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Use a Bloom filter for formatter comment lookups - #29852
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) ## Summary When source maps are disabled and the Bloom filter rules out comments on a node, the formatter can call `fmt_fields` directly. This skips cloning the comment handle and writing empty leading and trailing comments. Nodes with possible comments or source maps still take the existing path. Compared with #29852, the fast path used 4.44% fewer instructions across Ruff’s five formatter benchmarks and 2.79% fewer across ten Python standard-library modules. Synthetic assignments with leading and trailing comments used 0.13% more. These are medians from 21 paired arm64 trials that include trivia construction and printing. ## Test Plan The formatter tests passed, and the parent and this change produced identical formatted text and source-map markers across the comparison corpora.
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Summary
Most nodes have no attached comments. A 256-byte Bloom filter lets the formatter skip the comment map lookup when a node's address maps to a clear bit. On a hit, the formatter still checks the map.
Building and printing pre-parsed documents on arm64 took 4.82% fewer instructions across five Ruff benchmark fixtures and 3.40% fewer across ten Python standard-library modules, measured as the median of 21 paired runs against
main. A synthetic workload with leading and trailing comments on every assignment took 0.38% more instructions.Test Plan
The formatter tests passed, including a forced filter collision, and all benchmark inputs produced byte-for-byte identical output.