gcc/libgomp/teams.c
Jakub Jelinek fa4fcb111a 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.
2021-11-11 13:57:31 +01:00

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C

/* Copyright (C) 2018-2021 Free Software Foundation, Inc.
Contributed by Jakub Jelinek <jakub@redhat.com>.
This file is part of the GNU Offloading and Multi Processing Library
(libgomp).
Libgomp is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* This file handles the host TEAMS construct. */
#include "libgomp.h"
#include <limits.h>
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;
unsigned old_thread_limit_var = 0;
if (thread_limit == 0)
thread_limit = gomp_teams_thread_limit_var;
if (thread_limit)
{
struct gomp_task_icv *icv = gomp_icv (true);
old_thread_limit_var = icv->thread_limit_var;
icv->thread_limit_var
= thread_limit > INT_MAX ? UINT_MAX : thread_limit;
}
if (num_teams == 0)
num_teams = gomp_nteams_var ? gomp_nteams_var : 3;
thr->num_teams = num_teams - 1;
for (thr->team_num = 0; thr->team_num < num_teams; thr->team_num++)
fn (data);
thr->num_teams = 0;
thr->team_num = 0;
if (thread_limit)
{
struct gomp_task_icv *icv = gomp_icv (true);
icv->thread_limit_var = old_thread_limit_var;
}
}
int
omp_get_num_teams (void)
{
struct gomp_thread *thr = gomp_thread ();
return thr->num_teams + 1;
}
int
omp_get_team_num (void)
{
struct gomp_thread *thr = gomp_thread ();
return thr->team_num;
}
ialias (omp_get_num_teams)
ialias (omp_get_team_num)