Andres Freund <and...@anarazel.de> writes: > On 2020-01-03 18:49:18 -0500, Tom Lane wrote: >> On a machine with single-cycle divide, it's likely that the extra >> compare-and-branch is a net loss.
> Which architecture has single cycle division? I think it's way above > that, based on profiles I've seen. And Agner seems to back me up: > https://www.agner.org/optimize/instruction_tables.pdf > That lists a 32/64 idiv with a latency of ~26/~42-95 cycles, even on a > moder uarch like skylake-x. Huh. I figured Intel would have thrown sufficient transistors at that problem by now. But per that result, it's worth having the swap step even on CISC, never mind RISC. regards, tom lane
