On 04/07/2015 11:17 AM, Jan Engelhardt wrote:
On Tuesday 2015-04-07 19:45, Alexander Duyck wrote:
-#define prefetch(x) 1
+#define prefetch(x) ((void)0)
Why not just use "do {} while (0)"? I know that is what is used in the
kernel for functions that don't do anything.
I may be getting the terms wrong, but:
do{}while(0) is not an expression, it is a (block) control statement.
In particular, do{}while(0) won't evaluate to an rvalue.
Right. That is the point in this case. I am assuming what Arturo is trying to
accomplish since you shouldn't be able to evaluate ((void)0) as an rvalue
either.
The difference is that
int i;
i = 1, (void)0;
compiles, while
i = 1, do{}while(0);
Okay, that explains it. It is being used inside the init, condition,
and post process sections of a for loop. Thanks for explaining it.
- Alex
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