Re: Computer architects leaving Intel...

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Sujet : Re: Computer architects leaving Intel...
De : david.brown (at) *nospam* hesbynett.no (David Brown)
Groupes : comp.arch
Date : 15. Sep 2024, 17:09:56
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <vc70sl$285g2$4@dont-email.me>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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On 15/09/2024 14:40, Michael S wrote:
On Sun, 15 Sep 2024 12:19:02 -0000 (UTC)
Waldek Hebisch <antispam@fricas.org> wrote:
 
Michael S <already5chosen@yahoo.com> wrote:
On Thu, 12 Sep 2024 16:34:31 +0200
David Brown <david.brown@hesbynett.no> wrote:
  
On 12/09/2024 13:29, Michael S wrote:
On Thu, 12 Sep 2024 03:12:11 -0700
Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
    
BGB <cr88192@gmail.com> writes:
>
I fully agree that C is not, and should not be seen as, a
"high-level assembly language".  But it is a language that is very
useful to "hardware-type folks", and there are a few things that
could make it easier to write more portable code if they were
standardised.  As it is, we just have to accept that some things
are not portable.
Why not?
I don't see practical need for all those UBs apart from buffer
overflow. More so, I don't see the need for UB in certain limited
classes of buffer overflows.
>
struct {
   char x[8]
   int  y;
} bar;
bar.y = 0; bar.x[8] = 42;
>
IMHO, here behavior should be fully defined by implementation.
And in practice it is. Just not in theory.
    
>
And how should that be defined?
>
>
bar.x[8] = 42 should be defined to be the same as
   char tmp = 42
   memcpy(&bar.y, &tmp, sizeof(tmp));
>
That has two drawbacks: minor one that you need to know that
there are no padding between 'x' and 'y'.
 Padding is another thing that should be Implementation Defined.
It is.

I.e. compiler should provide complete documentation of its padding
algorithms.
They do.  Or, they should.  Often they are lazy and say "defined by the platform ABI".  Really, it is only the alignments that are needed.
C defines the minimum padding between members in a struct - you get the padding needed to ensure that members are correctly aligned.  I don't think the C standards disallow additional padding, but it would be an extraordinarily strange implementation if there were anything more than this minimum padding.
But I certainly wouldn't mind if the standards dictated this minimum padding, and then there would be nothing left to the implementation other than alignments.

In addition, some padding-related things can be defined by Standard
itself. Not in this particular case, but, for example, it could be
defined that when field of one integer type is immediately followed by
another field of integer type with the same or narrower width then
there should be no padding in-between.
 

Date Sujet#  Auteur
27 Aug 24 * Computer architects leaving Intel...539Thomas Koenig
27 Aug 24 +- Re: Computer architects leaving Intel...1Michael S
27 Aug 24 +- Re: Computer architects leaving Intel...1Stephen Fuld
27 Aug 24 `* Re: Computer architects leaving Intel...536John Dallman
28 Aug 24  +* Re: Computer architects leaving Intel...529BGB
28 Aug 24  i`* Re: Computer architects leaving Intel...528MitchAlsup1
28 Aug 24  i `* Re: Computer architects leaving Intel...527BGB
28 Aug 24  i  +* Re: Computer architects leaving Intel...2Robert Finch
28 Aug 24  i  i`- Re: Computer architects leaving Intel...1BGB
28 Aug 24  i  `* Re: Computer architects leaving Intel...524MitchAlsup1
29 Aug 24  i   `* Re: Computer architects leaving Intel...523BGB
29 Aug 24  i    +* Re: Computer architects leaving Intel...511MitchAlsup1
29 Aug 24  i    i`* Re: Computer architects leaving Intel...510BGB
30 Aug 24  i    i +* Re: Computer architects leaving Intel...499John Dallman
30 Aug 24  i    i i+* Re: Computer architects leaving Intel...11Thomas Koenig
30 Aug 24  i    i ii+- Re: Computer architects leaving Intel...1Michael S
30 Aug 24  i    i ii+* Re: Computer architects leaving Intel...8Anton Ertl
30 Aug 24  i    i iii+* Re: Computer architects leaving Intel...2Michael S
30 Aug 24  i    i iiii`- Re: Computer architects leaving Intel...1Anton Ertl
30 Aug 24  i    i iii`* Re: Computer architects leaving Intel...5John Dallman
30 Aug 24  i    i iii `* Re: Computer architects leaving Intel...4Brett
30 Aug 24  i    i iii  +- Re: Computer architects leaving Intel...1John Dallman
2 Sep 24  i    i iii  `* Re: Computer architects leaving Intel...2Terje Mathisen
2 Sep 24  i    i iii   `- Re: Computer architects leaving Intel...1Thomas Koenig
30 Aug 24  i    i ii`- Re: Computer architects leaving Intel...1BGB
30 Aug 24  i    i i`* Re: Computer architects leaving Intel...487Anton Ertl
30 Aug 24  i    i i +* Re: Computer architects leaving Intel...302John Dallman
30 Aug 24  i    i i i`* Re: Computer architects leaving Intel...301David Brown
30 Aug 24  i    i i i +* Re: Computer architects leaving Intel...293Anton Ertl
30 Aug 24  i    i i i i`* Re: Computer architects leaving Intel...292Bernd Linsel
31 Aug 24  i    i i i i +- Re: Computer architects leaving Intel...1Thomas Koenig
31 Aug 24  i    i i i i `* Re: Computer architects leaving Intel...290Thomas Koenig
31 Aug 24  i    i i i i  +- Re: Computer architects leaving Intel...1Thomas Koenig
31 Aug 24  i    i i i i  `* Re: Computer architects leaving Intel...288Bernd Linsel
31 Aug 24  i    i i i i   +- Re: Computer architects leaving Intel...1Thomas Koenig
31 Aug 24  i    i i i i   +* Re: Computer architects leaving Intel...2Thomas Koenig
31 Aug 24  i    i i i i   i`- Re: Computer architects leaving Intel...1Bernd Linsel
31 Aug 24  i    i i i i   `* Re: Computer architects leaving Intel...284Anton Ertl
31 Aug 24  i    i i i i    +* Re: Computer architects leaving Intel...279Thomas Koenig
31 Aug 24  i    i i i i    i+* Re: Computer architects leaving Intel...157Bernd Linsel
31 Aug 24  i    i i i i    ii+* Re: Computer architects leaving Intel...153MitchAlsup1
1 Sep 24  i    i i i i    iii`* Re: Computer architects leaving Intel...152Stephen Fuld
2 Sep 24  i    i i i i    iii `* Re: Computer architects leaving Intel...151Terje Mathisen
2 Sep 24  i    i i i i    iii  `* Re: Computer architects leaving Intel...150Stephen Fuld
3 Sep 24  i    i i i i    iii   +* Re: Computer architects leaving Intel...139David Brown
3 Sep 24  i    i i i i    iii   i+* Re: Computer architects leaving Intel...108Stephen Fuld
4 Sep 24  i    i i i i    iii   ii`* Re: Computer architects leaving Intel...107David Brown
4 Sep 24  i    i i i i    iii   ii +* Re: Computer architects leaving Intel...103Terje Mathisen
4 Sep 24  i    i i i i    iii   ii i+* Re: Computer architects leaving Intel...101David Brown
4 Sep 24  i    i i i i    iii   ii ii+* Re: Computer architects leaving Intel...97jseigh
4 Sep 24  i    i i i i    iii   ii iii`* Re: Computer architects leaving Intel...96David Brown
4 Sep 24  i    i i i i    iii   ii iii `* Re: Computer architects leaving Intel...95Brett
4 Sep 24  i    i i i i    iii   ii iii  +- Re: Computer architects leaving Intel...1Thomas Koenig
4 Sep 24  i    i i i i    iii   ii iii  +- Re: Computer architects leaving Intel...1MitchAlsup1
5 Sep 24  i    i i i i    iii   ii iii  +* Re: Computer architects leaving Intel...8BGB
5 Sep 24  i    i i i i    iii   ii iii  i`* Re: Computer architects leaving Intel...7MitchAlsup1
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5 Sep 24  i    i i i i    iii   ii iii  i  `* Re: Computer architects leaving Intel...5Niklas Holsti
5 Sep 24  i    i i i i    iii   ii iii  i   `* Re: Computer architects leaving Intel...4David Brown
6 Sep 24  i    i i i i    iii   ii iii  i    `* Re: Computer architects leaving Intel...3BGB
6 Sep 24  i    i i i i    iii   ii iii  i     `* Re: Computer architects leaving Intel...2David Brown
9 Sep 24  i    i i i i    iii   ii iii  i      `- Re: Computer architects leaving Intel...1BGB
5 Sep 24  i    i i i i    iii   ii iii  +* Re: Computer architects leaving Intel...83David Brown
5 Sep 24  i    i i i i    iii   ii iii  i`* Re: Computer architects leaving Intel...82Terje Mathisen
5 Sep 24  i    i i i i    iii   ii iii  i +* Re: Computer architects leaving Intel...79David Brown
5 Sep 24  i    i i i i    iii   ii iii  i i+* Re: Computer architects leaving Intel...2Thomas Koenig
7 Sep 24  i    i i i i    iii   ii iii  i ii`- Re: Computer architects leaving Intel...1Tim Rentsch
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5 Sep 24  i    i i i i    iii   ii iii  i ii+* Re: Computer architects leaving Intel...16David Brown
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10 Sep 24  i    i i i i    iii   ii iii  i iii i i`* Re: Computer architects leaving Intel...4Brett
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9 Sep 24  i    i i i i    iii   ii iii  i iii `* Re: Computer architects leaving Intel...2Michael S
10 Sep 24  i    i i i i    iii   ii iii  i iii  `- Re: Computer architects leaving Intel...1Michael S
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9 Sep 24  i    i i i i    iii   ii iii  i iii+* Re: Computer architects leaving Intel...2Terje Mathisen
9 Sep 24  i    i i i i    iii   ii iii  i iiii`- Re: Computer architects leaving Intel...1Tim Rentsch
14 Sep 24  i    i i i i    iii   ii iii  i iii`* Re: Computer architects leaving Intel...41Kent Dickey
14 Sep 24  i    i i i i    iii   ii iii  i iii +* Re: Computer architects leaving Intel...32Anton Ertl
14 Sep 24  i    i i i i    iii   ii iii  i iii i+* Re: Computer architects leaving Intel...29MitchAlsup1
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15 Sep 24  i    i i i i    iii   ii iii  i iii ii `* Re: Computer architects leaving Intel...27David Brown
16 Sep 24  i    i i i i    iii   ii iii  i iii ii  +* Re: Computer architects leaving Intel...5Thomas Koenig
16 Sep 24  i    i i i i    iii   ii iii  i iii ii  i`* Re: Computer architects leaving Intel...4David Brown
16 Sep 24  i    i i i i    iii   ii iii  i iii ii  i `* Re: Computer architects leaving Intel...3Thomas Koenig
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17 Sep 24  i    i i i i    iii   ii iii  i iii ii  i  `- Re: Computer architects leaving Intel...1David Brown
16 Sep 24  i    i i i i    iii   ii iii  i iii ii  `* Re: Computer architects leaving Intel...21Terje Mathisen
16 Sep 24  i    i i i i    iii   ii iii  i iii ii   `* Re: Computer architects leaving Intel...20David Brown
16 Sep 24  i    i i i i    iii   ii iii  i iii ii    +* Re: Computer architects leaving Intel...14Michael S
17 Sep 24  i    i i i i    iii   ii iii  i iii ii    `* Re: Computer architects leaving Intel...5Terje Mathisen
15 Sep 24  i    i i i i    iii   ii iii  i iii i`* Re: Computer architects leaving Intel...2BGB
14 Sep 24  i    i i i i    iii   ii iii  i iii +* Re: Computer architects leaving Intel...3Thomas Koenig
16 Sep 24  i    i i i i    iii   ii iii  i iii `* Re: Computer architects leaving Intel...5Tim Rentsch
6 Sep 24  i    i i i i    iii   ii iii  i ii+* Re: Computer architects leaving Intel...3Tim Rentsch
7 Sep 24  i    i i i i    iii   ii iii  i ii`* Re: Computer architects leaving Intel...9Chris M. Thomasson
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5 Sep 24  i    i i i i    iii   ii iii  i `* Re: Computer architects leaving Intel...2MitchAlsup1
7 Sep 24  i    i i i i    iii   ii iii  `- Re: Computer architects leaving Intel...1Tim Rentsch
4 Sep 24  i    i i i i    iii   ii ii`* Re: Computer architects leaving Intel...3Thomas Koenig
6 Sep 24  i    i i i i    iii   ii i`- Re: Computer architects leaving Intel...1Chris M. Thomasson
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3 Sep 24  i    i i i i    iii   i`* Re: Computer architects leaving Intel...30Stefan Monnier
3 Sep 24  i    i i i i    iii   `* Re: Computer architects leaving Intel...10Terje Mathisen
31 Aug 24  i    i i i i    ii`* Re: Computer architects leaving Intel...3Thomas Koenig
1 Sep 24  i    i i i i    i`* Re: Computer architects leaving Intel...121David Brown
1 Sep 24  i    i i i i    +* Re: Computer architects leaving Intel...3John Dallman
3 Sep 24  i    i i i i    `- Re: Computer architects leaving Intel...1Stefan Monnier
30 Aug 24  i    i i i +- Re: Computer architects leaving Intel...1MitchAlsup1
30 Aug 24  i    i i i +* Re: Computer architects leaving Intel...4Stefan Monnier
30 Aug 24  i    i i i `* Re: Computer architects leaving Intel...2John Dallman
8 Sep 24  i    i i `* Re: Computer architects leaving Intel...184Tim Rentsch
30 Aug 24  i    i `* Re: Computer architects leaving Intel...10MitchAlsup1
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29 Aug 24  `* Re: Computer architects leaving Intel...6Anton Ertl

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