Groups > comp.programming.threads > #1789

Re: forcing the compiler to reload from memory with c++0x

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From	Alexander Terekhov <terekhov@web.de>
Newsgroups	comp.programming.threads
Subject	Re: forcing the compiler to reload from memory with c++0x
Date	Wed, 02 Feb 2011 14:45:04 +0100
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Dmitriy Vyukov wrote:
[...]
> Alexander, you are inconsistent here.
> Why can't printf() output go to nowhere on its own in the first place?
> Abstract output is basically the same as abstract memory accesses on
> abstract machine, no? And what is that abstract "standard output"
> device or file? If we go down to that formal hair-splitting level,
> then I believe we won't conclude anything useful. For example, is
> there dynamic memory? Well, I'm not sure. Is zero bytes of dynamic
> memory still dynamic memory? I guess it's nothing.
> If you want, there is always an implementation. And it's possible to
> loosely define such group of implementations as "sane industrial
> implementations". And in that context volatile access indeed means the
> most natural memory access instruction in generated code (MOV, LD or
> whatever). And that is observable. And that is what Anthony meant, I
> think.

Stop abstracting into absurdity. "MOV, LD or whatever" are not
externally observable in the case of

int main() {
  volatile int i;
  // volatile write = has no observable effect
  i = 1;
  // volatile read = has no observable effect
  int n = i;
}

because the above program is the same as

int main() {
}

for any reasonable observer of the outcome.

regards,
alexander.

Thread

Re: forcing the compiler to reload from memory with c++0x Alexander Terekhov <terekhov@web.de> - 2011-02-01 14:17 +0100
  Re: forcing the compiler to reload from memory with c++0x Alexander Terekhov <terekhov@web.de> - 2011-02-02 14:45 +0100
    Re: forcing the compiler to reload from memory with c++0x Dmitriy Vyukov <dvyukov@gmail.com> - 2011-02-02 07:02 -0800
      Re: forcing the compiler to reload from memory with c++0x Alexander Terekhov <terekhov@web.de> - 2011-02-02 16:33 +0100
  Re: forcing the compiler to reload from memory with c++0x Alexander Terekhov <terekhov@web.de> - 2011-02-01 16:32 +0100
    Re: forcing the compiler to reload from memory with c++0x Alexander Terekhov <terekhov@web.de> - 2011-02-02 12:13 +0100
      Re: forcing the compiler to reload from memory with c++0x Dmitriy Vyukov <dvyukov@gmail.com> - 2011-02-02 04:54 -0800
    Re: forcing the compiler to reload from memory with c++0x Dmitriy Vyukov <dvyukov@gmail.com> - 2011-02-01 21:02 -0800
    Re: forcing the compiler to reload from memory with c++0x Joshua Maurice <joshuamaurice@gmail.com> - 2011-02-01 15:19 -0800
  Re: forcing the compiler to reload from memory with c++0x Anthony Williams <anthony.ajw@gmail.com> - 2011-02-01 13:51 +0000

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