[Bug fortran/127257] New: [OpenMP] Implicit declare target: Internal functions must inherit the device_type of the parent

[burnus at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127257

            Bug ID: 127257
           Summary: [OpenMP] Implicit declare target: Internal functions
                    must inherit the device_type of the parent
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: openmp
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

Currently, internal procedures are only implicitly typed to be 'declare target'
but they do not inherit the 'device_type'.

Likewise, inconsistent 'device_type' are not diagnosed.

* Note that device_type != any is only possible by an explicit
  'declare target' directive, i.e. handling the implicit marking
  as 'declare target' also works in the front end.

Example:

subroutine f()
  !$omp declare target enter(f) device_type(nohost)
  call bar()
contains
  subroutine bar
  end subroutine bar
end


This currently gives the following, i.e. the internal procedure does not have
the 'nohost' property.

gfortran -fopenmp -fdump-tree-gimple

__attribute__((omp declare target (device_type(nohost))))
__attribute__((fn spec (". ")))
void f ()
{
  static void bar (void);
  bar ();
}


__attribute__((omp declare target))
__attribute__((fn spec (". ")))
void bar ()
{
}

*****

However, for the following:

module m
contains
  subroutine outer()
    call inner()
  contains
    subroutine inner
      !$omp declare target enter(inner) device_type(nohost)
    end
  end subroutine outer

  subroutine caller
    !$omp target
      call outer()
    !$omp end target
  end subroutine caller
end

'outer' gets implicitly 'declare target device_type(any)' and no error is
diagnosed that the enclosed procedure 'inner' has a different device_type.