[gomp] New tests

[Jakub Jelinek]

On Mon, Oct 17, 2005 at 12:14:19PM -0400, Diego Novillo wrote:
> 
> These are all adapted from Appendix A of the standard.  We fail only a few.  
> I'm looking into those failures today.

By any chance, do you have the Fortran testcases as well?

> Of interest is the failure in libgomp/a.18.1.c.  We have a shared array 
> used to busy wait for neighbors:
> 
> #pragma omp flush(work,synch)
>     synch[iam] = 1;
> #pragma omp flush(synch)
>     neighbor = (iam > 0 ? iam : omp_get_num_threads ()) - 1;
>     while (synch[neighbor] == 0)
>       {
> #pragma omp flush(synch)
>       }
> #pragma omp flush(work,synch)
> 
> 
> When compiled at -O2, this program enters an infinite loop because the RTL 
> optimizers hoist the load from 'sync[neighbor]' out of the loop, so we end 
> up with
> 
> .L10:
>      testl   %edx, %edx
>      je      .L10
> 
> instead of
> 
> .L14:
>      movl    synch(,%edx,4), %eax
>      testl   %eax, %eax
>      je      .L12
> 
> This is "fixed" by marking 'synch' volatile.  However, IIUC, the standard 
> assumes this should not be necessary in the presence of 'flush'.  Richard, 
> Jakub?

Well, flush needs to translate into an optimization barrier.
So, IMHO either we should translate it into GOMP_flush function call and do
the __sync_synchronize (); in libgomp, or use something equally strong
to a non-pure function call to prevent optimizations across it.

	Jakub