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, 30 insertions, 14 deletions

diff --git a/libgomp/env.c b/libgomp/env.c
index ab22525..5a49ae6 100644
--- a/libgomp/env.c
+++ b/libgomp/env.c
@@ -68,12 +68,11 @@ struct gomp_task_icv gomp_global_icv = {
   .run_sched_chunk_size = 1,
   .default_device_var = 0,
   .dyn_var = false,
-  .nest_var = false,
+  .max_active_levels_var = 1,
   .bind_var = omp_proc_bind_false,
   .target_data = NULL
 };
 
-unsigned long gomp_max_active_levels_var = gomp_supported_active_levels;
 bool gomp_cancel_var = false;
 enum gomp_target_offload_t gomp_target_offload_var
   = GOMP_TARGET_OFFLOAD_DEFAULT;
@@ -959,16 +958,17 @@ parse_spincount (const char *name, unsigned long long *pvalue)
 }
 
 /* Parse a boolean value for environment variable NAME and store the
-   result in VALUE.  */
+   result in VALUE.  Return true if one was present and it was
+   successfully parsed.  */
 
-static void
+static bool
 parse_boolean (const char *name, bool *value)
 {
   const char *env;
 
   env = getenv (name);
   if (env == NULL)
-    return;
+    return false;
 
   while (isspace ((unsigned char) *env))
     ++env;
@@ -987,7 +987,11 @@ parse_boolean (const char *name, bool *value)
   while (isspace ((unsigned char) *env))
     ++env;
   if (*env != '\0')
-    gomp_error ("Invalid value for environment variable %s", name);
+    {
+      gomp_error ("Invalid value for environment variable %s", name);
+      return false;
+    }
+  return true;
 }
 
 /* Parse the OMP_WAIT_POLICY environment variable and return the value.  */
@@ -1252,7 +1256,7 @@ handle_omp_display_env (unsigned long stacksize, int wait_policy)
   fprintf (stderr, "  OMP_DYNAMIC = '%s'\n",
 	   gomp_global_icv.dyn_var ? "TRUE" : "FALSE");
   fprintf (stderr, "  OMP_NESTED = '%s'\n",
-	   gomp_global_icv.nest_var ? "TRUE" : "FALSE");
+	   gomp_global_icv.max_active_levels_var > 1 ? "TRUE" : "FALSE");
 
   fprintf (stderr, "  OMP_NUM_THREADS = '%lu", gomp_global_icv.nthreads_var);
   for (i = 1; i < gomp_nthreads_var_list_len; i++)
@@ -1344,8 +1348,8 @@ handle_omp_display_env (unsigned long stacksize, int wait_policy)
 	   wait_policy > 0 ? "ACTIVE" : "PASSIVE");
   fprintf (stderr, "  OMP_THREAD_LIMIT = '%u'\n",
 	   gomp_global_icv.thread_limit_var);
-  fprintf (stderr, "  OMP_MAX_ACTIVE_LEVELS = '%lu'\n",
-	   gomp_max_active_levels_var);
+  fprintf (stderr, "  OMP_MAX_ACTIVE_LEVELS = '%u'\n",
+	   gomp_global_icv.max_active_levels_var);
 
   fprintf (stderr, "  OMP_CANCELLATION = '%s'\n",
 	   gomp_cancel_var ? "TRUE" : "FALSE");
@@ -1410,6 +1414,7 @@ static void __attribute__((constructor))
 initialize_env (void)
 {
   unsigned long thread_limit_var, stacksize = GOMP_DEFAULT_STACKSIZE;
+  unsigned long max_active_levels_var;
   int wait_policy;
 
   /* Do a compile time check that mkomp_h.pl did good job.  */
@@ -1417,16 +1422,11 @@ initialize_env (void)
 
   parse_schedule ();
   parse_boolean ("OMP_DYNAMIC", &gomp_global_icv.dyn_var);
-  parse_boolean ("OMP_NESTED", &gomp_global_icv.nest_var);
   parse_boolean ("OMP_CANCELLATION", &gomp_cancel_var);
   parse_boolean ("OMP_DISPLAY_AFFINITY", &gomp_display_affinity_var);
   parse_int ("OMP_DEFAULT_DEVICE", &gomp_global_icv.default_device_var, true);
   parse_target_offload ("OMP_TARGET_OFFLOAD", &gomp_target_offload_var);
   parse_int ("OMP_MAX_TASK_PRIORITY", &gomp_max_task_priority_var, true);
-  parse_unsigned_long ("OMP_MAX_ACTIVE_LEVELS", &gomp_max_active_levels_var,
-		       true);
-  if (gomp_max_active_levels_var > gomp_supported_active_levels)
-    gomp_max_active_levels_var = gomp_supported_active_levels;
   gomp_def_allocator = parse_allocator ();
   if (parse_unsigned_long ("OMP_THREAD_LIMIT", &thread_limit_var, false))
     {
@@ -1451,6 +1451,22 @@ initialize_env (void)
 		      &gomp_bind_var_list_len)
       && gomp_global_icv.bind_var == omp_proc_bind_false)
     ignore = true;
+  if (parse_unsigned_long ("OMP_MAX_ACTIVE_LEVELS",
+			   &max_active_levels_var, true))
+    gomp_global_icv.max_active_levels_var
+      = (max_active_levels_var > gomp_supported_active_levels)
+	? gomp_supported_active_levels : max_active_levels_var;
+  else
+    {
+      bool nested = true;
+
+      /* OMP_NESTED is deprecated in OpenMP 5.0.  */
+      if (parse_boolean ("OMP_NESTED", &nested))
+	gomp_global_icv.max_active_levels_var
+	  = nested ? gomp_supported_active_levels : 1;
+      else if (gomp_nthreads_var_list_len > 1 || gomp_bind_var_list_len > 1)
+	gomp_global_icv.max_active_levels_var = gomp_supported_active_levels;
+    }
   /* Make sure OMP_PLACES and GOMP_CPU_AFFINITY env vars are always
      parsed if present in the environment.  If OMP_PROC_BIND was set
      explicitly to false, don't populate places list though.  If places