[Bug middle-end/114282] New: [OpenMP] Implicit mapping of function/procedure pointers should use 'firstprivate'

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114282

            Bug ID: 114282
           Summary: [OpenMP] Implicit mapping of function/procedure
                    pointers should use 'firstprivate'
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, openmp
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

For C/C++ function pointers and Fortran dummy procedures / procedure pointers,
the assumption is that pointer is either pointing to the desired function
or it has the address of a function on the initial device with 'declare target
indirect'.

GCC produces for implicit mapping:
 map(alloc:MEM[(char *)g] [len: 0]) map(firstprivate:g [pointer assign, bias:
0])

But a simple
  map(firstprivate:g)
would do here.

Likewise for an explicit map, where there is also no need for a pointer
assignment.

NOTE: For Fortran, it might be that explicit 'map' clauses will get disallowed
per pending OpenMP specification Issue #3823, which is tracked elsewhere.


Trivial testcases (for more complex, see 'indirect' testcases inside GCC or
just add an explicit 'map' clause yourself):


void f(){
  void (*g)();
  #pragma omp target
    g();
}


subroutine f(g)
  procedure(), pointer :: g
  !$omp target map(g)
    call g()
  !$omp end target
end