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Re: Performance of hand-optimised assembly

From jacob navia <jacob@spamsink.net>
Newsgroups comp.lang.c
Subject Re: Performance of hand-optimised assembly
Date 2012-01-07 10:33 +0100
Organization lccwin
Message-ID <je93gh$ij1$1@speranza.aioe.org> (permalink)
References <0.d0ecd8f477637819bed2.20111223184332GMT.87pqffjfhn.fsf@bsb.me.uk> <jd7sjj$gum$1@speranza.aioe.org> <11940381.755.1324841772361.JavaMail.geo-discussion-forums@pruu23> <jd81e9$qs5$1@speranza.aioe.org> <je8lqu$24b$1@dont-email.me>

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Le 07/01/12 06:39, Stephen Sprunk a écrit :
> On 25-Dec-11 14:35, jacob navia wrote:
>> Look at this:
>>
>> void doADD(double *L, double *R, double *result,size_t n)
>> {
>>      for(size_t i=0; i<n;i++) result[i]=L[i]+R[i];
>> }
>>
>> Assembly will always do better than standard C in the above specific
>> code. You can then use the ADDPD and add 2 integers at the same time
>> (under specific loop conditions).
>
> Really?  I don't know how to get GCC to assume the arrays above are
> properly aligned, though I'm sure there's a way.


Maybe, but that is exactly my point. Why couldn't we be able to
DECLARE that those arrays are properly aligned and are suitable
for SIMD processing?

Why should we expect that the compiler implements a HUGE and
brittle machinery to DEDUCE that instead?

Wouldn't it be simpler if we would just be able to declare those
in the same way that we say:
	int i;
instead of expecting the commpiler to DEDUCE that because of the
usage of that variable it must be an int?

See that other thread I started about containers and SIMD
programming.

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Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-23 18:43 +0000
  Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-23 19:40 +0000
    Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-23 21:26 +0000
      Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-23 22:02 +0000
        Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-24 02:52 +0000
          Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-23 20:32 -0800
            Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 13:09 +0000
              Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-24 05:49 -0800
                Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 15:30 +0000
                Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-24 08:15 -0800
                Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 17:10 +0000
                Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-24 23:25 +0000
                Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2012-01-04 03:24 +0000
                Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-04 09:59 +0100
                Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2012-01-04 20:57 +0000
                Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2012-01-04 23:04 +0000
                Re: Performance of hand-optimised assembly Noob <root@127.0.0.1> - 2012-01-05 13:32 +0100
              Re: Performance of hand-optimised assembly Philip Lantz <prl@canterey.us> - 2011-12-24 15:29 -0800
          Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 12:42 +0000
            Re: Performance of hand-optimised assembly Jens Gustedt <jens.gustedt@loria.fr> - 2011-12-24 16:58 +0100
          Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 13:55 +0000
            Re: Performance of hand-optimised assembly Seebs <usenet-nospam@seebs.net> - 2011-12-24 19:24 +0000
              Re: Performance of hand-optimised assembly Geoff <geoff@invalid.invalid> - 2011-12-24 13:44 -0800
            Re: Performance of hand-optimised assembly Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-29 02:53 +0200
              Re: Performance of hand-optimised assembly Rui Maciel <rui.maciel@gmail.com> - 2011-12-29 02:11 +0000
  Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2011-12-24 01:36 +0000
  Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2011-12-24 06:44 +0100
    Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2011-12-24 09:52 +0100
    Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2011-12-26 08:05 +0100
      Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-26 11:52 -0800
        Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2011-12-27 07:28 +0100
  Re: Performance of hand-optimised assembly Willem <willem@toad.stack.nl> - 2011-12-24 12:48 +0000
    Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-24 04:56 -0800
    Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-24 23:39 +0000
  Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-24 06:01 -0800
    Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-24 14:55 +0000
      Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-28 03:46 -0800
        Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-28 04:52 -0800
    Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-25 00:07 +0000
      Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-28 03:21 -0800
        Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-28 13:19 +0000
          Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-28 16:01 +0000
            Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-28 17:45 +0000
              Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-28 18:56 -0800
            Re: Performance of hand-optimised assembly Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-29 03:32 +0200
            Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 17:03 -0800
              Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-26 22:08 +0000
                Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 22:20 -0800
        Re: Performance of hand-optimised assembly James Kuyper <jameskuyper@verizon.net> - 2011-12-28 08:24 -0500
        Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-28 14:27 +0000
          Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 16:50 -0800
            Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-26 21:59 +0000
        Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-28 11:12 -0800
        Re: Performance of hand-optimised assembly Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-29 03:12 +0200
          Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-29 10:02 +0100
            Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-12-29 12:06 +0000
            Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 17:07 -0800
              Re: Performance of hand-optimised assembly Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-13 01:18 +0200
                Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 10:54 -0800
          Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-29 10:02 +0100
          Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-29 12:06 +0000
            Re: Performance of hand-optimised assembly Keith Thompson <kst-u@mib.org> - 2011-12-29 11:44 -0800
            Re: Performance of hand-optimised assembly Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 17:23 -0800
          Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2011-12-29 08:37 -0800
            Re: Performance of hand-optimised assembly Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-01-05 22:19 +0200
  Re: Performance of hand-optimised assembly James Dow Allen <gmail@jamesdowallen.nospam> - 2011-12-24 16:21 +0000
    Re: Performance of hand-optimised assembly Weland <weland@otaku.freeshell.org> - 2011-12-25 10:54 +0000
  Re: Performance of hand-optimised assembly "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2011-12-24 14:52 -0800
  Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-25 20:12 +0100
    Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-25 11:36 -0800
      Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-25 21:35 +0100
        Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2011-12-26 14:24 -0600
          Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-26 21:36 +0100
            Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2012-01-04 11:59 -0600
              Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-04 20:22 +0100
                Re: Performance of hand-optimised assembly Dann Corbit <dcorbit@connx.com> - 2012-01-04 12:59 -0800
                Re: Performance of hand-optimised assembly James Harris <james.harris.1@googlemail.com> - 2012-01-04 15:32 -0800
                Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2012-01-05 23:47 -0600
                Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-04 22:47 +0000
                Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-05 00:47 +0100
                Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-05 00:22 +0000
                Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-04 23:44 -0800
                Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2012-01-05 12:16 +0000
                Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2012-01-05 12:49 +0000
                Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2012-01-05 21:26 +0000
                Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2012-01-07 10:32 +0100
                Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-05 00:58 +0100
                Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-05 13:39 -0800
                Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-07 02:15 -0800
                Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-10 01:07 -0800
                Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2012-01-07 00:49 +0000
                Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-07 08:54 +0100
                Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-07 10:11 +0100
                Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2012-01-07 10:51 +0100
                Re: Performance of hand-optimised assembly jgk@panix.com (Joe keane) - 2012-01-07 20:09 +0000
        Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2012-01-06 23:39 -0600
          Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2012-01-07 10:33 +0100
            Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2012-01-07 07:36 -0600
              Re: Performance of hand-optimised assembly Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-07 21:03 +0000
                Re: Performance of hand-optimised assembly Stephen Sprunk <stephen@sprunk.org> - 2012-01-07 16:42 -0600
    Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-25 20:23 +0000
      Re: Performance of hand-optimised assembly jacob navia <jacob@spamsink.net> - 2011-12-25 21:50 +0100
        Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-25 22:10 +0000
      Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-25 13:11 -0800
        Re: Performance of hand-optimised assembly "BartC" <bc@freeuk.com> - 2011-12-25 22:07 +0000
          Re: Performance of hand-optimised assembly 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-25 16:39 -0800
  Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2011-12-26 05:55 +0100
    Re: Performance of hand-optimised assembly "io_x" <a@b.c.invalid> - 2012-02-17 17:58 +0100
  Re: Performance of hand-optimised assembly "Wolfgang.Draxinger" <Wolfgang.Draxinger@physik.uni-muenchen.de> - 2012-01-10 18:00 +0100

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