#900 pmpi- add basic runtime 'should log' control point

- This should (eventually) use option flags and/or the scheduler
  runtime depth information to determine if a PMPI call should
  be logged, regardless of overall tracing status.

  This also finishes up some component registration and exposure,
  as needed to be accessed from the free functions.

src/vt/pmpi/generate_mpi_wrappers.pl

@@ -100,7 +100,7 @@ sub register_event {
 sub log_event {
     my ($name) = @_;
     say "#if backend_check_enabled(trace_enabled)";
-    say "  auto scopedEvent = vt::trace::TraceScopedEvent(event_${name});";
+    say "  auto scopedEvent = vt::trace::TraceScopedEvent(vt::thePMPI()->shouldLogCall() ? event_${name} : vt::trace::no_user_event_id);";
     say "#endif";
 }
 

src/vt/pmpi/pmpi_component.h

@@ -72,6 +72,14 @@ struct PMPIComponent : runtime::component::Component<PMPIComponent> {
     registerEventHandlers();
   }
 
+  /**
+   * \internal
+   * \brief Return true iff a PMPI call should be logged in the current context.
+   */
+  bool shouldLogCall() {
+    return true;
+  }
+
 private:
 
   // n.b. This is exepcted to be generated by the generated pmpi wrapper code.
@@ -81,6 +89,10 @@ struct PMPIComponent : runtime::component::Component<PMPIComponent> {
 
 }} //end namespace vt::pmpi
 
+namespace vt {
+  extern pmpi::PMPIComponent* thePMPI();
+}
+
 #endif // backend_check_enabled(pmpi_access_guards)
 
 #endif /*INCLUDED_PMPI_PMPI_COMPONENT*/

src/vt/runtime/runtime_component_fwd.h

@@ -111,6 +111,11 @@ namespace trace {
 struct Trace;
 }
 #endif
+#if backend_check_enabled(mpi_access_guards)
+namespace pmpi {
+struct PMPIComponent;
+}
+#endif
 
 } /* end namespace vt */
 

src/vt/runtime/runtime_get.cc

@@ -132,7 +132,10 @@ vrt::collection::balance::StatsRestartReader* theStatsReader() { return CUR_RT->
 vrt::collection::balance::LBManager* theLBManager() { return CUR_RT->theLBManager;      }
 
 #if backend_check_enabled(trace_enabled)
-trace::Trace*               theTrace()          { return CUR_RT->theTrace;          }
+trace::Trace*               theTrace()              { return CUR_RT->theTrace;          }
+#endif
+#if backend_check_enabled(mpi_access_guards)
+pmpi::PMPIComponent*        thePMPI()               { return CUR_RT->thePMPI;           }
 #endif
 
 #undef CUR_RT