Use checked arithmetic in dense ZeroTrie#7443
Use checked arithmetic in dense ZeroTrie#7443robertbastian merged 4 commits intounicode-org:mainfrom
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| let trie = ZeroAsciiDenseSparse2dTrieOwned::try_from_btree_map_str(&data, b'/').unwrap(); | ||
| let trie = trie.as_borrowed(); | ||
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| // With empty dense matrix, all lookups should still work via sparse path |
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Suggestion: assert the Debug output of the trie, which encodes the values that went into sparse and the values that went into dense.
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Hey @sffc i can see there's 2 fail in the check (semver fails after 8m), looking at the logs, it is due to a pre-existing issue, they're in icu_calendar and icu_locale_core. |
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@sffc made the required changes, PTAL |
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sffc
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I would appreciate another review from @unicode-org/icu4x-owners since I think this adds branches to a hot path function which maybe doesn't pull its weight. We should avoid building tries that would cause this type of overflow.
Manishearth
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I think the brances are fine, we already have another branch below. These should all just branch predict together.
Maintainer feedback Co-authored-by: Shane F. Carr <[email protected]>
utils/zerotrie/src/dense.rs
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| return None; | ||
| } | ||
| Some(usize::from(offset) + row_value_offset) | ||
| usize::from(offset).checked_add(row_value_offset) |
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Thought: Maybe this one should debug assert, too
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@sffc please review the PRs, made the changes |
Closes #7442
Adds overflow protection to
ZeroAsciiDenseSparse2dTrieBorrowed::get()using checked arithmetic operations.Changes
File: utils/zerotrie/src/dense.rs
checked_mul()andchecked_add()checked_add()which perevents overflow when adding offset to row_value_offset