Re: First Patch

[Tobias Burnus <burnus at net-b dot de>]

Hi Daniel,

On 06/07/2011 08:44 PM, Daniel Carrera wrote:
> Ok, I'll prepare a new patch and then write again to this list and CC 
> to gcc-patches@... with an appropriate email subject. Do I need to 
> subscribe to gcc-patches@... first?

No, you don't, which is good as it is a high-volume list.

(By the way, one convenient way to read the GCC mailing lists - in 
particular gcc@ or gcc-patches@ - is a news reader, using the NNTP 
server of gmane, cf. http://dir.gmane.org/gmane.comp.gcc.patches)

[error diagnostic]
> Ok, how about this:
>
> void
> _gfortran_caf_sync_all (int *stat, char *errmsg, int errmsg_len)
> {
>   int ierr = MPI_Barrier (MPI_COMM_WORLD);
>
>   if (stat && !ierr)
>     *stat = 0

Well, one could just use:

  if (stat)
    *stat = ierr;

and drop the assignment part from the ierr != 0 part.

>       fprintf(stderr,"SYNC ALL failed\n");
>       exit(ierr);

I think at some point one needs to add a function which handle the error 
abort in the library. In for sync images, I used as interim solution 
"error_stop" instead of "exit" as the latter calls "MPI_Abort". I think 
calling MPI_Abort is cleaner as it might help preventing that the other 
MPI processes continue.
(Although, my experience was that either MPI aborts already after 
detecting that one process exited without calling MPI_Finalize - or that 
even though one process called MPI_Abort, the other processes continue 
until the wall time is exceeded.)

[Test case]
> Ok. I'll take a look at how the tests work. Should the test be added 
> to this patch or should it be a new patch?

I should be included - either as diff or as attached file. Could you 
also run the test case - manually - with the MPI version? How this is 
done is described at http://gcc.gnu.org/wiki/CoarrayLib
(The reason is that the test suite currently only tests -fcoarray=single 
and -fcoarray=lib with libcaf_single. The libcaf_mpi is currently not 
tested. Solution is to modify caf.exp to also allow for libcaf_mpi, 
using the specified options and using the specified mpiexec command. But 
a patch for this still has to be written.)

Tobias