[OMPT] Fix assertion for OpenMP code generated with outdated compilers

[protze.joachim]

Summary

For up-to-date compilers, this assertion is reasonable, but it breaks compatibility with the typical compiler installed on most systems.
This patch changes the default value to what we had when there was no compiler support. A warning about the outdated compiler is printed during runtime, when this point is reached.

Alternative solution:
Set a configure flag that explicitly asks for backwards compatibility and leave the assert there.

[omalyshe]

runtime/src/kmp_csupport.cpp

1777 ↗

(On Diff #122403)

I'd suggest using KMP_WARNING to emit standard RTL warning.
The message (in the message catalog) could be the following: "Cannot determine workshare type; using the default (loop) instead".

Also, it would be enough if only one thread emitted the warning.

[Hahnfeld]

To make the tests work with older compilers we need to reliably determine the compiler id and version. I'll be working on that.

runtime/src/kmp_csupport.cpp

1777 ↗

(On Diff #122403)

In addition I think it would also be enough to diagnose in __kmp_for_static_init: The compiler will either generate the information for both calls or not at all.

[protze.joachim]

Addressing Olgas suggestions

runtime/src/kmp_csupport.cpp

1777 ↗

(On Diff #122403)

Is there a standard approach to only provide a single warning? Looking at other warnings, they are not filtered at all.

[omalyshe]

runtime/src/kmp_sched.cpp

85 ↗

(On Diff #122428)

I think Jonas meant not to emit warning here; just silently set to the default value

[omalyshe]

runtime/src/kmp_sched.cpp

85 ↗

(On Diff #122428)

Sorry, this comment is about *_fini, of course.

[protze.joachim]

Remove warning for fini

[omalyshe]

runtime/src/kmp_sched.cpp

85 ↗

(On Diff #122431)

For a single warning something like this should work

@@ -68,6 +68,10 @@ static void __kmp_for_static_init(ident_t *loc, kmp_int32 global_tid,
   ompt_task_info_t *task_info = NULL;
   ompt_work_type_t ompt_work_type;

+  static kmp_int8 warn = 0;
+
   if (ompt_enabled.enabled) {
     // Only fully initialize variables needed by OMPT if OMPT is enabled.
     team_info = __ompt_get_teaminfo(0, NULL);
@@ -81,8 +85,12 @@ static void __kmp_for_static_init(ident_t *loc, kmp_int32 global_tid,
       } else if ((loc->flags & KMP_IDENT_WORK_DISTRIBUTE) != 0) {
         ompt_work_type = ompt_work_distribute;
       } else {
-        KMP_ASSERT2(0,
-                    "__kmpc_for_static_init: can't determine workshare type"); 
+        ompt_work_type = ompt_work_loop;
+       kmp_int8 bool_res = KMP_COMPARE_AND_STORE_ACQ8(&warn, (kmp_int8)0, (kmp_int8)1);
+       if(bool_res)
+           KMP_WARNING(...)
       }

[protze.joachim]

Using Olga's code to only trigger a single warning. Tested and works for me.

[Hahnfeld]

Please run clang-format on the changes.

runtime/src/kmp_sched.cpp

69 ↗

(On Diff #122435)

Maybe we should have the default ompt_work_loop go here, just in case loc == NULL? (same for _fini)

[protze.joachim]

Fix potentially uninitialized value. Thanks, Jonas!

[protze.joachim]

clang-format

[Hahnfeld]

This LGTM, @omalyshe?

[hbae]

LGTM

openmp/trunk/runtime/src/i18n/en_US.txt

 BarriersInDifferentOrder     "Threads encountered barriers in different order. "
 FunctionError                "Function %1$s failed:"
 TopologyExtra                "%1$s: %2$s packages x %3$d cores/pkg x %4$d threads/core (%5$d total cores)"
 WrongMessageCatalog          "Incompatible message catalog \"%1$s\": Version \"%2$s\" found, version \"%3$s\" expected."
 StgIgnored                   "%1$s: ignored because %2$s has been defined"
                                  # %1, -- name of ignored variable, %2 -- name of variable with higher priority.
 OBSOLETE                     "%1$s: overrides %3$s specified before"
                                  # %1, %2 -- name and value of the overriding variable, %3 -- name of overriden variable.
+OmptOutdatedWorkshare        "OMPT: Cannot determine workshare type; using the default (loop) instead. "
+                             "This issue is fixed in an up-to-date compiler."
 
 # --- OpenMP errors detected at runtime ---
 #
 #    %1 is the name of OpenMP construct (formatted with "Pragma" format).
 #
 CnsBoundToWorksharing        "%1$s must be bound to a work-sharing or work-queuing construct with an \"ordered\" clause"
 CnsDetectedEnd               "Detected end of %1$s without first executing a corresponding beginning."
 CnsIterationRangeTooLarge    "Iteration range too large in %1$s."

openmp/trunk/runtime/src/kmp_csupport.cpp

 
 Mark the end of a statically scheduled loop.
 */
 void __kmpc_for_static_fini(ident_t *loc, kmp_int32 global_tid) {
   KE_TRACE(10, ("__kmpc_for_static_fini called T#%d\n", global_tid));
 
 #if OMPT_SUPPORT && OMPT_OPTIONAL
   if (ompt_enabled.ompt_callback_work) {
-    ompt_work_type_t ompt_work_type;
+    ompt_work_type_t ompt_work_type = ompt_work_loop;
     ompt_team_info_t *team_info = __ompt_get_teaminfo(0, NULL);
     ompt_task_info_t *task_info = __ompt_get_task_info_object(0);
     // Determine workshare type
     if (loc != NULL) {
       if ((loc->flags & KMP_IDENT_WORK_LOOP) != 0) {
         ompt_work_type = ompt_work_loop;
       } else if ((loc->flags & KMP_IDENT_WORK_SECTIONS) != 0) {
         ompt_work_type = ompt_work_sections;
       } else if ((loc->flags & KMP_IDENT_WORK_DISTRIBUTE) != 0) {
         ompt_work_type = ompt_work_distribute;
       } else {
-        KMP_ASSERT2(0,
-                    "__kmpc_for_static_fini: can't determine workshare type");
+        // use default set above.
+        // a warning about this case is provided in __kmpc_for_static_init
       }
       KMP_DEBUG_ASSERT(ompt_work_type);
     }
     ompt_callbacks.ompt_callback(ompt_callback_work)(
         ompt_work_type, ompt_scope_end, &(team_info->parallel_data),
         &(task_info->task_data), 0, OMPT_GET_RETURN_ADDRESS(0));
   }
 #endif

openmp/trunk/runtime/src/kmp_sched.cpp

#endif
   kmp_uint32 nth;
   UT trip_count;
   kmp_team_t *team;
   kmp_info_t *th = __kmp_threads[gtid];
 
 #if OMPT_SUPPORT && OMPT_OPTIONAL
   ompt_team_info_t *team_info = NULL;
   ompt_task_info_t *task_info = NULL;
-  ompt_work_type_t ompt_work_type;
+  ompt_work_type_t ompt_work_type = ompt_work_loop;
 
-  if (ompt_enabled.enabled) {
+  static kmp_int8 warn = 0;
+
+  if (ompt_enabled.ompt_callback_work) {
     // Only fully initialize variables needed by OMPT if OMPT is enabled.
     team_info = __ompt_get_teaminfo(0, NULL);
     task_info = __ompt_get_task_info_object(0);
     // Determine workshare type
     if (loc != NULL) {
       if ((loc->flags & KMP_IDENT_WORK_LOOP) != 0) {
         ompt_work_type = ompt_work_loop;
       } else if ((loc->flags & KMP_IDENT_WORK_SECTIONS) != 0) {
         ompt_work_type = ompt_work_sections;
       } else if ((loc->flags & KMP_IDENT_WORK_DISTRIBUTE) != 0) {
         ompt_work_type = ompt_work_distribute;
       } else {
-        KMP_ASSERT2(0,
-                    "__kmpc_for_static_init: can't determine workshare type");
+        kmp_int8 bool_res =
+            KMP_COMPARE_AND_STORE_ACQ8(&warn, (kmp_int8)0, (kmp_int8)1);
+        if (bool_res)
+          KMP_WARNING(OmptOutdatedWorkshare);
       }
       KMP_DEBUG_ASSERT(ompt_work_type);
     }
   }
 #endif
 
   KMP_DEBUG_ASSERT(plastiter && plower && pupper && pstride);
   KE_TRACE(10, ("__kmpc_for_static_init called (%d)\n", global_tid));