Repository navigation
Make the scan SIMD helpers enforce their length contract - #1353
Merged
Merged
Conversation
vector_ascii_mismatch, vector_clean, vector_ascii64 and vector_case read a fixed number of bytes through raw pointers, but took slices and left the length to an unstated caller contract. Taking arrays puts that length in the type, so the helpers no longer need to be unsafe. vector_unicode already bounds its own loads and becomes safe too.
Codex Review SummaryThis comment shows the latest Codex review activity on this pull request.
ℹ️ About Codex in GitHubYour team has set up Codex to review pull requests in this repo. Reviews are triggered when you
Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings. |
Collaborator
Author
|
@codex review |
|
Codex Review: Didn't find any major issues. 🚀 Reviewed commit: ℹ️ About Codex in GitHubYour team has set up Codex to review pull requests in this repo. Reviews are triggered when you
If Codex has suggestions, it will comment; otherwise it will react with 👍. Codex can also answer questions or update the PR. Try commenting "@codex address that feedback". |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The SIMD helpers in
src/scan.rswereunsafe fns that read 16 or 64 bytes through raw pointers. They took slices, and the length they need was written down only inSAFETYcomments, so a future caller could pass a short slice and read out of bounds.Now
vector_ascii_mismatch,vector_cleanandvector_casetake&[u8; 16]or&mut [u8; 16], andvector_ascii64takes&[u8; 64]. The type enforces the length, and the helpers are safe functions with an internalunsafeblock.vector_unicodealready bounds its own loads, so it becomes safe too. Call sites convert theirchunks_exactchunks withtry_into().unwrap(), becauseas_chunksneeds Rust 1.88 and the MSRV is 1.85.No regression: on arm64 the release
comparebinaries disassemble to the same instructions as master, in both the SIMD and portable builds. The only difference is the file name. Timings against a master baseline (compare.py --baseline, 8 rounds, geomean of after/before medians):This is a type-level change with no behaviour change, so there's no new test. The existing lane and alignment tests in
scan.rscover the helpers. The x86_64 code gets compiled only in CI (ubuntu), because the build host has no x86_64 toolchain.