Re: gfortran, OpenMP and static linking

[Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>]

On 3 April 2021 20:55:39 CEST, Harald Anlauf via Fortran <fortran@gcc.gnu.org> wrote:
>Dear all,
>
>is there a reason that one should not be able to statically link a
>Fortran binary that has been compiled with -fopenmp?

Maybe Jakub knows more on this.

Not sure if static linking with glibc is still discouraged (it was, at least in former times) or if thread cancellation still is supposed to work in a pure static build.

As said, maybe Jakub can help.
thanks,
>
>A tiny example seems to fail for me with all gfortran versions:
>
>program p
>!$omp parallel
>!$omp end parallel
>end
>
>% gfortran -fopenmp foo.f90 -g -static
>% OMP_NUM_THREADS=1 ./a.out
>
>Program received signal SIGSEGV: Segmentation fault - invalid memory
>reference.
>[...]
>
>Running under gdb:
>
>Program received signal SIGSEGV, Segmentation fault.
>0x0000000000000000 in ?? ()
>(gdb) bt
>#0  0x0000000000000000 in ?? ()
>#1  0x0000000000405198 in __gthread_mutex_destroy (__mutex=0x72ced8)
>    at ../libgcc/gthr-default.h:739
>#2  destroy_unit_mutex (u=0x72ce00) at
>../../../libgfortran/io/unit.c:252
>#3  close_unit_1 (u=0x72ce00, locked=locked@entry=1) at
>../../../libgfortran/io/unit.c:743
>#4  0x0000000000405202 in _gfortrani_close_units () at
>../../../libgfortran/io/unit.c:780
>#5  0x000000000044c53c in __libc_csu_fini () at elf-init.c:100
>#6  0x0000000000452ef0 in __run_exit_handlers (status=0, listp=0x720630
><__exit_funcs>,
>run_list_atexit=run_list_atexit@entry=true,
>run_dtors=run_dtors@entry=true) at exit.c:83
>#7  0x0000000000452f4a in exit (status=<optimized out>) at exit.c:105
>#8  0x000000000044bdc6 in __libc_start_main (main=0x4030bd <main>,
>argc=1,
>argv=0x7fffffffc348, init=0x44c470 <__libc_csu_init>, fini=0x44c510
><__libc_csu_fini>,
>    rtld_fini=0x0, stack_end=0x7fffffffc338) at ../csu/libc-start.c:342
>#9  0x0000000000402fba in _start () at ../sysdeps/x86_64/start.S:120
>
>
>I suspect either a locking issue for unit_root in unit.c, or maybe bad
>initialization of it, but haven't stared long enough at the code.
>According to git blame almost all related references date back to 2005.
>
>Shall I open a PR against libfortran?  Or is there something I am
>missing?
>
>Thanks,
>Harald