Use shared helper function for faster index range checks #120176

#9784 (discussed in #72583 and #67741) introduced a helper function to reduce the number of comparisons in list index range checks (see https://godbolt.org/z/jM8oexT1d).

The same pattern can be applied in many other places in the code base like in arraymodule.c, mmapmodule.c, bytearrayobject.c, etc.

I'd propose to extract this helper function into a header and start using it in more places for index range checks. internal/pycore_abstract.h seems like it might be a decent place to put this helper in.

I'm happy to make a PR if people think a micro optimisation like this justifies the code churn, but let me know if I'm missing something.

Linked PRs

• gh-120176: Reduce number of compares in index range checks #120181