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Inline the per-item equality check in list.__contains__/index/count/remove #159092
Description
Feature or enhancement
list.__contains__(), index(), count(), remove(), and element comparisons in list.__eq__() use PyObject_RichCompareBool() for each element.
During a scan, the search value is fixed. Since we already know its type and its value, when an element has the same exact built-in type (int, float, or str), its comparison implementation is already known. Going through generic rich-comparison dispatch adds unnecessary type-dispatch and slot-handling overhead.
Add a fast path for these exact-type pairs, fall back to PyObject_RichCompareBool() for other cases.
Has this already been discussed elsewhere?
This is a minor feature, which does not need previous discussion elsewhere
Links to previous discussion of this feature:
No response
Activity
pythongh-159092: Optimize comparisons in list operations
pythongh-159092: Optimize comparisons in list operations
[-]Inline the per-item equality check in list.__contains__/index/count/remove[/-][+]Inline the per-item equality check in `list.__contains__/index/count/remove`[/+]corona10 commentedon Oct 10, 2026
My two cent is that if this workload is important this should be part of specializer rather than each implementation.
pythongh-159092: Optimize comparisons in list operations
pythongh-159092: Check inlined list comparisons in debug builds
pythongh-159092: Limit the list comparison fast path to list.__contai…