Fix PR libgomp/66761 and PR libgomp/67303 (tsan warnings)

[Jakub Jelinek]

On Sat, Aug 22, 2015 at 10:36:45AM +0000, VandeVondele  Joost wrote:
> OK for trunk ? 
> This applies without changes to the 5 branch, should I commit there as well ?

Ok, with a small change:

> 2015-08-22  Joost VandeVondele  <vondele@gnu.gcc.org>
> 
>         PR libgomp/66761
>         PR libgomp/67303
>         * iter.c (gomp_iter_dynamic_next): Employ an atomic load.
>         (gomp_iter_guided_next): Idem.
>         * iter_ull.c (gomp_iter_ull_dynamic_next): Idem.
>         (gomp_iter_ull_guided_next): Idem.
>         * config/linux/wait.h (do_spin): Idem.

> --- libgomp/config/linux/wait.h	(revision 227094)
> +++ libgomp/config/linux/wait.h	(working copy)
> @@ -49,7 +49,8 @@ static inline int do_spin (int *addr, in
>  {
>    unsigned long long i, count = gomp_spin_count_var;
>  
> -  if (__builtin_expect (gomp_managed_threads > gomp_available_cpus, 0))
> +  if (__builtin_expect (__atomic_load_n (&gomp_managed_threads,
> +      MEMMODEL_RELAXED) > gomp_available_cpus, 0))

Please fix up formatting here, MEMMODEL_RELAXED should be below
&gomp_managed_threads and most likely > will need to be below
__atomic_load_n.

>      count = gomp_throttled_spin_count_var;
>    for (i = 0; i < count; i++)
>      if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0))


	Jakub