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* [gcc r12-5151] libgomp: Use TLS storage for omp_get_num_teams()/omp_get_team_num() values
@ 2021-11-11 13:08 Jakub Jelinek
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From: Jakub Jelinek @ 2021-11-11 13:08 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:fa4fcb111ad4ef015c1caf7c4b5a60d35b3aa997
commit r12-5151-gfa4fcb111ad4ef015c1caf7c4b5a60d35b3aa997
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Nov 11 13:57:31 2021 +0100
libgomp: Use TLS storage for omp_get_num_teams()/omp_get_team_num() values
When thinking about GOMP_teams3, I've realized that using global variables
for the values returned by omp_get_num_teams()/omp_get_team_num() calls
is incorrect even with our right now dumb way of implementing host teams.
The problems are two, one is if host teams is used from multiple pthread_create
created threads - the spec says that host teams can't be nested inside of
explicit parallel or other teams constructs, but with pthread_create the
standard says obviously nothing about it. Another more important thing
is host fallback, right now we don't do anything for omp_get_num_teams()
or omp_get_team_num() which was fine before host teams was introduced and
the 5.1 requirement that num_teams clause specifies minimum of teams, but
with the global vars it means inside of target teams num_teams (2) we happily
return omp_get_num_teams() == 4 if the target teams is inside of host teams
with num_teams(4). With target fallback being invoked from parallel
regions global vars simply can't work right on the host.
So, this patch moves them to struct gomp_thread and propagates those for
parallel to child threads. For host fallback, the implicit zeroing of
*thr results in us returning omp_get_num_teams () == 1 and
omp_get_team_num () == 0 which is fine for target teams without num_teams
clause, for target teams with num_teams clause something to work on and
for target without teams nested in it I've asked on omp-lang what should
be done.
2021-11-11 Jakub Jelinek <jakub@redhat.com>
* libgomp.h (struct gomp_thread): Add num_teams and team_num members.
* team.c (struct gomp_thread_start_data): Likewise.
(gomp_thread_start): Initialize thr->num_teams and thr->team_num.
(gomp_team_start): Initialize start_data->num_teams and
start_data->team_num. Update nthr->num_teams and nthr->team_num.
* teams.c (gomp_num_teams, gomp_team_num): Remove.
(GOMP_teams_reg): Set and restore thr->num_teams and thr->team_num
instead of gomp_num_teams and gomp_team_num.
(omp_get_num_teams): Use thr->num_teams + 1 instead of gomp_num_teams.
(omp_get_team_num): Use thr->team_num instead of gomp_team_num.
* testsuite/libgomp.c/teams-4.c: New test.
Diff:
---
libgomp/libgomp.h | 8 ++++++++
libgomp/team.c | 8 ++++++++
libgomp/teams.c | 18 +++++++++---------
libgomp/testsuite/libgomp.c/teams-4.c | 30 ++++++++++++++++++++++++++++++
4 files changed, 55 insertions(+), 9 deletions(-)
diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index 023d8a8c1df..ceef643216c 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -768,6 +768,14 @@ struct gomp_thread
/* User pthread thread pool */
struct gomp_thread_pool *thread_pool;
+#ifdef LIBGOMP_USE_PTHREADS
+ /* omp_get_num_teams () - 1. */
+ unsigned int num_teams;
+
+ /* omp_get_team_num (). */
+ unsigned int team_num;
+#endif
+
#if defined(LIBGOMP_USE_PTHREADS) \
&& (!defined(HAVE_TLS) \
|| !defined(__GLIBC__) \
diff --git a/libgomp/team.c b/libgomp/team.c
index 11a2521057f..3bcc8174d1d 100644
--- a/libgomp/team.c
+++ b/libgomp/team.c
@@ -56,6 +56,8 @@ struct gomp_thread_start_data
struct gomp_task *task;
struct gomp_thread_pool *thread_pool;
unsigned int place;
+ unsigned int num_teams;
+ unsigned int team_num;
bool nested;
pthread_t handle;
};
@@ -88,6 +90,8 @@ gomp_thread_start (void *xdata)
thr->ts = data->ts;
thr->task = data->task;
thr->place = data->place;
+ thr->num_teams = data->num_teams;
+ thr->team_num = data->team_num;
#ifdef GOMP_NEEDS_THREAD_HANDLE
thr->handle = data->handle;
#endif
@@ -645,6 +649,8 @@ gomp_team_start (void (*fn) (void *), void *data, unsigned nthreads,
nthr->ts.single_count = 0;
#endif
nthr->ts.static_trip = 0;
+ nthr->num_teams = thr->num_teams;
+ nthr->team_num = thr->team_num;
nthr->task = &team->implicit_task[i];
nthr->place = place;
gomp_init_task (nthr->task, task, icv);
@@ -833,6 +839,8 @@ gomp_team_start (void (*fn) (void *), void *data, unsigned nthreads,
start_data->ts.single_count = 0;
#endif
start_data->ts.static_trip = 0;
+ start_data->num_teams = thr->num_teams;
+ start_data->team_num = thr->team_num;
start_data->task = &team->implicit_task[i];
gomp_init_task (start_data->task, task, icv);
team->implicit_task[i].icv.nthreads_var = nthreads_var;
diff --git a/libgomp/teams.c b/libgomp/teams.c
index 9409f8ee6aa..a93fb7cc6e1 100644
--- a/libgomp/teams.c
+++ b/libgomp/teams.c
@@ -28,14 +28,12 @@
#include "libgomp.h"
#include <limits.h>
-static unsigned gomp_num_teams = 1, gomp_team_num = 0;
-
void
GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
unsigned int thread_limit, unsigned int flags)
{
+ struct gomp_thread *thr = gomp_thread ();
(void) flags;
- (void) num_teams;
unsigned old_thread_limit_var = 0;
if (thread_limit == 0)
thread_limit = gomp_teams_thread_limit_var;
@@ -48,11 +46,11 @@ GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
}
if (num_teams == 0)
num_teams = gomp_nteams_var ? gomp_nteams_var : 3;
- gomp_num_teams = num_teams;
- for (gomp_team_num = 0; gomp_team_num < num_teams; gomp_team_num++)
+ thr->num_teams = num_teams - 1;
+ for (thr->team_num = 0; thr->team_num < num_teams; thr->team_num++)
fn (data);
- gomp_num_teams = 1;
- gomp_team_num = 0;
+ thr->num_teams = 0;
+ thr->team_num = 0;
if (thread_limit)
{
struct gomp_task_icv *icv = gomp_icv (true);
@@ -63,13 +61,15 @@ GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
int
omp_get_num_teams (void)
{
- return gomp_num_teams;
+ struct gomp_thread *thr = gomp_thread ();
+ return thr->num_teams + 1;
}
int
omp_get_team_num (void)
{
- return gomp_team_num;
+ struct gomp_thread *thr = gomp_thread ();
+ return thr->team_num;
}
ialias (omp_get_num_teams)
diff --git a/libgomp/testsuite/libgomp.c/teams-4.c b/libgomp/testsuite/libgomp.c/teams-4.c
new file mode 100644
index 00000000000..c1f5356c622
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/teams-4.c
@@ -0,0 +1,30 @@
+#include <omp.h>
+#include <stdlib.h>
+
+int
+main ()
+{
+ if (omp_get_num_teams () != 1 || omp_get_team_num () != 0)
+ abort ();
+ #pragma omp parallel num_threads (2)
+ if (omp_get_num_teams () != 1 || omp_get_team_num () != 0)
+ abort ();
+ #pragma omp teams num_teams (4)
+ {
+ int team = omp_get_team_num ();
+ if (omp_get_num_teams () != 4 || (unsigned) team >= 4U)
+ abort ();
+ #pragma omp parallel num_threads (3)
+ if (omp_get_num_teams () != 4 || omp_get_team_num () != team)
+ abort ();
+ #pragma omp parallel if (0)
+ #pragma omp target
+ #pragma omp teams num_teams (2)
+ if (omp_get_num_teams () > 2
+ || (unsigned) omp_get_team_num () >= 2U)
+ abort ();
+ if (omp_get_num_teams () != 4 || (unsigned) team >= 4U)
+ abort ();
+ }
+ return 0;
+}
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