuring the system produces valid and unique variable names even when provided with empty inputs.

Highlights

• Empty Variable Name Handling: The FreshName function in NameSupplyNode now explicitly checks for empty input names and, if found, reassigns them to the default variable name 'v' to prevent the generation of invalid empty variable names in GPU code.
• Prefixing Logic Correction: The add_prefix_to_name call within FreshName has been updated to use the potentially remapped unique_name instead of the original input name. This ensures that prefixes are applied correctly, especially when the original name was empty and remapped to 'v'.
• New Test Case: A new Python test test_fresh_name_empty_string has been added to verify that the NameSupply correctly handles empty input strings, producing 'v' for the first instance and 'v_1' for subsequent requests, ensuring uniqueness.

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Changelog

• src/ir/name_supply.cc
  • Modified NameSupplyNode::FreshName to map empty input name to 'v' before further processing.
  • Updated the call to add_prefix_to_name within FreshName to use the unique_name variable (which might have been remapped from an empty string) instead of the original name.
• tests/python/ir/test_name_supply.py
  • Added a new test file.
  • Implemented test_fresh_name_empty_string to verify that NameSupply.fresh_name correctly handles empty string inputs, returning 'v' and 'v_1' for successive calls.

Activity

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[gemini-code-assist]

Code Review

This pull request correctly addresses two issues in NameSupply::FreshName: it now handles empty input names by mapping them to "v", and it correctly applies prefixes to this remapped name. The changes are logical and prevent the generation of invalid code. A new test case has been added to verify the handling of empty names. I've suggested an additional test case to ensure the prefixing logic is also covered, which was part of the fix.

[MasterJH5574]

@tvm-bot rerun

[MasterJH5574]

@tvm-bot rerun