Horton

Re: Performance improvements for src/port/snprintf.c

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Kuzmenkov <a.kuzmenkov@postgrespro.ru>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2018-09-12T18:14:15Z
Lists: pgsql-hackers

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Alexander Kuzmenkov <a.kuzmenkov@postgrespro.ru> writes:
> I benchmarked this, using your testbed and comparing to libc sprintf 
> (Ubuntu GLIBC 2.27-0ubuntu3) and another implementation I know [1], all 
> compiled with gcc 5.

Thanks for reviewing!

The cfbot noticed that the recent dlopen patch conflicted with this in
configure.in, so here's a rebased version.  The code itself didn't change.

			regards, tom lane

Commits

  1. Improve snprintf.c's handling of NaN, Infinity, and minus zero.

  2. Rationalize snprintf.c's handling of "ll" formats.

  3. Provide fast path in snprintf.c for conversion specs that are just "%s".

  4. Make assorted performance improvements in snprintf.c.

  5. Set snprintf.c's maximum number of NL arguments to be 31.

  6. Always use our own versions of *printf().