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Re: RFC: #pragma optimization_level
Georg Bauhaus <bauhaus@futureapps.de> writes:
> | A busy-loop function is used to effect a delay, not too precise,
> | but portably. Like
> |
> | #define COUNT 1000
> |
> | void f() {
> | /*volatile*/ /*register*/ int i;
> |
> | for (i = 0; i < COUNT; ++i)
> | ;
On Sat, Apr 02, 2005 at 01:48:56AM +0200, Gabriel Dos Reis wrote:
> This must be an FAQ. The above is no way of (no matter how popular
> the urban legend makes it) implementing delay. Adding a #pragma just
> makes teh situation worse.
Unfortunately, where there is a good argument for not using empty loops
as busy-waits, at one time it was documented GCC behavior that it would
work, so we can't really blame the users for trusting the doc.
That's not to say that it was ever a good idea, because of the lack of
control. If you need a precisely timed busy-wait, an inline assembly
construct is the best bet.