[lelanthran]

> At this point UB and leveraging it for optimization are core parts of the most performant C implementations.

I am skeptical that NULL-pointer checks being removed contribute anything more than a rounding error in performance gains in any non-trivial program.

[charleslmunger]

I got a measurable improvement from eliminating a null pointer check within the last week. Billions of devices have arm little cores, and the extra branch predictor pressure and frontend bandwidth from those instructions can be significant.

A standard way to eliminate those is to invoke undefined behavior if some condition is not met;

    if (a == NULL) {
      __builtin_unreachable();
    }

Which then allows elimination of the null check in later code, possibly after inlining some function.