[mpich-discuss] MPI_Barrier segmentation fault

Eric A. Borisch eborisch at gmail.com
Fri May 27 17:57:40 CDT 2016

I believe that this line: (src/include/mpiimpl.h:1531)

} MPID_Request ATTRIBUTE((__aligned__(32)));

needs to be this:

} ATTRIBUTE((__aligned__(32))) MPID_Request;

>From the GCC docs, the attribute needs to be just after the closing brace.

As it is, it aligns single MPID_Request objects to be on a 32-byte
boundary, but it does make the sizeof(MPID_Request) a multiple of 32.

This, in combination with the compiler optimizing for the
advertised-to-be-aligned singleton object with a movaps instruction
causes the crash. Changing the above line and re-compiling mpich fixes
the issue.

There may be other instances of this issue in the codebase; I did not search...

 - Eric

On Fri, May 27, 2016 at 12:42 AM, Ben Whale <ben at benwhale.com> wrote:
> Ha! Sorry didn’t spot your previous email about XCode. Thanks for the hard work
> I’ve had issues with XCode updates in the past. In the mean time while this is fixed I’ll try building with an old version.
> Ben

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