Fix for large overhead in OpenMP runtime with itt notifications on region/barrier name composing

[jlpeyton]

Summary

Currently, there is a big overhead in reporting of loop metadata through ittnotify.
The pair of functions: __kmp_str_loc_init/__kmp_str_loc_free are replaced with strchr/atoi calls.
Thus, a lot of time consuming actions are skipped - many memory allocations/deallocations, heavy string duplication, etc.
The loop metadata only needs line and column info from the source string, so no allocations and string splitting actually needed.

Patch by Andrey Churbanov

[tlwilmar]

LGTM

openmp/trunk/runtime/src/kmp_itt.inl

if( metadata_domain == NULL) {
             __itt_suppress_push(__itt_suppress_memory_errors);
             metadata_domain = __itt_domain_create( "OMP Metadata" );
             __itt_suppress_pop();
         }
         __kmp_release_bootstrap_lock( & metadata_lock );
     }
 
     __itt_string_handle * string_handle = __itt_string_handle_create( "omp_metadata_loop");
-    kmp_str_loc_t str_loc = __kmp_str_loc_init( loc->psource, 1 );
+
+    // Parse line and column from psource string: ";file;func;line;col;;"
+    char * s_line;
+    char * s_col;
+    KMP_DEBUG_ASSERT(loc->psource);
+#ifdef __cplusplus
+    s_line = strchr((char*)loc->psource, ';');
+#else
+    s_line = strchr(loc->psource, ';');
+#endif
+    KMP_DEBUG_ASSERT(s_line);
+    s_line = strchr(s_line + 1, ';');   // 2-nd semicolon
+    KMP_DEBUG_ASSERT(s_line);
+    s_line = strchr(s_line + 1, ';');   // 3-rd semicolon
+    KMP_DEBUG_ASSERT(s_line);
+    s_col = strchr(s_line + 1, ';');    // 4-th semicolon
+    KMP_DEBUG_ASSERT(s_col);
 
     kmp_uint64 loop_data[ 5 ];
-    loop_data[ 0 ] = str_loc.line;
-    loop_data[ 1 ] = str_loc.col;
+    loop_data[ 0 ] = atoi(s_line + 1); // read line
+    loop_data[ 1 ] = atoi(s_col + 1);  // read column
     loop_data[ 2 ] = sched_type;
     loop_data[ 3 ] = iterations;
     loop_data[ 4 ] = chunk;
 
-    __kmp_str_loc_free( &str_loc );
-
     __itt_metadata_add(metadata_domain, __itt_null, string_handle, __itt_metadata_u64, 5, loop_data);
 #endif
 } // __kmp_itt_metadata_loop
 
 // -------------------------------------------------------------------------------------------------
 
 LINKAGE void
 __kmp_itt_metadata_single( ident_t * loc ) {