Wilco (Wilco.Dijkstra.delete@this.ntlworld.com) on October 21, 2017 7:16 am wrote:
> Adrian (a.delete@this.acm.org) on October 21, 2017 1:49 am wrote:
> > Maynard Handley (name99.delete@this.name99.org) on October 20, 2017 8:16 pm wrote:
>
> > The low performance for multi-precision operations is not surprising.
> >
> > While this version of Mathematica can probably be improved a lot, it cannot not reach parity
> > with x86, because this (support for multi-precision operations) is exactly the area were the
> > ARMv8 ISA is the most deficient compared with the x86 ISA (especially since Broadwell, but
> > also Intel since Nehalem & the AMD before Bulldozer were far above any competition).
>
> What essential instructions do you think are missing? It's trivial to do fast bignums on AArch64, so
> adding new instructions cannot give much gain, let alone 20x. Most likely the difference is due to using
> a badly written generic C implementation in one case and hand optimized assembly in the other.
>
> Wilco
>
>

clang has primitives for exactly that sort of tasks, but right now they appear to do more harm that good, at least on x86. Generated code is horrible.

https://godbolt.org/g/RT9hNL

So far I didn't figure out how to force clang of goldbolt to generate aarch64 code.