Re: a bit of history, Stealing a Great Idea from the 6600

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Sujet : Re: a bit of history, Stealing a Great Idea from the 6600
De : mitchalsup (at) *nospam* aol.com (MitchAlsup1)
Groupes : comp.arch
Date : 04. May 2024, 22:14:41
Autres entêtes
Organisation : Rocksolid Light
Message-ID : <fdfd2d7fde1050cbad7dd647f1cd991a@www.novabbs.org>
References : 1 2 3 4 5
User-Agent : Rocksolid Light
John Levine wrote:

According to Thomas Koenig  <tkoenig@netcologne.de>:
John Levine <johnl@taugh.com> schrieb:
>
It is my impression that
trapping on fixed point overflow is not very useful, and it's easier
to do a jump on overflow in the few cases where you care, or the x86
INTO which you put after the arithmetic operaion to trap if the
overflow flag is set.
>
Sanitzers would benefit greatly from trapping math.
>
However, this could get into murky territory - to be really
general, you would also need a version for trapping math with
unsigned numbers.  Just think of doing a unsigned loop with a
lower bound that, due to some error in the code or input, has an
upper bound of 0-1...

I suppose but my experience was always that the trap was the easy
part.
If it is the easy part, why does it take ~1,000* cycles ??
(*) x86 takes craploads of cycles to cross the trap barrier and back
{including the saving and restoration of registers}
Something like My 66000 takes 10 each way including the saving and restoring of registers, and the change of MMU state.

      Figuring out what to do after the trap happens is much harder.
Depends on what the trap delivers to the "other side", and also dependent
on the range of options the handler has to consider; and sometimes on
how many instructions go through that trap !?!

I've seen designs with instructions like "trap if greater than N" so
if you want to go that route, you can check for the range the
programemr declared rather than whatever word size it was rounded up
to.

Date Sujet#  Auteur
17 Apr 24 * Stealing a Great Idea from the 6600128John Savard
18 Apr 24 +* Re: Stealing a Great Idea from the 6600125MitchAlsup1
18 Apr 24 i`* Re: Stealing a Great Idea from the 6600124John Savard
18 Apr 24 i `* Re: Stealing a Great Idea from the 6600123MitchAlsup1
19 Apr 24 i  `* Re: Stealing a Great Idea from the 6600122John Savard
19 Apr 24 i   `* Re: Stealing a Great Idea from the 6600121John Savard
19 Apr 24 i    `* Re: Stealing a Great Idea from the 6600120MitchAlsup1
20 Apr 24 i     +* Re: Stealing a Great Idea from the 66002John Savard
21 Apr 24 i     i`- Re: Stealing a Great Idea from the 66001John Savard
20 Apr 24 i     `* Re: Stealing a Great Idea from the 6600117John Savard
20 Apr 24 i      `* Re: Stealing a Great Idea from the 6600116John Savard
20 Apr 24 i       `* Re: Stealing a Great Idea from the 6600115MitchAlsup1
20 Apr 24 i        +* Re: Stealing a Great Idea from the 6600105BGB
21 Apr 24 i        i`* Re: Stealing a Great Idea from the 6600104MitchAlsup1
21 Apr 24 i        i +* Re: Stealing a Great Idea from the 660063John Savard
21 Apr 24 i        i i+* Re: Stealing a Great Idea from the 660015John Savard
25 Apr 24 i        i ii`* Re: Stealing a Great Idea from the 660014Lawrence D'Oliveiro
25 Apr 24 i        i ii +* Re: Stealing a Great Idea from the 660012MitchAlsup1
25 Apr 24 i        i ii i+- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
30 Apr 24 i        i ii i`* Re: a bit of history, Stealing a Great Idea from the 660010John Levine
3 May 24 i        i ii i `* Re: a bit of history, Stealing a Great Idea from the 66009Anton Ertl
3 May 24 i        i ii i  +* Re: a bit of history, Stealing a Great Idea from the 66007John Levine
4 May 24 i        i ii i  i`* Re: a bit of history, Stealing a Great Idea from the 66006Thomas Koenig
4 May 24 i        i ii i  i +* Re: a bit of history, Stealing a Great Idea from the 66004John Levine
4 May 24 i        i ii i  i i`* Re: a bit of history, Stealing a Great Idea from the 66003MitchAlsup1
5 May 24 i        i ii i  i i `* Re: a bit of history, Stealing a Great Idea from the 66002Thomas Koenig
5 May 24 i        i ii i  i i  `- Re: a bit of history, Stealing a Great Idea from the 66001MitchAlsup1
28 Jul 24 i        i ii i  i `- Re: a bit of history, Stealing a Great Idea from the 66001Lawrence D'Oliveiro
3 May 24 i        i ii i  `- Re: a bit of history, Stealing a Great Idea from the 66001MitchAlsup1
25 Apr 24 i        i ii `- Re: Stealing a Great Idea from the 66001John Savard
21 Apr 24 i        i i`* Re: Stealing a Great Idea from the 660047MitchAlsup1
23 Apr 24 i        i i +* Re: Stealing a Great Idea from the 660045George Neuner
23 Apr 24 i        i i i`* Re: Stealing a Great Idea from the 660044MitchAlsup1
25 Apr 24 i        i i i `* Re: Stealing a Great Idea from the 660043George Neuner
26 Apr 24 i        i i i  `* Re: Stealing a Great Idea from the 660042BGB
26 Apr 24 i        i i i   `* Re: Stealing a Great Idea from the 660041MitchAlsup1
26 Apr 24 i        i i i    +* Re: Stealing a Great Idea from the 66002Anton Ertl
26 Apr 24 i        i i i    i`- Re: Stealing a Great Idea from the 66001MitchAlsup1
26 Apr 24 i        i i i    +* Re: Stealing a Great Idea from the 66004BGB
26 Apr 24 i        i i i    i+* Re: Stealing a Great Idea from the 66002MitchAlsup1
27 Apr 24 i        i i i    ii`- Re: Stealing a Great Idea from the 66001BGB
26 Apr 24 i        i i i    i`- Re: Stealing a Great Idea from the 66001MitchAlsup1
27 Apr 24 i        i i i    `* Re: Stealing a Great Idea from the 660034BGB
27 Apr 24 i        i i i     `* Re: Stealing a Great Idea from the 660033MitchAlsup1
28 Apr 24 i        i i i      `* Re: Stealing a Great Idea from the 660032BGB
28 Apr 24 i        i i i       `* Re: Stealing a Great Idea from the 660031MitchAlsup1
28 Apr 24 i        i i i        `* Re: Stealing a Great Idea from the 660030BGB
28 Apr 24 i        i i i         +* Re: Stealing a Great Idea from the 660024BGB
28 Apr 24 i        i i i         i`* Re: Stealing a Great Idea from the 660023BGB
28 Apr 24 i        i i i         i `* Re: Stealing a Great Idea from the 660022Thomas Koenig
28 Apr 24 i        i i i         i  `* Re: Stealing a Great Idea from the 660021BGB
28 Apr 24 i        i i i         i   `* Re: Stealing a Great Idea from the 660020BGB
28 Apr 24 i        i i i         i    +* Re: Stealing a Great Idea from the 66002Thomas Koenig
28 Apr 24 i        i i i         i    i`- Re: Stealing a Great Idea from the 66001BGB
29 Jul 24 i        i i i         i    +* Re: Stealing a Great Idea from the 660016Lawrence D'Oliveiro
29 Jul 24 i        i i i         i    i+* Re: Stealing a Great Idea from the 66006BGB
30 Jul 24 i        i i i         i    ii`* Re: Stealing a Great Idea from the 66005Lawrence D'Oliveiro
30 Jul 24 i        i i i         i    ii `* Re: Stealing a Great Idea from the 66004BGB
31 Jul 24 i        i i i         i    ii  `* Re: Stealing a Great Idea from the 66003Lawrence D'Oliveiro
31 Jul 24 i        i i i         i    ii   `* Re: Stealing a Great Idea from the 66002BGB
1 Aug 24 i        i i i         i    ii    `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
29 Jul 24 i        i i i         i    i`* Re: Stealing a Great Idea from the 66009Terje Mathisen
29 Jul 24 i        i i i         i    i `* Re: Stealing a Great Idea from the 66008MitchAlsup1
30 Jul 24 i        i i i         i    i  +- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
30 Jul 24 i        i i i         i    i  +* Re: Stealing a Great Idea from the 66004Michael S
30 Jul 24 i        i i i         i    i  i`* Re: Stealing a Great Idea from the 66003MitchAlsup1
31 Jul 24 i        i i i         i    i  i `* Re: Stealing a Great Idea from the 66002BGB
1 Aug 24 i        i i i         i    i  i  `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
1 Aug 24 i        i i i         i    i  `* Re: Stealing a Great Idea from the 66002Thomas Koenig
1 Aug 24 i        i i i         i    i   `- Re: Stealing a Great Idea from the 66001MitchAlsup1
29 Jul 24 i        i i i         i    `- Re: Stealing a Great Idea from the 66001George Neuner
28 Apr 24 i        i i i         `* Re: Stealing a Great Idea from the 66005MitchAlsup1
28 Apr 24 i        i i i          `* Re: Stealing a Great Idea from the 66004BGB
29 Apr 24 i        i i i           `* Re: Stealing a Great Idea from the 66003MitchAlsup1
29 Apr 24 i        i i i            `* Re: Stealing a Great Idea from the 66002BGB
29 Apr 24 i        i i i             `- Re: Stealing a Great Idea from the 66001Thomas Koenig
29 Apr 24 i        i i `- Re: Stealing a Great Idea from the 66001Tim Rentsch
21 Apr 24 i        i `* Re: Stealing a Great Idea from the 660040BGB
21 Apr 24 i        i  `* Re: Stealing a Great Idea from the 660039MitchAlsup1
22 Apr 24 i        i   +* Re: Stealing a Great Idea from the 66003BGB
22 Apr 24 i        i   i`* Re: Stealing a Great Idea from the 66002MitchAlsup1
22 Apr 24 i        i   i `- Re: Stealing a Great Idea from the 66001BGB
22 Apr 24 i        i   +* Re: Stealing a Great Idea from the 66002John Savard
22 Apr 24 i        i   i`- Re: Stealing a Great Idea from the 66001BGB
22 Apr 24 i        i   `* Re: Stealing a Great Idea from the 660033Terje Mathisen
22 Apr 24 i        i    +- Re: Stealing a Great Idea from the 66001BGB
13 Jun 24 i        i    `* Re: Stealing a Great Idea from the 660031Kent Dickey
13 Jun 24 i        i     +* Re: Stealing a Great Idea from the 660016Stefan Monnier
13 Jun 24 i        i     i`* Re: Stealing a Great Idea from the 660015BGB
13 Jun 24 i        i     i `* Re: Stealing a Great Idea from the 660014MitchAlsup1
14 Jun 24 i        i     i  `* Re: Stealing a Great Idea from the 660013BGB
18 Jun 24 i        i     i   `* Re: Stealing a Great Idea from the 660012MitchAlsup1
19 Jun 24 i        i     i    +* Re: Stealing a Great Idea from the 66008BGB
19 Jun 24 i        i     i    i`* Re: Stealing a Great Idea from the 66007MitchAlsup1
19 Jun 24 i        i     i    i +* Re: Stealing a Great Idea from the 66005BGB
19 Jun 24 i        i     i    i i`* Re: Stealing a Great Idea from the 66004MitchAlsup1
20 Jun 24 i        i     i    i i `* Re: Stealing a Great Idea from the 66003Thomas Koenig
20 Jun 24 i        i     i    i i  `* Re: Stealing a Great Idea from the 66002MitchAlsup1
21 Jun 24 i        i     i    i i   `- Re: Stealing a Great Idea from the 66001Thomas Koenig
20 Jun 24 i        i     i    i `- Re: Stealing a Great Idea from the 66001John Savard
19 Jun 24 i        i     i    +- Re: Stealing a Great Idea from the 66001Thomas Koenig
20 Jun 24 i        i     i    +- Re: Stealing a Great Idea from the 66001MitchAlsup1
31 Jul 24 i        i     i    `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
13 Jun 24 i        i     +* Re: Stealing a Great Idea from the 660013MitchAlsup1
14 Jun 24 i        i     `- Re: Stealing a Great Idea from the 66001Terje Mathisen
22 Apr 24 i        `* Re: Stealing a Great Idea from the 66009John Savard
18 Apr 24 `* Re: Stealing a Great Idea from the 66002Lawrence D'Oliveiro

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