Horton

Re: micro-optimizing json.c

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Joe Conway <mail@joeconway.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, Davin Shearer <davin@apache.org>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2023-12-08T04:51:15Z
Lists: pgsql-hackers 
On Fri, Dec 8, 2023 at 10:32 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> On Fri, Dec 08, 2023 at 04:11:52PM +1300, David Rowley wrote:
> > + seplen = use_line_feeds ? sizeof(",\n ") - 1 : sizeof(",") - 1;
> >
> > Most modern compilers will be fine with just:
> >
> > seplen = strlen(sep);
> >
> > I had to go back to clang 3.4.1 and GCC 4.1.2 to see the strlen() call
> > with that code [1].
>
> Hm.  I tried this first, but my compiler (gcc 9.4.0 on this machine) was
> still doing the strlen()...

This is less verbose and still compiles with constants:

use_line_feeds ? strlen(",\n ") : strlen(",");

Commits

  1. Micro-optimize datum_to_json_internal() some more.

  2. Micro-optimize JSONTYPE_NUMERIC code path in json.c.