Re: [boost] Yap's formal review is starting now!

Subject: Re: [boost] Yap's formal review is starting now!
From: Zach Laine (whatwasthataddress_at_[hidden])
Date: 2018-02-19 01:58:55

On Sun, Feb 18, 2018 at 7:22 PM, Louis Dionne via Boost <
boost_at_[hidden]> wrote:

> On Thu, Feb 15, 2018 at 2:30 PM, Peter Dimov via Boost <
> boost_at_[hidden]> wrote:
>
> > Zach Laine wrote:
> >
> > > Doesn't seem so according to metaben.ch.
> >>
> >> None of those measures time to compile simple construction.
> >>
> >
> > There is such a benchmark, "make", and it does show std::tuple a lot
> > slower (2-5x depending on number of elements.)
> >
> > YAP tuples aren't going to have 100 elements though, and for short
> tuples,
> > there isn't that much of a difference.
> >
>
> The problem is not that you're not creating long tuples, it's that you're
> creating many short ones. If you look at 10 elements, for example, it's
> still 10x faster to create a hana::tuple than a std::tuple (chart:
> https://imgur.com/a/To5JZ). If the cost of creating tuples dominates the
> compilation time for code that uses Yap, switching to std::tuple in the
> backend could incur a noticeable slowdown. Similarly, using something even
> more basic like hana::basic_tuple or rolling your own tuple (without EBO
> support for example) might yield additional speedups. Of course, it's hard
> to tell without doing the work and trying it out.
>

Thanks, Louis.  This is more like the very large difference in compile
times that I remembered when I last looked at this.

Zach