Add chat-template hooks to LMEvalORTGenAIEvaluator#2462
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xiaoyu-work merged 6 commits intoMay 21, 2026
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lm-eval's `simple_evaluate(..., apply_chat_template=True)` requires the
underlying LM class to implement `tokenizer_name` and `apply_chat_template`.
The HFLM backend has both; the ORT GenAI backend does not, so any attempt
to evaluate a chat-tuned ONNX model with chat-formatted prompts raises
`NotImplementedError: To use this model with chat templates, please
implement the 'tokenizer_name' property.`
This adds the two members with the minimum surface area:
- `tokenizer_name` returns the model path (for lm-eval's chat-aware
result caching), matching the HFLM convention of slash-replacement.
- `apply_chat_template` defers to the model's HF tokenizer via
`AutoTokenizer.apply_chat_template`, mirroring HFLM's
implementation.
The HF tokenizer is loaded once at `__init__` purely for chat-template
rendering; token-level encode/decode still goes through `og.Tokenizer`
and the runtime, so there is no change to generation behavior or any
existing code path.
Verified end-to-end on LFM2.5-350M (int4, k_quant_mixed) MBPP:
without chat-template hooks the eval raised at task start; with them
plus `num_fewshot=0` and a chat-friendly stop list, pass@1 went from
0.0/500 to 67/500 (13.4%) -- the original 0.0 was a prompt-format
artifact (instruct model + completion-style few-shot), not a
conversion regression.
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Pull request overview
This PR adds lm-eval “chat template” integration hooks to LMEvalORTGenAIEvaluator so ORT GenAI–backed models can be evaluated via lm_eval.simple_evaluate(..., apply_chat_template=True) (matching the capability available in the HuggingFace backend).
Changes:
- Add an HF tokenizer instance to
LMEvalORTGenAIEvaluatorfor rendering chat templates. - Implement
tokenizer_namefor lm-eval chat-template-aware caching. - Implement
apply_chat_template(...)by delegating to the HF tokenizer.
… key, tests
- Lazy-load the HF tokenizer on the first ``apply_chat_template`` call rather
than at ``__init__``. Callers that never enable chat templating no longer
need HF tokenizer files (``tokenizer_config.json`` etc.) in the model
directory; eager loading would have regressed those workflows.
- ``tokenizer_name`` now replaces both POSIX and Windows path separators with
``__`` so the lm-eval cache identifier is stable across platforms. The
previous implementation only handled forward slashes, leaving backslashes
in the key on Windows because ``str(Path(...))`` preserves the native
separator.
- Add unit tests for both behaviours:
- ``tokenizer_name`` parametrised over POSIX, relative, and Windows-style
paths to lock in the normalisation contract.
- ``apply_chat_template`` verified to (a) not load the HF tokenizer at
construction, (b) load once on first call, and (c) reuse the cached
tokenizer on subsequent calls. ``AutoTokenizer`` is patched so the
tests run without any HF tokenizer files on disk.
All four new tests pass; ``test_olive_evaluator.py`` as a whole stays green
(85 passed). ``lintrunner`` reports no new warnings on the changed files.
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Collaborator
|
@ykhrustalev Please add the following snippet on tests that depend on lm-eval package |
auto-merge was automatically disabled
May 20, 2026 18:32
Head branch was pushed to by a user without write access
xiaoyu-work
approved these changes
May 21, 2026
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Describe your changes
Implement
tokenizer_nameandapply_chat_templateonLMEvalORTGenAIEvaluatorso the backend supportslm_eval.simple_evaluate(apply_chat_template=True). Without these, lm-eval raisesNotImplementedErrorat task setup for any chat-formatted task.Parity with the HuggingFace backend in
lm_eval/models/huggingface.py. The HF tokenizer is loaded lazily on the firstapply_chat_templatecall, so model directories without HF tokenizer files still work for non-chat evaluation. Generation continues to go throughog.Tokenizer.Checklist before requesting a review
lintrunner -aapply_chat_template=Truein lm-eval for ortgenai-backed evaluators.(Optional) Issue link
N/A