Re: [boost] [sort] pdqsort

Subject: Re: [boost] [sort] pdqsort
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2017-01-30 18:11:58

On 26/01/2017 23:33, Orson Peters wrote:
> Hi, Orson here, I'm the original author of pdqsort.

Hi Orson,

> As discussed in this long github issue (
> https://github.com/boostorg/sort/issues/11), I have full copyright on the
> pdqsort implementation (which is freely available under the zlib license on
> https://github.com/orlp/pdqsort), and am willing to provide it to Boost
> free of charge under the Boost license.

Wonderful. I think it'll be very useful in Boost.

> I will revert pdqsort's default implementation to the old version, except
> when the passed in type is built-in, and the comparison operator is
> std::less / std::greater, then I will use the branchless code. I will
> provide the branchless code explicitly as well, under a different function
> name, for experienced users that know their comparison function is
> branchless. The old implementation was never slower than std::sort in my
> experiments, for the record.

Sounds good. The branchless part is interesting, but speed up in 
patterns (which I guess includes partially sorted data) is the most 
important feature IMHO.

> If any of you have further questions, please do let me know.

Thanks!

Ion