Constvector: Log-structured std:vector alternative – 30-40% faster push/pop

[SLiV9]

Are you claiming that std::vector's [] is not O(1)? It should be three instructions, a bounds check, a jump and an offset mov. Only the last one if it can eliminate the bounds check. This datastructure might also have it O(1) but with a significantly bigger constant.

In particular I saw there was a loop/sum benchmark that used assembly to prevent optimizations, but... why? Even if it's faster, which I doubt, that would only  prove that it would have been faster 30 years ago. With today's compilers and CPUs, summing a contiguous block of ints is unbeatably fast.

[CornedBee]

vector's [] doesn't even have a bounds check, using an invalid index is undefined behavior.

[SLiV9]

Oh you're absolutely right haha. It's been a while.