> On 1/21/21 7:45 PM, Jan Hubicka wrote:
> > For this reason we merge by computing average, which is stable over
> > reordering the indices....
>
> Looking at the implementation, we merge by using minimum value:
>
> /* Time profiles are merged so that minimum from all valid (greater than zero)
> is stored. There could be a fork that creates new counters. To have
> the profile stable, we chosen to pick the smallest function visit time. */
Yep, sorry for confussion. I just noticed that as well.
Minimum should be still safe for parallel-run profiling (not for
multithreaded where we probably really want to disabe it, but we can do
that on per-function basis using opt_for_fn so it works with LTO).
Honza
> void
> __gcov_merge_time_profile (gcov_type *counters, unsigned n_counters)
> {
> unsigned int i;
> gcov_type value;
>
> for (i = 0; i < n_counters; i++)
> {
> value = gcov_get_counter_target ();
>
> if (value && (!counters[i] || value < counters[i]))
> counters[i] = value;
> }
> }
> #endif /* L_gcov_merge_time_profile */
>
> Martin
