[OpenMP][OMPT][clang] task frame support fixed in __kmpc_fork_call

[vladaindjic]

Summary

__kmp_fork_call sets the enter_frame of the active task (th_curren_task)
before new parallel region begins. After the region is finished, the
enter_frame is cleared.

The old implementation of __kmpc_fork_call didn’t clear the enter_frame of active task.

Also, the way of initializing the enter_frame of the active task was wrong.
Consider the following two OpenMP programs.

The first program: Let R1 be the serialized parallel region that encloses another serialized
parallel region R2. Assume that thread that executes R2 is going to create a new serialized
parallel region R3 by executing __kmpc_fork_call. This thread is responsible to set enter_frame
of R2’s implicit task. Note that the information about R2’s implicit task is present inside
master_th->th.th_current_task at this moment, while lwt represents the information about
R1’s implicit task. The old implementation uses lwt and resets enter_frame of R1’s implicit
task instead of R2’s implicit task. The new implementation uses
master_th->th.th_current_task instead.

The second program: Consider the OpenMP program that contains parallel region R1 which encloses
an explicit task T. Assume that thread should create another parallel region R2 during the
execution of the T. The __kmpc_fork_call is responsible to create R2 and set enter frame of T
whose information is present inside the master_th->th.th_current_task.
Old implementation tries to set the frame of parent_team->t.t_implicit_task_taskdata[tid]
which corresponds to the implicit task of the R1, instead of T.

[vladaindjic]

• clang-formated diffs in kmp_csupport.cpp

[protze.joachim]

Looks like we missed to update the code in kmp_csupport, when the management of lwt was refactored.
lgtm

[vladaindjic]

@protze.joachim Thank you for the revision. Could you please land this commit for me?

openmp/runtime/src/kmp_csupport.cpp

#endif
   {
     va_list ap;
     va_start(ap, microtask);
 
 #if OMPT_SUPPORT
     ompt_frame_t *ompt_frame;
     if (ompt_enabled.enabled) {
       kmp_info_t *master_th = __kmp_threads[gtid];
-      kmp_team_t *parent_team = master_th->th.th_team;
-      ompt_lw_taskteam_t *lwt = parent_team->t.ompt_serialized_team_info;
-      if (lwt)
-        ompt_frame = &(lwt->ompt_task_info.frame);
-      else {
-        int tid = __kmp_tid_from_gtid(gtid);
-        ompt_frame = &(
-            parent_team->t.t_implicit_task_taskdata[tid].ompt_task_info.frame);
-      }
+      ompt_frame = &master_th->th.th_current_task->ompt_task_info.frame;
       ompt_frame->enter_frame.ptr = OMPT_GET_FRAME_ADDRESS(0);
     }
     OMPT_STORE_RETURN_ADDRESS(gtid);
 #endif
 
 #if INCLUDE_SSC_MARKS
     SSC_MARK_FORKING();
 #endif
     __kmp_fork_call(loc, gtid, fork_context_intel, argc,
                     VOLATILE_CAST(microtask_t) microtask, // "wrapped" task
                     VOLATILE_CAST(launch_t) __kmp_invoke_task_func,
                     kmp_va_addr_of(ap));
 #if INCLUDE_SSC_MARKS
     SSC_MARK_JOINING();
 #endif
     __kmp_join_call(loc, gtid
 #if OMPT_SUPPORT
                     ,
                     fork_context_intel
 #endif
     );
 
     va_end(ap);
+
+#if OMPT_SUPPORT
+    if (ompt_enabled.enabled) {
+      ompt_frame->enter_frame = ompt_data_none;
+    }
+#endif
   }
 
 #if KMP_STATS_ENABLED
   if (previous_state == stats_state_e::SERIAL_REGION) {
     KMP_EXCHANGE_PARTITIONED_TIMER(OMP_serial);
     KMP_SET_THREAD_STATE(previous_state);
   } else {
     KMP_POP_PARTITIONED_TIMER();

openmp/runtime/test/ompt/parallel/nested_serialized_task_frames.c

+// RUN: %libomp-compile-and-run | %sort-threads | FileCheck %s
+// REQUIRES: ompt
+
+#include "callback.h"
+#include <omp.h>
+
+int main()
+{
+#pragma omp parallel num_threads(1)
+  {
+    // region 0
+#pragma omp parallel num_threads(1)
+    {
+      // region 1
+#pragma omp parallel num_threads(1)
+      {
+        // region 2
+        // region 2's implicit task
+        print_ids(0);
+        // region 1's implicit task
+        print_ids(1);
+        // region 0's implicit task
+        print_ids(2);
+        // initial task
+        print_ids(3);
+      }
+    }
+  }
+
+  // Check if libomp supports the callbacks for this test.
+  // CHECK-NOT: {{^}}0: Could not register callback 'ompt_callback_task_create'
+  // CHECK-NOT: {{^}}0: Could not register callback 'ompt_callback_implicit_task'
+
+
+  // CHECK: {{^}}0: NULL_POINTER=[[NULL:.*$]]
+  // CHECK: {{^}}[[MASTER_ID:[0-9]+]]: ompt_event_initial_task_begin: parallel_id=[[INITIAL_PARALLEL_ID:[0-9]+]], task_id=[[INITIAL_TASK_ID:[0-9]+]], actual_parallelism=1, index=1, flags=1
+
+  // region 0
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_parallel_begin
+  // CHECK-SAME: parent_task_frame.exit=[[NULL]], parent_task_frame.reenter=[[INITIAL_TASK_FRAME_ENTER:0x[0-f]+]],
+  // CHECK-SAME: parallel_id=[[PARALLEL_ID_0:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_implicit_task_begin: parallel_id=[[PARALLEL_ID_0]], task_id=[[TASK_ID_0:[0-9]+]]
+
+  // region 1
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_parallel_begin
+  // CHECK-SAME: parent_task_frame.exit=[[REGION_0_FRAME_EXIT:0x[0-f]+]], parent_task_frame.reenter=[[REGION_0_FRAME_ENTER:0x[0-f]+]],
+  // CHECK-SAME: parallel_id=[[PARALLEL_ID_1:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_implicit_task_begin: parallel_id=[[PARALLEL_ID_1]], task_id=[[TASK_ID_1:[0-9]+]]
+
+  // region 2
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_parallel_begin
+  // CHECK-SAME: parent_task_frame.exit=[[REGION_1_FRAME_EXIT:0x[0-f]+]], parent_task_frame.reenter=[[REGION_1_FRAME_ENTER:0x[0-f]+]],
+  // CHECK-SAME: parallel_id=[[PARALLEL_ID_2:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_implicit_task_begin: parallel_id=[[PARALLEL_ID_2]], task_id=[[TASK_ID_2:[0-9]+]]
+
+  // region 2's implicit task information (exit frame should be set, while enter should be NULL)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 0: parallel_id=[[PARALLEL_ID_2]], task_id=[[TASK_ID_2]]
+  // CHECK-SAME: exit_frame={{0x[0-f]+}}
+  // CHECK-SAME: reenter_frame=[[NULL]]
+  // CHECK-SAME: task_type=ompt_task_implicit
+
+  // region 1's implicit task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 1: parallel_id=[[PARALLEL_ID_1]], task_id=[[TASK_ID_1]]
+  // CHECK-SAME: exit_frame=[[REGION_1_FRAME_EXIT]]
+  // CHECK-SAME: reenter_frame=[[REGION_1_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_implicit
+
+  // region 0's implicit task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 2: parallel_id=[[PARALLEL_ID_0]], task_id=[[TASK_ID_0]]
+  // CHECK-SAME: exit_frame=[[REGION_0_FRAME_EXIT]]
+  // CHECK-SAME: reenter_frame=[[REGION_0_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_implicit
+
+  // region 0's initial task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 3: parallel_id=[[INITIAL_PARALLEL_ID]], task_id=[[INITIAL_TASK_ID]]
+  // CHECK-SAME: exit_frame=[[NULL]]
+  // CHECK-SAME: reenter_frame=[[INITIAL_TASK_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_initial
+
+  return 0;
+}
 No newline at end of file

openmp/runtime/test/ompt/parallel/region_in_expl_task_task_frames.c

+// RUN: %libomp-compile-and-run | %sort-threads | FileCheck %s
+// REQUIRES: ompt
+
+#include "callback.h"
+#include <omp.h>
+
+int main()
+{
+#pragma omp parallel num_threads(2)
+  {
+    if (omp_get_thread_num() == 0) {
+      // region 0
+#pragma omp task if(0)
+      {
+        // explicit task immediately executed by the initial master thread
+#pragma omp parallel num_threads(2)
+        {
+          if (omp_get_thread_num() == 0) {
+            // Note that this is executed by the initial master thread
+            // region 1
+            // region 1's implicit task
+            print_ids(0);
+            // explicit task
+            print_ids(1);
+            // region 0's implicit task
+            print_ids(2);
+            // initial task
+            print_ids(3);
+          }
+        }
+      }
+    }
+  }
+
+  // Check if libomp supports the callbacks for this test.
+  // CHECK-NOT: {{^}}0: Could not register callback 'ompt_callback_task_create'
+  // CHECK-NOT: {{^}}0: Could not register callback 'ompt_callback_implicit_task'
+
+
+  // CHECK: {{^}}0: NULL_POINTER=[[NULL:.*$]]
+  // CHECK: {{^}}[[MASTER_ID:[0-9]+]]: ompt_event_initial_task_begin: parallel_id=[[INITIAL_PARALLEL_ID:[0-9]+]], task_id=[[INITIAL_TASK_ID:[0-9]+]], actual_parallelism=1, index=1, flags=1
+
+  // region 0
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_parallel_begin
+  // CHECK-SAME: parent_task_frame.exit=[[NULL]], parent_task_frame.reenter=[[INITIAL_TASK_FRAME_ENTER:0x[0-f]+]],
+  // CHECK-SAME: parallel_id=[[PARALLEL_ID_0:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_implicit_task_begin: parallel_id=[[PARALLEL_ID_0]], task_id=[[TASK_ID_0:[0-9]+]]
+
+  // explicit task
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_task_create: parent_task_id=[[TASK_ID_0]]
+  // CHECK-SAME: parent_task_frame.exit=[[REGION_0_FRAME_EXIT:0x[0-f]+]]
+  // CHECK-SAME: parent_task_frame.reenter=[[REGION_0_FRAME_ENTER:0x[0-f]+]]
+  // CHECK-SAME: new_task_id=[[TASK_ID_1:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_task_schedule: first_task_id=[[TASK_ID_0]], second_task_id=[[TASK_ID_1]]
+
+  // region 1
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_parallel_begin
+  // CHECK-SAME: parent_task_frame.exit=[[EXPLICIT_TASK_FRAME_EXIT:0x[0-f]+]], parent_task_frame.reenter=[[EXPLICIT_TASK_FRAME_ENTER:0x[0-f]+]],
+  // CHECK-SAME: parallel_id=[[PARALLEL_ID_1:[0-9]+]]
+  // CHECK: {{^}}[[MASTER_ID]]: ompt_event_implicit_task_begin: parallel_id=[[PARALLEL_ID_1]], task_id=[[TASK_ID_2:[0-9]+]]
+
+  // region 1's implicit task information (exit frame should be set, while enter should be NULL)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 0: parallel_id=[[PARALLEL_ID_1]], task_id=[[TASK_ID_2]]
+  // CHECK-SAME: exit_frame={{0x[0-f]+}}
+  // CHECK-SAME: reenter_frame=[[NULL]]
+  // CHECK-SAME: task_type=ompt_task_implicit
+
+  // explicit task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 1: parallel_id=[[PARALLEL_ID_0]], task_id=[[TASK_ID_1]]
+  // CHECK-SAME: exit_frame=[[EXPLICIT_TASK_FRAME_EXIT]]
+  // CHECK-SAME: reenter_frame=[[EXPLICIT_TASK_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_explicit
+
+  // region 0's implicit task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 2: parallel_id=[[PARALLEL_ID_0]], task_id=[[TASK_ID_0]]
+  // CHECK-SAME: exit_frame=[[REGION_0_FRAME_EXIT]]
+  // CHECK-SAME: reenter_frame=[[REGION_0_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_implicit
+
+  // region 0's initial task information (both exit and enter frames should be set)
+  // CHECK: {{^}}[[MASTER_ID]]: task level 3: parallel_id=[[INITIAL_PARALLEL_ID]], task_id=[[INITIAL_TASK_ID]]
+  // CHECK-SAME: exit_frame=[[NULL]]
+  // CHECK-SAME: reenter_frame=[[INITIAL_TASK_FRAME_ENTER]]
+  // CHECK-SAME: task_type=ompt_task_initial
+
+  return 0;
+}
 No newline at end of file