[mpich-discuss] gcc 6.0 miscompiles mpich ?

[Halim Amer]

This information is insufficient to blame the compiler.
We don't know if the user (application code), MPICH, or gcc is doing 
something wrong.

First, you need to use a stable compiler version (not trunk) and a 
recent MPICH (3.2 not the old 3.1 version).

Second, you need to make sure the user code is not doing something wrong 
(e.g. MPI_Alltoall could have gotten an invalid buffer address or 
count). If you send us a toy program that reproduces the problem, we 
could help with this.

--Halim
www.mcs.anl.gov/~aamer

On 4/6/16 10:24 AM, VandeVondele  Joost wrote:
> Hi,
>
> when compiling mpich-3.1.2 using gcc trunk (which will be gcc 6.0 in a
> couple of days/weeks), I noticed mpich gets miscompiled when building
> with CFLAGS='-O2 -ftree-vectorize -g' (but not with just -O2 -g or -O3 -g).
>
> I believe that the miscompilation happens with the macro
> MPIDI_Request_create_sreq since a typical trace looks like:
>
> Program received signal SIGSEGV: Segmentation fault - invalid memory
> reference.
>
> Backtrace for this error:
> #0  0x33ac83269f in ???
> #1  0x7f3743953d69 in MPIDI_Isend_self
>      at src/mpid/ch3/src/mpidi_isend_self.c:34
> #2  0x7f374394dfa3 in MPID_Isend
>      at src/mpid/ch3/src/mpid_isend.c:55
> #3  0x7f374390793a in MPIC_Isend
>      at src/mpi/coll/helper_fns.c:646
> #4  0x7f37438628c5 in MPIR_Alltoall_intra
>      at src/mpi/coll/alltoall.c:520
> #5  0x7f374386376e in MPIR_Alltoall
>      at src/mpi/coll/alltoall.c:726
> #6  0x7f3743863827 in MPIR_Alltoall_impl
>      at src/mpi/coll/alltoall.c:761
> #7  0x7f3743863e7a in PMPI_Alltoall
>      at src/mpi/coll/alltoall.c:884
> #8  0x7f37424181bf in pmpi_alltoall_
>      at src/binding/fortran/mpif_h/alltoallf.c:272
>
> I don't know mpich well enough to extract a testcase, but it would be
> great if somebody could extract that and report to the gcc team (I'm
> happy to do the reporting if needed).
>
> thanks in advance,
>
> Joost
>
>
>
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