Andrew Stubbs <[email protected]> writes:
> On 05/05/2026 14:14, Arsen Arsenović wrote:
>> + /* TODO(arsen): This should be part of a mechanism that allows us to
>> override
>> + nthreads-var with OMP_NUM_THREADS. But, we currently don't have
>> access to
>> + that list on the device.
>> +
>> + thr->task->icv.nthreads_var = ...; */
>
> The previous code did write to this field. Why does the new thread not do at
> least the same? (This does not seem like "no functional changes".)
This write was redundant with gomp_init_task, which does:
/* task = thr->task, prev_icv = &start_data->prev_icvs */
gomp_init_task (struct gomp_task *task, struct gomp_task *parent_task,
struct gomp_task_icv *prev_icv)
/* [...] */
task->icv = *prev_icv;
The generic team.c implementation does (abridged):
nthreads_var = icv->nthreads_var;
if (__builtin_expect (gomp_nthreads_var_list != NULL, 0)
&& thr->ts.level < gomp_nthreads_var_list_len)
nthreads_var = gomp_nthreads_var_list[thr->ts.level];
gomp_init_task (thr->task, task, icv);
thr->task->taskgroup = taskgroup;
team->implicit_task[0].icv.nthreads_var = nthreads_var;
... i.e. it allows replacing the value of nthreads_var with an element
of gomp_nthreads_var_list, before writing it back.
On the device, however, that list is always empty, and analogous logic
was not even present, so the value of nthreads_var is necessarily the
same as prev_icv->nthreads_var, being written into a field where
prev_icv->nthreads_var was already copied.
So, it never had an effect.
--
Arsen Arsenović
