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Move multiproof hashes allocation under condition to avoid zero-length alloc #6092

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Move multiproof hashes allocation under condition to avoid zero-length alloc #6092

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@Snezhkko Snezhkko commented Nov 10, 2025

This change relocates the allocation of the temporary hashes array and related counters inside the if (proofFlagsLen > 0) branch across all four multiproof functions in MerkleProof.sol. When proofFlagsLen == 0, the function returns early and hashes is never used; previously this still incurred an unnecessary zero-length memory allocation and variable initialization. The refactor avoids that overhead without changing semantics, consistent with existing docs and tests.

@Snezhkko Snezhkko requested a review from a team as a code owner November 10, 2025 20:07
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coderabbitai bot commented Nov 10, 2025

Walkthrough

Code blocks handling hashes array initialization and the main per-proof loop processing in MerkleProof functions have been refactored to execute conditionally. These operations are now placed inside the if (proofFlagsLen > 0) guards, restricting their execution to when the proof flags length is greater than zero. Previously, these allocations and iterations were unconditionally executed. The surrounding control flow logic, post-loop proof length validation, and conditional return statements remain unchanged. No modifications to public function signatures were introduced.

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✅ Passed checks (3 passed)
Check name Status Explanation
Title check ✅ Passed The title accurately and concisely summarizes the main change: moving the hashes allocation under a conditional to avoid zero-length allocation in multiproof functions.
Description check ✅ Passed The description clearly explains the change, the reason for it, and confirms that semantics are preserved, which directly relates to the changeset.
Docstring Coverage ✅ Passed No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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  • contracts/utils/cryptography/MerkleProof.sol (4 hunks)
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🔇 Additional comments (4)
contracts/utils/cryptography/MerkleProof.sol (4)

223-238: LGTM! Clean optimization that avoids zero-length allocation.

Moving the hashes array allocation and loop variables inside the if (proofFlagsLen > 0) guard is correct and improves gas efficiency. When proofFlagsLen == 0, the loop never executed anyway, so this change simply avoids the unnecessary zero-length memory allocation and variable initialization.

310-325: LGTM! Consistent optimization applied.

The same optimization pattern correctly applied to the custom hashing variant. The refactor maintains semantic equivalence while avoiding unnecessary allocations.

395-410: LGTM! Optimization correctly applied to calldata variant.

The refactor correctly extends the optimization to the calldata variant, maintaining consistency across all multiproof function variants.

482-497: LGTM! Complete and consistent optimization across all variants.

The final multiproof function variant correctly implements the same optimization. All four multiproof functions now consistently avoid unnecessary allocations when proofFlagsLen == 0.

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ernestognw
ernestognw approved these changes Nov 13, 2025
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Thanks. We'll need a second review here

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