[mpich-discuss] Segfault with MPICH 3.2+Clang but not GCC

[Eric A. Borisch]

Sorry; traveling and didn't see the whole thread.
 - Eric

On Wednesday, July 27, 2016, Eric A. Borisch <eborisch at gmail.com> wrote:

> This might be the struct alignment bug I tracked down a few months ago?
> (Alignment attribute in the wrong place.)
>
> On Tuesday, July 26, 2016, Andreas Noack <andreasnoackjensen at gmail.com
> <javascript:_e(%7B%7D,'cvml','andreasnoackjensen at gmail.com');>> wrote:
>
>> On my El Capitan macbook I get a segfault when running the program below
>> with more than a single process but only when MPICH has been compiled with
>> Clang.
>>
>> I don't get that good debug info but here is some of what I got
>>
>> (lldb) c
>> Process 61129 resuming
>> Process 61129 stopped
>> * thread #1: tid = 0x32c438, 0x00000003119d0432
>> libpmpi.12.dylib`MPID_Request_create + 244, queue =
>> 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
>>     frame #0: 0x00000003119d0432 libpmpi.12.dylib`MPID_Request_create +
>> 244
>> libpmpi.12.dylib`MPID_Request_create:
>> ->  0x3119d0432 <+244>: movaps %xmm0, 0x230(%rax)
>>     0x3119d0439 <+251>: movq   $0x0, 0x240(%rax)
>>     0x3119d0444 <+262>: movl   %ecx, 0x210(%rax)
>>     0x3119d044a <+268>: popq   %rbp
>>
>> My version of Clang is
>>
>> Apple LLVM version 7.3.0 (clang-703.0.31)
>> Target: x86_64-apple-darwin15.6.0
>> Thread model: posix
>> InstalledDir: /Library/Developer/CommandLineTools/usr/bin
>>
>> and the bug has been confirmed by my colleague who is running Linux and
>> compiling with Clang 3.8. The program runs fine with OpenMPI+Clang.
>>
>> #include <mpi.h>
>> #include <stdio.h>
>> #include <stdlib.h>
>>
>> int main(int argc, char *argv[])
>> {
>>     MPI_Init(&argc, &argv);
>>
>>     MPI_Comm comm = MPI_COMM_WORLD;
>>     uint64_t *A, *C;
>>     int rnk;
>>
>>     MPI_Comm_rank(comm, &rnk);
>>     A = calloc(1, sizeof(uint64_t));
>>     C = calloc(2, sizeof(uint64_t));
>>     A[0] = rnk + 1;
>>
>>     MPI_Allgather(A, 1, MPI_UINT64_T, C, 1, MPI_UINT64_T, comm);
>>
>>     MPI_Finalize();
>>     return 0;
>> }
>>
>>
>> Best regards
>>
>> Andreas Noack
>> Postdoctoral Associate
>> Computer Science and Artificial Intelligence Laboratory
>> Massachusetts Institute of Technology
>>
>
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