[OMPT] Fix interoperability test with GCC

hahnjo · hahnjo · commit b0f051ae63e0 · 2018-03-01T14:03:18.000Z
We have to ensure that the runtime is initialized _before_ waiting for the two started threads to guarantee that the master threads post their ompt_event_thread_begin before the worker threads. This is not guaranteed in the parallel region where one worker thread could start before the other master thread has invoked the callback. The problem did not happen with Clang becauses the generated code calls __kmpc_global_thread_num() and cashes its result for functions that contain OpenMP pragmas. Differential Revision: https://reviews.llvm.org/D43882 llvm-svn: 326435
diff --git a/openmp/runtime/test/ompt/misc/interoperability.cpp b/openmp/runtime/test/ompt/misc/interoperability.cpp
@@ -3,19 +3,31 @@
 
 #include <iostream>
 #include <thread>
+
 #include "callback.h"
+#include "omp.h"
+
 int condition = 0;
+
 void f() {
+  // Call OpenMP API function to force initialization of OMPT.
+  // (omp_get_thread_num() does not work because it just returns 0 if the
+  // runtime isn't initialized yet...)
+  omp_get_num_threads();
+
   OMPT_SIGNAL(condition);
-  // wait for both pthreads to arrive
+  // Wait for both initial threads to arrive that will eventually become the
+  // master threads in the following parallel region.
   OMPT_WAIT(condition, 2);
-  int i = 0;
+
 #pragma omp parallel num_threads(2)
   {
+    // Wait for all threads to arrive so that no worker thread can be reused...
     OMPT_SIGNAL(condition);
     OMPT_WAIT(condition, 6);
   }
 }
+
 int main() {
   std::thread t1(f);
   std::thread t2(f);
