Re: is Vax addressing sane today

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Sujet : Re: is Vax addressing sane today
De : niklas.holsti (at) *nospam* tidorum.invalid (Niklas Holsti)
Groupes : comp.arch
Date : 10. Sep 2024, 19:55:37
Autres entêtes
Organisation : Tidorum Ltd
Message-ID : <lkbfgpFamojU1@mid.individual.net>
References : 1 2 3 4 5 6 7 8 9 10 11 12
User-Agent : Mozilla Thunderbird
On 2024-09-10 18:42, Anton Ertl wrote:

And it seems to me that Swift with its trapping arithmetic is a
blast from the past
The dominance of C and its descendants has corrupted the world of programming on this point. :-(
Fortunately, among up-and-coming new languages Rust is in the overflow-checking camp, at least in DEBUG-mode compilations.

(with Algol, Pascal etc. usually erroring out on overflow, and Ada raising an exception (with famously explosive consequences for the Ariane 5)),
A bit misleading, as so often when the Ariane 501 incident is brought up.
The Ariane 501 failure was a HW trap on an instruction converting a floating-point value into a 16-bit integer, not an Ada exception.
As I understand it, the analogous C code could have used the same instruction and failed in the same way (an example of Undefined Behavior)
The original designers of that Ada SW had carefully analysed the possible ranges of the numbers and correctly concluded that an overflow could not happen if the HW operated correctly. Correctly, that is, for the Ariane 4, but not for the Ariane 5 where the SW was sloppily reused through multiple process skimps and failures.
Several other similar conversions were protected with programmed range checks and suitable alternative code paths, but the analysis showed that this particular conversion did not need such checks for the Ariane 4.
One of the process failures was that the SW was never tested with the Ariane 5 launch trajectory, which would have revealed the error.
If the SW had really used Ada exceptions (difficult as the processor was
quite maxed out) a reasonable SW designer would have added an exception
handler and could have made this part of the SW fail gracefully. But
the mission would probably not have been saved because the failure investigation found other potentially fatal flaws in the systems, pointing to more process failures.

and that the trend in safe languages is to eliminate integer overflow
by allowing arbitrarily large integers.
That is not practical in a real-time, resource-limited context, at least not without a large over-provision of computing resources. And sending the resulting over-large integer to a HW register will still fail in some way if the value is too large for the HW to accept.

Date Sujet#  Auteur
5 Sep 24 * is Vax adressing sane today134Brett
5 Sep 24 +* Re: is Vax adressing sane today122John Dallman
6 Sep 24 i+- Re: is Vax adressing sane today1Lawrence D'Oliveiro
6 Sep 24 i`* Re: is Vax adressing sane today120Anton Ertl
6 Sep 24 i +- Re: is Vax adressing sane today1Lawrence D'Oliveiro
6 Sep 24 i +* Re: is Vax adressing sane today5MitchAlsup1
7 Sep 24 i i`* Re: is Vax adressing sane today4Anton Ertl
7 Sep 24 i i `* Re: is Vax adressing sane today3Anton Ertl
7 Sep 24 i i  `* Re: is Vax addressing sane today2John Dallman
7 Sep 24 i i   `- Re: is Vax addressing sane today1Anton Ertl
7 Sep 24 i +* Re: is Vax adressing sane today111John Levine
8 Sep 24 i i`* Re: is Vax adressing sane today110Anton Ertl
8 Sep 24 i i +* Re: is Vax adressing sane today102MitchAlsup1
8 Sep 24 i i i`* Re: is Vax addressing sane today101Lawrence D'Oliveiro
9 Sep 24 i i i +* Re: is Vax addressing sane today31MitchAlsup1
9 Sep 24 i i i i`* Re: is Vax addressing sane today30Brett
9 Sep 24 i i i i +* Re: is Vax addressing sane today3MitchAlsup1
10 Sep 24 i i i i i`* Re: is Vax addressing sane today2Niklas Holsti
11 Sep 24 i i i i i `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
10 Sep 24 i i i i `* Re: is Vax addressing sane today26Anton Ertl
10 Sep 24 i i i i  +* Re: is Vax addressing sane today4Michael S
10 Sep 24 i i i i  i`* Re: is Vax addressing sane today3Anton Ertl
10 Sep 24 i i i i  i +- Re: is Vax addressing sane today1Niklas Holsti
11 Sep 24 i i i i  i `- Re: is Vax addressing sane today1Michael S
11 Sep 24 i i i i  +* Re: is Vax addressing sane today7Lawrence D'Oliveiro
11 Sep 24 i i i i  i`* Re: is Vax addressing sane today6Michael S
11 Sep 24 i i i i  i `* Re: is Vax addressing sane today5David Brown
11 Sep 24 i i i i  i  +* Re: is Vax addressing sane today2Thomas Koenig
11 Sep 24 i i i i  i  i`- Re: is Vax addressing sane today1David Brown
11 Sep 24 i i i i  i  `* Re: is Vax addressing sane today2David Schultz
13 Sep 24 i i i i  i   `- Re: is Vax addressing sane today1David Brown
11 Sep 24 i i i i  +* Re: is Vax addressing sane today5John Levine
11 Sep 24 i i i i  i`* Re: is Vax addressing sane today4Thomas Koenig
11 Sep 24 i i i i  i +* Re: is Vax addressing sane today2Anton Ertl
11 Sep 24 i i i i  i i`- Re: is Vax addressing sane today1jseigh
11 Sep 24 i i i i  i `- Re: is Vax addressing sane today1John Levine
20 Sep20:35 i i i i  `* Re: is Vax addressing sane today9Kent Dickey
21 Sep00:00 i i i i   +* Re: is Vax addressing sane today4MitchAlsup1
21 Sep03:09 i i i i   i`* Re: is Vax addressing sane today3Lawrence D'Oliveiro
21 Sep03:52 i i i i   i `* Re: is Vax addressing sane today2MitchAlsup1
21 Sep10:17 i i i i   i  `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
21 Sep03:12 i i i i   `* Re: is Vax addressing sane today4Lawrence D'Oliveiro
21 Sep03:51 i i i i    `* Re: is Vax addressing sane today3MitchAlsup1
21 Sep09:56 i i i i     +- Re: is Vax addressing sane today1Niklas Holsti
21 Sep10:18 i i i i     `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
9 Sep 24 i i i `* Re: is Vax addressing sane today69Anton Ertl
9 Sep 24 i i i  +* Re: is Vax addressing sane today3Michael S
9 Sep 24 i i i  i`* Re: is Vax addressing sane today2Anton Ertl
9 Sep 24 i i i  i `- Re: is Vax addressing sane today1Michael S
9 Sep 24 i i i  +- Re: is Vax addressing sane today1Lawrence D'Oliveiro
9 Sep 24 i i i  `* Re: is Vax addressing sane today64John Levine
10 Sep 24 i i i   `* Re: is Vax addressing sane today63Anton Ertl
10 Sep 24 i i i    `* Re: is Vax addressing sane today62Michael S
10 Sep 24 i i i     `* Re: is Vax addressing sane today61Anton Ertl
11 Sep 24 i i i      `* Re: is Vax addressing sane today60Lawrence D'Oliveiro
11 Sep 24 i i i       `* Re: is Vax addressing sane today59Anton Ertl
11 Sep 24 i i i        +* Re: what's a mainframe, was is Vax addressing sane today19John Levine
11 Sep 24 i i i        i+* Re: what's a mainframe, was is Vax addressing sane today7Stephen Fuld
11 Sep 24 i i i        ii`* Re: what's a mainframe, was is Vax addressing sane today6John Levine
11 Sep 24 i i i        ii +- Re: what's a mainframe, was is Vax addressing sane today1Stephen Fuld
11 Sep 24 i i i        ii +- Re: what's a mainframe, was is Vax addressing sane today1Thomas Koenig
12 Sep 24 i i i        ii +- Re: what's a mainframe, was is Vax addressing sane today1Terje Mathisen
13 Sep 24 i i i        ii `* Re: what's a mainframe, was is Vax addressing sane today2Lynn Wheeler
14 Sep 24 i i i        ii  `- Re: what's a mainframe, was is Vax addressing sane today1Lawrence D'Oliveiro
11 Sep 24 i i i        i+- Re: what's a mainframe, was is Vax addressing sane today1MitchAlsup1
12 Sep 24 i i i        i+* Re: what's a mainframe, was is Vax addressing sane today8Lars Poulsen
12 Sep 24 i i i        ii`* Re: what's a mainframe, was is Vax addressing sane today7John Levine
12 Sep 24 i i i        ii +- Re: what's a mainframe1Lars Poulsen
12 Sep 24 i i i        ii `* Re: what's a mainframe, was is Vax addressing sane today5Lawrence D'Oliveiro
13 Sep 24 i i i        ii  `* Re: what's a mainframe, was is Vax addressing sane today4Terje Mathisen
13 Sep 24 i i i        ii   +* Re: what's a mainframe, was is Vax addressing sane today2Lawrence D'Oliveiro
13 Sep 24 i i i        ii   i`- Re: what's a mainframe, was is Vax addressing sane today1Terje Mathisen
13 Sep 24 i i i        ii   `- Re: what's a mainframe, was is Vax addressing sane today1Lynn Wheeler
12 Sep 24 i i i        i+- Re: what's a mainframe, was is Vax addressing sane today1Lawrence D'Oliveiro
13 Sep 24 i i i        i`- Re: what's a mainframe, was is Vax addressing sane today1Lynn Wheeler
11 Sep 24 i i i        +* Re: is Vax addressing sane today35Brett
12 Sep 24 i i i        i`* Re: is Vax addressing sane today34Lawrence D'Oliveiro
12 Sep 24 i i i        i `* Re: big, fast, etc, was is Vax addressing sane today33John Levine
13 Sep 24 i i i        i  +- Re: big, fast, etc, was is Vax addressing sane today1Lawrence D'Oliveiro
13 Sep 24 i i i        i  +* Re: big, fast, etc, was is Vax addressing sane today6Terje Mathisen
13 Sep 24 i i i        i  i`* Re: big, fast, etc, was is Vax addressing sane today5Thomas Koenig
13 Sep 24 i i i        i  i +* Re: big, fast, etc, was is Vax addressing sane today3Michael S
13 Sep 24 i i i        i  i i`* Re: big, fast, etc, was is Vax addressing sane today2Thomas Koenig
14 Sep 24 i i i        i  i i `- Re: big, fast, etc, was is Vax addressing sane today1MitchAlsup1
14 Sep 24 i i i        i  i `- Re: big, fast, etc, was is Vax addressing sane today1Lawrence D'Oliveiro
13 Sep 24 i i i        i  +- Re: big, fast, etc, was is Vax addressing sane today1Anton Ertl
13 Sep 24 i i i        i  +* Re: big, fast, etc, was is Vax addressing sane today23Michael S
13 Sep 24 i i i        i  i+* Re: big, fast, etc, was is Vax addressing sane today4John Dallman
13 Sep 24 i i i        i  ii`* Re: big, fast, etc, was is Vax addressing sane today3Michael S
13 Sep 24 i i i        i  ii `* Re: big, fast, etc, was is Vax addressing sane today2John Dallman
14 Sep 24 i i i        i  ii  `- Re: big, fast, etc, was is Vax addressing sane today1Lawrence D'Oliveiro
13 Sep 24 i i i        i  i+* Re: big, fast, etc, was is Vax addressing sane today3MitchAlsup1
14 Sep21:17 i i i        i  ii`* Re: big, fast, etc, was is Vax addressing sane today2Michael S
14 Sep22:42 i i i        i  ii `- Re: big, fast, etc, was is Vax addressing sane today1MitchAlsup1
13 Sep 24 i i i        i  i+* Re: big, fast, etc, was is Vax addressing sane today14John Levine
14 Sep11:21 i i i        i  ii+* Re: big, fast, etc, was is Vax addressing sane today6Anton Ertl
14 Sep11:59 i i i        i  iii`* In-memory database (was: big, fast, etc, was is Vax addressing sane today)5Thomas Koenig
14 Sep12:45 i i i        i  iii `* Re: In-memory database (was: big, fast, etc, was is Vax addressing sane today)4Anton Ertl
14 Sep13:46 i i i        i  iii  `* Re: In-memory database (was: big, fast, etc, was is Vax addressing sane today)3Thomas Koenig
14 Sep14:48 i i i        i  iii   `* Re: In-memory database (was: big, fast, etc, was is Vax addressing sane today)2Anton Ertl
14 Sep15:41 i i i        i  iii    `- Re: In-memory database (was: big, fast, etc, was is Vax addressing sane today)1Anton Ertl
14 Sep11:42 i i i        i  ii+- Re: big, fast, etc, was is Vax addressing sane today1Lawrence D'Oliveiro
14 Sep22:32 i i i        i  ii+- Re: big, fast, etc, was is Vax addressing sane today1Michael S
14 Sep22:57 i i i        i  ii`* Re: big, fast, etc, was is Vax addressing sane today5Lynn Wheeler
14 Sep 24 i i i        i  i`- Re: big, fast, etc, was is Vax addressing sane today1Lawrence D'Oliveiro
13 Sep 24 i i i        i  `- Re: big, fast, etc, was is Vax addressing sane today1Lynn Wheeler
11 Sep 24 i i i        +* Re: is Vax addressing sane today2Stephen Fuld
11 Sep 24 i i i        `* Re: is Vax addressing sane today2MitchAlsup1
8 Sep 24 i i `* Re: is Vax adressing sane today7Brett
8 Sep 24 i `* Re: is Vax adressing sane today2MitchAlsup1
6 Sep 24 +* Re: is Vax adressing sane today2MitchAlsup1
6 Sep 24 +- Re: is Vax adressing sane today1Lawrence D'Oliveiro
6 Sep 24 `* Re: is Vax adressing sane today8Anton Ertl

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