emacs-orgmode@gnu.org archives
 help / color / mirror / code / Atom feed
From: Bernhard Voelker <mail@bernhard-voelker.de>
To: Paul Eggert <eggert@cs.ucla.edu>, Eli Zaretskii <eliz@gnu.org>
Cc: emacs-orgmode@gnu.org, manikulin@gmail.com,
	Gnulib bugs <bug-gnulib@gnu.org>,
	54764@debbugs.gnu.org
Subject: Re: bug#54764: encode-time: make DST and TIMEZONE fields of the list argument optional ones
Date: Sat, 23 Apr 2022 16:35:41 +0200	[thread overview]
Message-ID: <199c2d68-7057-ca0e-477c-645ca39f1709@bernhard-voelker.de> (raw)
In-Reply-To: <9e4781b2-2ffa-b1ce-09b4-ead82cad9038@cs.ucla.edu>

On 4/20/22 20:19, Paul Eggert wrote:
> diff --git a/lib/gettime-res.c b/lib/gettime-res.c
> index 611f83ad27..bb4d0b191d 100644
> --- a/lib/gettime-res.c
> +++ b/lib/gettime-res.c
> @@ -53,6 +53,8 @@ gettime_res (void)
>
>    long int hz = TIMESPEC_HZ;
>    long int r = hz * res.tv_sec + res.tv_nsec;
> +  struct timespec earlier;
> +  earlier.tv_nsec = -1;
>
>    /* On some platforms, clock_getres (CLOCK_REALTIME, ...) yields a
>       too-large resolution, under the mistaken theory that it should
> @@ -61,9 +63,22 @@ gettime_res (void)
>       resolution.  Work around the problem with high probability by
>       trying clock_gettime several times and observing the resulting
>       bounds on resolution.  */
> -  for (int i = 0; 1 < r && i < 32; i++)
> +  int nsamples = 32;
> +  for (int i = 0; 1 < r && i < nsamples; i++)
>      {
> -      struct timespec now = current_timespec ();
> +      /* If successive timestamps disagree the clock resolution must
> +         be small, so exit the inner loop to check this sample.
> +         Otherwise, arrange for the outer loop to exit but continue
> +         the inner-loop search for a differing timestamp sample.  */
> +      struct timespec now;
> +      for (;; i = nsamples)
> +        {
> +          now = current_timespec ();
> +          if (earlier.tv_nsec != now.tv_nsec || earlier.tv_sec != now.tv_sec)
> +            break;
> +        }
> +      earlier = now;
> +
>        r = gcd (r, now.tv_nsec ? now.tv_nsec : hz);
>      }

lib/gettime-res.c: In function 'gettime_res':
lib/gettime-res.c:77:46: error: 'earlier.tv_sec' may be used uninitialized in this function \
[-Werror=maybe-uninitialized]
   77 |           if (earlier.tv_nsec != now.tv_nsec || earlier.tv_sec != now.tv_sec)
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


We know that earlier.tv_sec is set when tv_nsec is set, but the compiler does not,
obviously.  Considering the nested loops, I'd say initializing tv_sec doesn't
harm performance-wise.

Have a nice day,
Berny


  parent reply	other threads:[~2022-04-23 15:00 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-07 12:37 Max Nikulin
2022-04-09  7:52 ` Paul Eggert
2022-04-10  3:57   ` Max Nikulin
2022-04-13 14:40   ` Max Nikulin
2022-04-13 18:35     ` Paul Eggert
2022-04-14 13:19       ` Max Nikulin
2022-04-14 22:46         ` Paul Eggert
2022-04-15  2:14           ` Tim Cross
2022-04-15 17:23           ` Max Nikulin
2022-04-16 19:23             ` Paul Eggert
2022-04-21 16:59               ` Max Nikulin
2022-04-19  2:02             ` Paul Eggert
2022-04-19  5:50               ` Eli Zaretskii
2022-04-19 22:22                 ` Paul Eggert
2022-04-20  7:23                   ` Eli Zaretskii
2022-04-20 18:19                     ` Paul Eggert
2022-04-20 18:41                       ` Eli Zaretskii
2022-04-20 19:01                         ` Paul Eggert
2022-04-20 19:14                           ` Eli Zaretskii
2022-04-20 19:23                             ` Paul Eggert
2022-04-20 19:30                               ` Eli Zaretskii
2022-04-21  0:11                                 ` Paul Eggert
2022-04-21  6:44                                   ` Eli Zaretskii
2022-04-21 23:56                                     ` Paul Eggert
2022-04-22  5:01                                       ` Eli Zaretskii
2022-04-23 14:35                       ` Bernhard Voelker [this message]
2022-04-20 15:07               ` Max Nikulin
2022-04-20 18:29                 ` Paul Eggert
2022-04-25 15:30                   ` Max Nikulin
2022-04-25 15:37                     ` Paul Eggert
2022-04-25 19:49                       ` Paul Eggert
2022-04-30 11:22                         ` Max Nikulin
2022-05-01  2:32                           ` Paul Eggert
2022-05-01 17:15                             ` Max Nikulin
2022-04-13 15:12   ` Max Nikulin
2022-04-16 16:26   ` Max Nikulin
2022-04-17  1:58     ` Paul Eggert
2022-04-20 16:56       ` Max Nikulin
2022-04-20 19:17         ` Paul Eggert

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.orgmode.org/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=199c2d68-7057-ca0e-477c-645ca39f1709@bernhard-voelker.de \
    --to=mail@bernhard-voelker.de \
    --cc=54764@debbugs.gnu.org \
    --cc=bug-gnulib@gnu.org \
    --cc=eggert@cs.ucla.edu \
    --cc=eliz@gnu.org \
    --cc=emacs-orgmode@gnu.org \
    --cc=manikulin@gmail.com \
    --subject='Re: bug#54764: encode-time: make DST and TIMEZONE fields of the list argument optional ones' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Code repositories for project(s) associated with this inbox:

	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).