Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #98862

Re: Mars lander crash

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: Mars lander crash
Date 2016-12-11 19:55 +0100
Organization A noiseless patient Spider
Message-ID <o2k7c2$crl$1@dont-email.me> (permalink)
References (7 earlier) <o2es0l$sea$1@dont-email.me> <o2jgbu$ih7$1@dont-email.me> <87d1gyzhsd.fsf@bsb.me.uk> <o2k3vc$ahp$1@dont-email.me> <o2k5gi$ofr$1@dont-email.me>

Show all headers | View raw

On 11/12/16 19:23, jacobnavia wrote:
> Le 11/12/2016 à 18:57, David Brown a écrit :
>> One is that people want wildly different things for overflow detection.
>> Many are perfectly happy with today's behaviour - signed integer
>> overflow is undefined behaviour.  Others might want saturation, or
>> wrapping, or a signal, or a sentinel value (like NaN), or a testable
>> flag, or setting errno, or adding exceptions to C.
>
> You do not read the answers I give damm!
>
> The signal mechanism can cater for ALL of those!
>
> And besides (as I stated in a different message) the C standard ALREADY
> prescribes the signal mechanism for this.
>
> Integer overflow should raise the SIGFPE!

The signal mechanism is okay for a "integer overflow causes crash" 
mechanism during testing.  But it is no use for a "overflow causes 
saturation", or "overflow causes predictable wraparound", or "overflow 
detectable by the programmer at runtime", or "overflow checked in 
advance" solution.  And for processors that don't have a suitable 
trapping mechanism such as an "add and trap on overflow" instruction or 
at least a "trap if overflow flag set" instruction, it would be 
hopelessly inefficient.

And like all overflow detection mechanisms, you either wave goodbye to 
all sorts of optimisations based on the associativity and commutativity 
of integer arithmetic, or your results and possible overflows are 
totally dependent on the arrangement of code by the optimiser.

So again, this is /one/ possible type of overflow detection that may be 
of use to some people during testing and debugging.  This might be 
enough to make it worth the effort implementing it - but it is very far 
from being a universal, useful, efficient and helpful method that could 
sensibly be standardised in C.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 13:26 +0100
  Re: Mars lander crash Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 12:44 +0000
    Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 14:53 +0100
      Re: Mars lander crash already5chosen@yahoo.com - 2016-12-09 05:58 -0800
        Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 15:11 +0100
        Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 16:56 +0100
          Re: Mars lander crash supercat@casperkitty.com - 2016-12-09 08:51 -0800
          Re: Mars lander crash already5chosen@yahoo.com - 2016-12-11 02:23 -0800
            Re: Mars lander crash Gareth Owen <gwowen@gmail.com> - 2016-12-11 10:57 +0000
          Re: Mars lander crash "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-11 12:34 -0500
            Re: Mars lander crash Robert Wessel <robertwessel2@yahoo.com> - 2016-12-11 23:33 -0600
      Re: Mars lander crash Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 14:22 +0000
        Re: Mars lander crash asetofsymbols@gmail.com - 2016-12-09 06:30 -0800
          Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 15:48 +0100
        Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 15:46 +0100
          Re: Mars lander crash Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 14:55 +0000
            Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 16:08 +0100
              Re: Mars lander crash Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 15:52 +0000
          Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 17:35 +0100
            Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 18:35 +0100
              Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 19:10 +0100
                Re: Mars lander crash "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-09 19:18 -0500
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-09 16:49 -0800
                Re: Mars lander crash "J. Clarke" <j.clarke.873638@gmail.com> - 2016-12-20 20:03 -0500
                Re: Mars lander crash <william@wilbur.25thandClement.com> - 2016-12-09 22:04 -0800
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-10 10:59 -0800
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-11 13:22 +0100
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 14:18 +0100
                Re: Mars lander crash already5chosen@yahoo.com - 2016-12-11 06:03 -0800
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 15:08 +0100
                Re: Mars lander crash already5chosen@yahoo.com - 2016-12-11 06:20 -0800
                Re: Mars lander crash luser droog <luser.droog@gmail.com> - 2016-12-11 07:08 -0800
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-11 11:56 -0800
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 21:05 +0100
                Re: Mars lander crash jameskuyper@verizon.net - 2016-12-11 12:57 -0800
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 21:26 +0000
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-11 09:23 -0800
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 14:01 +0000
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 15:11 +0100
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-11 18:57 +0100
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 19:23 +0100
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-11 19:55 +0100
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 20:52 +0100
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-11 23:37 +0100
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-11 16:10 -0800
                Re: Mars lander crash BartC <bc@freeuk.com> - 2016-12-12 01:13 +0000
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-12 09:53 +0100
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-12 08:30 -0800
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-12 09:25 +0100
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-11 10:36 -0800
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 18:46 +0000
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-11 09:12 -0800
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 18:53 +0100
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-11 12:09 -0800
                Re: Mars lander crash Jean-Marc Bourguet <jm@bourguet.org> - 2016-12-11 21:30 +0100
                Re: Mars lander crash Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-11 15:50 -0500
                Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-11 23:02 +0100
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-11 18:29 -0800
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-11 12:03 -0800
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-11 11:55 -0800
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-11 23:42 +0100
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-11 14:53 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-12 17:09 +1300
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-12 10:00 +0100
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-12 22:20 +1300
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-12 01:28 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-12 22:38 +1300
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-12 02:43 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-13 08:20 +1300
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-12 12:57 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-13 14:14 +1300
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-13 01:19 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-13 22:56 +1300
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-13 05:16 -0800
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-14 18:05 +1300
                Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-13 08:19 -0800
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-13 17:01 +0000
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-13 10:48 -0800
                Re: Mars lander crash Geoff <geoff@invalid.invalid> - 2016-12-13 11:56 -0800
                Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-13 13:37 -0800
                Re: Mars lander crash Geoff <geoff@invalid.invalid> - 2016-12-13 19:11 -0800
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-13 20:13 +0100
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-13 11:45 -0800
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-13 23:10 +0000
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-14 10:18 +0100
                Re: Mars lander crash Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-14 12:37 +0000
                Re: Mars lander crash Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-14 21:31 -0800
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-15 13:26 +0100
                Re: Mars lander crash Ian Collins <ian-news@hotmail.com> - 2016-12-12 22:40 +1300
                Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-12 13:22 +0100
                Re: Mars lander crash supercat@casperkitty.com - 2016-12-12 08:35 -0800
        Re: Mars lander crash supercat@casperkitty.com - 2016-12-09 08:43 -0800
      Re: Mars lander crash Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 09:47 -0500
        Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 16:11 +0100
          Re: Mars lander crash Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 10:49 -0500
  Re: Mars lander crash already5chosen@yahoo.com - 2016-12-09 05:53 -0800
    Re: Mars lander crash asetofsymbols@gmail.com - 2016-12-09 06:04 -0800
      Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 15:09 +0100
        Re: Mars lander crash Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 10:06 -0500
          Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 16:32 +0100
    Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 17:30 +0100
      Re: Mars lander crash BartC <bc@freeuk.com> - 2016-12-09 16:42 +0000
      Re: Mars lander crash Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-09 11:43 -0500
      Re: Mars lander crash Keith Thompson <kst-u@mib.org> - 2016-12-09 08:59 -0800
      Re: Mars lander crash "J. Clarke" <j.clarke.873638@gmail.com> - 2016-12-20 19:36 -0500
  Re: Mars lander crash "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-09 06:46 -0800
    Re: Mars lander crash Richard Heathfield <rjh@cpax.org.uk> - 2016-12-09 14:57 +0000
      Re: Mars lander crash Noob <root@127.0.0.1> - 2016-12-09 16:07 +0100
    Re: Mars lander crash David Brown <david.brown@hesbynett.no> - 2016-12-09 16:03 +0100
      Re: Mars lander crash "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-09 12:41 -0500
    Re: Mars lander crash Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 10:52 -0500
      Re: Mars lander crash jameskuyper@verizon.net - 2016-12-09 12:13 -0800
        Re: Mars lander crash jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-09 21:56 +0100
          Re: Mars lander crash jameskuyper@verizon.net - 2016-12-09 14:11 -0800
        Re: Mars lander crash Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-09 22:46 -0500
          Re: Mars lander crash <william@wilbur.25thandClement.com> - 2016-12-09 22:34 -0800
          Re: Mars lander crash James Kuyper <jameskuyper@verizon.net> - 2016-12-10 18:38 -0500
      Re: Mars lander crash Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-11 06:06 -0800
  Re: Mars lander crash "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-12-10 01:17 +0800
  Re: Mars lander crash Ken Brody <kenbrody@spamcop.net> - 2016-12-13 14:28 -0500
  Re: Mars lander crash Ken Brody <kenbrody@spamcop.net> - 2016-12-13 14:30 -0500

csiph-web