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 : 07. Oct 2024, 20:51:31
Autres entêtes
Organisation : Tidorum Ltd
Message-ID : <lmise3F45acU2@mid.individual.net>
References : 1 2 3 4 5 6
User-Agent : Mozilla Thunderbird
On 2024-10-07 22:12, MitchAlsup1 wrote:
On Mon, 7 Oct 2024 18:55:26 +0000, Kent Dickey wrote:
 
In article <efXIO.169388$1m96.45507@fx15.iad>,
EricP  <ThatWouldBeTelling@thevillage.com> wrote:
Kent Dickey wrote:
In article <O2DHO.184073$kxD8.113118@fx11.iad>,
EricP  <ThatWouldBeTelling@thevillage.com> wrote:
Kent Dickey wrote:
>
In no way was I ever arguing that checking for overflow was a bad idea,
or a language issue, or anything else.  Just that CPUs should not bother
having trap-on-overflow instructions.
>
I understand, and I disagree with this conclusion.
I think all forms of software error detection are useful and
HW should make them simple and eliminate cost when possible.
>
I think I am not explaining the issue well.
>
I'm not arguing what you want to do with overflow.  I'm trying to show
that for all uses of detecting overflow other than crashing with no
recovery, hardware trapping on overflow is a poor approach.
>
If you enable hardware traps on integer overflow, then to do anything
other than crash the program would require engineering a very complex
set of data structures, roughly approximately the complexity of adding
debug information to the executable, in order to make this work.  As
far as I know, no one in the history of computers has yet undertaken
this task.
 And yet, this is exactly the kind of data C++ needs in order to
use its Try-Throw-Catch exception model. The stack walker needs
to know where on the stack is the list of stuff to free on block
exit, where are the preserved registers and how many, ...
Ada too.
There are at least two ways to do that (at least for Ada, probably also for C++):
- Dynamically maintain a stack-like data structure (a chain, linked list) that describes the current nesting of "code blocks" and their exception handlers. Whenever the program enters a block with an exception handler, there is entry code that pushes the description of that exception handler on this chain, including the address of its code; and vice versa pop on exiting such a block.
- Statically construct a mapping table that is stored in the executable and maps code ranges to exception handlers.
Ada implementations started with the dynamic method, which is simpler but adds some execution cost to all blocks with exception handlers, even if an exception never happens. Current implementations tend to the static method, also called "zero-cost exceptions" because there is no extra execution cost for blocks with exception handlers /unless/ an exception does occur.

Date Sujet#  Auteur
5 Sep 24 * is Vax adressing sane today336Brett
5 Sep 24 +* Re: is Vax adressing sane today324John Dallman
6 Sep 24 i+- Re: is Vax adressing sane today1Lawrence D'Oliveiro
6 Sep 24 i`* Re: is Vax adressing sane today322Anton 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 today313John Levine
8 Sep 24 i i`* Re: is Vax adressing sane today312Anton Ertl
8 Sep 24 i i +* Re: is Vax adressing sane today304MitchAlsup1
8 Sep 24 i i i`* Re: is Vax addressing sane today303Lawrence D'Oliveiro
9 Sep 24 i i i +* Re: is Vax addressing sane today231MitchAlsup1
9 Sep 24 i i i i`* Re: is Vax addressing sane today230Brett
9 Sep 24 i i i i +* Re: is Vax addressing sane today7MitchAlsup1
10 Sep 24 i i i i i`* Re: is Vax addressing sane today6Niklas Holsti
11 Sep 24 i i i i i +- Re: is Vax addressing sane today1Lawrence D'Oliveiro
25 Sep 24 i i i i i `* Re: is Vax addressing sane today4Stephen Fuld
25 Sep 24 i i i i i  `* Re: is Vax addressing sane today3Michael S
25 Sep 24 i i i i i   `* Re: is Vax addressing sane today2MitchAlsup1
25 Sep 24 i i i i i    `- Re: is Vax addressing sane today1Niklas Holsti
10 Sep 24 i i i i `* Re: is Vax addressing sane today222Anton 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 Sep 24 i i i i  `* Re: is Vax addressing sane today205Kent Dickey
21 Sep 24 i i i i   +* Re: is Vax addressing sane today4MitchAlsup1
21 Sep 24 i i i i   i`* Re: is Vax addressing sane today3Lawrence D'Oliveiro
21 Sep 24 i i i i   i `* Re: is Vax addressing sane today2MitchAlsup1
21 Sep 24 i i i i   i  `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
21 Sep 24 i i i i   +* Re: is Vax addressing sane today4Lawrence D'Oliveiro
21 Sep 24 i i i i   i`* Re: is Vax addressing sane today3MitchAlsup1
21 Sep 24 i i i i   i +- Re: is Vax addressing sane today1Niklas Holsti
21 Sep 24 i i i i   i `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
21 Sep 24 i i i i   +* Re: is Vax addressing sane today30MitchAlsup1
22 Sep 24 i i i i   i+* Re: except what, is Vax addressing sane today18John Levine
22 Sep 24 i i i i   ii+- Re: except what, is Vax addressing sane today1Michael S
22 Sep 24 i i i i   ii+* Re: except what, is Vax addressing sane today8Lawrence D'Oliveiro
22 Sep 24 i i i i   iii`* Re: except what, is Vax addressing sane today7Chris M. Thomasson
22 Sep 24 i i i i   iii `* Re: except what, is Vax addressing sane today6MitchAlsup1
22 Sep 24 i i i i   iii  +* Re: except what, is Vax addressing sane today2Lawrence D'Oliveiro
22 Sep 24 i i i i   iii  i`- Re: except what, is Vax addressing sane today1MitchAlsup1
22 Sep 24 i i i i   iii  +- Re: except what, is Vax addressing sane today1Chris M. Thomasson
22 Sep 24 i i i i   iii  `* Re: except what, is Vax addressing sane today2John Dallman
22 Sep 24 i i i i   iii   `- Re: except what, is Vax addressing sane today1MitchAlsup1
22 Sep 24 i i i i   ii+* Re: except what, is Vax addressing sane today5Terje Mathisen
24 Sep 24 i i i i   iii`* Re: except what, is Vax addressing sane today4Lawrence D'Oliveiro
24 Sep 24 i i i i   iii `* Re: except what, is Vax addressing sane today3Chris M. Thomasson
24 Sep 24 i i i i   iii  `* Re: except what, is Vax addressing sane today2MitchAlsup1
16 Oct 24 i i i i   iii   `- Re: except what, is Vax addressing sane today1Chris M. Thomasson
22 Sep 24 i i i i   ii`* Re: except what, is Vax addressing sane today3Lars Poulsen
24 Sep 24 i i i i   ii `* Re: except what, is Vax addressing sane today2Lawrence D'Oliveiro
24 Sep 24 i i i i   ii  `- Re: except what, is Vax addressing sane today1Michael S
22 Sep 24 i i i i   i+* Re: is Vax addressing sane today7Lawrence D'Oliveiro
22 Sep 24 i i i i   ii`* Re: is Vax addressing sane today6MitchAlsup1
22 Sep 24 i i i i   ii +* Re: is Vax addressing sane today3Lawrence D'Oliveiro
22 Sep 24 i i i i   ii i`* Re: is Vax addressing sane today2MitchAlsup1
22 Sep 24 i i i i   ii i `- Re: is Vax addressing sane today1Lawrence D'Oliveiro
22 Sep 24 i i i i   ii `* Re: is Vax addressing sane today2Anton Ertl
24 Sep 24 i i i i   ii  `- Re: is Vax addressing sane today1MitchAlsup1
24 Sep 24 i i i i   i+* Re: is Vax addressing sane today2Stefan Monnier
24 Sep 24 i i i i   ii`- Re: is Vax addressing sane today1MitchAlsup1
25 Sep 24 i i i i   i+- Re: is Vax addressing sane today1MitchAlsup1
12 Oct 24 i i i i   i`- Re: is Vax addressing sane today1Anton Ertl
22 Sep 24 i i i i   +* Re: is Vax addressing sane today4Thomas Koenig
24 Sep 24 i i i i   i`* Re: is Vax addressing sane today3Kent Dickey
24 Sep 24 i i i i   i +- Re: is Vax addressing sane today1Bill Findlay
24 Sep 24 i i i i   i `- Re: is Vax addressing sane today1Thomas Koenig
23 Sep 24 i i i i   +- Re: is Vax addressing sane today1Stefan Monnier
23 Sep 24 i i i i   `* Re: is Vax addressing sane today161Kent Dickey
24 Sep 24 i i i i    +* Re: is Vax addressing sane today11MitchAlsup1
24 Sep 24 i i i i    i+- Re: is Vax addressing sane today1Lawrence D'Oliveiro
24 Sep 24 i i i i    i`* Re: is Vax addressing sane today9Terje Mathisen
24 Sep 24 i i i i    i +* Re: is Vax addressing sane today4Michael S
24 Sep 24 i i i i    i i`* Re: is Vax addressing sane today3Terje Mathisen
24 Sep 24 i i i i    i i `* Re: is Vax addressing sane today2Michael S
24 Sep 24 i i i i    i i  `- Re: is Vax addressing sane today1MitchAlsup1
24 Sep 24 i i i i    i +* Re: is Vax addressing sane today3Stephen Fuld
24 Sep 24 i i i i    i i`* Re: is Vax addressing sane today2MitchAlsup1
25 Sep 24 i i i i    i i `- Re: is Vax addressing sane today1Stephen Fuld
12 Oct 24 i i i i    i `- Re: is Vax addressing sane today1Anton Ertl
24 Sep 24 i i i i    +* Re: is Vax addressing sane today3Terje Mathisen
29 Sep 24 i i i i    i+- Re: is Vax addressing sane today1Michael S
7 Oct 24 i i i i    i`- Re: is Vax addressing sane today1Kent Dickey
25 Sep 24 i i i i    +* Re: is Vax addressing sane today133MitchAlsup1
26 Sep 24 i i i i    i+- Re: is Vax addressing sane today1MitchAlsup1
28 Sep 24 i i i i    i`* Re: is Vax addressing sane today131Lawrence D'Oliveiro
28 Sep 24 i i i i    +* Re: is Vax addressing sane today3George Neuner
7 Oct 24 i i i i    +* Re: is Vax addressing sane today8Kent Dickey
12 Oct 24 i i i i    `* Re: is Vax addressing sane today2Anton Ertl
9 Sep 24 i i i `* Re: is Vax addressing sane today71Anton Ertl
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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