[Bug libgomp/67141] New: wrong libgomp mutex initialisation order

[mattiase at acm dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67141

            Bug ID: 67141
           Summary: wrong libgomp mutex initialisation order
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mattiase at acm dot org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

Libgomp may use a mutex, acc_device_lock, prior to initialising it depending on
the constructor calling order: it is initialised in initialize_env and used in
goacc_host_init, both declared __attribute__ ((constructor)) but in different
files.

This was discovered on Windows after a change to the pthread library in
mingw-w64, making all-zero an invalid mutex value. Apparently the constructors
were called in the "wrong" order, and pthread_mutex_lock called before
pthread_mutex_init.