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Re: For those arguing over languages...

From	The Natural Philosopher <tnp@invalid.invalid>
Newsgroups	comp.os.linux.misc
Subject	Re: For those arguing over languages...
Date	2026-02-13 10:11 +0000
Organization	A little, after lunch
Message-ID	<10mmtca$27ag8$3@dont-email.me> (permalink)
References	(3 earlier) <mv4dtrFbh74U1@mid.individual.net> <10mkhl0$1er09$2@dont-email.me> <mv65j1FklieU3@mid.individual.net> <10ml29o$1kt9q$1@dont-email.me> <mv6lrpFmeg8U1@mid.individual.net>

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On 12/02/2026 18:52, Carlos E. R. wrote:
> On 2026-02-12 18:23, Rich wrote:
>> Carlos E. R. <robin_listas@es.invalid> wrote:
>>> On 2026-02-12 13:38, The Natural Philosopher wrote:
>>>> On 11/02/2026 22:24, Carlos E. R. wrote:
>>>>> On 2026-02-11 19:50, Rich wrote:
>>>>>> c186282 <c186282@nnada.net> wrote:
>>>>>>> On 2/10/26 04:09, The Natural Philosopher wrote:
>>>>>>>> ...more fuel on the fire...
>>>>>>>>
> 
> 
> 
>>>> I think the point is that the compiler knows that isn't necessary, and
>>>> doesnt bother.
>>>>
>>>
>>> Then don't optimize. Optimization has always been somewhat problematic.
>>> Sometimes it introduced bugs that could not be debugged, because
>>> debugging altered the code, possibly removing the optimizations.
>>
>> It wasn't the optimizer causing the "skipping" of the rest of the
>> checks.  It was a byproduct of boolean short-circuiting of boolean
>> expressions.  Most languages only evaluate just enough of a complex
>> boolean expression to reach a true or false indication, then skip the
>> rest of the expression (yes, this is an 'optimization', but not by the
>> code optimizer but the language specification itself).
>>
>> The skipping of the remaining character checks in the example posted
>> here was due to this boolean short-circuit behavior.  Once the first
>> 'false' arrived for the first incorrect character, the compiled code
>> skipped over evaluating the boolean expression for subsequent
>> characters.  So -O0 (no optimizations) or -O3 (full optimizations) made
>> no difference, portions of the 'constant time execution' were skipped,
>> opening a timing side channel attack.
> 
> Ah, yes, I remember that now. Can play havoc when one of the expression 
> is actually a function and the later code relies on the prior execution 
> of that code.
> 
the keyword 'volatile' helps in this case

> 
> 

-- 
Truth welcomes investigation because truth knows investigation will lead 
to converts. It is deception that uses all the other techniques.

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For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-10 09:09 +0000
  Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-10 13:11 +0000
  Re: For those arguing over languages... Farley Flud <ff@linux.rocks> - 2026-02-10 14:08 +0000
    Re: For those arguing over languages... Marc Haber <mh+usenetspam1118@zugschl.us> - 2026-02-10 15:16 +0100
      Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-10 16:19 +0000
        Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-10 18:20 +0000
      Re: For those arguing over languages... Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-02-10 11:22 -0500
      Re: For those arguing over languages... John  <john@panix.com> - 2026-02-17 16:23 +0000
        Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-19 19:26 +0000
          Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-22 09:28 +0000
    Re: For those arguing over languages... John Ames <commodorejohn@gmail.com> - 2026-02-10 08:24 -0800
      Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-10 18:16 +0000
  Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-10 22:34 -0500
    Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-11 18:50 +0000
      Re: For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-11 19:28 +0000
        Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-11 21:27 +0000
          Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-12 09:48 +0000
            Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-12 20:48 -0500
      Re: For those arguing over languages... Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-02-11 16:24 -0500
        Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-11 22:45 +0000
          Re: For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-12 12:42 +0000
      Re: For those arguing over languages... "Carlos E. R." <robin_listas@es.invalid> - 2026-02-11 23:24 +0100
        Re: For those arguing over languages... Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-02-11 22:48 +0000
        Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-11 22:49 +0000
        Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-12 09:55 +0000
          Re: For those arguing over languages... "Carlos E. R." <robin_listas@es.invalid> - 2026-02-12 11:49 +0100
          Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-12 20:54 -0500
            Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-13 03:20 +0000
              Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-12 23:44 -0500
        Re: For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-12 12:38 +0000
          Re: For those arguing over languages... "Carlos E. R." <robin_listas@es.invalid> - 2026-02-12 15:14 +0100
            Re: For those arguing over languages... Rich <rich@example.invalid> - 2026-02-12 17:23 +0000
              Re: For those arguing over languages... "Carlos E. R." <robin_listas@es.invalid> - 2026-02-12 19:52 +0100
                Re: For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-13 10:11 +0000
                Re: For those arguing over languages... Richard Kettlewell <invalid@invalid.invalid> - 2026-02-13 10:20 +0000
            Re: For those arguing over languages... The Natural Philosopher <tnp@invalid.invalid> - 2026-02-13 10:10 +0000
              Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-13 19:57 -0500
          Re: For those arguing over languages... c186282 <c186282@nnada.net> - 2026-02-12 20:56 -0500

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