This repo contains 3 different examples testing different implementations of a '#pragma omp atomic' for floats

1. parallel_with_atomic.c
    we rely on the transformation of the compiler.

2. parallel_with_builtin_01.c
    the atomic operation is implemented using the
    '__sync_bool_compare_and_swap_4' intrinsic + an extra memory fence per
    iteration. Note that is not clear whether the atomic builtin implies a
    memory fence:

    https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/_005f_005fsync-Builtins.html#_005f_005fsync-Builtins

3. parallel_with_builtin_02.c
    Similar to the previous test but removing the memory fence (__sync_synchronize).