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Re: volatile semantics
- From: Nathan Sidwell <nathan at codesourcery dot com>
- To: Mike Stump <mrs at apple dot com>
- Cc: Gcc Mailing List <gcc at gcc dot gnu dot org>
- Date: Tue, 03 May 2005 15:41:29 +0100
- Subject: Re: volatile semantics
- References: <851D2CB0-93DF-4C49-A6A8-8895DB1A08F9@apple.com>
Mike Stump wrote:
int avail;
int main() {
while (*(volatile int *)&avail == 0)
continue;
return 0;
}
Ok, so, the question is, should gcc produce code that infinitely loops,
or should it be obligated to actually fetch from memory? Hint, 3.3
fetched.
I beleive the compiler is so licensed. [5.1.2.3/2] talks about accessing
a volatile object. If the compiled can determine the actual object
being accessed through a series of pointer and volatile cast conversions,
then I see nothing in the std saying it must behave as-if the object
were volatile when it is not.
This, of course, might not be useful to users :)
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC
nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk