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Groups > comp.arch.embedded > #26007

Re: Language feature selection

From Paul Rubin <no.email@nospam.invalid>
Newsgroups comp.arch.embedded
Subject Re: Language feature selection
Date 2017-03-11 02:22 -0800
Organization A noiseless patient Spider
Message-ID <871su4qfj7.fsf@nightsong.com> (permalink)
References (7 earlier) <zBGwA.237681$qK5.83287@fx45.am4> <4gj6cc5c94jm8ikg4ntkprj8pugasrbqvf@4ax.com> <87h930r2ed.fsf@nightsong.com> <dcg7cch6th0jau9eodd7c2dd0nljqh088t@4ax.com> <dXPwA.64578$PU6.59964@fx13.am4>

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Tom Gardner <spamjunk@blueyonder.co.uk> writes:
> Is that a long way to making the program fast or to making it correct?

It's for speed.  If the compiler can figure out that that *x and *y are
in separate memory locations, then it knows updating *x won't change *y.
That means more temporaries can be kept in registers, avoiding some
memory loads and stores.  The speedups are significant.

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Thread

Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-05 16:03 -0700
  Re: Language feature selection Wouter van Ooijen <wouter@voti.nl> - 2017-03-06 08:04 +0100
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 10:31 -0700
      Re: Language feature selection Wouter van Ooijen <wouter@voti.nl> - 2017-03-07 23:29 +0100
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-08 02:49 -0700
          Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-08 13:18 +0100
            Re: Language feature selection Wouter van Ooijen <wouter@voti.nl> - 2017-03-08 16:58 +0100
            Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-08 10:35 -0700
              Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-08 22:07 +0100
  Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-06 08:40 +0100
    Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-06 10:31 +0100
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 08:47 -0700
      Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-06 21:33 +0100
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 13:44 -0700
          Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-07 12:24 +0100
            Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 09:34 -0700
              Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-08 10:14 +0100
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-08 10:37 -0700
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-08 22:09 +0100
    Re: Language feature selection Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-06 22:50 +0200
      Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-07 12:31 +0100
    Re: Language feature selection rickman <gnuarm@gmail.com> - 2017-03-07 14:45 -0500
  Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-06 08:39 +0000
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 08:39 -0700
      Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-06 17:27 +0000
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 13:30 -0700
  Re: Language feature selection Dimiter_Popoff <dp@tgi-sci.com> - 2017-03-06 11:11 +0200
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 13:38 -0700
      Re: Language feature selection Dimiter_Popoff <dp@tgi-sci.com> - 2017-03-07 12:18 +0200
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 10:28 -0700
  Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-06 13:33 -0500
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 13:36 -0700
      Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-06 22:15 -0500
        Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-06 22:22 -0500
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 00:27 -0700
          Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-08 12:20 -0500
            Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-08 11:23 -0700
              Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-10 13:43 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 16:49 -0700
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-11 04:17 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 12:33 -0700
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-12 18:08 -0400
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-12 17:25 -0700
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-15 21:05 -0400
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-16 17:23 -0700
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-17 23:59 -0400
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-17 23:25 -0700
                Re: Language feature selection Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-18 12:05 +0200
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-18 04:04 -0700
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-18 04:39 -0700
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-18 03:55 -0700
                Re: Language feature selection upsidedown@downunder.com - 2017-03-18 16:00 +0200
                Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-11 16:35 -0600
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 15:39 -0700
  Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-06 18:59 +0000
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-06 12:36 -0700
  Re: Language feature selection Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-07 19:02 +0000
    Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-07 19:18 +0000
      Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-07 19:19 +0000
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 12:38 -0700
  Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-07 22:10 -0600
    Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-07 20:35 -0800
      Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-08 20:43 -0600
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-07 23:48 -0700
      Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-08 20:48 -0600
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-08 21:15 -0700
        Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-09 01:33 -0800
        Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-09 14:47 +0000
          Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-09 16:40 +0100
            Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-09 16:15 +0000
              Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-09 22:04 +0100
                Re: Language feature selection John Devereux <john@devereux.me.uk> - 2017-03-10 07:46 +0000
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-10 13:21 +0100
              Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-09 17:57 -0600
                Re: Language feature selection Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-10 11:16 +0200
        Re: Language feature selection Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2017-03-10 20:39 +0100
          Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-10 13:32 -0800
            Re: Language feature selection Niklas Holsti <niklas.holsti@tidorum.invalid> - 2017-03-11 14:58 +0200
              Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-13 13:02 +0100
    Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-08 10:46 +0100
      Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-08 20:33 -0600
        Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-09 11:08 +0100
          Re: Language feature selection Britt <britt.snodgrass@gmail.com> - 2017-03-09 07:04 -0800
            Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-09 16:36 +0100
              Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-09 16:11 +0000
              Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-09 12:06 -0600
              Re: Language feature selection Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2017-03-09 19:26 +0100
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-09 22:08 +0100
            Re: Language feature selection Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-09 19:04 +0000
              Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-09 15:34 -0700
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-09 15:40 -0700
                Re: Language feature selection Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-10 14:19 +0000
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 11:10 -0700
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 11:49 -0700
        Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-09 18:00 -0600
    Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-09 17:54 -0600
      Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-09 18:54 -0600
        Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-10 04:07 +0000
          Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-10 08:07 -0600
        Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-10 13:59 +0100
      Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-10 08:17 +0000
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 11:24 -0700
          Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-10 19:09 +0000
            Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 12:33 -0700
              Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-10 23:25 +0000
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-10 20:22 -0500
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 01:32 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-10 18:16 -0800
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 09:59 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-11 02:23 -0800
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 11:13 +0000
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-11 14:28 -0500
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-11 17:20 -0500
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-12 16:26 -0400
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-12 21:46 +0100
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-12 23:15 +0000
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-13 14:14 -0400
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-13 18:48 +0000
                Re: Language feature selection "Brian G. Lucas" <bagel99@gmail.com> - 2017-03-13 15:17 -0500
                Re: Language feature selection Niklas Holsti <niklas.holsti@tidorum.invalid> - 2017-03-13 23:17 +0200
                Re: Language feature selection "Brian G. Lucas" <bagel99@gmail.com> - 2017-03-13 17:27 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-13 17:10 -0700
                Re: Language feature selection Niklas Holsti <niklas.holsti@tidorum.invalid> - 2017-03-14 10:11 +0200
                Re: Language feature selection "Brian G. Lucas" <bagel99@gmail.com> - 2017-03-14 12:23 -0500
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-14 13:27 +0100
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-14 13:30 -0400
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-14 22:03 +0100
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-14 17:24 -0400
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-11 07:19 -0600
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 19:43 +0000
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-12 09:28 -0600
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-12 15:15 -0400
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-12 19:38 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-10 18:08 -0800
                Re: Language feature selection George Neuner <gneuner2@comcast.net> - 2017-03-11 04:22 -0500
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 10:02 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-11 02:22 -0800
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 11:07 +0000
          Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-10 14:30 -0600
            Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-10 13:37 -0800
              Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-10 16:30 -0600
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-10 18:14 -0800
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-11 07:46 -0600
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 12:53 -0700
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-12 09:45 -0600
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-12 11:56 -0700
                Re: Language feature selection Dimiter_Popoff <dp@tgi-sci.com> - 2017-03-12 21:05 +0200
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-12 14:40 -0700
                Re: Language feature selection Dimiter_Popoff <dp@tgi-sci.com> - 2017-03-13 00:36 +0200
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-12 17:00 -0700
                Re: Language feature selection Robert Wessel <robertwessel2@yahoo.com> - 2017-03-13 16:50 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-13 17:08 -0700
                Re: Language feature selection Robert Wessel <robertwessel2@yahoo.com> - 2017-03-13 20:51 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-13 20:31 -0700
                Re: Language feature selection Robert Wessel <robertwessel2@yahoo.com> - 2017-03-14 21:45 -0500
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-14 21:16 -0700
                Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-11 16:40 -0600
            Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 15:10 -0700
              Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-10 16:42 -0600
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 17:02 -0700
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 00:46 +0000
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 13:05 -0700
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 21:58 +0000
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 15:19 -0700
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-11 23:27 +0000
                Re: Language feature selection Walter Banks <walter@bytecraft.com> - 2017-03-10 20:14 -0600
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 12:16 -0700
        Re: Language feature selection Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2017-03-10 20:40 +0100
          Re: Language feature selection Wouter van Ooijen <wouter@voti.nl> - 2017-03-10 22:28 +0100
  Re: Language feature selection Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2017-03-10 20:03 +0100
    Re: Language feature selection Grant Edwards <invalid@invalid.invalid> - 2017-03-10 19:48 +0000
      Re: Language feature selection Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2017-03-13 21:25 +0100
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-10 13:03 -0700
      Re: Language feature selection Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2017-03-13 21:40 +0100
        Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-13 14:35 -0700
          Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-14 01:06 +0000
            Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-13 19:23 -0700
              Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-14 08:48 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-14 02:14 -0700
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-14 09:33 +0000
                Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-14 09:21 -0700
                Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-17 06:01 -0500
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-17 11:39 +0000
                Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-17 07:16 -0500
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-17 13:49 +0000
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-17 11:03 -0700
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-17 19:21 +0100
                Re: Language feature selection Paul Rubin <no.email@nospam.invalid> - 2017-03-17 11:34 -0700
                Re: Language feature selection David Brown <david.brown@hesbynett.no> - 2017-03-17 20:26 +0100
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-17 20:07 +0000
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-17 20:29 +0000
                Re: Language feature selection Les Cargill <lcargill99@comcast.com> - 2017-03-17 19:19 -0500
                Re: Language feature selection Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-18 08:18 +0000
            Re: Language feature selection Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2017-03-14 21:20 +0100
  Re: Language feature selection jim.brakefield@ieee.org - 2017-03-10 18:46 -0800
    Re: Language feature selection Niklas Holsti <niklas.holsti@tidorum.invalid> - 2017-03-11 15:41 +0200
      Re: Language feature selection jim.brakefield@ieee.org - 2017-03-11 14:20 -0800
        Re: Language feature selection upsidedown@downunder.com - 2017-03-12 00:54 +0200
          Re: Language feature selection jim.brakefield@ieee.org - 2017-03-12 18:08 -0700
            Re: Language feature selection upsidedown@downunder.com - 2017-03-13 23:36 +0200
          Re: Language feature selection Robert Wessel <robertwessel2@yahoo.com> - 2017-03-13 17:03 -0500
    Re: Language feature selection Don Y <blockedofcourse@foo.invalid> - 2017-03-11 14:21 -0700

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