On 11/04, George Spelvin wrote:
>
> Grand poo-bah Linus wrote:
> > Now, I doubt you'll find an architecture or C compiler where this will
> > actually ever make a difference, but the fact remains that you
> > shouldn't use signed integers for counters like this. You should use
> > unsigned, and you should rely on the well-defined modulo-2**n
> > semantics.
>
> Actually, this is another C standard undefined case that recent versions of
> GCC exploit for optimization.
^^^^^^^^^^^^
This is another thing,
> For example, the loop:
> for (i = 1; i; i++)
> /* Code */
> will never terminate! Feed the following to gcc -O2 and see for yourself:
Yes, because ...
> Notice the lack of test in the "jmp .L2" loop.
Exactly.
But if we have like
int A, B;
int sum(void)
{
return A + B;
}
then I doubt there is any architecture (at least supported by linux)
which can generate the different code if you do s/int/unsigned/.
Anyway I agree, unsigned makes more sense, and I changed this patch
accordingly..
Oleg.
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