[gcc r13-3257] libgomp: Fix up creation of artificial teams

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:a58a965eb73253759f6a3e1c7380392557da89c8

commit r13-3257-ga58a965eb73253759f6a3e1c7380392557da89c8
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Oct 12 17:54:08 2022 +0200

    libgomp: Fix up creation of artificial teams
    
    When not in explicit parallel/target/teams construct, we in some cases create
    an artificial parallel with a single thread (either to handle target nowait
    or for task reduction purposes).  In those cases, it handled again artificially
    created implicit task (created by gomp_new_icv for cases where we needed to write
    to some ICVs), but as the testcases show, didn't take into account possibility
    of this being done from explicit task(s).  The code would destroy/free the previous
    task and replace it with the new implicit task.  If task is an explicit task
    (when teams is NULL, all explicit tasks behave like if (0)), it is a pointer to
    a local stack variable, so freeing it doesn't work, and additionally we shouldn't
    lose the explicit tasks - the new implicit task should instead replace the
    ancestor task which is the first implicit one.
    
    2022-10-12  Jakub Jelinek  <jakub@redhat.com>
    
            * task.c (gomp_create_artificial_team): Fix up handling of invocations
            from within explicit task.
            * target.c (GOMP_target_ext): Likewise.
            * testsuite/libgomp.c/task-7.c: New test.
            * testsuite/libgomp.c/task-8.c: New test.
            * testsuite/libgomp.c-c++-common/task-reduction-17.c: New test.
            * testsuite/libgomp.c-c++-common/task-reduction-18.c: New test.

Diff:
---
 libgomp/target.c                                   | 15 +++++++--
 libgomp/task.c                                     | 15 +++++++--
 .../libgomp.c-c++-common/task-reduction-17.c       | 36 ++++++++++++++++++++++
 .../libgomp.c-c++-common/task-reduction-18.c       | 17 ++++++++++
 libgomp/testsuite/libgomp.c/task-7.c               | 26 ++++++++++++++++
 libgomp/testsuite/libgomp.c/task-8.c               | 14 +++++++++
 6 files changed, 117 insertions(+), 6 deletions(-)

diff --git a/libgomp/target.c b/libgomp/target.c
index 57634839c8f..73c99c7c2e7 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -2813,6 +2813,7 @@ GOMP_target_ext (int device, void (*fn) (void *), size_t mapnum,
 	{
 	  struct gomp_team *team = gomp_new_team (1);
 	  struct gomp_task *task = thr->task;
+	  struct gomp_task **implicit_task = &task;
 	  struct gomp_task_icv *icv = task ? &task->icv : &gomp_global_icv;
 	  team->prev_ts = thr->ts;
 	  thr->ts.team = team;
@@ -2825,15 +2826,23 @@ GOMP_target_ext (int device, void (*fn) (void *), size_t mapnum,
 	  thr->ts.static_trip = 0;
 	  thr->task = &team->implicit_task[0];
 	  gomp_init_task (thr->task, NULL, icv);
-	  if (task)
+	  while (*implicit_task
+		 && (*implicit_task)->kind != GOMP_TASK_IMPLICIT)
+	    implicit_task = &(*implicit_task)->parent;
+	  if (*implicit_task)
 	    {
-	      thr->task = task;
+	      thr->task = *implicit_task;
 	      gomp_end_task ();
-	      free (task);
+	      free (*implicit_task);
 	      thr->task = &team->implicit_task[0];
 	    }
 	  else
 	    pthread_setspecific (gomp_thread_destructor, thr);
+	  if (implicit_task != &task)
+	    {
+	      *implicit_task = thr->task;
+	      thr->task = task;
+	    }
 	}
       if (thr->ts.team
 	  && !thr->task->final_task)
diff --git a/libgomp/task.c b/libgomp/task.c
index 30cd046df2a..7766535d1aa 100644
--- a/libgomp/task.c
+++ b/libgomp/task.c
@@ -2465,6 +2465,7 @@ gomp_create_artificial_team (void)
   struct gomp_task_icv *icv;
   struct gomp_team *team = gomp_new_team (1);
   struct gomp_task *task = thr->task;
+  struct gomp_task **implicit_task = &task;
   icv = task ? &task->icv : &gomp_global_icv;
   team->prev_ts = thr->ts;
   thr->ts.team = team;
@@ -2477,17 +2478,25 @@ gomp_create_artificial_team (void)
   thr->ts.static_trip = 0;
   thr->task = &team->implicit_task[0];
   gomp_init_task (thr->task, NULL, icv);
-  if (task)
+  while (*implicit_task
+	 && (*implicit_task)->kind != GOMP_TASK_IMPLICIT)
+    implicit_task = &(*implicit_task)->parent;
+  if (*implicit_task)
     {
-      thr->task = task;
+      thr->task = *implicit_task;
       gomp_end_task ();
-      free (task);
+      free (*implicit_task);
       thr->task = &team->implicit_task[0];
     }
 #ifdef LIBGOMP_USE_PTHREADS
   else
     pthread_setspecific (gomp_thread_destructor, thr);
 #endif
+  if (implicit_task != &task)
+    {
+      *implicit_task = thr->task;
+      thr->task = task;
+    }
 }
 
 /* The format of data is:
diff --git a/libgomp/testsuite/libgomp.c-c++-common/task-reduction-17.c b/libgomp/testsuite/libgomp.c-c++-common/task-reduction-17.c
new file mode 100644
index 00000000000..4a8d1e8bb73
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/task-reduction-17.c
@@ -0,0 +1,36 @@
+/* { dg-do run } */
+
+#include <omp.h>
+#include <stdlib.h>
+
+int a;
+
+int
+main ()
+{
+  #pragma omp task final (1)
+  {
+    if (!omp_in_final ())
+      abort ();
+    #pragma omp task
+    {
+      if (!omp_in_final ())
+	abort ();
+      #pragma omp taskgroup task_reduction (+: a)
+      {
+	if (!omp_in_final ())
+	  abort ();
+	#pragma omp task in_reduction (+: a)
+	{
+	  ++a;
+	  if (!omp_in_final ())
+	    abort ();
+	}
+      }
+      if (!omp_in_final ())
+	abort ();
+      #pragma omp taskwait
+    }
+  }
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/task-reduction-18.c b/libgomp/testsuite/libgomp.c-c++-common/task-reduction-18.c
new file mode 100644
index 00000000000..483f4406f6f
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/task-reduction-18.c
@@ -0,0 +1,17 @@
+/* { dg-do run } */
+
+int a;
+
+int
+main ()
+{
+  #pragma omp task
+  {
+    #pragma omp taskgroup task_reduction (+: a)
+    {
+      #pragma omp task in_reduction (+: a)
+      ++a;
+    }
+  }
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c/task-7.c b/libgomp/testsuite/libgomp.c/task-7.c
new file mode 100644
index 00000000000..0307575f978
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/task-7.c
@@ -0,0 +1,26 @@
+/* { dg-do run } */
+
+#include <omp.h>
+#include <stdlib.h>
+
+int
+main ()
+{
+  #pragma omp task final (1)
+  {
+    if (!omp_in_final ())
+      abort ();
+    #pragma omp task
+    {
+      if (!omp_in_final ())
+	abort ();
+      #pragma omp target nowait
+      if (omp_in_final ())
+	abort ();
+      if (!omp_in_final ())
+	abort ();
+      #pragma omp taskwait
+    }
+  }
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c/task-8.c b/libgomp/testsuite/libgomp.c/task-8.c
new file mode 100644
index 00000000000..f03aef6a030
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/task-8.c
@@ -0,0 +1,14 @@
+/* { dg-do run } */
+
+int
+main ()
+{
+  int i = 0;
+  #pragma omp task
+  {
+    #pragma omp target nowait private (i)
+    i = 1;
+    #pragma omp taskwait
+  }
+  return 0;
+}