[None][fix] Remove redundant residual bound check in EAGLE3 hidden-state capture

[eopXD]

Description

Follow-up to review feedback on #15708. During review, @lancelly noted that the residual bound check in Eagle3OneModelSpecMetadata.maybe_capture_hidden_states is redundant with the preceding hidden_states check. This PR removes it.

In every caller, residual and hidden_states are produced by the same decoder layer and therefore share their leading (token) dimension, so once the num_tokens > hidden_states.shape[0] check passes, num_tokens <= residual.shape[0] is already guaranteed — the residual branch was unreachable dead code. It is replaced with a short comment explaining why no separate check is needed, so it is not re-added.

The two remaining checks are intentionally kept because they guard different tensors:

• the buffer-capacity check (self.hidden_states.shape[0]) protects the preallocated capture buffer that inplace_slice_copy writes into (the overrun the original fix addresses);
• the available-hidden-states check (hidden_states.shape[0]) protects the input read.

No behavior change.

Test Coverage

No new tests. The existing GPU-gated test_eagle3_one_model_capture_uses_real_token_count in tests/unittest/_torch/speculative/test_eagle3.py exercises the retained residual path (hidden_states[:4] + residual[:4]); the removed branch was never reachable, so no test regresses. This is a pure dead-code removal on the CUDA-only maybe_capture_hidden_states → inplace_slice_copy path, covered by the same CI stages that passed on #15708.

PR Checklist

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Summary by CodeRabbit

• Bug Fixes
  • Improved reliability when capturing hidden states during speculative decoding by simplifying internal bounds handling.
  • Reduced the chance of unnecessary runtime checks while preserving safe token-limited copying behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 60583d2 and 2690e4c.

📒 Files selected for processing (1)

• tensorrt_llm/_torch/speculative/eagle3.py

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📝 Walkthrough

Walkthrough

Removed a redundant explicit runtime bounds check on residual.shape[0] within Eagle3OneModelSpecMetadata.maybe_capture_hidden_states, relying instead on the pre-existing hidden_states-based validation, with added comments explaining the assumption before slicing residual[:num_tokens].

Changes

Eagle3 hidden states capture bounds check removal

Layer / File(s)	Summary
Simplify residual bounds validation tensorrt_llm/_torch/speculative/eagle3.py	Removed the explicit RuntimeError check for residual.shape[0] vs num_tokens, replacing it with comments asserting the earlier hidden_states-based bound check already guarantees safe slicing.

Estimated code review effort: 2 (Simple) | ~5 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: removing a redundant residual bound check.
Description check	✅ Passed	The description follows the template with Description, Test Coverage, and PR Checklist sections and explains the change clearly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[eopXD]

/bot skip --comment "This is a trvial change that addresses comments from my previous merge request. This should be safe to land."

[tensorrt-cicd]

PR_Github #58392 [ skip ] triggered by Bot. Commit: 2690e4c Link to invocation

[tensorrt-cicd]

PR_Github #58392 [ skip ] completed with state SUCCESS. Commit: 2690e4c
Skipping testing for commit 2690e4c

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