unlikely compiler flag propagation

Matthias Brugger matthias.bgg at gmail.com
Wed Feb 18 13:09:47 EST 2015

Hi all,

I have a question about the unlikely compiler flag.
When a called function is only returns an error with the unlikely flag
set, should I set the unlikely compiler flag for the return value
check in the callee as well?

For example:

int function_one(int *list, int num_elements)
    int i;
    for (i =0; i < num_elements; i++) {
        if (unlikely(check_element(list + i)))
           return 1;


    return 0;

int function_two(...)

     if (function_one(list, num))
         return -1;

So my question is, if function_two should instead implement:
if (unlikely(function_one(list, num))

Or does the unlikely compiler flag propagate to calling functions?

Thanks a lot,

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