openmp: Retire nest-var ICV for OpenMP 5.1

This removes the nest-var ICV, expressing nesting in terms of the
max-active-levels-var ICV instead.  The max-active-levels-var ICV
is now per data environment rather than per device.

2020-11-18  Kwok Cheung Yeung  <kcy@codesourcery.com>

	libgomp/
	* env.c (gomp_global_icv): Remove nest_var field.  Add
	max_active_levels_var field.
	(gomp_max_active_levels_var): Remove.
	(parse_boolean): Return true on success.
	(handle_omp_display_env): Express OMP_NESTED in terms of
	max_active_levels_var.  Change format specifier for
	max_active_levels_var.
	(initialize_env): Set max_active_levels_var from
	OMP_MAX_ACTIVE_LEVELS, OMP_NESTED, OMP_NUM_THREADS and
	OMP_PROC_BIND.
	* icv.c (omp_set_nested): Express in terms of
	max_active_levels_var.
	(omp_get_nested): Likewise.
	(omp_set_max_active_levels): Use max_active_levels_var field instead
	of gomp_max_active_levels_var.
	(omp_get_max_active_levels): Likewise.
	* libgomp.h (struct gomp_task_icv): Remove nest_var field.  Add
	max_active_levels_var field.
	(gomp_supported_active_levels): Set to UCHAR_MAX.
	(gomp_max_active_levels_var): Delete.
	* libgomp.texi (omp_get_nested): Update documentation.
	(omp_set_nested): Likewise.
	(OMP_MAX_ACTIVE_LEVELS): Likewise.
	(OMP_NESTED): Likewise.
	(OMP_NUM_THREADS): Likewise.
	(OMP_PROC_BIND): Likewise.
	* parallel.c (gomp_resolve_num_threads): Replace reference
	to nest_var with max_active_levels_var.  Use max_active_levels_var
	field instead of gomp_max_active_levels_var.

1 files changed, 12 insertions, 5 deletions

diff --git a/libgomp/icv.c b/libgomp/icv.c
index 8df15e3..c0c0305 100644
--- a/libgomp/icv.c
+++ b/libgomp/icv.c
@@ -57,14 +57,18 @@ void
 omp_set_nested (int val)
 {
   struct gomp_task_icv *icv = gomp_icv (true);
-  icv->nest_var = val;
+  if (val)
+    icv->max_active_levels_var = gomp_supported_active_levels;
+  else if (icv->max_active_levels_var > 1)
+    icv->max_active_levels_var = 1;
 }
 
 int
 omp_get_nested (void)
 {
   struct gomp_task_icv *icv = gomp_icv (false);
-  return icv->nest_var;
+  return (icv->max_active_levels_var > 1
+	  && icv->max_active_levels_var > omp_get_active_level ());
 }
 #pragma GCC diagnostic pop
 
@@ -120,17 +124,20 @@ omp_set_max_active_levels (int max_levels)
 {
   if (max_levels >= 0)
     {
+      struct gomp_task_icv *icv = gomp_icv (true);
+
       if (max_levels <= gomp_supported_active_levels)
-	gomp_max_active_levels_var = max_levels;
+	icv->max_active_levels_var = max_levels;
       else
-	gomp_max_active_levels_var = gomp_supported_active_levels;
+	icv->max_active_levels_var = gomp_supported_active_levels;
     }
 }
 
 int
 omp_get_max_active_levels (void)
 {
-  return gomp_max_active_levels_var;
+  struct gomp_task_icv *icv = gomp_icv (false);
+  return icv->max_active_levels_var;
 }
 
 int