Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design)

From	Ivan Godard <ivan@ootbcomp.com>
Newsgroups	comp.compilers
Subject	Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design)
Date	2014-01-13 12:47 -0800
Organization	A noiseless patient Spider
Message-ID	<14-01-012@comp.compilers> (permalink)
References	<13-11-025@comp.compilers> <14-01-007@comp.compilers> <14-01-008@comp.compilers> <14-01-011@comp.compilers>

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On 1/10/2014 3:08 PM, glen herrmannsfeldt wrote:
> Kaz Kylheku <kaz@kylheku.com> wrote:
>> On 2014-01-08, Ivan Godard <ivan@ootbcomp.com> wrote:
>
> (snip)
>>> I am such a CPU designer. We faced the "undefined" issue in our Mill
>>> family of general-purpose CPUs (ootbcomp.com). Not only are languages
>>> under-constraining, they are also sometimes over-constraining: signed
>>> integer overflow is undefined in C but required to wrap in Java.
>
>> It's only undefined on paper. In reality, if you don't make it
>> wrap in C like in Java, unknown numbers of C programs will break,
>> and not all of them doing it by accident.
>
> Well, C has unsigned with defined wrap on overflow. C still allows for
> ones complement or sign magnitude along with the more usual twos
> complement. As I understand it, Unisys still sells some ones
> complement machines. I am still waiting for a C compiler for the 7090
> to test out sign magnitude in C.

Unisys sells *both* one's complement (Univac 1100 descendants) and
sign-magnitude (Burroughs B6500 descendants).
[Wow. Is it custom hardware, or really funky simulators on normal chips? -John]

Thread

Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2013-11-20 10:29 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Joshua Cranmer 🐧 <Pidgeot18@verizon.net> - 2013-11-23 01:06 -0600
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-24 21:51 +0000
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2014-01-06 19:23 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Kaz Kylheku <kaz@kylheku.com> - 2013-12-17 23:07 +0000
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2014-01-06 19:32 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-08 09:02 -0800
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Kaz Kylheku <kaz@kylheku.com> - 2014-01-08 18:21 +0000
      Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-10 09:11 -0800
      Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-01-10 23:08 +0000
        Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-13 12:47 -0800
        Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-01-14 14:16 +0000

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