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perf(core): use index-based SafeArrayIterator in primordials - #36543
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Avoid allocating a real ArrayIterator and calling the user-patchable ArrayIteratorPrototype.next path. Microbenches show ~1.1–2.7× speedup depending on for-of vs spread call patterns. Track exhaustion explicitly so an iterator remains done after its backing array grows, matching built-in ArrayIterator semantics. Add regression coverage for resuming after an early exit and remaining done after exhaustion.
bartlomieju
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Aug 27, 2026
Avoid allocating a real `ArrayIterator` and calling the user-patchable `ArrayIteratorPrototype.next` path. Microbenches show ~1.1–2.7× speedup depending on for-of vs spread call patterns. Track exhaustion explicitly so an iterator remains done after its backing array grows, matching built-in `ArrayIterator` semantics. Add regression coverage for resuming after an early exit and remaining done after exhaustion.
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Avoid allocating a real
ArrayIteratorand calling the user-patchableArrayIteratorPrototype.nextpath. Microbenches show ~1.1–2.7× speedup depending on for-of vs spread call patterns.Track exhaustion explicitly so an iterator remains done after its backing array grows, matching built-in
ArrayIteratorsemantics. Add regression coverage for resuming after an early exit and remaining done after exhaustion.I used Codex for this implementation.