Re: Copypasta in the PostgreSQL source

On Tue, Dec 18, 2018 at 9:46 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> > On the other hand, I'm not clear on why do we need four copies of
> > number_of_ones.
>
> Yeah, it might be time to move something like that into a common
> location.  Not sure where the threshold of pain is, though.

Yeah.  I think we need bitutils.c as discussed here:


https://www.postgresql.org/message-id/flat/CAEepm%3D3k%2B%2BYtf2LNQCvpP6m1%3DgY9zZHP_cfnn47%3DWTsoCrLCvA%40mail.gmail.com

I sort of foundered on the the difficulty of using popcnt and
bitscan/log2 instructions/builtins without putting a runtime test and
a honking great function pointer in front of them.  +1 for at least
deduplicating all these implementations as discussed in that thread.

-- 
Thomas Munro
http://www.enterprisedb.com