Rust: Speedup AccessAfterLifetime.ql

[hvitved]

DCA shows a massive 58 % total analysis time speedup on rust.

[Copilot]

Pull Request Overview

This PR refactors the AccessAfterLifetime.ql query to improve performance by 58% on total Rust analysis time. The optimization is achieved by moving filtering logic from a helper predicate that was called during dataflow analysis into the isSource and isSink predicates, which reduces the scope of the dataflow computation.

Key changes:

• Moved macro expansion and unsafe block filtering from narrowDereferenceAfterLifetime to isSource and isSink predicates
• Removed the narrowDereferenceAfterLifetime helper predicate
• Simplified the query logic by calling AccessAfterLifetime::dereferenceAfterLifetime directly

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
rust/ql/src/queries/security/CWE-825/AccessAfterLifetime.ql	Refactored filtering logic to move constraints into source/sink predicates for better performance
rust/ql/test/query-tests/security/CWE-825/AccessAfterLifetime.expected	Updated test expectations to reflect filtered results (macro expansions and non-unsafe dereferences)

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[paldepind]

LGTM.

If I understand correctly this shouldn't change the results. But now the filtering that only depends on sources/sinks is simply done before the data flow library does any work, instead of after, and thus we get the performance improvement.

[hvitved]

If I understand correctly this shouldn't change the results. But now the filtering that only depends on sources/sinks is simply done before the data flow library does any work, instead of after, and thus we get the performance improvement.

Correct.

[geoffw0]

Oh wow, good spot. 6.2% average analysis speedup across all projects 🚀

The new code also reads cleaner to me. 👍