Remove dead cache from IndexSet#262
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The `IndexSet::cache` field was never populated with a real value, and `cache.set()` was only ever called with the `(INVALID, 0)` sentinel, so the fast-path in `maybe_elem()` was unreachable and the invalidation stores in `elem()` and `maybe_elem_mut()` were pure-overhead on every `set`/`get`/`union_with`. Removing it additionally shrinks `IndexSet` by 16 bytes.
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(FWIW, I also experimented with fixing the cache so that it would actually get populated, but it wasn't a speed up on Sightglass.) |
cfallin
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Jul 20, 2026
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Ah, the actual cache usage was removed a while ago -- thanks for catching this!
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The
IndexSet::cachefield was never populated with a real value, andcache.set()was only ever called with the(INVALID, 0)sentinel, so the fast-path inmaybe_elem()was unreachable and the invalidation stores inelem()andmaybe_elem_mut()were pure-overhead on everyset/get/union_with. Removing it additionally shrinksIndexSetby 16 bytes.