cannot get Helgrind/DRD work with C++11 thread - c++

Question

I have problems getting Helgrind and DRD working with g++ and C++11 threads.
My setup:
- RedHad Linux 2.6
- g++ 4.7.2
- Valgrind 3.7.0
I tried the program posted here, after adding the definitions listed in the first answer, thus:
#include <valgrind/helgrind.h>
#define _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(addr) ANNOTATE_HAPPENS_BEFORE(addr)
#define _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(addr) ANNOTATE_HAPPENS_AFTER(addr)
#define _GLIBCXX_EXTERN_TEMPLATE -1
#include <thread>
int main()
{
std::thread t( []() { } );
t.join();
return 0;
}
I then build the program:
$ g++ -std=c++11 -Wall -Wextra -pthread main.cc
The program (which doesn't do much) runs correctly:
$ ./a.out
also with valgrind:
$ valgrind ./a.out
==21284== Memcheck, a memory error detector
==21284== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==21284== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==21284== Command: ./a.out
==21284==
==21284==
==21284== HEAP SUMMARY:
==21284== in use at exit: 0 bytes in 0 blocks
==21284== total heap usage: 2 allocs, 2 frees, 344 bytes allocated
==21284==
==21284== All heap blocks were freed -- no leaks are possible
==21284==
==21284== For counts of detected and suppressed errors, rerun with: -v
==21284== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 6)
But then, with Helgrind, I get false positives:
$ valgrind --tool=helgrind ./a.out
==21467== Helgrind, a thread error detector
==21467== Copyright (C) 2007-2011, and GNU GPL'd, by OpenWorks LLP et al.
==21467== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==21467== Command: ./a.out
==21467==
==21467== ---Thread-Announcement------------------------------------------
==21467==
==21467== Thread #1 is the program's root thread
==21467==
==21467== ---Thread-Announcement------------------------------------------
==21467== [lines removed]
==21467==
==21467== ----------------------------------------------------------------
==21467==
==21467== Possible data race during write of size 8 at 0x5B7A058 by thread #1
==21467== Locks held: none
==21467== [lines removed]
==21467==
==21467== This conflicts with a previous write of size 8 by thread #2
==21467== Locks held: none
==21467== at 0x4EE0A25: execute_native_thread_routine (shared_ptr_base.h:587)
==21467== by 0x4C2D3AD: mythread_wrapper (hg_intercepts.c:219)
==21467== by 0x55D1850: start_thread (in /lib64/libpthread-2.12.so)
==21467== by 0x58CF90C: clone (in /lib64/libc-2.12.so)
==21467==
==21467== [lines removed]
==21467==
==21467==
==21467== For counts of detected and suppressed errors, rerun with: -v
==21467== Use --history-level=approx or =none to gain increased speed, at
==21467== the cost of reduced accuracy of conflicting-access information
==21467== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)
Similar bogus reports with DRD instead of Helgrind.
Any idea what could be wrong?

Answer 1

I found this in drd manual. It seems you need to recompile the functions execute_native_thread_routine() and std::thread::_M_start_thread(), and link it with your program(And not using the shared library at execution time for these functions).
Actually the macros _GLIBCXX_SYNCHRONIZATION_HAPPENS_* are seen by your code but they were not seen by the internal functions of the c++ library code when this library was built. That's why you need to recompile them using the same header inclusion and macro definition you used for your code.