[OpenMP][libomp] omp_in_explicit_task() implementation.

[AndreyChurbanov]

Summary

Implementation of OpenMP 5.2 omp_in_explicit_task().

[jlpeyton]

LGTM

[protze.joachim]

openmp/runtime/src/kmp_ftn_entry.h

1574

Is this code sufficient for all scenarios of lazily initialized OpenMP threads?
Should this function handle uninitialized

openmp/runtime/test/api/omp_in_explicit_task.c

33

Would it make sense to test different kinds of tasks, like undeferred (and detachable) tasks, instead of two simple tasks?
At the moment it should not make a difference, but things might change in the future.

[AndreyChurbanov]

openmp/runtime/src/kmp_ftn_entry.h

1574

The __kmp_entry_gtid() initializes the library if needed and initializes the calling thread including its implicit task.
Thus the structures cannot be uninitialized here.

openmp/runtime/test/api/omp_in_explicit_task.c

33

I doubt an explicit task can become implicit in future. That would be very strange. And we can always adjust the test in future, or write a new one for some particular case.

openmp/runtime/src/dllexports

kmp_set_disp_num_buffers                    890
     omp_display_env                         733
     omp_calloc                              776
     omp_realloc                             777
     omp_aligned_alloc                       778
     omp_aligned_calloc                      806
     omp_get_interop_int                     807
     omp_get_interop_ptr                     808
     omp_get_interop_str                     809
+    omp_in_explicit_task                    769
 
     omp_null_allocator                     DATA
     omp_default_mem_alloc                  DATA
     omp_large_cap_mem_alloc                DATA
     omp_const_mem_alloc                    DATA
     omp_high_bw_mem_alloc                  DATA
     omp_low_lat_mem_alloc                  DATA
     omp_cgroup_mem_alloc                   DATA

openmp/runtime/src/include/omp.h.var

#   if defined(_OPENMP) && _OPENMP >= 201811
     #pragma omp begin declare variant match(device={kind(host)})
     static inline int omp_is_initial_device(void) { return 1; }
     #pragma omp end declare variant
     #pragma omp begin declare variant match(device={kind(nohost)})
     static inline int omp_is_initial_device(void) { return 0; }
     #pragma omp end declare variant
 #   endif
 
+    /* OpenMP 5.2 */
+    extern int __KAI_KMPC_CONVENTION omp_in_explicit_task(void);
+
 #   undef __KAI_KMPC_CONVENTION
 #   undef __KMP_IMP
 
     /* Warning:
        The following typedefs are not standard, deprecated and will be removed in a future release.
     */
     typedef int     omp_int_t;
     typedef double  omp_wtime_t;
 
 #   ifdef __cplusplus
     }
 #   endif
 
 #endif /* __OMP_H */

openmp/runtime/src/include/omp_lib.h.var

&      free_allocator) bind(c)
 
         subroutine omp_free(ptr, allocator) bind(c)
           use, intrinsic :: iso_c_binding, only : c_ptr
           import :: omp_allocator_handle_kind
           type(c_ptr), value :: ptr
           integer(omp_allocator_handle_kind), value :: allocator
         end subroutine omp_free
 
+        function omp_in_explicit_task() bind(c)
+          import
+          logical (kind=omp_logical_kind) omp_in_explicit_task
+        end function omp_in_explicit_task
+
 !       ***
 !       *** kmp_* entry points
 !       ***
 
         subroutine kmp_set_stacksize(size) bind(c)
           import
           integer (kind=omp_integer_kind), value :: size
         end subroutine kmp_set_stacksize

openmp/runtime/src/include/omp_lib.f90.var

!DIR$ ENDIF
 
           subroutine omp_free(ptr, allocator) bind(c)
             use omp_lib_kinds
             use, intrinsic :: iso_c_binding, only : c_ptr
             type(c_ptr), value :: ptr
             integer(omp_allocator_handle_kind), value :: allocator
           end subroutine omp_free
 
+          function omp_in_explicit_task() bind(c)
+            use omp_lib_kinds
+            logical (kind=omp_logical_kind) omp_in_explicit_task
+          end function omp_in_explicit_task
+
 !         ***
 !         *** kmp_* entry points
 !         ***
 
           subroutine kmp_set_stacksize(size) bind(c)
             use omp_lib_kinds
             integer (kind=omp_integer_kind), value :: size
           end subroutine kmp_set_stacksize

openmp/runtime/src/kmp_ftn_entry.h

 
 // display environment variables when requested
 void FTN_STDCALL FTN_DISPLAY_ENV(int verbose) {
 #ifndef KMP_STUB
   __kmp_omp_display_env(verbose);
 #endif
 }
 
+int FTN_STDCALL FTN_IN_EXPLICIT_TASK(void) {
+#ifdef KMP_STUB
+  return 0;
+#else
+  int gtid = __kmp_entry_gtid();
+  return __kmp_thread_from_gtid(gtid)->th.th_current_task->td_flags.tasktype;
+#endif
+}
+
 // GCC compatibility (versioned symbols)
 #ifdef KMP_USE_VERSION_SYMBOLS
 
 /* These following sections create versioned symbols for the
    omp_* routines. The KMP_VERSION_SYMBOL macro expands the API name and
    then maps it to a versioned symbol.
    libgomp ``versions'' its symbols (OMP_1.0, OMP_2.0, OMP_3.0, ...) while also
    retaining the default version which libomp uses: VERSION (defined in

openmp/runtime/src/kmp_ftn_os.h

 #define FTN_SET_AFFINITY_FORMAT omp_set_affinity_format
 #define FTN_GET_AFFINITY_FORMAT omp_get_affinity_format
 #define FTN_DISPLAY_AFFINITY omp_display_affinity
 #define FTN_CAPTURE_AFFINITY omp_capture_affinity
 #define FTN_PAUSE_RESOURCE omp_pause_resource
 #define FTN_PAUSE_RESOURCE_ALL omp_pause_resource_all
 #define FTN_GET_SUPPORTED_ACTIVE_LEVELS omp_get_supported_active_levels
 #define FTN_DISPLAY_ENV omp_display_env
+#define FTN_IN_EXPLICIT_TASK omp_in_explicit_task
 #define FTN_FULFILL_EVENT omp_fulfill_event
 #define FTN_SET_NUM_TEAMS omp_set_num_teams
 #define FTN_GET_MAX_TEAMS omp_get_max_teams
 #define FTN_SET_TEAMS_THREAD_LIMIT omp_set_teams_thread_limit
 #define FTN_GET_TEAMS_THREAD_LIMIT omp_get_teams_thread_limit
 
 #define FTN_GET_NUM_INTEROP_PROPERTIES omp_get_num_interop_properties
 #define FTN_GET_INTEROP_INT omp_get_interop_int

 #define FTN_SET_AFFINITY_FORMAT omp_set_affinity_format_
 #define FTN_GET_AFFINITY_FORMAT omp_get_affinity_format_
 #define FTN_DISPLAY_AFFINITY omp_display_affinity_
 #define FTN_CAPTURE_AFFINITY omp_capture_affinity_
 #define FTN_PAUSE_RESOURCE omp_pause_resource_
 #define FTN_PAUSE_RESOURCE_ALL omp_pause_resource_all_
 #define FTN_GET_SUPPORTED_ACTIVE_LEVELS omp_get_supported_active_levels_
 #define FTN_DISPLAY_ENV omp_display_env_
+#define FTN_IN_EXPLICIT_TASK omp_in_explicit_task_
 #define FTN_FULFILL_EVENT omp_fulfill_event_
 #define FTN_SET_NUM_TEAMS omp_set_num_teams_
 #define FTN_GET_MAX_TEAMS omp_get_max_teams_
 #define FTN_SET_TEAMS_THREAD_LIMIT omp_set_teams_thread_limit_
 #define FTN_GET_TEAMS_THREAD_LIMIT omp_get_teams_thread_limit_
 
 #define FTN_GET_NUM_INTEROP_PROPERTIES omp_get_num_interop_properties_
 #define FTN_GET_INTEROP_INT omp_get_interop_int_

 #define FTN_SET_AFFINITY_FORMAT OMP_SET_AFFINITY_FORMAT
 #define FTN_GET_AFFINITY_FORMAT OMP_GET_AFFINITY_FORMAT
 #define FTN_DISPLAY_AFFINITY OMP_DISPLAY_AFFINITY
 #define FTN_CAPTURE_AFFINITY OMP_CAPTURE_AFFINITY
 #define FTN_PAUSE_RESOURCE OMP_PAUSE_RESOURCE
 #define FTN_PAUSE_RESOURCE_ALL OMP_PAUSE_RESOURCE_ALL
 #define FTN_GET_SUPPORTED_ACTIVE_LEVELS OMP_GET_SUPPORTED_ACTIVE_LEVELS
 #define FTN_DISPLAY_ENV OMP_DISPLAY_ENV
+#define FTN_IN_EXPLICIT_TASK OMP_IN_EXPLICIT_TASK
 #define FTN_FULFILL_EVENT OMP_FULFILL_EVENT
 #define FTN_SET_NUM_TEAMS OMP_SET_NUM_TEAMS
 #define FTN_GET_MAX_TEAMS OMP_GET_MAX_TEAMS
 #define FTN_SET_TEAMS_THREAD_LIMIT OMP_SET_TEAMS_THREAD_LIMIT
 #define FTN_GET_TEAMS_THREAD_LIMIT OMP_GET_TEAMS_THREAD_LIMIT
 
 #define FTN_GET_NUM_INTEROP_PROPERTIES OMP_GET_NUM_INTEROP_PROPERTIES
 #define FTN_GET_INTEROP_INT OMP_GET_INTEROP_INT

 #define FTN_SET_AFFINITY_FORMAT OMP_SET_AFFINITY_FORMAT_
 #define FTN_GET_AFFINITY_FORMAT OMP_GET_AFFINITY_FORMAT_
 #define FTN_DISPLAY_AFFINITY OMP_DISPLAY_AFFINITY_
 #define FTN_CAPTURE_AFFINITY OMP_CAPTURE_AFFINITY_
 #define FTN_PAUSE_RESOURCE OMP_PAUSE_RESOURCE_
 #define FTN_PAUSE_RESOURCE_ALL OMP_PAUSE_RESOURCE_ALL_
 #define FTN_GET_SUPPORTED_ACTIVE_LEVELS OMP_GET_SUPPORTED_ACTIVE_LEVELS_
 #define FTN_DISPLAY_ENV OMP_DISPLAY_ENV_
+#define FTN_IN_EXPLICIT_TASK OMP_IN_EXPLICIT_TASK_
 #define FTN_FULFILL_EVENT OMP_FULFILL_EVENT_
 #define FTN_SET_NUM_TEAMS OMP_SET_NUM_TEAMS_
 #define FTN_GET_MAX_TEAMS OMP_GET_MAX_TEAMS_
 #define FTN_SET_TEAMS_THREAD_LIMIT OMP_SET_TEAMS_THREAD_LIMIT_
 #define FTN_GET_TEAMS_THREAD_LIMIT OMP_GET_TEAMS_THREAD_LIMIT_
 
 #define FTN_GET_NUM_INTEROP_PROPERTIES OMP_GET_NUM_INTEROP_PROPERTIES_
 #define FTN_GET_INTEROP_INT OMP_GET_INTEROP_INT_

openmp/runtime/test/api/omp_in_explicit_task.c

+// RUN: %libomp-compile-and-run
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <omp.h>
+
+int main()
+{
+  int res;
+  res = omp_in_explicit_task();
+  if (res) {
+    printf("error: omp_in_explicit_task: serial1 returned %d\n", res);
+    return 1;
+  }
+  #pragma omp parallel num_threads(2)
+  {
+    int r = omp_in_explicit_task();
+    if (r) {
+      printf("error: omp_in_explicit_task: par #%d returned %d\n",
+             omp_get_thread_num(), r);
+      exit(1);
+    }
+    #pragma omp task
+    {
+      int r = omp_in_explicit_task();
+      if (!r) {
+        printf("error: omp_in_explicit_task: task1 #%d returned %d\n",
+               omp_get_thread_num(), r);
+        exit(1);
+      }
+    }
+    #pragma omp task
+    {
+      int r = omp_in_explicit_task();
+      if (!r) {
+        printf("error: omp_in_explicit_task: task2 #%d returned %d\n",
+               omp_get_thread_num(), r);
+        exit(1);
+      }
+    }
+  }
+  res = omp_in_explicit_task();
+  if (res) {
+    printf("error: omp_in_explicit_task: serial2 returned %d\n", res);
+    return 1;
+  }
+  printf("passed\n");
+  return 0;
+}