[OpenMP] Rename worker threads for improved debuggability (#102065)

Rename the worker threads "openmp_worker"

---------

Co-authored-by: h2h <[email protected]>
Co-authored-by: Matthias Braun <[email protected]>

Author: HighW4y2H3ll

openmp/runtime/cmake/LibompDefinitions.cmake

@@ -23,6 +23,8 @@ function(libomp_get_definitions_flags cppflags)
   else()
     libomp_append(cppflags_local "-D _GNU_SOURCE")
     libomp_append(cppflags_local "-D _REENTRANT")
+    # or use HAVE_PTHREAD_SETNAME_NP from top-level cmake/config-ix.cmake
+    libomp_append(cppflags_local "-D LIBOMP_HAVE_LINUX_PTHREAD_SETNAME" LIBOMP_HAVE_LINUX_PTHREAD_SETNAME)
   endif()
 
   # CMake doesn't include CPPFLAGS from environment, but we will.

openmp/runtime/cmake/config-ix.cmake

@@ -101,6 +101,11 @@ if(${LIBOMP_FORTRAN_MODULES})
   libomp_check_fortran_flag(-m32 LIBOMP_HAVE_M32_FORTRAN_FLAG)
 endif()
 
+# Check non-posix pthread API here before CMAKE_REQUIRED_DEFINITIONS gets messed up
+if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux")
+  check_symbol_exists(pthread_setname_np "pthread.h" LIBOMP_HAVE_LINUX_PTHREAD_SETNAME)
+endif()
+
 # Check for Unix shared memory
 check_symbol_exists(shm_open "sys/mman.h" LIBOMP_HAVE_SHM_OPEN_NO_LRT)
 if (NOT LIBOMP_HAVE_SHM_OPEN_NO_LRT)

openmp/runtime/src/z_Linux_util.cpp

@@ -878,6 +878,13 @@ void __kmp_create_worker(int gtid, kmp_info_t *th, size_t stack_size) {
     KMP_SYSFAIL("pthread_create", status);
   }
 
+#ifdef LIBOMP_HAVE_LINUX_PTHREAD_SETNAME
+  // Rename worker threads for improved debuggability
+  if (!KMP_UBER_GTID(gtid)) {
+    pthread_setname_np(handle, "openmp_worker");
+  }
+#endif
+
   th->th.th_info.ds.ds_thread = handle;
 
 #ifdef KMP_THREAD_ATTR