OpenMP: Set default-device-var with OMP_TARGET_OFFLOAD=mandatory

OMP_TARGET_OFFLOAD=mandatory handling was before inconsistent. Hence, in
OpenMP 5.2 it was clarified/extended by having implications on the
default-device-var; additionally, omp_initial_device and omp_invalid_device
enum values/PARAMETERs were added; support for it was added
in r13-1066-g1158fe43407568 including aborting for omp_invalid_device and
non-conforming device numbers. Only the mandatory handling was missing.

Namely, while the default-device-var is usually initialized to value 0,
with 'mandatory' it must have the value 'omp_invalid_device' if and only if
zero non-host devices are available. (The OMP_DEFAULT_DEVICE env var
overrides this as it comes semantically after the initialization.)

To achieve this, default-device-var is now initialized to MIN_INT. If
there is no 'mandatory', it is set to 0 directly after env var parsing.
Otherwise, it is updated in gomp_target_init to either 0 or
omp_invalid_device. To ensure INT_MIN is never seen by the user, both
the omp_get_default_device API routine and omp_display_env (user call
and OMP_DISPLAY_ENV env var) call gomp_init_targets_once() in that case.

libgomp/ChangeLog:

	* env.c (gomp_default_icv_values): Init default_device_var to
	an nonconforming value - INT_MIN.
	(initialize_env): After env-var parsing, set default_device_var to
	device 0 unless OMP_TARGET_OFFLOAD=mandatory.
	(omp_display_env): If default_device_var is INT_MIN, call
	gomp_init_targets_once.
	* icv-device.c (omp_get_default_device): Likewise.
	* libgomp.texi (OMP_DEFAULT_DEVICE): Update init description.
	(OpenMP 5.2 Impl. Status): Mark OMP_TARGET_OFFLOAD=mandatory as 'Y'.
	* target.c (resolve_device): Improve error message device-num < 0
	with 'mandatory' and no no-host devices available.
	(gomp_target_init): Set default-device-var if INT_MIN.
	* testsuite/libgomp.c/target-48.c: New test.
	* testsuite/libgomp.c/target-49.c: New test.
	* testsuite/libgomp.c/target-50.c: New test.
	* testsuite/libgomp.c/target-50a.c: New test.
	* testsuite/libgomp.c/target-51.c: New test.
	* testsuite/libgomp.c/target-52.c: New test.
	* testsuite/libgomp.c/target-53.c: New test.
	* testsuite/libgomp.c/target-54.c: New test.

1 files changed, 14 insertions, 1 deletions

diff --git a/libgomp/target.c b/libgomp/target.c
index e3c4121..f1020fa 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -150,7 +150,11 @@ resolve_device (int device_id, bool remapped)
       if (device_id == (remapped ? GOMP_DEVICE_HOST_FALLBACK
 				 : omp_initial_device))
 	return NULL;
-      if (device_id == omp_invalid_device)
+      if (gomp_target_offload_var == GOMP_TARGET_OFFLOAD_MANDATORY
+	  && gomp_get_num_devices () == 0)
+	gomp_fatal ("OMP_TARGET_OFFLOAD is set to MANDATORY but only the host "
+		    "device is available");
+      else if (device_id == omp_invalid_device)
 	gomp_fatal ("omp_invalid_device encountered");
       else if (gomp_target_offload_var == GOMP_TARGET_OFFLOAD_MANDATORY)
 	gomp_fatal ("OMP_TARGET_OFFLOAD is set to MANDATORY, "
@@ -5184,6 +5188,15 @@ gomp_target_init (void)
       if (devs[i].capabilities & GOMP_OFFLOAD_CAP_OPENACC_200)
 	goacc_register (&devs[i]);
     }
+  if (gomp_global_icv.default_device_var == INT_MIN)
+    {
+       /* This implies OMP_TARGET_OFFLOAD=mandatory.  */
+       struct gomp_icv_list *none;
+       none = gomp_get_initial_icv_item (GOMP_DEVICE_NUM_FOR_NO_SUFFIX);
+       gomp_global_icv.default_device_var = (num_devs_openmp
+					     ? 0 : omp_invalid_device);
+       none->icvs.default_device_var = gomp_global_icv.default_device_var;
+    }
 
   num_devices = num_devs;
   num_devices_openmp = num_devs_openmp;